Justin Stephens
MBED port of the Physacs library
physac.h
- Committer:
- jstephens78
- Date:
- 21 months ago
- Revision:
- 0:e39efa4f4f58
- Child:
- 1:ebc0214989c0
File content as of revision 0:e39efa4f4f58:
/**********************************************************************************************
*
* Physac v1.1 - 2D Physics library for videogames
*
* DESCRIPTION:
*
* Physac is a small 2D physics library written in pure C. The engine uses a fixed time-step thread loop
* to simluate physics. A physics step contains the following phases: get collision information,
* apply dynamics, collision solving and position correction. It uses a very simple struct for physic
* bodies with a position vector to be used in any 3D rendering API.
*
* CONFIGURATION:
*
* #define PHYSAC_IMPLEMENTATION
* Generates the implementation of the library into the included file.
* If not defined, the library is in header only mode and can be included in other headers
* or source files without problems. But only ONE file should hold the implementation.
*
* #define PHYSAC_STATIC (defined by default)
* The generated implementation will stay private inside implementation file and all
* internal symbols and functions will only be visible inside that file.
*
* #define PHYSAC_NO_THREADS
* The generated implementation won't include pthread library and user must create a secondary thread to call PhysicsThread().
* It is so important that the thread where PhysicsThread() is called must not have v-sync or any other CPU limitation.
*
* #define PHYSAC_STANDALONE
* Avoid raylib.h header inclusion in this file. Data types defined on raylib are defined
* internally in the library and input management and drawing functions must be provided by
* the user (check library implementation for further details).
*
* #define PHYSAC_DEBUG
* Traces log messages when creating and destroying physics bodies and detects errors in physics
* calculations and reference exceptions; it is useful for debug purposes
*
* #define PHYSAC_MALLOC()
* #define PHYSAC_FREE()
* You can define your own malloc/free implementation replacing stdlib.h malloc()/free() functions.
* Otherwise it will include stdlib.h and use the C standard library malloc()/free() function.
*
*
* NOTE 1: Physac requires multi-threading, when InitPhysics() a second thread is created to manage physics calculations.
* NOTE 2: Physac requires static C library linkage to avoid dependency on MinGW DLL (-static -lpthread)
*
* Use the following code to compile:
* gcc -o $(NAME_PART).exe $(FILE_NAME) -s -static -lraylib -lpthread -lopengl32 -lgdi32 -lwinmm -std=c99
*
* VERY THANKS TO:
* - raysan5: helped with library design
* - ficoos: added support for Linux
* - R8D8: added support for Linux
* - jubalh: fixed implementation of time calculations
* - a3f: fixed implementation of time calculations
* - define-private-public: added support for OSX
* - pamarcos: fixed implementation of physics steps
* - noshbar: fixed some memory leaks
*
*
* LICENSE: zlib/libpng
*
* Copyright (c) 2016-2020 Victor Fisac (github: @victorfisac)
*
* This software is provided "as-is", without any express or implied warranty. In no event
* will the authors be held liable for any damages arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose, including commercial
* applications, and to alter it and redistribute it freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not claim that you
* wrote the original software. If you use this software in a product, an acknowledgment
* in the product documentation would be appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must not be misrepresented
* as being the original software.
*
* 3. This notice may not be removed or altered from any source distribution.
*
**********************************************************************************************/
#if !defined(PHYSAC_H)
#define PHYSAC_H
// #define PHYSAC_STATIC
// #define PHYSAC_NO_THREADS
// #define PHYSAC_STANDALONE
// #define PHYSAC_DEBUG
#if defined(PHYSAC_STATIC)
#define PHYSACDEF static // Functions just visible to module including this file
#else
#if defined(__cplusplus)
#define PHYSACDEF extern "C" // Functions visible from other files (no name mangling of functions in C++)
#else
#define PHYSACDEF extern // Functions visible from other files
#endif
#endif
//----------------------------------------------------------------------------------
// Defines and Macros
//----------------------------------------------------------------------------------
#define PHYSAC_MAX_BODIES 64
#define PHYSAC_MAX_MANIFOLDS 256
#define PHYSAC_MAX_VERTICES 4
#define PHYSAC_CIRCLE_VERTICES 6
#define PHYSAC_COLLISION_ITERATIONS 100
#define PHYSAC_PENETRATION_ALLOWANCE 0.05f
#define PHYSAC_PENETRATION_CORRECTION 0.4f
#define PHYSAC_PI 3.14159265358979323846
#define PHYSAC_DEG2RAD (PHYSAC_PI/180.0f)
#define PHYSAC_MALLOC(size) malloc(size)
#define PHYSAC_FREE(ptr) free(ptr)
//----------------------------------------------------------------------------------
// Types and Structures Definition
// NOTE: Below types are required for PHYSAC_STANDALONE usage
//----------------------------------------------------------------------------------
#if defined(PHYSAC_STANDALONE)
// Vector2 type
typedef struct Vector2 {
float x;
float y;
} Vector2;
// Boolean type
#if !defined(_STDBOOL_H)
typedef enum { false, true } bool;
#define _STDBOOL_H
#endif
#endif
typedef enum PhysicsShapeType { PHYSICS_CIRCLE, PHYSICS_POLYGON } PhysicsShapeType;
// Previously defined to be used in PhysicsShape struct as circular dependencies
typedef struct PhysicsBodyData *PhysicsBody;
// Mat2 type (used for polygon shape rotation matrix)
typedef struct Mat2 {
float m00;
float m01;
float m10;
float m11;
} Mat2;
typedef struct PolygonData {
unsigned int vertexCount; // Current used vertex and normals count
Vector2 positions[PHYSAC_MAX_VERTICES]; // Polygon vertex positions vectors
Vector2 normals[PHYSAC_MAX_VERTICES]; // Polygon vertex normals vectors
} PolygonData;
typedef struct PhysicsShape {
PhysicsShapeType type; // Physics shape type (circle or polygon)
PhysicsBody body; // Shape physics body reference
float radius; // Circle shape radius (used for circle shapes)
Mat2 transform; // Vertices transform matrix 2x2
PolygonData vertexData; // Polygon shape vertices position and normals data (just used for polygon shapes)
} PhysicsShape;
typedef struct PhysicsBodyData {
unsigned int id; // Reference unique identifier
bool enabled; // Enabled dynamics state (collisions are calculated anyway)
Vector2 position; // Physics body shape pivot
Vector2 velocity; // Current linear velocity applied to position
Vector2 force; // Current linear force (reset to 0 every step)
float angularVelocity; // Current angular velocity applied to orient
float torque; // Current angular force (reset to 0 every step)
float orient; // Rotation in radians
float inertia; // Moment of inertia
float inverseInertia; // Inverse value of inertia
float mass; // Physics body mass
float inverseMass; // Inverse value of mass
float staticFriction; // Friction when the body has not movement (0 to 1)
float dynamicFriction; // Friction when the body has movement (0 to 1)
float restitution; // Restitution coefficient of the body (0 to 1)
bool useGravity; // Apply gravity force to dynamics
bool isGrounded; // Physics grounded on other body state
bool freezeOrient; // Physics rotation constraint
PhysicsShape shape; // Physics body shape information (type, radius, vertices, normals)
} PhysicsBodyData;
typedef struct PhysicsManifoldData {
unsigned int id; // Reference unique identifier
PhysicsBody bodyA; // Manifold first physics body reference
PhysicsBody bodyB; // Manifold second physics body reference
float penetration; // Depth of penetration from collision
Vector2 normal; // Normal direction vector from 'a' to 'b'
Vector2 contacts[2]; // Points of contact during collision
unsigned int contactsCount; // Current collision number of contacts
float restitution; // Mixed restitution during collision
float dynamicFriction; // Mixed dynamic friction during collision
float staticFriction; // Mixed static friction during collision
} PhysicsManifoldData, *PhysicsManifold;
#if defined(__cplusplus)
extern "C" { // Prevents name mangling of functions
#endif
//----------------------------------------------------------------------------------
// Module Functions Declaration
//----------------------------------------------------------------------------------
PHYSACDEF void InitPhysics(void); // Initializes physics values, pointers and creates physics loop thread
PHYSACDEF void RunPhysicsStep(void); // Run physics step, to be used if PHYSICS_NO_THREADS is set in your main loop
PHYSACDEF void SetPhysicsTimeStep(double delta); // Sets physics fixed time step in milliseconds. 1.666666 by default
PHYSACDEF bool IsPhysicsEnabled(void); // Returns true if physics thread is currently enabled
PHYSACDEF void SetPhysicsGravity(float x, float y); // Sets physics global gravity force
PHYSACDEF PhysicsBody CreatePhysicsBodyCircle(Vector2 pos, float radius, float density); // Creates a new circle physics body with generic parameters
PHYSACDEF PhysicsBody CreatePhysicsBodyRectangle(Vector2 pos, float width, float height, float density); // Creates a new rectangle physics body with generic parameters
PHYSACDEF PhysicsBody CreatePhysicsBodyPolygon(Vector2 pos, float radius, int sides, float density); // Creates a new polygon physics body with generic parameters
PHYSACDEF void PhysicsAddForce(PhysicsBody body, Vector2 force); // Adds a force to a physics body
PHYSACDEF void PhysicsAddTorque(PhysicsBody body, float amount); // Adds an angular force to a physics body
PHYSACDEF void PhysicsShatter(PhysicsBody body, Vector2 position, float force); // Shatters a polygon shape physics body to little physics bodies with explosion force
PHYSACDEF int GetPhysicsBodiesCount(void); // Returns the current amount of created physics bodies
PHYSACDEF PhysicsBody GetPhysicsBody(int index); // Returns a physics body of the bodies pool at a specific index
PHYSACDEF int GetPhysicsShapeType(int index); // Returns the physics body shape type (PHYSICS_CIRCLE or PHYSICS_POLYGON)
PHYSACDEF int GetPhysicsShapeVerticesCount(int index); // Returns the amount of vertices of a physics body shape
PHYSACDEF Vector2 GetPhysicsShapeVertex(PhysicsBody body, int vertex); // Returns transformed position of a body shape (body position + vertex transformed position)
PHYSACDEF void SetPhysicsBodyRotation(PhysicsBody body, float radians); // Sets physics body shape transform based on radians parameter
PHYSACDEF void DestroyPhysicsBody(PhysicsBody body); // Unitializes and destroy a physics body
PHYSACDEF void ClosePhysics(void); // Unitializes physics pointers and closes physics loop thread
#if defined(__cplusplus)
}
#endif
#endif // PHYSAC_H
/***********************************************************************************
*
* PHYSAC IMPLEMENTATION
*
************************************************************************************/
#if defined(PHYSAC_IMPLEMENTATION)
#if !defined(PHYSAC_NO_THREADS)
#include <pthread.h> // Required for: pthread_t, pthread_create()
#endif
#if defined(PHYSAC_DEBUG)
#include <stdio.h> // Required for: printf()
#endif
#include <stdlib.h> // Required for: malloc(), free(), srand(), rand()
#include <math.h> // Required for: cosf(), sinf(), fabs(), sqrtf()
#include <stdint.h> // Required for: uint64_t
#if !defined(PHYSAC_STANDALONE)
#include "raymath.h" // Required for: Vector2Add(), Vector2Subtract()
#endif
// Time management functionality
#include <time.h> // Required for: time(), clock_gettime()
#if defined(_WIN32)
// Functions required to query time on Windows
#if defined(__cplusplus)
extern "C" { // Prevents name mangling of functions
#endif
int __stdcall QueryPerformanceCounter(unsigned long long int* lpPerformanceCount);
int __stdcall QueryPerformanceFrequency(unsigned long long int* lpFrequency);
#if defined(__cplusplus)
}
#endif
#elif defined(__linux__)
#if _POSIX_C_SOURCE < 199309L
#undef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 199309L // Required for CLOCK_MONOTONIC if compiled with c99 without gnu ext.
