From 659f83c800fb980b5c137e027dde3a099ab1a6d7 Mon Sep 17 00:00:00 2001
From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Mon, 18 Dec 2017 09:51:48 +0100
Subject: [PATCH] test ray/sphere intersect

---
 tst/math/IntersectTest.cpp | 66 ++++++++++++++++++++++++++++++++++++++
 tst/math/IntersectTest.hpp |  2 ++
 2 files changed, 68 insertions(+)

diff --git a/tst/math/IntersectTest.cpp b/tst/math/IntersectTest.cpp
index 2ed07fb..cd50845 100644
--- a/tst/math/IntersectTest.cpp
+++ b/tst/math/IntersectTest.cpp
@@ -223,6 +223,72 @@ void IntersectTest::testBoxBoxIntersection() {
 	);
 }
 
+void IntersectTest::testRaySphereIntersection() {
+	const double epsilon = std::numeric_limits<double>::epsilon();
+	Ray ray{ { 0.0, 0.0, 0.0 }, { 1.0, 0.0, 0.0 } }; // at origin, pointing right
+	Sphere sphere{ { 0.0, 0.0, 0.0 }, 1.0 }; // unit sphere at origin
+
+	glm::dvec3 normal(0.0);
+	double dist = 0.0;
+	CPPUNIT_ASSERT_MESSAGE(
+		"ray at origin does not intersect sphere at origin",
+		Intersect(ray, sphere, normal, dist)
+	);
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"distance along ray to unit sphere, both at origin, is not 1",
+		1.0, dist, epsilon
+	);
+	AssertEqual(
+		"bad intersection normal",
+		glm::dvec3(1.0, 0.0, 0.0), normal
+	);
+
+	ray.Origin({ 2.0, 0.0, 0.0 }); // move outside
+	CPPUNIT_ASSERT_MESSAGE(
+		"ray pointing away from sphere intersects it for some reason",
+		!Intersect(ray, sphere, normal, dist)
+	);
+
+	ray.Direction({ -1.0, 0.0, 0.0 }); // flip it around
+	CPPUNIT_ASSERT_MESSAGE(
+		"negative X ray does not intersect sphere",
+		Intersect(ray, sphere, normal, dist)
+	);
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"distance along ray to unit sphere at origin is not 1",
+		1.0, dist, epsilon
+	);
+	AssertEqual(
+		"bad intersection normal",
+		glm::dvec3(1.0, 0.0, 0.0), normal
+	);
+
+	// sphere at 3,0,0; ray at 0,4,0 pointing directly at it
+	// should be 5 units apart, minus one for the radius
+	ray.Origin({ 0.0, 4.0, 0.0 });
+	ray.Direction(glm::normalize(glm::dvec3(3.0, -4.0, 0.0)));
+	sphere.origin = { 3.0, 0.0, 0.0 };
+	CPPUNIT_ASSERT_MESSAGE(
+		"diagonal ray does not intersect sphere",
+		Intersect(ray, sphere, normal, dist)
+	);
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"distance along ray to unit sphere is not 4",
+		4.0, dist, epsilon
+	);
+	AssertEqual(
+		"bad intersection normal",
+		glm::normalize(glm::dvec3(-3.0, 4.0, 0.0)), normal
+	);
+
+	// point the ray straight down, so it misses
+	ray.Direction({ 0.0, -1.0, 0.0});
+	CPPUNIT_ASSERT_MESSAGE(
+		"vertical ray should not intersect sphere",
+		!Intersect(ray, sphere, normal, dist)
+	);
+}
+
 }
 }
 }
diff --git a/tst/math/IntersectTest.hpp b/tst/math/IntersectTest.hpp
index 13ac134..85d88fa 100644
--- a/tst/math/IntersectTest.hpp
+++ b/tst/math/IntersectTest.hpp
@@ -15,6 +15,7 @@ CPPUNIT_TEST_SUITE(IntersectTest);
 
 CPPUNIT_TEST(testRayBoxIntersection);
 CPPUNIT_TEST(testBoxBoxIntersection);
+CPPUNIT_TEST(testRaySphereIntersection);
 
 CPPUNIT_TEST_SUITE_END();
 
@@ -24,6 +25,7 @@ public:
 
 	void testRayBoxIntersection();
 	void testBoxBoxIntersection();
+	void testRaySphereIntersection();
 
 };
 
-- 
2.39.2