From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Fri, 2 Dec 2016 11:40:14 +0000 (+0100)
Subject: simple AABB intersection test
X-Git-Url: http://git.localhorst.tv/?p=gong.git;a=commitdiff_plain;h=bda41b98427c8d34f954dae0dcaf261c5ad6cb43

simple AABB intersection test
---

diff --git a/src/geometry/geometry.cpp b/src/geometry/geometry.cpp
index 1c1bfd6..002c68f 100644
--- a/src/geometry/geometry.cpp
+++ b/src/geometry/geometry.cpp
@@ -46,6 +46,16 @@ std::ostream &operator <<(std::ostream &out, const AABB &box) {
 	return out << "AABB(" << box.min << ", " << box.max << ')';
 }
 
+bool Intersection(const AABB &a, const AABB &b) noexcept {
+	if (a.max.x < b.min.x) return false;
+	if (b.max.x < a.min.x) return false;
+	if (a.max.y < b.min.y) return false;
+	if (b.max.y < a.min.y) return false;
+	if (a.max.z < b.min.z) return false;
+	if (b.max.z < a.min.z) return false;
+	return true;
+}
+
 std::ostream &operator <<(std::ostream &out, const Ray &ray) {
 	return out << "Ray(" << ray.orig << ", " << ray.dir << ')';
 }
diff --git a/src/geometry/primitive.hpp b/src/geometry/primitive.hpp
index 819ef04..c922506 100644
--- a/src/geometry/primitive.hpp
+++ b/src/geometry/primitive.hpp
@@ -30,10 +30,17 @@ struct AABB {
 		glm::vec3 high(glm::max(glm::abs(min), glm::abs(max)));
 		return glm::length(high);
 	}
+
+	void Move(const glm::vec3 &delta) noexcept {
+		min += delta;
+		max += delta;
+	}
 };
 
 std::ostream &operator <<(std::ostream &, const AABB &);
 
+bool Intersection(const AABB &, const AABB &) noexcept;
+
 // TODO: this should really use setters/getters for dir and inv_dir so
 //       manipulating code doesn't "forget" to call Update()
 struct Ray {
diff --git a/tst/geometry/IntersectionTest.cpp b/tst/geometry/IntersectionTest.cpp
index d2332fe..36cacdf 100644
--- a/tst/geometry/IntersectionTest.cpp
+++ b/tst/geometry/IntersectionTest.cpp
@@ -21,6 +21,64 @@ void IntersectionTest::tearDown() {
 }
 
 
+void IntersectionTest::testAABB() {
+	AABB a{ { -1, -1, -1 }, { 1, 1, 1 } };
+	AABB b(a);
+
+	CPPUNIT_ASSERT_MESSAGE(
+		"coincidental AABBs should intersect",
+		Intersection(a, b)
+	);
+
+	b.Move({ 1, 0, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should intersect",
+		Intersection(a, b)
+	);
+
+	b.Move({ 2, 0, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should not intersect",
+		!Intersection(a, b)
+	);
+
+	b.Move({ -4, 0, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should intersect",
+		Intersection(a, b)
+	);
+
+	b.Move({ -2, 0, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should not intersect",
+		!Intersection(a, b)
+	);
+
+	b.Move({ 3, 1, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should intersect",
+		Intersection(a, b)
+	);
+
+	b.Move({ 0, 2, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should not intersect",
+		!Intersection(a, b)
+	);
+
+	b.Move({ 2, 0, 0 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should not intersect",
+		!Intersection(a, b)
+	);
+
+	b.Move({ 0, 0, 2 });
+	CPPUNIT_ASSERT_MESSAGE(
+		"AABBs should not intersect",
+		!Intersection(a, b)
+	);
+}
+
 void IntersectionTest::testSimpleRayBox() {
 	Ray ray{ { 0, 0, 0 }, { 1, 0, 0 }, { } }; // at origin, pointing right
 	ray.Update();
diff --git a/tst/geometry/IntersectionTest.hpp b/tst/geometry/IntersectionTest.hpp
index d0c7d80..4865c88 100644
--- a/tst/geometry/IntersectionTest.hpp
+++ b/tst/geometry/IntersectionTest.hpp
@@ -13,6 +13,7 @@ class IntersectionTest
 
 CPPUNIT_TEST_SUITE(IntersectionTest);
 
+CPPUNIT_TEST(testAABB);
 CPPUNIT_TEST(testSimpleRayBox);
 CPPUNIT_TEST(testRayBox);
 CPPUNIT_TEST(testBoxBox);
@@ -25,6 +26,7 @@ public:
 	void setUp();
 	void tearDown();
 
+	void testAABB();
 	void testSimpleRayBox();
 	void testRayBox();
 	void testBoxBox();