#endif
#include <sys/time.h> // Required for: timespec
#elif defined(__APPLE__) // macOS also defines __MACH__
#include <mach/mach_time.h> // Required for: mach_absolute_time()
#endif
//----------------------------------------------------------------------------------
// Defines and Macros
//----------------------------------------------------------------------------------
#define min(a,b) (((a)<(b))?(a):(b))
#define max(a,b) (((a)>(b))?(a):(b))
#define PHYSAC_FLT_MAX 3.402823466e+38f
#define PHYSAC_EPSILON 0.000001f
#define PHYSAC_K 1.0f/3.0f
#define PHYSAC_VECTOR_ZERO (Vector2){ 0.0f, 0.0f }
//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
#if !defined(PHYSAC_NO_THREADS)
static pthread_t physicsThreadId; // Physics thread id
#endif
static unsigned int usedMemory = 0; // Total allocated dynamic memory
static bool physicsThreadEnabled = false; // Physics thread enabled state
static double baseTime = 0.0; // Offset time for MONOTONIC clock
static double startTime = 0.0; // Start time in milliseconds
static double deltaTime = 1.0/60.0/10.0 * 1000; // Delta time used for physics steps, in milliseconds
static double currentTime = 0.0; // Current time in milliseconds
static uint64_t frequency = 0; // Hi-res clock frequency
static double accumulator = 0.0; // Physics time step delta time accumulator
static unsigned int stepsCount = 0; // Total physics steps processed
static Vector2 gravityForce = { 0.0f, 9.81f }; // Physics world gravity force
static PhysicsBody bodies[PHYSAC_MAX_BODIES]; // Physics bodies pointers array
static unsigned int physicsBodiesCount = 0; // Physics world current bodies counter
static PhysicsManifold contacts[PHYSAC_MAX_MANIFOLDS]; // Physics bodies pointers array
static unsigned int physicsManifoldsCount = 0; // Physics world current manifolds counter
//----------------------------------------------------------------------------------
// Module Internal Functions Declaration
//----------------------------------------------------------------------------------
static int FindAvailableBodyIndex(); // Finds a valid index for a new physics body initialization
static PolygonData CreateRandomPolygon(float radius, int sides); // Creates a random polygon shape with max vertex distance from polygon pivot
static PolygonData CreateRectanglePolygon(Vector2 pos, Vector2 size); // Creates a rectangle polygon shape based on a min and max positions
static void *PhysicsLoop(void *arg); // Physics loop thread function
static void PhysicsStep(void); // Physics steps calculations (dynamics, collisions and position corrections)
static int FindAvailableManifoldIndex(); // Finds a valid index for a new manifold initialization
static PhysicsManifold CreatePhysicsManifold(PhysicsBody a, PhysicsBody b); // Creates a new physics manifold to solve collision
static void DestroyPhysicsManifold(PhysicsManifold manifold); // Unitializes and destroys a physics manifold
static void SolvePhysicsManifold(PhysicsManifold manifold); // Solves a created physics manifold between two physics bodies
static void SolveCircleToCircle(PhysicsManifold manifold); // Solves collision between two circle shape physics bodies
static void SolveCircleToPolygon(PhysicsManifold manifold); // Solves collision between a circle to a polygon shape physics bodies
static void SolvePolygonToCircle(PhysicsManifold manifold); // Solves collision between a polygon to a circle shape physics bodies
static void SolveDifferentShapes(PhysicsManifold manifold, PhysicsBody bodyA, PhysicsBody bodyB); // Solve collision between two different types of shapes
static void SolvePolygonToPolygon(PhysicsManifold manifold); // Solves collision between two polygons shape physics bodies
static void IntegratePhysicsForces(PhysicsBody body); // Integrates physics forces into velocity
static void InitializePhysicsManifolds(PhysicsManifold manifold); // Initializes physics manifolds to solve collisions
static void IntegratePhysicsImpulses(PhysicsManifold manifold); // Integrates physics collisions impulses to solve collisions
static void IntegratePhysicsVelocity(PhysicsBody body); // Integrates physics velocity into position and forces
static void CorrectPhysicsPositions(PhysicsManifold manifold); // Corrects physics bodies positions based on manifolds collision information
static float FindAxisLeastPenetration(int *faceIndex, PhysicsShape shapeA, PhysicsShape shapeB); // Finds polygon shapes axis least penetration
static void FindIncidentFace(Vector2 *v0, Vector2 *v1, PhysicsShape ref, PhysicsShape inc, int index); // Finds two polygon shapes incident face
static int Clip(Vector2 normal, float clip, Vector2 *faceA, Vector2 *faceB); // Calculates clipping based on a normal and two faces
static bool BiasGreaterThan(float valueA, float valueB); // Check if values are between bias range
static Vector2 TriangleBarycenter(Vector2 v1, Vector2 v2, Vector2 v3); // Returns the barycenter of a triangle given by 3 points
static void InitTimer(void); // Initializes hi-resolution MONOTONIC timer
static uint64_t GetTimeCount(void); // Get hi-res MONOTONIC time measure in mseconds
static double GetCurrentTime(void); // Get current time measure in milliseconds
// Math functions
static Vector2 MathCross(float value, Vector2 vector); // Returns the cross product of a vector and a value
static float MathCrossVector2(Vector2 v1, Vector2 v2); // Returns the cross product of two vectors
static float MathLenSqr(Vector2 vector); // Returns the len square root of a vector
static float MathDot(Vector2 v1, Vector2 v2); // Returns the dot product of two vectors
static inline float DistSqr(Vector2 v1, Vector2 v2); // Returns the square root of distance between two vectors
static void MathNormalize(Vector2 *vector); // Returns the normalized values of a vector
#if defined(PHYSAC_STANDALONE)
static Vector2 Vector2Add(Vector2 v1, Vector2 v2); // Returns the sum of two given vectors
static Vector2 Vector2Subtract(Vector2 v1, Vector2 v2); // Returns the subtract of two given vectors
#endif
static Mat2 Mat2Radians(float radians); // Creates a matrix 2x2 from a given radians value
static void Mat2Set(Mat2 *matrix, float radians); // Set values from radians to a created matrix 2x2
static inline Mat2 Mat2Transpose(Mat2 matrix); // Returns the transpose of a given matrix 2x2
static inline Vector2 Mat2MultiplyVector2(Mat2 matrix, Vector2 vector); // Multiplies a vector by a matrix 2x2
//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
// Initializes physics values, pointers and creates physics loop thread
PHYSACDEF void InitPhysics(void)
{
#if !defined(PHYSAC_NO_THREADS)
// NOTE: if defined, user will need to create a thread for PhysicsThread function manually
// Create physics thread using POSIXS thread libraries
pthread_create(&physicsThreadId, NULL, &PhysicsLoop, NULL);
#endif
// Initialize high resolution timer
InitTimer();
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] physics module initialized successfully\n");
#endif
accumulator = 0.0;
}
// Returns true if physics thread is currently enabled
PHYSACDEF bool IsPhysicsEnabled(void)
{
return physicsThreadEnabled;
}
// Sets physics global gravity force
PHYSACDEF void SetPhysicsGravity(float x, float y)
{
gravityForce.x = x;
gravityForce.y = y;
}
// Creates a new circle physics body with generic parameters
PHYSACDEF PhysicsBody CreatePhysicsBodyCircle(Vector2 pos, float radius, float density)
{
PhysicsBody newBody = (PhysicsBody)PHYSAC_MALLOC(sizeof(PhysicsBodyData));
usedMemory += sizeof(PhysicsBodyData);
int newId = FindAvailableBodyIndex();
if (newId != -1)
{
// Initialize new body with generic values
newBody->id = newId;
newBody->enabled = true;
newBody->position = pos;
newBody->velocity = PHYSAC_VECTOR_ZERO;
newBody->force = PHYSAC_VECTOR_ZERO;
newBody->angularVelocity = 0.0f;
newBody->torque = 0.0f;
newBody->orient = 0.0f;
newBody->shape.type = PHYSICS_CIRCLE;
newBody->shape.body = newBody;
newBody->shape.radius = radius;
newBody->shape.transform = Mat2Radians(0.0f);
newBody->shape.vertexData = (PolygonData) { 0 };
