That is essentially my problem. The colour is equal to the distance along the ray that is needed to reach the surface of the sphere. Other than that white spot in the center, it looks correct to me. However, I cannot figure out what that white spot is. Here is my intersection code:
float sphere::intersect(const ray &r)
{
// ray(t) = o + t * d
// sphere(p): dot(p - c, p - c) = r^2
// substitute and solve for t and we get a quadratic:
// a = dot(d, d)
// b = 2 * dot(o - c, d)
// c = dot(o - c, o - c) - r^2
vec3 dir = r.orig - pos;
float a = r.dir.sqlength();
float b = 2.0f * dir.dot(r.dir);
float c = dir.sqlength() - radius * radius;
float disc = b * b - 4.0f * a * c;
// imaginary roots, doesn't intersect the sphere
if (disc < 0)
return -1; // the renderer ignores negative distances
float t = (-b - std::sqrt(disc)) / (2.0f * a);
return t;
}
Any ideas? I've tried multiple intersection routines besides my own (above), and they all end up doing the same thing. Here is my ray-generation code:
vec3 plane(float(x) / WIDTH * 2 - 1, float(y) / HEIGHT * 2 - 1, 0);
r.orig = vec3(0, 0, 0);
r.dir = plane + vec3(0, 0, -1);
r.dir.normalize();
I'm pretty sure that's not the issue, though, since even making some simple orthographic rays yields the same issue.
