int CPhysEnv::CheckForCollisions( tParticle *system )
{
// be optimistic!
int collisionState = NOT_COLLIDING;
float const depthEpsilon = 0.001f;
int loop;
tParticle *curParticle;
m_ContactCnt = 0; // THERE ARE CURRENTLY NO CONTACTS
curParticle = system;
for (loop = 0; (loop < m_ParticleCnt) && (collisionState != PENETRATING);
loop++,curParticle++)
{
// CHECK THE MAIN BOUNDARY PLANES FIRST
for(int planeIndex = 0;(planeIndex < m_CollisionPlaneCnt) &&
(collisionState != PENETRATING);planeIndex++)
{
tCollisionPlane *plane = &m_CollisionPlane[planeIndex];
float axbyczd = DotProduct(&curParticle->pos,&plane->normal) + plane->d;
if(axbyczd < -depthEpsilon)
{
// ONCE ANY PARTICLE PENETRATES, QUIT THE LOOP
collisionState = PENETRATING;
}
else
if(axbyczd < depthEpsilon)
{
float relativeVelocity = DotProduct(&plane->normal,&curParticle->v);
if(relativeVelocity < 0.0f)
{
collisionState = COLLIDING;
m_Contact[m_ContactCnt].particle = loop;
memcpy(&m_Contact[m_ContactCnt].normal,&plane->normal,sizeof(tVector));
m_ContactCnt++;
}
}
}
if (m_CollisionActive)
{
// THIS IS NEW FROM MARCH - ADDED SPHERE BOUNDARIES
// CHECK ANY SPHERE BOUNDARIES
for(int sphereIndex = 0;(sphereIndex < m_SphereCnt) &&
(collisionState != PENETRATING);sphereIndex++)
{
tCollisionSphere *sphere = &m_Sphere[sphereIndex];
tVector distVect;
VectorDifference(&curParticle->pos, &sphere->pos, &distVect);
float radius = VectorSquaredLength(&distVect);
// SINCE IT IS TESTING THE SQUARED DISTANCE, SQUARE THE RADIUS ALSO
float dist = radius - (sphere->radius * sphere->radius);
if(dist < -depthEpsilon)
{
// ONCE ANY PARTICLE PENETRATES, QUIT THE LOOP
collisionState = PENETRATING;
}
else
if(dist < depthEpsilon)
{
// NORMALIZE THE VECTOR
NormalizeVector(&distVect);
float relativeVelocity = DotProduct(&distVect,&curParticle->v);
if(relativeVelocity < 0.0f)
{
collisionState = COLLIDING;
m_Contact[m_ContactCnt].particle = loop;
memcpy(&m_Contact[m_ContactCnt].normal,&distVect,sizeof(tVector));
m_ContactCnt++;
}
}
}
}
}
return collisionState;
}
/* returns length of input vector */
double VectorLength(vertex *v)
{
return(sqrt(VectorSquaredLength(v)));
}