newBody->mass = PHYSAC_PI*radius*radius*density;
newBody->inverseMass = ((newBody->mass != 0.0f) ? 1.0f/newBody->mass : 0.0f);
newBody->inertia = newBody->mass*radius*radius;
newBody->inverseInertia = ((newBody->inertia != 0.0f) ? 1.0f/newBody->inertia : 0.0f);
newBody->staticFriction = 0.4f;
newBody->dynamicFriction = 0.2f;
newBody->restitution = 0.0f;
newBody->useGravity = true;
newBody->isGrounded = false;
newBody->freezeOrient = false;
// Add new body to bodies pointers array and update bodies count
bodies[physicsBodiesCount] = newBody;
physicsBodiesCount++;
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] created polygon physics body id %i\n", newBody->id);
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] new physics body creation failed because there is any available id to use\n");
#endif
return newBody;
}
// Creates a new rectangle physics body with generic parameters
PHYSACDEF PhysicsBody CreatePhysicsBodyRectangle(Vector2 pos, float width, float height, float density)
{
PhysicsBody newBody = (PhysicsBody)PHYSAC_MALLOC(sizeof(PhysicsBodyData));
usedMemory += sizeof(PhysicsBodyData);
int newId = FindAvailableBodyIndex();
if (newId != -1)
{
// Initialize new body with generic values
newBody->id = newId;
newBody->enabled = true;
newBody->position = pos;
newBody->velocity = (Vector2){ 0.0f };
newBody->force = (Vector2){ 0.0f };
newBody->angularVelocity = 0.0f;
newBody->torque = 0.0f;
newBody->orient = 0.0f;
newBody->shape.type = PHYSICS_POLYGON;
newBody->shape.body = newBody;
newBody->shape.radius = 0.0f;
newBody->shape.transform = Mat2Radians(0.0f);
newBody->shape.vertexData = CreateRectanglePolygon(pos, (Vector2){ width, height });
// Calculate centroid and moment of inertia
Vector2 center = { 0.0f, 0.0f };
float area = 0.0f;
float inertia = 0.0f;
for (int i = 0; i < newBody->shape.vertexData.vertexCount; i++)
{
// Triangle vertices, third vertex implied as (0, 0)
Vector2 p1 = newBody->shape.vertexData.positions[i];
int nextIndex = (((i + 1) < newBody->shape.vertexData.vertexCount) ? (i + 1) : 0);
Vector2 p2 = newBody->shape.vertexData.positions[nextIndex];
float D = MathCrossVector2(p1, p2);
float triangleArea = D/2;
area += triangleArea;
// Use area to weight the centroid average, not just vertex position
center.x += triangleArea*PHYSAC_K*(p1.x + p2.x);
center.y += triangleArea*PHYSAC_K*(p1.y + p2.y);
float intx2 = p1.x*p1.x + p2.x*p1.x + p2.x*p2.x;
float inty2 = p1.y*p1.y + p2.y*p1.y + p2.y*p2.y;
inertia += (0.25f*PHYSAC_K*D)*(intx2 + inty2);
}
center.x *= 1.0f/area;
center.y *= 1.0f/area;
// Translate vertices to centroid (make the centroid (0, 0) for the polygon in model space)
// Note: this is not really necessary
for (int i = 0; i < newBody->shape.vertexData.vertexCount; i++)
{
newBody->shape.vertexData.positions[i].x -= center.x;
newBody->shape.vertexData.positions[i].y -= center.y;
}
newBody->mass = density*area;
newBody->inverseMass = ((newBody->mass != 0.0f) ? 1.0f/newBody->mass : 0.0f);
newBody->inertia = density*inertia;
newBody->inverseInertia = ((newBody->inertia != 0.0f) ? 1.0f/newBody->inertia : 0.0f);
newBody->staticFriction = 0.4f;
newBody->dynamicFriction = 0.2f;
newBody->restitution = 0.0f;
newBody->useGravity = true;
newBody->isGrounded = false;
newBody->freezeOrient = false;
// Add new body to bodies pointers array and update bodies count
bodies[physicsBodiesCount] = newBody;
physicsBodiesCount++;
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] created polygon physics body id %i\n", newBody->id);
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] new physics body creation failed because there is any available id to use\n");
#endif
return newBody;
}
// Creates a new polygon physics body with generic parameters
PHYSACDEF PhysicsBody CreatePhysicsBodyPolygon(Vector2 pos, float radius, int sides, float density)
{
PhysicsBody newBody = (PhysicsBody)PHYSAC_MALLOC(sizeof(PhysicsBodyData));
usedMemory += sizeof(PhysicsBodyData);
int newId = FindAvailableBodyIndex();
if (newId != -1)
{
// Initialize new body with generic values
newBody->id = newId;
newBody->enabled = true;
newBody->position = pos;
newBody->velocity = PHYSAC_VECTOR_ZERO;
newBody->force = PHYSAC_VECTOR_ZERO;
newBody->angularVelocity = 0.0f;
newBody->torque = 0.0f;
newBody->orient = 0.0f;
newBody->shape.type = PHYSICS_POLYGON;
newBody->shape.body = newBody;
newBody->shape.transform = Mat2Radians(0.0f);
newBody->shape.vertexData = CreateRandomPolygon(radius, sides);
// Calculate centroid and moment of inertia
Vector2 center = { 0.0f, 0.0f };
float area = 0.0f;
float inertia = 0.0f;
for (int i = 0; i < newBody->shape.vertexData.vertexCount; i++)
{
// Triangle vertices, third vertex implied as (0, 0)
Vector2 position1 = newBody->shape.vertexData.positions[i];
int nextIndex = (((i + 1) < newBody->shape.vertexData.vertexCount) ? (i + 1) : 0);
Vector2 position2 = newBody->shape.vertexData.positions[nextIndex];
float cross = MathCrossVector2(position1, position2);
float triangleArea = cross/2;
area += triangleArea;
// Use area to weight the centroid average, not just vertex position
center.x += triangleArea*PHYSAC_K*(position1.x + position2.x);
center.y += triangleArea*PHYSAC_K*(position1.y + position2.y);
float intx2 = position1.x*position1.x + position2.x*position1.x + position2.x*position2.x;
float inty2 = position1.y*position1.y + position2.y*position1.y + position2.y*position2.y;
inertia += (0.25f*PHYSAC_K*cross)*(intx2 + inty2);
}
center.x *= 1.0f/area;
center.y *= 1.0f/area;
// Translate vertices to centroid (make the centroid (0, 0) for the polygon in model space)
// Note: this is not really necessary
for (int i = 0; i < newBody->shape.vertexData.vertexCount; i++)
{
newBody->shape.vertexData.positions[i].x -= center.x;
newBody->shape.vertexData.positions[i].y -= center.y;
}
newBody->mass = density*area;
newBody->inverseMass = ((newBody->mass != 0.0f) ? 1.0f/newBody->mass : 0.0f);
newBody->inertia = density*inertia;
newBody->inverseInertia = ((newBody->inertia != 0.0f) ? 1.0f/newBody->inertia : 0.0f);
newBody->staticFriction = 0.4f;
newBody->dynamicFriction = 0.2f;
newBody->restitution = 0.0f;
newBody->useGravity = true;
newBody->isGrounded = false;
newBody->freezeOrient = false;
// Add new body to bodies pointers array and update bodies count
bodies[physicsBodiesCount] = newBody;
physicsBodiesCount++;
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] created polygon physics body id %i\n", newBody->id);
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] new physics body creation failed because there is any available id to use\n");
#endif
return newBody;
}
// Adds a force to a physics body
PHYSACDEF void PhysicsAddForce(PhysicsBody body, Vector2 force)
{
if (body != NULL)
body->force = Vector2Add(body->force, force);
}
// Adds an angular force to a physics body
PHYSACDEF void PhysicsAddTorque(PhysicsBody body, float amount)
{
if (body != NULL)
body->torque += amount;
}
// Shatters a polygon shape physics body to little physics bodies with explosion force
PHYSACDEF void PhysicsShatter(PhysicsBody body, Vector2 position, float force)
{
if (body != NULL)
{
if (body->shape.type == PHYSICS_POLYGON)
{
PolygonData vertexData = body->shape.vertexData;
bool collision = false;
for (int i = 0; i < vertexData.vertexCount; i++)
{
Vector2 positionA = body->position;
Vector2 positionB = Mat2MultiplyVector2(body->shape.transform, Vector2Add(body->position, vertexData.positions[i]));
int nextIndex = (((i + 1) < vertexData.vertexCount) ? (i + 1) : 0);
Vector2 positionC = Mat2MultiplyVector2(body->shape.transform, Vector2Add(body->position, vertexData.positions[nextIndex]));
// Check collision between each triangle
float alpha = ((positionB.y - positionC.y)*(position.x - positionC.x) + (positionC.x - positionB.x)*(position.y - positionC.y))/
((positionB.y - positionC.y)*(positionA.x - positionC.x) + (positionC.x - positionB.x)*(positionA.y - positionC.y));
float beta = ((positionC.y - positionA.y)*(position.x - positionC.x) + (positionA.x - positionC.x)*(position.y - positionC.y))/
