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C++ check collision issue

[2 Replies]
- 05-May-2013 08:00 PM
- Forum: General Discussion
1. Ball::Ball(GLdouble x, GLdouble y, GLdouble z, GLdouble velX, GLdouble velY, GLdouble velZ, GLdouble accelX, GLdouble accelY, GLdouble accelZ, int ballIndex, GLuint textureObject):x(x),y(y),z(z),velX(velX),velY(velY),velZ(velZ),accelX(accelX),accelY(accelY),accelZ(accelZ),ballIndex(ballIndex),textureObject(textureObject)
  {
      setupTexture();
      radius = BALL_SIZE;
      collided = false;
  }
  
  Ball::Ball(GLdouble x, GLdouble y, GLdouble z, int ballIndex, GLuint textureObject):x(x),y(y),z(z),ballIndex(ballIndex),textureObject(textureObject)
  {
      init();
      setupTexture();
  }
  void Ball::init()
  {
  
      velX=0;
      velY=0;
      velZ=0;
      accelX=0;
      accelY=0;
      accelZ=0;
      rotateDeg = 0;
      rotX = 1;
      rotY = 0;
      rotZ = 0;
      angularVelocity=0;
      angularAcceleration=0;
      radius = BALL_SIZE;
      collided = false;
  
  }
  //check collision with table
  bool Ball::checkCollision(GLdouble planex1, GLdouble planex2,GLdouble planez1,GLdouble planez2,double secSinceLastTime)
  {
      bool collisionFlag = false;
      M3DVector3d myMoveVec = {velX * secSinceLastTime,velY * secSinceLastTime,velZ * secSinceLastTime};
      if (x-radius+myMoveVec[0] < planex1)
      {
          velX = -velX;
          x=planex1+radius;
          collisionFlag = true;
      }
      else if (x+radius+myMoveVec[0] > planex2)
      {
          velX = -velX;
          x=planex2-radius;
          collisionFlag = true;
      }
      if (z-radius+myMoveVec[2] < planez2)
      {
          velZ = -velZ;
          z=planez2 + radius;
          collisionFlag = true;
      }
      else if (z+radius+myMoveVec[2] > planez1)
      {
          velZ = -velZ;
          z=planez1 - radius;
          collisionFlag = true;
      }
  
      return false;
  }
  
              double magnitudeFromComponents3D(float x,float y,float z)
              {
                  return sqrt(pow(x,2)+pow(y,2)+pow(z,2));
              }
              double radiansToDegrees(double A)
              {
                  return A*(180 / PI);
              }
              double degreesToRadians(double A)
              {
                  return A*0.0174532925;
              }
              double angleBetweenVectors(float Vx, float Vy, float Vz, float Bx, float By, float Bz)
              {
                  double topLine = (Vx*Bx) + (Vy*By) + (Vz*Bz);
                  double bottomLine = magnitudeFromComponents3D(Vx,Vy,Vz)*magnitudeFromComponents3D(Bx,By,Bz);
  
                  return radiansToDegrees(acos(topLine/bottomLine));
              }
              double sec(double theta)
              {
                  return 1/radiansToDegrees(cos(theta));
              }
              float applyFrictionTo(float pre)
              {
                  float k = 0.03;    // coefficient of friction
                  return (pre*(1-exp(-k)))/k;    // t = 1
              }
  
  //check collision with another ball
  bool Ball::checkCollision(Ball *otherBall,double secSinceLastTime)
  {
  
      if(collided)
      {
  
          return true;
      }
  
      if(otherBall->collided)
      {
          if(otherBall->collidedBall->ballIndex == this->ballIndex)
          {
              return true;
          }
      }
  
      return true;
  }
  
  void Ball::collide(Ball *otherBall,double secSinceLastTime)
  {
  
  
      if((pow((x-otherBall ->x),2)+pow((z-otherBall ->z),2))<0.015)
              {
                  float bx = otherBall ->x-x;
                  float by = otherBall ->y-y;
                  float bz = otherBall ->z-z;
                  float mag = magnitudeFromComponents3D(bx,by,bz);
  
                  // get unit normal
                  float ubx = bx/mag;
                  float ubz = bz/mag;
  
                  // get unit tangent
                  float utx = -ubz;
                  float utz = ubx;
  
                  // project velocities onto normal and tangent
                  float v1n = ubx*velX+ubz*velZ;
                  float v1tA = utx*velX+utz*velZ;
                  float v2n = ubx*otherBall ->velX+ubz*otherBall->velZ;
                  float v2tA = utx*otherBall->velX+utz*otherBall->velZ;
  
                  float v1nA = (v1n*(1-1)+2*v2n)/2;
                  float v2nA = (v2n*(1-1)+2*v1n)/2;
  
                  float v1nx = ubx*v1nA;
                  float v1nz = ubz*v1nA;
                  float v1tx = utx*v1tA;
                  float v1tz = utz*v1tA;
                  float v2nx = ubx*v2nA;
                  float v2nz = ubz*v2nA;
                  float v2tx = utx*v2tA;
                  float v2tz = utz*v2tA;
  
  
                  velX=v1nx+v1tx;
                  velZ=v1nz+v1tz;
                  otherBall->velX=v2nx+v2tx;
                  otherBall->velZ=v2nz+v2tz;
              }
  
  }
I am really new to opengl and c++, I was working on a billiards game. I have everything working except for the collisions. I needed to try to finish up my CheckCollision method also double checking my collide method would be appreciated as well. I can't figure out how to compare to balls and then find there distance and then calculate there speed before and after the collision. I have some of the ideas down but I am lost on how I can get to where I need to go. I've just been reading online articles and so forth trying to figure it all out. Any suggestions or help would be greatly appreciated.

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