+#include "geometry.hpp"
+
+
+namespace blank {
+
+bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *dist) {
+ float t_min = 0.0f;
+ float t_max = 1.0e5f;
+ const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
+ const glm::vec3 delta = aabb_pos - ray.orig;
+
+ { // X
+ const glm::vec3 xaxis(M[0].x, M[0].y, M[0].z);
+ const float e = glm::dot(xaxis, delta);
+ const float f = glm::dot(ray.dir, xaxis);
+
+ if (std::abs(f) > 0.001f) {
+ float t1 = (e + aabb.min.x) / f;
+ float t2 = (e + aabb.max.x) / f;
+
+ if (t1 > t2) {
+ std::swap(t1, t2);
+ }
+ if (t1 > t_min) {
+ t_min = t1;
+ }
+ if (t2 < t_max) {
+ t_max = t2;
+ }
+ if (t_max < t_min) {
+ return false;
+ }
+ } else {
+ if (aabb.min.x - e > 0.0f || aabb.max.x < 0.0f) {
+ return false;
+ }
+ }
+ }
+
+ { // Y
+ const glm::vec3 yaxis(M[1].x, M[1].y, M[1].z);
+ const float e = glm::dot(yaxis, delta);
+ const float f = glm::dot(ray.dir, yaxis);
+
+ if (std::abs(f) > 0.001f) {
+ float t1 = (e + aabb.min.y) / f;
+ float t2 = (e + aabb.max.y) / f;
+
+ if (t1 > t2) {
+ std::swap(t1, t2);
+ }
+ if (t1 > t_min) {
+ t_min = t1;
+ }
+ if (t2 < t_max) {
+ t_max = t2;
+ }
+ if (t_max < t_min) {
+ return false;
+ }
+ } else {
+ if (aabb.min.y - e > 0.0f || aabb.max.y < 0.0f) {
+ return false;
+ }
+ }
+ }
+
+ { // Z
+ const glm::vec3 zaxis(M[2].x, M[2].y, M[2].z);
+ const float e = glm::dot(zaxis, delta);
+ const float f = glm::dot(ray.dir, zaxis);
+
+ if (std::abs(f) > 0.001f) {
+ float t1 = (e + aabb.min.z) / f;
+ float t2 = (e + aabb.max.z) / f;
+
+ if (t1 > t2) {
+ std::swap(t1, t2);
+ }
+ if (t1 > t_min) {
+ t_min = t1;
+ }
+ if (t2 < t_max) {
+ t_max = t2;
+ }
+ if (t_max < t_min) {
+ return false;
+ }
+ } else {
+ if (aabb.min.z - e > 0.0f || aabb.max.z < 0.0f) {
+ return false;
+ }
+ }
+ }
+
+ if (dist) {
+ *dist = t_min;
+ }
+ return true;
+}
+
+}