((positionB.y - positionC.y)*(positionA.x - positionC.x) + (positionC.x - positionB.x)*(positionA.y - positionC.y));
float gamma = 1.0f - alpha - beta;
if ((alpha > 0.0f) && (beta > 0.0f) && (gamma > 0.0f))
{
collision = true;
break;
}
}
if (collision)
{
int count = vertexData.vertexCount;
Vector2 bodyPos = body->position;
Vector2 *vertices = (Vector2*)PHYSAC_MALLOC(sizeof(Vector2) * count);
Mat2 trans = body->shape.transform;
for (int i = 0; i < count; i++)
vertices[i] = vertexData.positions[i];
// Destroy shattered physics body
DestroyPhysicsBody(body);
for (int i = 0; i < count; i++)
{
int nextIndex = (((i + 1) < count) ? (i + 1) : 0);
Vector2 center = TriangleBarycenter(vertices[i], vertices[nextIndex], PHYSAC_VECTOR_ZERO);
center = Vector2Add(bodyPos, center);
Vector2 offset = Vector2Subtract(center, bodyPos);
PhysicsBody newBody = CreatePhysicsBodyPolygon(center, 10, 3, 10); // Create polygon physics body with relevant values
PolygonData newData = { 0 };
newData.vertexCount = 3;
newData.positions[0] = Vector2Subtract(vertices[i], offset);
newData.positions[1] = Vector2Subtract(vertices[nextIndex], offset);
newData.positions[2] = Vector2Subtract(position, center);
// Separate vertices to avoid unnecessary physics collisions
newData.positions[0].x *= 0.95f;
newData.positions[0].y *= 0.95f;
newData.positions[1].x *= 0.95f;
newData.positions[1].y *= 0.95f;
newData.positions[2].x *= 0.95f;
newData.positions[2].y *= 0.95f;
// Calculate polygon faces normals
for (int j = 0; j < newData.vertexCount; j++)
{
int nextVertex = (((j + 1) < newData.vertexCount) ? (j + 1) : 0);
Vector2 face = Vector2Subtract(newData.positions[nextVertex], newData.positions[j]);
newData.normals[j] = (Vector2){ face.y, -face.x };
MathNormalize(&newData.normals[j]);
}
// Apply computed vertex data to new physics body shape
newBody->shape.vertexData = newData;
newBody->shape.transform = trans;
// Calculate centroid and moment of inertia
center = PHYSAC_VECTOR_ZERO;
float area = 0.0f;
float inertia = 0.0f;
for (int j = 0; j < newBody->shape.vertexData.vertexCount; j++)
{
// Triangle vertices, third vertex implied as (0, 0)
Vector2 p1 = newBody->shape.vertexData.positions[j];
int nextVertex = (((j + 1) < newBody->shape.vertexData.vertexCount) ? (j + 1) : 0);
Vector2 p2 = newBody->shape.vertexData.positions[nextVertex];
float D = MathCrossVector2(p1, p2);
float triangleArea = D/2;
area += triangleArea;
// Use area to weight the centroid average, not just vertex position
center.x += triangleArea*PHYSAC_K*(p1.x + p2.x);
center.y += triangleArea*PHYSAC_K*(p1.y + p2.y);
float intx2 = p1.x*p1.x + p2.x*p1.x + p2.x*p2.x;
float inty2 = p1.y*p1.y + p2.y*p1.y + p2.y*p2.y;
inertia += (0.25f*PHYSAC_K*D)*(intx2 + inty2);
}
center.x *= 1.0f/area;
center.y *= 1.0f/area;
newBody->mass = area;
newBody->inverseMass = ((newBody->mass != 0.0f) ? 1.0f/newBody->mass : 0.0f);
newBody->inertia = inertia;
newBody->inverseInertia = ((newBody->inertia != 0.0f) ? 1.0f/newBody->inertia : 0.0f);
// Calculate explosion force direction
Vector2 pointA = newBody->position;
Vector2 pointB = Vector2Subtract(newData.positions[1], newData.positions[0]);
pointB.x /= 2.0f;
pointB.y /= 2.0f;
Vector2 forceDirection = Vector2Subtract(Vector2Add(pointA, Vector2Add(newData.positions[0], pointB)), newBody->position);
MathNormalize(&forceDirection);
forceDirection.x *= force;
forceDirection.y *= force;
// Apply force to new physics body
PhysicsAddForce(newBody, forceDirection);
}
PHYSAC_FREE(vertices);
}
}
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error when trying to shatter a null reference physics body");
#endif
}
// Returns the current amount of created physics bodies
PHYSACDEF int GetPhysicsBodiesCount(void)
{
return physicsBodiesCount;
}
// Returns a physics body of the bodies pool at a specific index
PHYSACDEF PhysicsBody GetPhysicsBody(int index)
{
if (index < physicsBodiesCount)
{
if (bodies[index] == NULL)
{
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] error when trying to get a null reference physics body");
#endif
}
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] physics body index is out of bounds");
#endif
return bodies[index];
}
// Returns the physics body shape type (PHYSICS_CIRCLE or PHYSICS_POLYGON)
PHYSACDEF int GetPhysicsShapeType(int index)
{
int result = -1;
if (index < physicsBodiesCount)
{
if (bodies[index] != NULL)
result = bodies[index]->shape.type;
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error when trying to get a null reference physics body");
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] physics body index is out of bounds");
#endif
return result;
}
// Returns the amount of vertices of a physics body shape
PHYSACDEF int GetPhysicsShapeVerticesCount(int index)
{
int result = 0;
if (index < physicsBodiesCount)
{
if (bodies[index] != NULL)
{
switch (bodies[index]->shape.type)
{
case PHYSICS_CIRCLE: result = PHYSAC_CIRCLE_VERTICES; break;
case PHYSICS_POLYGON: result = bodies[index]->shape.vertexData.vertexCount; break;
default: break;
}
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error when trying to get a null reference physics body");
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] physics body index is out of bounds");
#endif
return result;
}
// Returns transformed position of a body shape (body position + vertex transformed position)
PHYSACDEF Vector2 GetPhysicsShapeVertex(PhysicsBody body, int vertex)
{
Vector2 position = { 0.0f, 0.0f };
if (body != NULL)
{
switch (body->shape.type)
{
case PHYSICS_CIRCLE:
{
position.x = body->position.x + cosf(360.0f/PHYSAC_CIRCLE_VERTICES*vertex*PHYSAC_DEG2RAD)*body->shape.radius;
position.y = body->position.y + sinf(360.0f/PHYSAC_CIRCLE_VERTICES*vertex*PHYSAC_DEG2RAD)*body->shape.radius;
} break;
case PHYSICS_POLYGON:
{
PolygonData vertexData = body->shape.vertexData;
position = Vector2Add(body->position, Mat2MultiplyVector2(body->shape.transform, vertexData.positions[vertex]));
} break;
default: break;
}
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error when trying to get a null reference physics body");
#endif
return position;
}
// Sets physics body shape transform based on radians parameter
PHYSACDEF void SetPhysicsBodyRotation(PhysicsBody body, float radians)
{
if (body != NULL)
{
body->orient = radians;
if (body->shape.type == PHYSICS_POLYGON)
body->shape.transform = Mat2Radians(radians);
}
}
// Unitializes and destroys a physics body
PHYSACDEF void DestroyPhysicsBody(PhysicsBody body)
{
if (body != NULL)
{
int id = body->id;
int index = -1;
for (int i = 0; i < physicsBodiesCount; i++)
{
if (bodies[i]->id == id)
{
index = i;
break;
}
}
if (index == -1)
{
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] Not possible to find body id %i in pointers array\n", id);
#endif
return;
}
// Free body allocated memory
PHYSAC_FREE(body);
usedMemory -= sizeof(PhysicsBodyData);
bodies[index] = NULL;
// Reorder physics bodies pointers array and its catched index
for (int i = index; i < physicsBodiesCount; i++)
{
if ((i + 1) < physicsBodiesCount)
bodies[i] = bodies[i + 1];
}
// Update physics bodies count
physicsBodiesCount--;
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] destroyed physics body id %i\n", id);
#endif
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error trying to destroy a null referenced body\n");
#endif
}
// Unitializes physics pointers and exits physics loop thread
PHYSACDEF void ClosePhysics(void)
{
// Exit physics loop thread
physicsThreadEnabled = false;
#if !defined(PHYSAC_NO_THREADS)
pthread_join(physicsThreadId, NULL);
#endif
// Unitialize physics manifolds dynamic memory allocations
for (int i = physicsManifoldsCount - 1; i >= 0; i--)
DestroyPhysicsManifold(contacts[i]);
// Unitialize physics bodies dynamic memory allocations
for (int i = physicsBodiesCount - 1; i >= 0; i--)
DestroyPhysicsBody(bodies[i]);
#if defined(PHYSAC_DEBUG)
if (physicsBodiesCount > 0 || usedMemory != 0)
printf("[PHYSAC] physics module closed with %i still allocated bodies [MEMORY: %i bytes]\n", physicsBodiesCount, usedMemory);
