slight GJK fix

Author: Sploder12

src/include/sndx/collision/gjk.hpp

@@ -382,9 +382,11 @@ namespace sndx::collision {
 		size_t iterations = 0;
 
 		auto dir = glm::normalize(-support.out);
-		while (true) {
+		while (iterations < 1024) {
 			support = detail::gjkMinkowski(supportA, supportB, dir);
-			if (!detail::similarDir(support.out, dir)) {
+
+			// it is okay for the 2nd point to have a negative dot product.
+			if (!detail::similarDir(support.out, dir) && iterations > 0) {
 				return std::nullopt;
 			}
 
@@ -534,8 +536,6 @@ namespace sndx::collision {
 			float sDistance = glm::dot(minNormal, support.out);
 
 			if (abs(sDistance - minDistance) > 0.0001f) {
-				minDistance = FLT_MAX;
-
 				std::vector<std::pair<size_t, size_t>> uniqueEdges;
 
 				for (size_t i = 0; i < normals.size(); i++) {
@@ -557,6 +557,12 @@ namespace sndx::collision {
 					}
 				}
 
+				if (uniqueEdges.empty()) {
+					// @TODO figure out why this happens
+					return EpaResult{};
+				}
+				assert(uniqueEdges.size() > 0);
+
 				std::vector<size_t> newFaces;
 				for (auto [edgeIndex1, edgeIndex2] : uniqueEdges) {
 					newFaces.emplace_back(edgeIndex1);
@@ -582,6 +588,8 @@ namespace sndx::collision {
 
 				faces.insert(faces.end(), newFaces.begin(), newFaces.end());
 				normals.insert(normals.end(), newNormals.begin(), newNormals.end());
+
+				minDistance = FLT_MAX;
 			}
 		}
 

src/tests/collision/gjk.cpp

@@ -97,6 +97,27 @@ TEST(GJK, circleAndTriangleCollide) {
 	EXPECT_TRUE(result);
 }
 
+TEST(GJK, circleAndTriangleCollide2) {
+	Circle3D circle{ glm::vec3{4.41356277f, 3.2411015f, -2.31648755f}, 0.5f };
+	const std::array<glm::vec3, 3> triangle{
+		glm::vec3{1.0f, 1.0f, -1.0f},
+		glm::vec3{-1.0f, 1.0f, -1.0f},
+		glm::vec3{-1.0f, 1.0f, 1.0f},
+	};
+
+	glm::mat4 transform = glm::translate(glm::mat4{ 1.0f }, glm::vec3(5.0, 1.5, 0.0));
+	transform = glm::scale(transform, glm::vec3(2.0, 1.5, 5.0));
+	auto inv = glm::inverse(transform);
+
+	auto ttri = transformSupportFn(getSupportFn(std::span{ triangle }), transform, inv);
+
+	auto result = gjk(getSupportFn(circle), ttri);
+	EXPECT_TRUE(result);
+
+	result = gjk(ttri, getSupportFn(circle));
+	EXPECT_TRUE(result);
+}
+
 // because EXPECT_FLOAT_EQ is WAYYYYY too strict.
 bool floatEq(float a, float b) {
 	return std::abs(a - b) <= 0.00005f;