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);
77 glm::vec3 a_corners[8] = {
78 glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.min.z, 1)),
79 glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.max.z, 1)),
80 glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.min.z, 1)),
81 glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.max.z, 1)),
82 glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.min.z, 1)),
83 glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.max.z, 1)),
84 glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.min.z, 1)),
85 glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.max.z, 1)),
88 glm::vec3 b_corners[8] = {
89 glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.min.z, 1)),
90 glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.max.z, 1)),
91 glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.min.z, 1)),
92 glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.max.z, 1)),
93 glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.min.z, 1)),
94 glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.max.z, 1)),
95 glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.min.z, 1)),
96 glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.max.z, 1)),
100 glm::vec3(a_m * glm::vec4(1, 0, 0, 0)),
101 glm::vec3(a_m * glm::vec4(0, 1, 0, 0)),
102 glm::vec3(a_m * glm::vec4(0, 0, 1, 0)),
103 glm::vec3(b_m * glm::vec4(1, 0, 0, 0)),
104 glm::vec3(b_m * glm::vec4(0, 1, 0, 0)),
105 glm::vec3(b_m * glm::vec4(0, 0, 1, 0)),
108 depth = std::numeric_limits<float>::infinity();
112 for (const glm::vec3 &axis : axes) {
113 float a_min = std::numeric_limits<float>::infinity();
114 float a_max = -std::numeric_limits<float>::infinity();
115 for (const glm::vec3 &corner : a_corners) {
116 float val = glm::dot(corner, axis);
117 a_min = std::min(a_min, val);
118 a_max = std::max(a_max, val);
121 float b_min = std::numeric_limits<float>::infinity();
122 float b_max = -std::numeric_limits<float>::infinity();
123 for (const glm::vec3 &corner : b_corners) {
124 float val = glm::dot(corner, axis);
125 b_min = std::min(b_min, val);
126 b_max = std::max(b_max, val);
129 if (a_max < b_min || b_max < a_min) return false;
131 float overlap = std::min(a_max, b_max) - std::max(a_min, b_min);
132 if (overlap < depth) {
140 normal = axes[min_axis];
145 bool CullTest(const AABB &box, const glm::mat4 &MVP) noexcept {
146 // transform corners into clip space
147 glm::vec4 corners[8] = {
148 { box.min.x, box.min.y, box.min.z, 1.0f },
149 { box.min.x, box.min.y, box.max.z, 1.0f },
150 { box.min.x, box.max.y, box.min.z, 1.0f },
151 { box.min.x, box.max.y, box.max.z, 1.0f },
152 { box.max.x, box.min.y, box.min.z, 1.0f },
153 { box.max.x, box.min.y, box.max.z, 1.0f },
154 { box.max.x, box.max.y, box.min.z, 1.0f },
155 { box.max.x, box.max.y, box.max.z, 1.0f },
157 for (glm::vec4 &corner : corners) {
158 corner = MVP * corner;
162 int hits[6] = { 0, 0, 0, 0, 0, 0 };
164 // check how many corners lie outside
165 for (const glm::vec4 &corner : corners) {
166 if (corner.x > 1.0f) ++hits[0];
167 if (corner.x < -1.0f) ++hits[1];
168 if (corner.y > 1.0f) ++hits[2];
169 if (corner.y < -1.0f) ++hits[3];
170 if (corner.z > 1.0f) ++hits[4];
171 if (corner.z < -1.0f) ++hits[5];
174 // if all corners are outside any given clip plane, the test is true
175 for (int hit : hits) {
176 if (hit == 8) return true;
179 // otherwise the box might still get culled completely, but can't say for sure ;)