else if (physicsManifoldsCount > 0 || usedMemory != 0)
printf("[PHYSAC] physics module closed with %i still allocated manifolds [MEMORY: %i bytes]\n", physicsManifoldsCount, usedMemory);
else
printf("[PHYSAC] physics module closed successfully\n");
#endif
}
//----------------------------------------------------------------------------------
// Module Internal Functions Definition
//----------------------------------------------------------------------------------
// Finds a valid index for a new physics body initialization
static int FindAvailableBodyIndex()
{
int index = -1;
for (int i = 0; i < PHYSAC_MAX_BODIES; i++)
{
int currentId = i;
// Check if current id already exist in other physics body
for (int k = 0; k < physicsBodiesCount; k++)
{
if (bodies[k]->id == currentId)
{
currentId++;
break;
}
}
// If it is not used, use it as new physics body id
if (currentId == i)
{
index = i;
break;
}
}
return index;
}
// Creates a random polygon shape with max vertex distance from polygon pivot
static PolygonData CreateRandomPolygon(float radius, int sides)
{
PolygonData data = { 0 };
data.vertexCount = sides;
// Calculate polygon vertices positions
for (int i = 0; i < data.vertexCount; i++)
{
data.positions[i].x = cosf(360.0f/sides*i*PHYSAC_DEG2RAD)*radius;
data.positions[i].y = sinf(360.0f/sides*i*PHYSAC_DEG2RAD)*radius;
}
// Calculate polygon faces normals
for (int i = 0; i < data.vertexCount; i++)
{
int nextIndex = (((i + 1) < sides) ? (i + 1) : 0);
Vector2 face = Vector2Subtract(data.positions[nextIndex], data.positions[i]);
data.normals[i] = (Vector2){ face.y, -face.x };
MathNormalize(&data.normals[i]);
}
return data;
}
// Creates a rectangle polygon shape based on a min and max positions
static PolygonData CreateRectanglePolygon(Vector2 pos, Vector2 size)
{
PolygonData data = { 0 };
data.vertexCount = 4;
// Calculate polygon vertices positions
data.positions[0] = (Vector2){ pos.x + size.x/2, pos.y - size.y/2 };
data.positions[1] = (Vector2){ pos.x + size.x/2, pos.y + size.y/2 };
data.positions[2] = (Vector2){ pos.x - size.x/2, pos.y + size.y/2 };
data.positions[3] = (Vector2){ pos.x - size.x/2, pos.y - size.y/2 };
// Calculate polygon faces normals
for (int i = 0; i < data.vertexCount; i++)
{
int nextIndex = (((i + 1) < data.vertexCount) ? (i + 1) : 0);
Vector2 face = Vector2Subtract(data.positions[nextIndex], data.positions[i]);
data.normals[i] = (Vector2){ face.y, -face.x };
MathNormalize(&data.normals[i]);
}
return data;
}
// Physics loop thread function
static void *PhysicsLoop(void *arg)
{
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] physics thread created successfully\n");
#endif
// Initialize physics loop thread values
physicsThreadEnabled = true;
// Physics update loop
while (physicsThreadEnabled)
{
RunPhysicsStep();
}
return NULL;
}
// Physics steps calculations (dynamics, collisions and position corrections)
static void PhysicsStep(void)
{
// Update current steps count
stepsCount++;
// Clear previous generated collisions information
for (int i = physicsManifoldsCount - 1; i >= 0; i--)
{
PhysicsManifold manifold = contacts[i];
if (manifold != NULL)
DestroyPhysicsManifold(manifold);
}
// Reset physics bodies grounded state
for (int i = 0; i < physicsBodiesCount; i++)
{
PhysicsBody body = bodies[i];
body->isGrounded = false;
}
// Generate new collision information
for (int i = 0; i < physicsBodiesCount; i++)
{
PhysicsBody bodyA = bodies[i];
if (bodyA != NULL)
{
for (int j = i + 1; j < physicsBodiesCount; j++)
{
PhysicsBody bodyB = bodies[j];
if (bodyB != NULL)
{
if ((bodyA->inverseMass == 0) && (bodyB->inverseMass == 0))
continue;
PhysicsManifold manifold = CreatePhysicsManifold(bodyA, bodyB);
SolvePhysicsManifold(manifold);
if (manifold->contactsCount > 0)
{
// Create a new manifold with same information as previously solved manifold and add it to the manifolds pool last slot
PhysicsManifold newManifold = CreatePhysicsManifold(bodyA, bodyB);
newManifold->penetration = manifold->penetration;
newManifold->normal = manifold->normal;
newManifold->contacts[0] = manifold->contacts[0];
newManifold->contacts[1] = manifold->contacts[1];
newManifold->contactsCount = manifold->contactsCount;
newManifold->restitution = manifold->restitution;
newManifold->dynamicFriction = manifold->dynamicFriction;
newManifold->staticFriction = manifold->staticFriction;
}
}
}
}
}
// Integrate forces to physics bodies
for (int i = 0; i < physicsBodiesCount; i++)
{
PhysicsBody body = bodies[i];
if (body != NULL)
IntegratePhysicsForces(body);
}
// Initialize physics manifolds to solve collisions
for (int i = 0; i < physicsManifoldsCount; i++)
{
PhysicsManifold manifold = contacts[i];
if (manifold != NULL)
InitializePhysicsManifolds(manifold);
}
// Integrate physics collisions impulses to solve collisions
for (int i = 0; i < PHYSAC_COLLISION_ITERATIONS; i++)
{
for (int j = 0; j < physicsManifoldsCount; j++)
{
PhysicsManifold manifold = contacts[i];
if (manifold != NULL)
IntegratePhysicsImpulses(manifold);
}
}
// Integrate velocity to physics bodies
for (int i = 0; i < physicsBodiesCount; i++)
{
PhysicsBody body = bodies[i];
if (body != NULL)
IntegratePhysicsVelocity(body);
}
// Correct physics bodies positions based on manifolds collision information
for (int i = 0; i < physicsManifoldsCount; i++)
{
PhysicsManifold manifold = contacts[i];
if (manifold != NULL)
CorrectPhysicsPositions(manifold);
}
// Clear physics bodies forces
for (int i = 0; i < physicsBodiesCount; i++)
{
PhysicsBody body = bodies[i];
if (body != NULL)
{
body->force = PHYSAC_VECTOR_ZERO;
body->torque = 0.0f;
}
}
}
// Wrapper to ensure PhysicsStep is run with at a fixed time step
PHYSACDEF void RunPhysicsStep(void)
{
// Calculate current time
currentTime = GetCurrentTime();
// Calculate current delta time
const double delta = currentTime - startTime;
// Store the time elapsed since the last frame began
accumulator += delta;
// Fixed time stepping loop
while (accumulator >= deltaTime)
{
PhysicsStep();
accumulator -= deltaTime;
}
// Record the starting of this frame
startTime = currentTime;
}
PHYSACDEF void SetPhysicsTimeStep(double delta)
{
deltaTime = delta;
}
// Finds a valid index for a new manifold initialization
static int FindAvailableManifoldIndex()
{
int index = -1;
for (int i = 0; i < PHYSAC_MAX_MANIFOLDS; i++)
{
int currentId = i;
// Check if current id already exist in other physics body
for (int k = 0; k < physicsManifoldsCount; k++)
{
if (contacts[k]->id == currentId)
{
currentId++;
break;
}
}
// If it is not used, use it as new physics body id
if (currentId == i)
{
index = i;
break;
}
}
return index;
}
// Creates a new physics manifold to solve collision
static PhysicsManifold CreatePhysicsManifold(PhysicsBody a, PhysicsBody b)
{
PhysicsManifold newManifold = (PhysicsManifold)PHYSAC_MALLOC(sizeof(PhysicsManifoldData));
usedMemory += sizeof(PhysicsManifoldData);
int newId = FindAvailableManifoldIndex();
if (newId != -1)
{
// Initialize new manifold with generic values
newManifold->id = newId;
newManifold->bodyA = a;
newManifold->bodyB = b;
newManifold->penetration = 0;
newManifold->normal = PHYSAC_VECTOR_ZERO;
newManifold->contacts[0] = PHYSAC_VECTOR_ZERO;
newManifold->contacts[1] = PHYSAC_VECTOR_ZERO;
newManifold->contactsCount = 0;
newManifold->restitution = 0.0f;
newManifold->dynamicFriction = 0.0f;
newManifold->staticFriction = 0.0f;
// Add new body to bodies pointers array and update bodies count
contacts[physicsManifoldsCount] = newManifold;
physicsManifoldsCount++;
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] new physics manifold creation failed because there is any available id to use\n");
#endif
return newManifold;
}
// Unitializes and destroys a physics manifold
static void DestroyPhysicsManifold(PhysicsManifold manifold)
{
if (manifold != NULL)
{
int id = manifold->id;
int index = -1;
for (int i = 0; i < physicsManifoldsCount; i++)
{
if (contacts[i]->id == id)
{
index = i;
break;
}
}
if (index == -1)
{
#if defined(PHYSAC_DEBUG)
