BOOL Plane::GetIntersection(const Vect &p1, const Vect &p2, float &fT) const
{
float P1Dist = p1.DistFromPlane(*this);
float P2Dist = p2.DistFromPlane(*this);
if(CloseFloat(P1Dist, 0.0f, EPSILON))
{
if(P2Dist == 0.0f)
return 0;
fT = 0.0f;
return 1;
}
else if(CloseFloat(P2Dist, 0.0f, EPSILON))
{
fT = 1.0f;
return 1;
}
BOOL bP1Over = (P1Dist > 0.0f);
BOOL bP2Over = (P2Dist > 0.0f);
if(bP1Over == bP2Over)
return FALSE;
float P1AbsDist = fabs(P1Dist);
float dist2 = (P1AbsDist+fabs(P2Dist));
if(dist2 < EPSILON)
return FALSE;
fT = P1AbsDist/dist2;
return TRUE;
}
BOOL PointOnFiniteLine(const Vect &lineV1, const Vect &lineV2, const Vect &p)
{
Vect line = lineV2-lineV1;
float lineDist = line.Len();
Plane plane;
plane.Dir = line*(1.0f/lineDist);
plane.Dist = plane.Dir.Dot(lineV1);
float dist = p.DistFromPlane(plane);
if((dist < 0.0f) || (dist > lineDist))
return FALSE;
float fT = (dist/lineDist);
return p.CloseTo(Lerp(lineV1, lineV2, fT));
}
// yes, I realize this breaks on caps when the ray origin is inside the cylinder.
// it's not like it's actually going to be in there anyway.
BOOL CylinderRayCollision(const Vect ¢er, float radius, float height, const Vect &rayOrig, const Vect &rayDir, Vect *collision, Plane *collisionPlane)
{
Vect collisionValue;
BOOL bHit = FALSE;
float fT;
Plane axisPlane(0.0f, 1.0f, 0.0f, center.y);
//---------------------------------------
// test the cap
if(fabs(rayDir.y) > EPSILON)
{
BOOL bUnder = (rayDir.y<0.0f);
Plane planeCap;
planeCap.Dir.Set(0.0f, bUnder ? 1.0f : -1.0f, 0.0f);
planeCap.Dist = (bUnder ? center.y : -center.y)+height;
if(rayOrig.DistFromPlane(planeCap) > 0.0f)
{
if(planeCap.GetRayIntersection(rayOrig, rayDir, fT))
{
collisionValue = rayOrig+(rayDir*fT);
Vect CapCenter = center+(planeCap.Dir*height);
if(collisionValue.Dist(CapCenter) <= radius)
{
if(collisionPlane)
*collisionPlane = planeCap;
bHit = TRUE;
}
}
}
}
if(!bHit && ((1.0f-fabs(rayDir.y)) > EPSILON))
{
//---------------------------------------
// test the body
Vect adjDir, adjCenter;
adjDir.Set(rayDir.x, 0.0f, rayDir.z).Norm();
adjCenter.Set(center.x, rayOrig.y, center.z);
Vect l = (adjCenter-rayOrig);
float d = l | adjDir; //distance from adjDir Plane
float l2 = l | l; //c-o distance squared
float r2 = radius*radius;
if(l2 < r2) //if inside the cylinder, fail
return FALSE;
if((d < 0.0f) && (l2 > r2)) //if the plane distance is negative, and
return FALSE; //the distance is over the radius, fail
float m2 = l2 - (d*d); //distance from the cylinder center to
//the closest ray point
if(m2 > r2) //if m2 is larger than the radius, fail
return FALSE;
float q = sqrt(r2-m2); //real distance from the edge of the
//cylinder to the cloest ray point
//(forms a sort of triangle)
fT = (l2 > r2) ? (d-q) : (d+q); //if the distance is over the radius,
//d-q = T, else d+q=T
//distance
fT /= (adjDir|rayDir); //divide by angle to get the proper
//value
collisionValue = rayOrig+(rayDir*fT);
if(fabs(collisionValue.DistFromPlane(axisPlane)) >= height)
return FALSE;
if(collisionPlane)
{
Vect temp = collisionValue;
temp.y = center.y;
collisionPlane->Dir = (temp-center).Norm();
collisionPlane->Dist = collisionPlane->Dir|temp;
}
bHit = TRUE;
}
if(!bHit)
return FALSE;
if(collision)
*collision = collisionValue;
return TRUE;
}
