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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2011-2022 Blender Foundation */
#ifndef __UTIL_MATH_INTERSECT_H__
#define __UTIL_MATH_INTERSECT_H__
CCL_NAMESPACE_BEGIN
/* Ray Intersection */
ccl_device bool ray_sphere_intersect(float3 ray_P,
float3 ray_D,
float ray_tmin,
float ray_tmax,
float3 sphere_P,
float sphere_radius,
ccl_private float3 *isect_P,
ccl_private float *isect_t)
{
const float3 d = sphere_P - ray_P;
const float radiussq = sphere_radius * sphere_radius;
const float tsq = dot(d, d);
if (tsq > radiussq) {
/* Ray origin outside sphere. */
const float tp = dot(d, ray_D);
if (tp < 0.0f) {
/* Ray points away from sphere. */
return false;
}
const float dsq = tsq - tp * tp; /* Pythagoras. */
if (dsq > radiussq) {
/* Closest point on ray outside sphere. */
return false;
}
const float t = tp - sqrtf(radiussq - dsq); /* pythagoras */
if (t > ray_tmin && t < ray_tmax) {
*isect_t = t;
*isect_P = ray_P + ray_D * t;
return true;
}
}
return false;
}
ccl_device bool ray_aligned_disk_intersect(float3 ray_P,
float3 ray_D,
float ray_tmin,
float ray_tmax,
float3 disk_P,
float disk_radius,
ccl_private float3 *isect_P,
ccl_private float *isect_t)
{
/* Aligned disk normal. */
float disk_t;
const float3 disk_N = normalize_len(ray_P - disk_P, &disk_t);
const float div = dot(ray_D, disk_N);
if (UNLIKELY(div == 0.0f)) {
return false;
}
/* Compute t to intersection point. */
const float t = -disk_t / div;
if (!(t > ray_tmin && t < ray_tmax)) {
return false;
}
/* Test if within radius. */
float3 P = ray_P + ray_D * t;
if (len_squared(P - disk_P) > disk_radius * disk_radius) {
return false;
}
*isect_P = P;
*isect_t = t;
return true;
}
ccl_device bool ray_disk_intersect(float3 ray_P,
float3 ray_D,
float ray_tmin,
float ray_tmax,
float3 disk_P,
float3 disk_N,
float disk_radius,
ccl_private float3 *isect_P,
ccl_private float *isect_t)
{
const float3 vp = ray_P - disk_P;
const float dp = dot(vp, disk_N);
const float cos_angle = dot(disk_N, -ray_D);
if (dp * cos_angle > 0.f) // front of light
{
float t = dp / cos_angle;
if (t < 0.f) { /* Ray points away from the light. */
return false;
}
float3 P = ray_P + t * ray_D;
float3 T = P - disk_P;
if (dot(T, T) < sqr(disk_radius) && (t > ray_tmin && t < ray_tmax)) {
*isect_P = ray_P + t * ray_D;
*isect_t = t;
return true;
}
}
return false;
}
ccl_device_forceinline bool ray_triangle_intersect(float3 ray_P,
float3 ray_dir,
float ray_tmin,
float ray_tmax,
const float3 tri_a,
const float3 tri_b,
const float3 tri_c,
ccl_private float *isect_u,
ccl_private float *isect_v,
ccl_private float *isect_t)
{
#define dot3(a, b) dot(a, b)
const float3 P = ray_P;
const float3 dir = ray_dir;
/* Calculate vertices relative to ray origin. */
const float3 v0 = tri_c - P;
const float3 v1 = tri_a - P;
const float3 v2 = tri_b - P;
/* Calculate triangle edges. */
const float3 e0 = v2 - v0;
const float3 e1 = v0 - v1;
const float3 e2 = v1 - v2;
/* Perform edge tests. */
const float U = dot(cross(v2 + v0, e0), ray_dir);
const float V = dot(cross(v0 + v1, e1), ray_dir);
const float W = dot(cross(v1 + v2, e2), ray_dir);
const float minUVW = min(U, min(V, W));
const float maxUVW = max(U, max(V, W));
if (minUVW < 0.0f && maxUVW > 0.0f) {
return false;
}
/* Calculate geometry normal and denominator. */
const float3 Ng1 = cross(e1, e0);
// const Vec3vfM Ng1 = stable_triangle_normal(e2,e1,e0);
const float3 Ng = Ng1 + Ng1;
const float den = dot3(Ng, dir);
/* Avoid division by 0. */
if (UNLIKELY(den == 0.0f)) {
return false;
}
/* Perform depth test. */
const float T = dot3(v0, Ng);
const float t = T / den;
if (!(t >= ray_tmin && t <= ray_tmax)) {
return false;
}
*isect_u = U / den;
*isect_v = V / den;
*isect_t = t;
return true;
#undef dot3
}
/* Tests for an intersection between a ray and a quad defined by
* its midpoint, normal and sides.
* If ellipse is true, hits outside the ellipse that's enclosed by the
* quad are rejected.
*/
ccl_device bool ray_quad_intersect(float3 ray_P,
float3 ray_D,
float ray_tmin,
float ray_tmax,
float3 quad_P,
float3 quad_u,
float3 quad_v,
float3 quad_n,
ccl_private float3 *isect_P,
ccl_private float *isect_t,
ccl_private float *isect_u,
ccl_private float *isect_v,
bool ellipse)
{
/* Perform intersection test. */
float t = -(dot(ray_P, quad_n) - dot(quad_P, quad_n)) / dot(ray_D, quad_n);
if (!(t > ray_tmin && t < ray_tmax)) {
return false;
}
const float3 hit = ray_P + t * ray_D;
const float3 inplane = hit - quad_P;
const float u = dot(inplane, quad_u) / dot(quad_u, quad_u);
if (u < -0.5f || u > 0.5f) {
return false;
}
const float v = dot(inplane, quad_v) / dot(quad_v, quad_v);
if (v < -0.5f || v > 0.5f) {
return false;
}
if (ellipse && (u * u + v * v > 0.25f)) {
return false;
}
/* Store the result. */
/* TODO(sergey): Check whether we can avoid some checks here. */
if (isect_P != NULL)
*isect_P = hit;
if (isect_t != NULL)
*isect_t = t;
if (isect_u != NULL)
*isect_u = u + 0.5f;
if (isect_v != NULL)
*isect_v = v + 0.5f;
return true;
}
CCL_NAMESPACE_END
#endif /* __UTIL_MATH_INTERSECT_H__ */
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