printf("[PHYSAC] Not possible to manifold id %i in pointers array\n", id);
#endif
return;
}
// Free manifold allocated memory
PHYSAC_FREE(manifold);
usedMemory -= sizeof(PhysicsManifoldData);
contacts[index] = NULL;
// Reorder physics manifolds pointers array and its catched index
for (int i = index; i < physicsManifoldsCount; i++)
{
if ((i + 1) < physicsManifoldsCount)
contacts[i] = contacts[i + 1];
}
// Update physics manifolds count
physicsManifoldsCount--;
}
#if defined(PHYSAC_DEBUG)
else
printf("[PHYSAC] error trying to destroy a null referenced manifold\n");
#endif
}
// Solves a created physics manifold between two physics bodies
static void SolvePhysicsManifold(PhysicsManifold manifold)
{
switch (manifold->bodyA->shape.type)
{
case PHYSICS_CIRCLE:
{
switch (manifold->bodyB->shape.type)
{
case PHYSICS_CIRCLE: SolveCircleToCircle(manifold); break;
case PHYSICS_POLYGON: SolveCircleToPolygon(manifold); break;
default: break;
}
} break;
case PHYSICS_POLYGON:
{
switch (manifold->bodyB->shape.type)
{
case PHYSICS_CIRCLE: SolvePolygonToCircle(manifold); break;
case PHYSICS_POLYGON: SolvePolygonToPolygon(manifold); break;
default: break;
}
} break;
default: break;
}
// Update physics body grounded state if normal direction is down and grounded state is not set yet in previous manifolds
if (!manifold->bodyB->isGrounded)
manifold->bodyB->isGrounded = (manifold->normal.y < 0);
}
// Solves collision between two circle shape physics bodies
static void SolveCircleToCircle(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
// Calculate translational vector, which is normal
Vector2 normal = Vector2Subtract(bodyB->position, bodyA->position);
float distSqr = MathLenSqr(normal);
float radius = bodyA->shape.radius + bodyB->shape.radius;
// Check if circles are not in contact
if (distSqr >= radius*radius)
{
manifold->contactsCount = 0;
return;
}
float distance = sqrtf(distSqr);
manifold->contactsCount = 1;
if (distance == 0.0f)
{
manifold->penetration = bodyA->shape.radius;
manifold->normal = (Vector2){ 1.0f, 0.0f };
manifold->contacts[0] = bodyA->position;
}
else
{
manifold->penetration = radius - distance;
manifold->normal = (Vector2){ normal.x/distance, normal.y/distance }; // Faster than using MathNormalize() due to sqrt is already performed
manifold->contacts[0] = (Vector2){ manifold->normal.x*bodyA->shape.radius + bodyA->position.x, manifold->normal.y*bodyA->shape.radius + bodyA->position.y };
}
// Update physics body grounded state if normal direction is down
if (!bodyA->isGrounded)
bodyA->isGrounded = (manifold->normal.y < 0);
}
// Solves collision between a circle to a polygon shape physics bodies
static void SolveCircleToPolygon(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
SolveDifferentShapes(manifold, bodyA, bodyB);
}
// Solves collision between a circle to a polygon shape physics bodies
static void SolvePolygonToCircle(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
SolveDifferentShapes(manifold, bodyB, bodyA);
manifold->normal.x *= -1.0f;
manifold->normal.y *= -1.0f;
}
// Solve collision between two different types of shapes
static void SolveDifferentShapes(PhysicsManifold manifold, PhysicsBody bodyA, PhysicsBody bodyB)
{
manifold->contactsCount = 0;
// Transform circle center to polygon transform space
Vector2 center = bodyA->position;
center = Mat2MultiplyVector2(Mat2Transpose(bodyB->shape.transform), Vector2Subtract(center, bodyB->position));
// Find edge with minimum penetration
// It is the same concept as using support points in SolvePolygonToPolygon
float separation = -PHYSAC_FLT_MAX;
int faceNormal = 0;
PolygonData vertexData = bodyB->shape.vertexData;
for (int i = 0; i < vertexData.vertexCount; i++)
{
float currentSeparation = MathDot(vertexData.normals[i], Vector2Subtract(center, vertexData.positions[i]));
if (currentSeparation > bodyA->shape.radius)
return;
if (currentSeparation > separation)
{
separation = currentSeparation;
faceNormal = i;
}
}
// Grab face's vertices
Vector2 v1 = vertexData.positions[faceNormal];
int nextIndex = (((faceNormal + 1) < vertexData.vertexCount) ? (faceNormal + 1) : 0);
Vector2 v2 = vertexData.positions[nextIndex];
// Check to see if center is within polygon
if (separation < PHYSAC_EPSILON)
{
manifold->contactsCount = 1;
Vector2 normal = Mat2MultiplyVector2(bodyB->shape.transform, vertexData.normals[faceNormal]);
manifold->normal = (Vector2){ -normal.x, -normal.y };
manifold->contacts[0] = (Vector2){ manifold->normal.x*bodyA->shape.radius + bodyA->position.x, manifold->normal.y*bodyA->shape.radius + bodyA->position.y };
manifold->penetration = bodyA->shape.radius;
return;
}
// Determine which voronoi region of the edge center of circle lies within
float dot1 = MathDot(Vector2Subtract(center, v1), Vector2Subtract(v2, v1));
float dot2 = MathDot(Vector2Subtract(center, v2), Vector2Subtract(v1, v2));
manifold->penetration = bodyA->shape.radius - separation;
if (dot1 <= 0.0f) // Closest to v1
{
if (DistSqr(center, v1) > bodyA->shape.radius*bodyA->shape.radius)
return;
manifold->contactsCount = 1;
Vector2 normal = Vector2Subtract(v1, center);
normal = Mat2MultiplyVector2(bodyB->shape.transform, normal);
MathNormalize(&normal);
manifold->normal = normal;
v1 = Mat2MultiplyVector2(bodyB->shape.transform, v1);
v1 = Vector2Add(v1, bodyB->position);
manifold->contacts[0] = v1;
}
else if (dot2 <= 0.0f) // Closest to v2
{
if (DistSqr(center, v2) > bodyA->shape.radius*bodyA->shape.radius)
return;
manifold->contactsCount = 1;
Vector2 normal = Vector2Subtract(v2, center);
v2 = Mat2MultiplyVector2(bodyB->shape.transform, v2);
v2 = Vector2Add(v2, bodyB->position);
manifold->contacts[0] = v2;
normal = Mat2MultiplyVector2(bodyB->shape.transform, normal);
MathNormalize(&normal);
manifold->normal = normal;
}
else // Closest to face
{
Vector2 normal = vertexData.normals[faceNormal];
if (MathDot(Vector2Subtract(center, v1), normal) > bodyA->shape.radius)
return;
normal = Mat2MultiplyVector2(bodyB->shape.transform, normal);
manifold->normal = (Vector2){ -normal.x, -normal.y };
manifold->contacts[0] = (Vector2){ manifold->normal.x*bodyA->shape.radius + bodyA->position.x, manifold->normal.y*bodyA->shape.radius + bodyA->position.y };
manifold->contactsCount = 1;
}
}
// Solves collision between two polygons shape physics bodies
static void SolvePolygonToPolygon(PhysicsManifold manifold)
{
if ((manifold->bodyA == NULL) || (manifold->bodyB == NULL))
return;
PhysicsShape bodyA = manifold->bodyA->shape;
PhysicsShape bodyB = manifold->bodyB->shape;
manifold->contactsCount = 0;
// Check for separating axis with A shape's face planes
int faceA = 0;
float penetrationA = FindAxisLeastPenetration(&faceA, bodyA, bodyB);
if (penetrationA >= 0.0f)
return;
// Check for separating axis with B shape's face planes
int faceB = 0;
float penetrationB = FindAxisLeastPenetration(&faceB, bodyB, bodyA);
if (penetrationB >= 0.0f)
return;
int referenceIndex = 0;
bool flip = false; // Always point from A shape to B shape
PhysicsShape refPoly; // Reference
PhysicsShape incPoly; // Incident
// Determine which shape contains reference face
if (BiasGreaterThan(penetrationA, penetrationB))
{
refPoly = bodyA;
incPoly = bodyB;
referenceIndex = faceA;
}
else
{
refPoly = bodyB;
incPoly = bodyA;
referenceIndex = faceB;
flip = true;
}
// World space incident face
Vector2 incidentFace[2];
FindIncidentFace(&incidentFace[0], &incidentFace[1], refPoly, incPoly, referenceIndex);
// Setup reference face vertices
PolygonData refData = refPoly.vertexData;
Vector2 v1 = refData.positions[referenceIndex];
referenceIndex = (((referenceIndex + 1) < refData.vertexCount) ? (referenceIndex + 1) : 0);
Vector2 v2 = refData.positions[referenceIndex];
// Transform vertices to world space
v1 = Mat2MultiplyVector2(refPoly.transform, v1);
v1 = Vector2Add(v1, refPoly.body->position);
v2 = Mat2MultiplyVector2(refPoly.transform, v2);
v2 = Vector2Add(v2, refPoly.body->position);
// Calculate reference face side normal in world space
Vector2 sidePlaneNormal = Vector2Subtract(v2, v1);
MathNormalize(&sidePlaneNormal);
// Orthogonalize
