Hello folks, I've created a basic collision detection routine following this document: http://www.lighthouse3d.com/tutorials/maths/ray-triangle-intersection/
I'd like to monitor the distance from the point P and the triangle being tested for intersection, so that I can stop the routine when the distance falls below a certain value.
I tried modifying the 0.00001 values in the code thinking that it was meant to be a tolerance value for such collision "distance", but it seems to be ineffective.
What do you think? There is a way to do it? Here below is the routine derived from the document above:
int rayIntersectsTriangle(vector3_t orig, vector3_t dir, vector3_t v0, vector3_t v1, vector3_t v2) {
float a,f,u,v,t;
vector3_t e1= v1-v0;
vector3_t e2= v2-v0;
vector3_t h=dir^e2;
a = e1*h;
if (a > -0.00001 && a < 0.00001) return(false);
f = 1.0/a;
vector3_t s=orig-v0;
u = f * (s*h);
if (u < 0.0 || u > 1.0) return(false);
vector3_t q=s^e1;
v = f * (dir*q);
if (v < 0.0 || u + v > 1.0) return(false);
// at this stage we can compute t to find out where the intersection point is on the line
t = f * (e2*q);
if (t > 0.00001) // ray intersection
return(true);
else // this means that there is a line intersection
// but not a ray intersection
return (false);
}
Can you try to describe more clearly what you mean by "I'd like to monitor the distance from the point P and the triangle being tested for intersection, so that I can stop the routine when the distance falls below a certain value."
FWIW, the line if (a > -0.00001 && a < 0.00001) return(false); is testing if the ray is parallel to the triangle face, if it is, then the function is deciding that there's no collision.
Is it possible that what you want is for your ray to have some thickness? If so, then you need to look at swept/moving sphere vs triangle intersections.
