Question

I have this SphereInFrustrum function here:

0.49%  int FrustumG::sphereInFrustum(Vec3 &p, float radius) {

        int result = INSIDE;
        float distance;

2.40%   for(int i=0; i < 6; i++) {
7.94%       distance = pl[i].distance(p);
12.21%      if (distance < -radius)
0.67%           return OUTSIDE;
3.67%       else if (distance < radius)
                result =  INTERSECT;
        }
        return(result);

       }

The numbers are from my code profiler. The issue is that, this check is taking longer than actually rendering. The whole point of implementing geometry culling was so that I could have really big levels. I really just need a very quick and dirty way to see if an AABB is in or out. Right now I provide it with the radius of the cube and the center. Given that my boxes are AABB, is there a faster way to do this? I favor speed over accuracy.

Thanks

If I provided the cube’s min and max would that make it faster? I’m sure there must be a way to do this without the distance formula with an expensif square root;

float Plane::distance(Vec3 &p) {

    return (d + normal.innerProduct(p));
}


float Vec3::innerProduct(Vec3 &v) {

    return (x * v.x + y * v.y + z * v.z);
}

Answer 1

I wanted to just leave a comment to ask a question but i only seem to be able to leave an answer, this is just an observation:

Does this code really do what you want to do?

        int result = INSIDE;
        float distance;

2.40%   for(int i=0; i < 6; i++) {
7.94%       distance = pl[i].distance(p);
12.21%      if (distance < -radius)
0.67%           return OUTSIDE;
3.67%       else if (distance < radius)
                result =  INTERSECT;

how this function reads to me is, assume the sphere is inside, for each point on your frustrum i, take the distance between i and the center of sphere p, if this distance is less than negative radius… and here my paradigm is destroyed.

So this returns early if you have a negative distance that is less than your negative radius? Is that really what you want right there?