a

1 files changed, 30 insertions, 0 deletions

diff --git a/src/util/aabb.h b/src/util/aabb.h
new file mode 100644
index 0000000..f2fd251
--- /dev/null
+++ b/src/util/aabb.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "vector.h"
+
+struct AABB {
+  VEC3 min;
+  VEC3 max;
+};
+
+inline VEC3 aabb_center( const AABB& aabb ) { return (aabb.min + aabb.max) * 0.5f; }
+inline VEC3 aabb_half( const AABB& aabb ) { return (aabb.max - aabb.min) * 0.5f; }
+inline F32 aabb_support_radius( const AABB& aabb, const VEC3& dir ) {
+  VEC3 half = aabb_half( aabb );
+  return fabsf(dir.x) * half.x + fabsf(dir.y) * half.y + fabsf(dir.z) * half.z;
+}
+
+inline VEC2 aabb_extend_at_feet( const AABB& aabb, const VEC3& dir ) {
+  VEC3 half = aabb_half( aabb );
+
+  F32 hx = half.x;
+  F32 hy = half.y;
+  F32 hz = half.z * 2;
+
+  F32 lateral = fabsf( dir.x ) * hx + fabsf( dir.y ) * hy;
+
+  F32 pos_z = dir.z > 0 ? dir.z * hz : 0.f;
+  F32 neg_z = dir.z < 0 ? (-dir.z) * hz : 0.f;
+
+  return { lateral + pos_z, lateral + neg_z };
+}