Ball.cpp

00001 #include "Ball.h"
00002 #include "Paddle.h"
00003 #include <math.h>
00004 
00005 Ball::Ball()
00006 {
00007     reset(); // initial parameters of ball 
00008 }
00009 
00010 Ball::~Ball()
00011 {
00012 }
00013 
00014 void Ball::move()
00015 {
00016     GameObject::move();
00017     
00018     // Right edge 
00019     if (pos.x > WIDTH-1) {
00020         velocity.x = -velocity.x;
00021         pos.x = WIDTH-1;
00022     } 
00023     // Left edge 
00024     else if(pos.x < 1) {
00025         velocity.x = -velocity.x;
00026         pos.x = 1;
00027     }
00028     // Top edge 
00029     if (pos.y < 1) {
00030         velocity.y = -velocity.y;
00031         pos.y = 1;
00032     }
00033     // Bottom edge  
00034     else if (pos.y > HEIGHT-1) {
00035         velocity.y = -velocity.y;
00036         pos.y = HEIGHT-1;
00037     }
00038 }
00039 
00040 
00041 #define PI 3.14159265
00042 float Deg2Rad = PI / 180;
00043 float Rad2Deg = 180 / PI;
00044 
00045 // NOTE: This is how our coordinate system is setup. 
00046 // angles go clock-wise, right is zero, up is -pi/2, down is pi/2 
00047 // printf("angle of down: %.02f\n", atan2(1.f, 0)); 
00048 // printf("angle of right: %.02f\n", atan2(0.f, 1)); 
00049 // printf("angle of up: %.02f\n", atan2(-1.f, 0)); 
00050 
00051 // Standard rotation of a vector by given degrees 
00052 // Example of this function to play around with: https://repl.it/repls/HopefulTrimWordprocessing 
00053 void Rotate(Vector2D& v, float degrees) 
00054 {
00055     float s = (float)sin(degrees * Deg2Rad); // stores sin value betweem -1 and 1 
00056     float c = (float)cos(degrees * Deg2Rad); // stores cos value betweem -1 and 1 
00057      
00058     float tx = v.x;     // 2D Vector (tx, ty) for the velocity 
00059     float ty = v.y;
00060     
00061     // Rotation: Multiply vector by rotation matrix
00062     v.x = (c * tx) - (s * ty);
00063     v.y = (s * tx) + (c * ty);
00064 }
00065 
00066 /** Sets upper and lower boundary for angle 
00067 * @return clamped angle between sane boundaries 
00068 */
00069 float clamp(float x, float minn, float maxx) 
00070 {
00071     return min(max(x, minn), maxx);
00072 }
00073  
00074 
00075 void Ball::hitPad(Paddle &paddle)
00076 {
00077     const Vector2D& posPad = paddle.getPos();
00078     if (pos.y >= posPad.y - 1 && (pos.x >= posPad.x && pos.x <= posPad.x + paddle.getW())) {
00079         // We hit the pad 
00080         
00081         // First: rotate about paddle's surface normal (flip upward) 
00082         velocity.y = -velocity.y;
00083         
00084         // Change angle based on distance to center
00085         float distanceSensitivity = 120;            // Add at most this many degrees 
00086         float maxDx = paddle.getW()/2;              // Maximum distance from centre 
00087         float cx = posPad.x + paddle.getW()/2.0f;   // Maximum distance from current paddle centre 
00088         float dx = pos.x - cx;                      // Positive dx means right of center, 0 means at center 
00089         
00090         float dangle = dx/maxDx * distanceSensitivity; // Delta angle, meaning change in angle 
00091         float currentAngle = atan2(velocity.y, velocity.x)*Rad2Deg; // Angle of our original outgoing velocity vector 
00092         float newAngle = currentAngle + dangle; // The current angle + the change in the angle 
00093         
00094         //printf("angle: %.02f %.02f, %.02f\n", dx, currentAngle, newAngle);
00095         
00096         
00097         // Always clamp angle in sane boundaries 
00098         newAngle = clamp(newAngle, -160, -20); // Clamp to the range of an upward facing cone (NOTE: -90 degrees is up) 
00099         
00100         // Rotate the outgoing vector by the clamped dangle 
00101         dangle = newAngle - currentAngle;
00102         Rotate(velocity, dangle);
00103         
00104     }
00105 
00106 }
00107 
00108 int Ball::randomize()
00109 {
00110     AnalogIn noisy(PTB0);           // Disconnected pin so will have random noise 
00111     srand(1000000*noisy.read());    // Read the random noise and seed 
00112     int direction = rand() % 2;     // Randomise initial direction 
00113     int movement;                   // Int to store the x-direction 
00114     if (direction == 0) {
00115         movement = -1;
00116     } else if (direction == 1) {
00117         movement = 1;
00118     }
00119     return movement;
00120 }
00121 
00122 void Ball::reset()
00123 {
00124     pos.x = WIDTH/2;                // initial position of ball on x-axis 
00125     pos.y = HEIGHT - GAP - 2;       // initial position of ball on y-axis 
00126     velocity.x = randomize();       // initial x-velocity of ball 
00127     velocity.y = -1;                // initial y-velocity of ball 
00128     w = 1;                          // width of the ball 
00129     h = 1;                          // height of the ball
00130 }