box/box intersection test

[blank.git] / src / model / geometry.cpp

diff --git a/src/model/geometry.cpp b/src/model/geometry.cpp
index ed9b4b7ed5339d5805fb33287b491c6ef2e5eb6d..b08d59fe5b556ebcdbc680b568cf36358f89a5f7 100644 (file)
--- a/src/model/geometry.cpp
+++ b/src/model/geometry.cpp
@@ -65,6 +65,71 @@ bool Intersection(
        return true;
 }
 
+
+bool Intersection(
+       const AABB &a_box,
+       const glm::mat4 &a_m,
+       const AABB &b_box,
+       const glm::mat4 &b_m
+) noexcept {
+       glm::vec3 a_corners[8] = {
+               glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.min.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.max.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.min.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.max.y, a_box.max.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.min.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.min.y, a_box.max.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.min.z, 1)),
+               glm::vec3(a_m * glm::vec4(a_box.max.x, a_box.max.y, a_box.max.z, 1)),
+       };
+
+       glm::vec3 b_corners[8] = {
+               glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.min.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.min.y, b_box.max.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.min.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.min.x, b_box.max.y, b_box.max.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.min.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.min.y, b_box.max.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.min.z, 1)),
+               glm::vec3(b_m * glm::vec4(b_box.max.x, b_box.max.y, b_box.max.z, 1)),
+       };
+
+       glm::vec3 axes[6] = {
+               glm::vec3(a_m * glm::vec4(1, 0, 0, 0)),
+               glm::vec3(a_m * glm::vec4(0, 1, 0, 0)),
+               glm::vec3(a_m * glm::vec4(0, 0, 1, 0)),
+               glm::vec3(b_m * glm::vec4(1, 0, 0, 0)),
+               glm::vec3(b_m * glm::vec4(0, 1, 0, 0)),
+               glm::vec3(b_m * glm::vec4(0, 0, 1, 0)),
+       };
+
+       for (const glm::vec3 &axis : axes) {
+               float a_min = std::numeric_limits<float>::infinity();
+               float a_max = -std::numeric_limits<float>::infinity();
+               for (const glm::vec3 &corner : a_corners) {
+                       float val = glm::dot(corner, axis);
+                       a_min = std::min(a_min, val);
+                       a_max = std::max(a_max, val);
+               }
+
+               float b_min = std::numeric_limits<float>::infinity();
+               float b_max = -std::numeric_limits<float>::infinity();
+               for (const glm::vec3 &corner : b_corners) {
+                       float val = glm::dot(corner, axis);
+                       b_min = std::min(b_min, val);
+                       b_max = std::max(b_max, val);
+               }
+
+               if (a_max < b_min || b_max < a_min) return false;
+       }
+
+       // TODO: find intersection point and normals
+       // normal could be deduced from the axis with the lowest min?
+
+       return true;
+}
+
+
 bool CullTest(const AABB &box, const glm::mat4 &MVP) noexcept {
        // transform corners into clip space
        glm::vec4 corners[8] = {