float rayIntersectDisk(ShadeRec* sr, Disk* disk, const Ray ray)
{
vec3 displacement;
vec3_sub(displacement, disk->center, ray.origin);
float t = vec3_dot(displacement, disk->normal) / vec3_dot(ray.direction, disk->normal);
if(t > K_EPSILON)
{
vec3 hit_point;
getPointOnRay(hit_point, ray, t);
vec3_sub(displacement, hit_point, disk->center);
if(vec3_length(displacement) <= disk->radius)
{
vec3_negate(sr->wo, ray.direction);
if(vec3_dot(sr->wo, disk->normal) < 0)
{
vec3_negate(sr->wo, disk->normal);
}else
{
vec3_copy(sr->normal, disk->normal);
}
vec3_copy(sr->hit_point, hit_point);
sr->mat = *(disk->mat);
return t;
}
}
return TMAX;
}
Vector Ray::nearestPointOnZAxis(Vector Origin) const
{
Origin[3] = 0;
float t = nearestTOnZAxis(Origin);
Vector result = getPointOnRay(t);
// project to axis
result[0] = Origin[0];
result[1] = Origin[1];
return result;
}
float shadowRayIntersectDisk(const Disk* disk, const Ray ray)
{
vec3 displacement;
vec3_sub(displacement, disk->center, ray.origin);
float t = vec3_dot(displacement, disk->normal) / vec3_dot(ray.direction, disk->normal);
if(t > K_EPSILON)
{
vec3 hit_point;
getPointOnRay(hit_point, ray, t);
vec3_sub(displacement, hit_point, disk->center);
if(vec3_length(displacement) <= disk->radius)
{
return t;
}
}
return TMAX;
}
