classPointMass.h

00001 /*
00002  *  pointMass.h
00003  *  laserBlob
00004  *
00005  *  Created by CASSINELLI ALVARO on 5/19/11.
00006  *  Copyright 2011 TOKYO UNIVERSITY. All rights reserved.
00007  *
00008  */
00009 
00010 #ifndef POINTMASS_H
00011 #define POINTMASS_H
00012 
00013 #include "myVectorClass.h"
00014 
00015 #define VERLET_METHOD // comment this to have EULER method
00016 
00017 #define MAX_PERMISSIBLE_SPEED 35
00018 
00019 class pointMass
00020 {
00021 public:
00022     
00023     // ==================================== Static variables and methods ============== 
00024     static vector2Df maxWall, minWall; //equal for ALL THE MASS OBJECTS (declare static). But it could be per-mass. The problem with that approach would be too much wasted memory. 
00025     // NOTE: - a static member variable has the same value in any instance of the class and doesn't even require an instance of the class to exist.
00026     //       - a static class member cannot be initialized inside of the class declaration. In fact, if you decide to put your code in a header file, you cannot even initialize the static variable 
00027     //         inside of the header file; do it in a .cpp file instead. Moreover, you are required to initialize the static class member or it will not be in scope. 
00028     //         The syntax is a bit weird: "type class_name::static_variable = value", or in this case vector2Df pointMass::maxWall(4095, 4095)
00029    
00030     // methods:
00031     static void setWallLimits(float mminx, float mminy, float mmaxx, float mmaxy);
00032     
00033     // ==================================== METHODS ====================================
00034     pointMass();
00035     virtual ~pointMass(){};
00036         
00037     // Adding forces to total force:
00038     void resetForce();
00039     void addForce(float x, float y);
00040     void addForce(vector2Df force);
00041     void addDampingForce();
00042     void addInvSquareForce(float x, float y, float radiusMax, float radiusMin, float scale);
00043     void addInterInvSquareForce(pointMass &p, float radiusMin, float radiusMax, float scale);
00044         
00045     // (a blob object could be defined by a "cord" of chained particles, plus a center)
00046     void addSpringForce(float x, float y,  float radius, float scale);
00047     void addInterSpringForce(pointMass &p, float radius, float scale);
00048     //void addClockwiseForce(particle &p, float radius, float scale);
00049     //void addCounterClockwiseForce(particle &p, float radius, float scale);
00050     
00051     //void addDampingForce(); // this work in the case of the euler integration; in case of Verlet, we need to do pseudo-damping while calculating
00052     // the acceleration... 
00053     
00054     // Set parameters:
00055     void setInitialCondition(float px, float py, float vx, float vy);
00056     void setInitialCondition(vector2Df _pos, vector2Df _speed);
00057     void setIntegrationStep(float _dt);
00058     
00059     void setPos(float px, float py); // assuming the speed is unchanged (must do some tweaking in case of Verlet integration)
00060     
00061     // dynamic update:
00062     void update();
00063     
00064     // kinematic constraints (could be based on a force too...)
00065     //void setWallLimits(float mminx, float mminy, float mmaxx, float mmaxy); // DECLARED STATIC
00066     void bounceOffWalls();
00067     
00068     vector2Df getSpeed(); // get an estimation of the speed (also update speed variable - this variable is not needed in case of VERLET)
00069     void setSpeed(const vector2Df& vel);
00070     void setSpeed(float vx, float vy);
00071     
00072     // ==================================== VARIABLES ====================================
00073     
00074     int identifier; // this may be needed in particular in case we don't use vector<> (case of poor C Arduino compiler)
00075     
00076     // kinematic variables:
00077     vector2Df  pos, posOld; // I will use verlet integration (perhaps we could have a switch to choose the integration method?)
00078     //vector2D  speed; // speed at time t (this is not explicitly calculated in case of verlet method, HENCE PRIVATE)
00079     vector2Df  acc;   // Acceleration at time t (equal to the total force divided by the mass). No real need to have it here, but convenient to check. 
00080     vector2Df  totalForce; // this is just for convenience and speeding up calculation when adding forces, before computing acc. 
00081     
00082     // integration step:
00083     float dt; 
00084     
00085     // physical parameters:
00086     float dampMotion;
00087     float dampBorder;
00088     float mass;
00089     bool  bFixed; // these could act as control points that could be loaded (letters...). In fact, we could use mass to set this (like mass=-1)
00090     
00091     // other things:   
00092     bool bWallCollision; // this is generic (detect any collision with a side)
00093     vector2Df innerCollitionDirection; // this is smarter than a boolean, because I can detect which side was touched and do different things (but may be memory consuming)
00094     
00095 protected:
00096     
00097 private:
00098       vector2Df  speed; // speed at time t (this is not explicitly calculated in case of verlet method, HENCE MAY BE PRIVATE)
00099     
00100 };
00101 
00102 
00103 #endif //POINTMASS_H