void StressTest( void )
{
volatile float v1 = 2.0f;
volatile float v2 = 3.0f;
volatile float v3 = 7.0f;
volatile float v4 = -5.0f;
volatile float v5 = 9.0f;
volatile float v6 = 4.0f;
volatile float v7 = 22.23f;
volatile float v8 = 0.234f;
Vect2D A;
Vect2D B;
B.setX(v1);
B.setY(v2);
Vect2D C;
C.set(v3,v4);
Vect2D D;
D.set(v5, v6);
Vect2D sum;
sum = A + B + C + D;
Vect2D ScaledA = B * v7;
Vect2D ScaledB = C / v8;
Vect2D DiffVect = ScaledB - ScaledA;
sum.setX( v1 );
ScaledA.setX( v3 );
DiffVect.setX( v7 );
A = sum + ScaledA;
B = DiffVect - C;
D = DiffVect / ScaledA.getY();
A = B + C;
A = A - B - C;
A = A * v4;
A = A / v5;
volatile Vect2D F = A;
}
Collision::Collision(PObject* obj1, PObject* obj2)
{
trueCollision = false;
objects = new PObject*[2];
objects[0] = obj1;
objects[1] = obj2;
/*
* the following was written before the Vect2D class was written
* (and that's why it's so messy)
*/
Vect2D norm;
Point p1,p2;
const Point* obj1vertices = objects[0]->getVertices();
const Point* obj2vertices = objects[1]->getVertices();
int numPoints=0;
float sumx=0;
float sumy=0;
float parametric;
float parametric2;
float denominator;
float vec1x;
float vec1y;
float vec1deltax;//between this point and the next one in the shape (going counterclockwise)
float vec1deltay;
float vec2x;
float vec2y;
float vec2deltax;
float vec2deltay;
float deltax, deltay; //between the two points on different shapes
/*
* x1+k*t = x2+c*k
* y1+b*t = y2+d*k
*/
for (int i = 0; i < objects[0]->getNumVertices(); i++)
{
vec1x = obj1vertices[i].x;//x1
vec1y = obj1vertices[i].y;//y1
vec1deltax = obj1vertices[(i + 1) % objects[0]->getNumVertices()].x - vec1x;//a
vec1deltay = obj1vertices[(i + 1) % objects[0]->getNumVertices()].y - vec1y;//b
for (int j = 0; j < objects[1]->getNumVertices(); j++)
{
vec2x = obj2vertices[j].x;//x2
vec2y = obj2vertices[j].y;//y2
vec2deltax = obj2vertices[(j + 1) % objects[1]->getNumVertices()].x - vec2x;//c
vec2deltay = obj2vertices[(j + 1) % objects[1]->getNumVertices()].y - vec2y;//d
denominator = (vec1deltax * vec2deltay) - (vec2deltax * vec1deltay);//ad-bc
if (denominator != 0)
{
deltax = vec1x-vec2x;//x1-x2
deltay = vec1y-vec2y;//y1-y2
parametric = ((vec2deltax * (deltay)) - vec2deltay * (deltax)) / (denominator);//t
parametric2 = ((vec1deltax * (deltay)) - vec1deltay * (deltax)) / (denominator);//k
if (parametric <= 1 && parametric >= 0 && parametric2 <= 1 && parametric2 >= 0)
{
numPoints++;
sumx += vec1x + (parametric * vec1deltax);//x = x1+a*t
sumy += vec1y + (parametric * vec1deltay);//y = y1+b*t
//uses the normal vector of the first collision
if (!trueCollision){
/* old way of finding
//figure out which one collided on the corner
if (abs(parametric2-.5) < abs(parametric-.5)){
//vector1's point of collision was closer to the corner
norm.set(vec2deltay,-vec2deltax);
}
else
{
norm.set(vec2deltax,-vec2deltay);
}*/
//VERY crude approximation for normal vector at collision point
norm.set(objects[1]->get_centerx()-objects[0]->get_centerx(), objects[1]->get_centery()-objects[0]->get_centery());
norm.normalize();
}
trueCollision = true;
}
}
}
}
if (trueCollision)
{
intersection.x = sumx/numPoints;
intersection.y = sumy/numPoints;
//calculate impulse here
float e = objects[0]->get_elasticity()*objects[1]->get_elasticity();
Vect2D r1(intersection.x-objects[0]->get_centerx(), intersection.y-objects[0]->get_centery());
Vect2D r2(intersection.x-objects[1]->get_centerx(), intersection.y-objects[1]->get_centery());
//vap = vcenter + w x r1 where w is angular velocity vector that points into screen
//vap = velocity of point of collision on each object
Vect2D vap(objects[0]->get_vx()-objects[0]->get_dtheta()*r1.y, objects[0]->get_vy()+objects[0]->get_dtheta()*r1.x);
Vect2D vbp(objects[1]->get_vx()-objects[1]->get_dtheta()*r2.y, objects[1]->get_vy()+objects[1]->get_dtheta()*r2.x);
Vect2D& vabp = vap-vbp;
float ran = r1.cross(norm);
float rbn = r2.cross(norm);
//source: http://www.myphysicslab.com/collision.html
float j= (-(1+e)*vabp.dot(norm))/(1/objects[0]->get_mass() + 1/objects[1]->get_mass() + ran*ran/objects[0]->get_momentInertia() + rbn*rbn/objects[1]->get_momentInertia());
impulse.set(norm);
impulse.scale(j);
}
}
