basic aiming

[blank.git] / src / geometry.cpp

diff --git a/src/geometry.cpp b/src/geometry.cpp
new file mode 100644 (file)
index 0000000..c5f8069
--- /dev/null
+++ b/src/geometry.cpp
@@ -0,0 +1,102 @@
+#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;
+}
+
+}