Vector2 refFaceNormal = { sidePlaneNormal.y, -sidePlaneNormal.x };
float refC = MathDot(refFaceNormal, v1);
float negSide = MathDot(sidePlaneNormal, v1)*-1;
float posSide = MathDot(sidePlaneNormal, v2);
// Clip incident face to reference face side planes (due to floating point error, possible to not have required points
if (Clip((Vector2){ -sidePlaneNormal.x, -sidePlaneNormal.y }, negSide, &incidentFace[0], &incidentFace[1]) < 2)
return;
if (Clip(sidePlaneNormal, posSide, &incidentFace[0], &incidentFace[1]) < 2)
return;
// Flip normal if required
manifold->normal = (flip ? (Vector2){ -refFaceNormal.x, -refFaceNormal.y } : refFaceNormal);
// Keep points behind reference face
int currentPoint = 0; // Clipped points behind reference face
float separation = MathDot(refFaceNormal, incidentFace[0]) - refC;
if (separation <= 0.0f)
{
manifold->contacts[currentPoint] = incidentFace[0];
manifold->penetration = -separation;
currentPoint++;
}
else
manifold->penetration = 0.0f;
separation = MathDot(refFaceNormal, incidentFace[1]) - refC;
if (separation <= 0.0f)
{
manifold->contacts[currentPoint] = incidentFace[1];
manifold->penetration += -separation;
currentPoint++;
// Calculate total penetration average
manifold->penetration /= currentPoint;
}
manifold->contactsCount = currentPoint;
}
// Integrates physics forces into velocity
static void IntegratePhysicsForces(PhysicsBody body)
{
if ((body == NULL) || (body->inverseMass == 0.0f) || !body->enabled)
return;
body->velocity.x += (body->force.x*body->inverseMass)*(deltaTime/2.0);
body->velocity.y += (body->force.y*body->inverseMass)*(deltaTime/2.0);
if (body->useGravity)
{
body->velocity.x += gravityForce.x*(deltaTime/1000/2.0);
body->velocity.y += gravityForce.y*(deltaTime/1000/2.0);
}
if (!body->freezeOrient)
body->angularVelocity += body->torque*body->inverseInertia*(deltaTime/2.0);
}
// Initializes physics manifolds to solve collisions
static void InitializePhysicsManifolds(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
// Calculate average restitution, static and dynamic friction
manifold->restitution = sqrtf(bodyA->restitution*bodyB->restitution);
manifold->staticFriction = sqrtf(bodyA->staticFriction*bodyB->staticFriction);
manifold->dynamicFriction = sqrtf(bodyA->dynamicFriction*bodyB->dynamicFriction);
for (int i = 0; i < manifold->contactsCount; i++)
{
// Caculate radius from center of mass to contact
Vector2 radiusA = Vector2Subtract(manifold->contacts[i], bodyA->position);
Vector2 radiusB = Vector2Subtract(manifold->contacts[i], bodyB->position);
Vector2 crossA = MathCross(bodyA->angularVelocity, radiusA);
Vector2 crossB = MathCross(bodyB->angularVelocity, radiusB);
Vector2 radiusV = { 0.0f, 0.0f };
radiusV.x = bodyB->velocity.x + crossB.x - bodyA->velocity.x - crossA.x;
radiusV.y = bodyB->velocity.y + crossB.y - bodyA->velocity.y - crossA.y;
// Determine if we should perform a resting collision or not;
// The idea is if the only thing moving this object is gravity, then the collision should be performed without any restitution
if (MathLenSqr(radiusV) < (MathLenSqr((Vector2){ gravityForce.x*deltaTime/1000, gravityForce.y*deltaTime/1000 }) + PHYSAC_EPSILON))
manifold->restitution = 0;
}
}
// Integrates physics collisions impulses to solve collisions
static void IntegratePhysicsImpulses(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
// Early out and positional correct if both objects have infinite mass
if (fabs(bodyA->inverseMass + bodyB->inverseMass) <= PHYSAC_EPSILON)
{
bodyA->velocity = PHYSAC_VECTOR_ZERO;
bodyB->velocity = PHYSAC_VECTOR_ZERO;
return;
}
for (int i = 0; i < manifold->contactsCount; i++)
{
// Calculate radius from center of mass to contact
Vector2 radiusA = Vector2Subtract(manifold->contacts[i], bodyA->position);
Vector2 radiusB = Vector2Subtract(manifold->contacts[i], bodyB->position);
// Calculate relative velocity
Vector2 radiusV = { 0.0f, 0.0f };
radiusV.x = bodyB->velocity.x + MathCross(bodyB->angularVelocity, radiusB).x - bodyA->velocity.x - MathCross(bodyA->angularVelocity, radiusA).x;
radiusV.y = bodyB->velocity.y + MathCross(bodyB->angularVelocity, radiusB).y - bodyA->velocity.y - MathCross(bodyA->angularVelocity, radiusA).y;
// Relative velocity along the normal
float contactVelocity = MathDot(radiusV, manifold->normal);
// Do not resolve if velocities are separating
if (contactVelocity > 0.0f)
return;
float raCrossN = MathCrossVector2(radiusA, manifold->normal);
float rbCrossN = MathCrossVector2(radiusB, manifold->normal);
float inverseMassSum = bodyA->inverseMass + bodyB->inverseMass + (raCrossN*raCrossN)*bodyA->inverseInertia + (rbCrossN*rbCrossN)*bodyB->inverseInertia;
// Calculate impulse scalar value
float impulse = -(1.0f + manifold->restitution)*contactVelocity;
impulse /= inverseMassSum;
impulse /= (float)manifold->contactsCount;
// Apply impulse to each physics body
Vector2 impulseV = { manifold->normal.x*impulse, manifold->normal.y*impulse };
if (bodyA->enabled)
{
bodyA->velocity.x += bodyA->inverseMass*(-impulseV.x);
bodyA->velocity.y += bodyA->inverseMass*(-impulseV.y);
if (!bodyA->freezeOrient)
bodyA->angularVelocity += bodyA->inverseInertia*MathCrossVector2(radiusA, (Vector2){ -impulseV.x, -impulseV.y });
}
if (bodyB->enabled)
{
bodyB->velocity.x += bodyB->inverseMass*(impulseV.x);
bodyB->velocity.y += bodyB->inverseMass*(impulseV.y);
if (!bodyB->freezeOrient)
bodyB->angularVelocity += bodyB->inverseInertia*MathCrossVector2(radiusB, impulseV);
}
// Apply friction impulse to each physics body
radiusV.x = bodyB->velocity.x + MathCross(bodyB->angularVelocity, radiusB).x - bodyA->velocity.x - MathCross(bodyA->angularVelocity, radiusA).x;
radiusV.y = bodyB->velocity.y + MathCross(bodyB->angularVelocity, radiusB).y - bodyA->velocity.y - MathCross(bodyA->angularVelocity, radiusA).y;
Vector2 tangent = { radiusV.x - (manifold->normal.x*MathDot(radiusV, manifold->normal)), radiusV.y - (manifold->normal.y*MathDot(radiusV, manifold->normal)) };
MathNormalize(&tangent);
// Calculate impulse tangent magnitude
float impulseTangent = -MathDot(radiusV, tangent);
impulseTangent /= inverseMassSum;
impulseTangent /= (float)manifold->contactsCount;
float absImpulseTangent = fabs(impulseTangent);
// Don't apply tiny friction impulses
if (absImpulseTangent <= PHYSAC_EPSILON)
return;
// Apply coulumb's law
Vector2 tangentImpulse = { 0.0f, 0.0f };
if (absImpulseTangent < impulse*manifold->staticFriction)
tangentImpulse = (Vector2){ tangent.x*impulseTangent, tangent.y*impulseTangent };
else
tangentImpulse = (Vector2){ tangent.x*-impulse*manifold->dynamicFriction, tangent.y*-impulse*manifold->dynamicFriction };
// Apply friction impulse
if (bodyA->enabled)
{
bodyA->velocity.x += bodyA->inverseMass*(-tangentImpulse.x);
bodyA->velocity.y += bodyA->inverseMass*(-tangentImpulse.y);
if (!bodyA->freezeOrient)
bodyA->angularVelocity += bodyA->inverseInertia*MathCrossVector2(radiusA, (Vector2){ -tangentImpulse.x, -tangentImpulse.y });
}
if (bodyB->enabled)
{
bodyB->velocity.x += bodyB->inverseMass*(tangentImpulse.x);
bodyB->velocity.y += bodyB->inverseMass*(tangentImpulse.y);
if (!bodyB->freezeOrient)
bodyB->angularVelocity += bodyB->inverseInertia*MathCrossVector2(radiusB, tangentImpulse);
}
}
}
// Integrates physics velocity into position and forces
static void IntegratePhysicsVelocity(PhysicsBody body)
{
if ((body == NULL) ||!body->enabled)
return;
body->position.x += body->velocity.x*deltaTime;
body->position.y += body->velocity.y*deltaTime;
if (!body->freezeOrient)
body->orient += body->angularVelocity*deltaTime;
Mat2Set(&body->shape.transform, body->orient);
IntegratePhysicsForces(body);
}
// Corrects physics bodies positions based on manifolds collision information
static void CorrectPhysicsPositions(PhysicsManifold manifold)
{
PhysicsBody bodyA = manifold->bodyA;
PhysicsBody bodyB = manifold->bodyB;
if ((bodyA == NULL) || (bodyB == NULL))
return;
Vector2 correction = { 0.0f, 0.0f };
correction.x = (max(manifold->penetration - PHYSAC_PENETRATION_ALLOWANCE, 0.0f)/(bodyA->inverseMass + bodyB->inverseMass))*manifold->normal.x*PHYSAC_PENETRATION_CORRECTION;
