From 816860d38ea06f4f0c183bc9edac6297cc3593ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Mon, 26 May 2014 16:55:46 -0700
Subject: [PATCH] Added AABB overlap test.

---
 examples/common/bounds.cpp | 29 +++++++++++++++++++++++++++++
 examples/common/bounds.h   |  7 +++++++
 2 files changed, 36 insertions(+)

diff --git a/examples/common/bounds.cpp b/examples/common/bounds.cpp
index dce2c1a42..947320f14 100644
--- a/examples/common/bounds.cpp
+++ b/examples/common/bounds.cpp
@@ -119,6 +119,35 @@ void calcAabb(Aabb& _aabb, const float* _mtx, const void* _vertices, uint32_t _n
 	_aabb.m_max[2] = max[2];
 }
 
+void aabbExpand(Aabb& _aabb, float _factor)
+{
+	_aabb.m_min[0] -= _factor;
+	_aabb.m_min[1] -= _factor;
+	_aabb.m_min[2] -= _factor;
+	_aabb.m_max[0] += _factor;
+	_aabb.m_max[1] += _factor;
+	_aabb.m_max[2] += _factor;
+}
+
+uint32_t aabbOverlapTest(Aabb& _aabb0, Aabb& _aabb1)
+{
+	const uint32_t ltMinX = _aabb0.m_max[0] < _aabb1.m_min[0];
+	const uint32_t gtMaxX = _aabb0.m_min[0] > _aabb1.m_max[0];
+	const uint32_t ltMinY = _aabb0.m_max[1] < _aabb1.m_min[1];
+	const uint32_t gtMaxY = _aabb0.m_min[1] > _aabb1.m_max[1];
+	const uint32_t ltMinZ = _aabb0.m_max[2] < _aabb1.m_min[2];
+	const uint32_t gtMaxZ = _aabb0.m_min[2] > _aabb1.m_max[2];
+
+	return 0
+		| (ltMinX<<0)
+		| (gtMaxX<<1)
+		| (ltMinY<<2)
+		| (gtMaxY<<3)
+		| (ltMinZ<<4)
+		| (gtMaxZ<<5)
+		;
+}
+
 void calcObb(Obb& _obb, const void* _vertices, uint32_t _numVertices, uint32_t _stride, uint32_t _steps)
 {
 	Aabb aabb;
diff --git a/examples/common/bounds.h b/examples/common/bounds.h
index fc12a6900..4d9d75e9a 100644
--- a/examples/common/bounds.h
+++ b/examples/common/bounds.h
@@ -38,6 +38,13 @@ void calcAabb(Aabb& _aabb, const void* _vertices, uint32_t _numVertices, uint32_
 /// Transform vertices and calculate axis aligned bounding box.
 void calcAabb(Aabb& _aabb, const float* _mtx, const void* _vertices, uint32_t _numVertices, uint32_t _stride);
 
+/// Expand AABB.
+void aabbExpand(Aabb& _aabb, float _factor);
+
+/// Returns 0 is two AABB don't overlap, otherwise returns flags of overlap
+/// test.
+uint32_t aabbOverlapTest(Aabb& _aabb0, Aabb& _aabb1);
+
 /// Calculate oriented bounding box.
 void calcObb(Obb& _obb, const void* _vertices, uint32_t _numVertices, uint32_t _stride, uint32_t _steps = 17);