1 #include "geometry.hpp"
16 float t_max = std::numeric_limits<float>::infinity();
17 const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
18 const glm::vec3 delta = aabb_pos - ray.orig;
20 glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
22 for (int i = 0; i < 3; ++i) {
23 const glm::vec3 axis(M[i].x, M[i].y, M[i].z);
24 const float e = glm::dot(axis, delta);
25 const float f = glm::dot(axis, ray.dir);
27 if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
28 t1[i] = (e + aabb.min[i]) / f;
29 t2[i] = (e + aabb.max[i]) / f;
31 t_min = std::max(t_min, std::min(t1[i], t2[i]));
32 t_max = std::min(t_max, std::max(t1[i], t2[i]));
38 if (aabb.min[i] - e < 0.0f || -aabb.max[i] - e > 0.0f) {
44 glm::vec3 min_all(min(t1, t2));
51 if (min_all.x > min_all.y) {
52 if (min_all.x > min_all.z) {
53 norm.x = t2.x < t1.x ? 1 : -1;
55 norm.z = t2.z < t1.z ? 1 : -1;
57 } else if (min_all.y > min_all.z) {
58 norm.y = t2.y < t1.y ? 1 : -1;
60 norm.z = t2.z < t1.z ? 1 : -1;
63 *normal = glm::vec3(norm);
68 bool CullTest(const AABB &box, const glm::mat4 &MVP) {
69 // transform corners into clip space
70 glm::vec4 corners[8] = {
71 { box.min.x, box.min.y, box.min.z, 1.0f },
72 { box.min.x, box.min.y, box.max.z, 1.0f },
73 { box.min.x, box.max.y, box.min.z, 1.0f },
74 { box.min.x, box.max.y, box.max.z, 1.0f },
75 { box.max.x, box.min.y, box.min.z, 1.0f },
76 { box.max.x, box.min.y, box.max.z, 1.0f },
77 { box.max.x, box.max.y, box.min.z, 1.0f },
78 { box.max.x, box.max.y, box.max.z, 1.0f },
80 for (glm::vec4 &corner : corners) {
81 corner = MVP * corner;
85 int hits[6] = { 0, 0, 0, 0, 0, 0 };
87 // check how many corners lie outside
88 for (const glm::vec4 &corner : corners) {
89 if (corner.x > 1.0f) ++hits[0];
90 if (corner.x < -1.0f) ++hits[1];
91 if (corner.y > 1.0f) ++hits[2];
92 if (corner.y < -1.0f) ++hits[3];
93 if (corner.z > 1.0f) ++hits[4];
94 if (corner.z < -1.0f) ++hits[5];
97 // if all corners are outside any given clip plane, the test is true
98 for (int hit : hits) {
99 if (hit == 8) return true;
102 // otherwise the box might still get culled completely, but can't say for sure ;)