correction.y = (max(manifold->penetration - PHYSAC_PENETRATION_ALLOWANCE, 0.0f)/(bodyA->inverseMass + bodyB->inverseMass))*manifold->normal.y*PHYSAC_PENETRATION_CORRECTION;
if (bodyA->enabled)
{
bodyA->position.x -= correction.x*bodyA->inverseMass;
bodyA->position.y -= correction.y*bodyA->inverseMass;
}
if (bodyB->enabled)
{
bodyB->position.x += correction.x*bodyB->inverseMass;
bodyB->position.y += correction.y*bodyB->inverseMass;
}
}
// Returns the extreme point along a direction within a polygon
static Vector2 GetSupport(PhysicsShape shape, Vector2 dir)
{
float bestProjection = -PHYSAC_FLT_MAX;
Vector2 bestVertex = { 0.0f, 0.0f };
PolygonData data = shape.vertexData;
for (int i = 0; i < data.vertexCount; i++)
{
Vector2 vertex = data.positions[i];
float projection = MathDot(vertex, dir);
if (projection > bestProjection)
{
bestVertex = vertex;
bestProjection = projection;
}
}
return bestVertex;
}
// Finds polygon shapes axis least penetration
static float FindAxisLeastPenetration(int *faceIndex, PhysicsShape shapeA, PhysicsShape shapeB)
{
float bestDistance = -PHYSAC_FLT_MAX;
int bestIndex = 0;
PolygonData dataA = shapeA.vertexData;
for (int i = 0; i < dataA.vertexCount; i++)
{
// Retrieve a face normal from A shape
Vector2 normal = dataA.normals[i];
Vector2 transNormal = Mat2MultiplyVector2(shapeA.transform, normal);
// Transform face normal into B shape's model space
Mat2 buT = Mat2Transpose(shapeB.transform);
normal = Mat2MultiplyVector2(buT, transNormal);
// Retrieve support point from B shape along -n
Vector2 support = GetSupport(shapeB, (Vector2){ -normal.x, -normal.y });
// Retrieve vertex on face from A shape, transform into B shape's model space
Vector2 vertex = dataA.positions[i];
vertex = Mat2MultiplyVector2(shapeA.transform, vertex);
vertex = Vector2Add(vertex, shapeA.body->position);
vertex = Vector2Subtract(vertex, shapeB.body->position);
vertex = Mat2MultiplyVector2(buT, vertex);
// Compute penetration distance in B shape's model space
float distance = MathDot(normal, Vector2Subtract(support, vertex));
// Store greatest distance
if (distance > bestDistance)
{
bestDistance = distance;
bestIndex = i;
}
}
*faceIndex = bestIndex;
return bestDistance;
}
// Finds two polygon shapes incident face
static void FindIncidentFace(Vector2 *v0, Vector2 *v1, PhysicsShape ref, PhysicsShape inc, int index)
{
PolygonData refData = ref.vertexData;
PolygonData incData = inc.vertexData;
Vector2 referenceNormal = refData.normals[index];
// Calculate normal in incident's frame of reference
referenceNormal = Mat2MultiplyVector2(ref.transform, referenceNormal); // To world space
referenceNormal = Mat2MultiplyVector2(Mat2Transpose(inc.transform), referenceNormal); // To incident's model space
// Find most anti-normal face on polygon
int incidentFace = 0;
float minDot = PHYSAC_FLT_MAX;
for (int i = 0; i < incData.vertexCount; i++)
{
float dot = MathDot(referenceNormal, incData.normals[i]);
if (dot < minDot)
{
minDot = dot;
incidentFace = i;
}
}
// Assign face vertices for incident face
*v0 = Mat2MultiplyVector2(inc.transform, incData.positions[incidentFace]);
*v0 = Vector2Add(*v0, inc.body->position);
incidentFace = (((incidentFace + 1) < incData.vertexCount) ? (incidentFace + 1) : 0);
*v1 = Mat2MultiplyVector2(inc.transform, incData.positions[incidentFace]);
*v1 = Vector2Add(*v1, inc.body->position);
}
// Calculates clipping based on a normal and two faces
static int Clip(Vector2 normal, float clip, Vector2 *faceA, Vector2 *faceB)
{
int sp = 0;
Vector2 out[2] = { *faceA, *faceB };
// Retrieve distances from each endpoint to the line
float distanceA = MathDot(normal, *faceA) - clip;
float distanceB = MathDot(normal, *faceB) - clip;
// If negative (behind plane)
if (distanceA <= 0.0f)
out[sp++] = *faceA;
if (distanceB <= 0.0f)
out[sp++] = *faceB;
// If the points are on different sides of the plane
if ((distanceA*distanceB) < 0.0f)
{
// Push intersection point
float alpha = distanceA/(distanceA - distanceB);
out[sp] = *faceA;
Vector2 delta = Vector2Subtract(*faceB, *faceA);
delta.x *= alpha;
delta.y *= alpha;
out[sp] = Vector2Add(out[sp], delta);
sp++;
}
// Assign the new converted values
*faceA = out[0];
*faceB = out[1];
return sp;
}
// Check if values are between bias range
static bool BiasGreaterThan(float valueA, float valueB)
{
return (valueA >= (valueB*0.95f + valueA*0.01f));
}
// Returns the barycenter of a triangle given by 3 points
static Vector2 TriangleBarycenter(Vector2 v1, Vector2 v2, Vector2 v3)
{
Vector2 result = { 0.0f, 0.0f };
result.x = (v1.x + v2.x + v3.x)/3;
result.y = (v1.y + v2.y + v3.y)/3;
return result;
}
// Initializes hi-resolution MONOTONIC timer
static void InitTimer(void)
{
srand(time(NULL)); // Initialize random seed
#if defined(_WIN32)
QueryPerformanceFrequency((unsigned long long int *) &frequency);
#endif
#if defined(__linux__)
struct timespec now;
if (clock_gettime(CLOCK_MONOTONIC, &now) == 0)
frequency = 1000000000;
#endif
#if defined(__APPLE__)
mach_timebase_info_data_t timebase;
mach_timebase_info(&timebase);
frequency = (timebase.denom*1e9)/timebase.numer;
#endif
baseTime = GetTimeCount(); // Get MONOTONIC clock time offset
startTime = GetCurrentTime(); // Get current time
}
// Get hi-res MONOTONIC time measure in seconds
static uint64_t GetTimeCount(void)
{
uint64_t value = 0;
#if defined(_WIN32)
QueryPerformanceCounter((unsigned long long int *) &value);
#endif
#if defined(__linux__)
struct timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
value = (uint64_t)now.tv_sec*(uint64_t)1000000000 + (uint64_t)now.tv_nsec;
#endif
#if defined(__APPLE__)
value = mach_absolute_time();
#endif
return value;
}
// Get current time in milliseconds
static double GetCurrentTime(void)
{
return (double)(GetTimeCount() - baseTime)/frequency*1000;
}
// Returns the cross product of a vector and a value
static inline Vector2 MathCross(float value, Vector2 vector)
{
return (Vector2){ -value*vector.y, value*vector.x };
}
// Returns the cross product of two vectors
static inline float MathCrossVector2(Vector2 v1, Vector2 v2)
{
return (v1.x*v2.y - v1.y*v2.x);
}
// Returns the len square root of a vector
static inline float MathLenSqr(Vector2 vector)
{
return (vector.x*vector.x + vector.y*vector.y);
}
// Returns the dot product of two vectors
static inline float MathDot(Vector2 v1, Vector2 v2)
{
return (v1.x*v2.x + v1.y*v2.y);
}
// Returns the square root of distance between two vectors
static inline float DistSqr(Vector2 v1, Vector2 v2)
{
Vector2 dir = Vector2Subtract(v1, v2);
return MathDot(dir, dir);
}
// Returns the normalized values of a vector
static void MathNormalize(Vector2 *vector)
{
float length, ilength;
Vector2 aux = *vector;
length = sqrtf(aux.x*aux.x + aux.y*aux.y);
if (length == 0)
length = 1.0f;
ilength = 1.0f/length;
vector->x *= ilength;
vector->y *= ilength;
}
#if defined(PHYSAC_STANDALONE)
// Returns the sum of two given vectors
static inline Vector2 Vector2Add(Vector2 v1, Vector2 v2)
{
return (Vector2){ v1.x + v2.x, v1.y + v2.y };
}
// Returns the subtract of two given vectors
static inline Vector2 Vector2Subtract(Vector2 v1, Vector2 v2)
{
return (Vector2){ v1.x - v2.x, v1.y - v2.y };
}
#endif
// Creates a matrix 2x2 from a given radians value
static Mat2 Mat2Radians(float radians)
{
float c = cosf(radians);
float s = sinf(radians);
return (Mat2){ c, -s, s, c };
}
// Set values from radians to a created matrix 2x2
static void Mat2Set(Mat2 *matrix, float radians)
{
float cos = cosf(radians);
float sin = sinf(radians);
matrix->m00 = cos;
matrix->m01 = -sin;
matrix->m10 = sin;
matrix->m11 = cos;
}
// Returns the transpose of a given matrix 2x2
static inline Mat2 Mat2Transpose(Mat2 matrix)
{
return (Mat2){ matrix.m00, matrix.m10, matrix.m01, matrix.m11 };
}
// Multiplies a vector by a matrix 2x2
static inline Vector2 Mat2MultiplyVector2(Mat2 matrix, Vector2 vector)
{
return (Vector2){ matrix.m00*vector.x + matrix.m01*vector.y, matrix.m10*vector.x + matrix.m11*vector.y };
}
#endif // PHYSAC_IMPLEMENTATION