X-Git-Url: https://git.lukelau.me/?p=opengl.git;a=blobdiff_plain;f=shapes.hpp;h=876ce3c550ebf97c3951850d4483f1ddaf6fe1ae;hp=92cc8adb0882ecd6c3d3c54955bad6eb0a25d286;hb=b91a0d30ae6484b6c4d981aeafa8d4996c98effe;hpb=9886c33eb8cd31f28234585718410cd51aef2a4c

diff --git a/shapes.hpp b/shapes.hpp
index 92cc8ad..876ce3c 100644
--- a/shapes.hpp
+++ b/shapes.hpp
@@ -1,4 +1,6 @@
 #include <array>
+#include <vector>
+#include <cmath>
 #define GLM_FORCE_PURE
 #include <glm/glm.hpp>
 
@@ -24,7 +26,70 @@ constexpr array<glm::vec3, 6> plane() {
 	});
 }
 
-constexpr array<glm::vec3, 36> cube() {
+inline vector<glm::vec3> cube() {
+	int i = 0;
+	vector<glm::vec3> vertices(36);
+	
+	const array<glm::vec3, 4> front = {
+		glm::vec3(1, -1, -1),
+		glm::vec3(-1, -1, -1),
+		glm::vec3(-1, 1, -1),
+		glm::vec3(1, 1, -1)
+	};
+	
+	for (auto v: quadToTriangles(front))
+		vertices[i++] = v;
+
+	const array<glm::vec3, 4> back = {
+		glm::vec3(1, 1, 1),
+		glm::vec3(-1, 1, 1),
+		glm::vec3(-1, -1, 1),
+		glm::vec3(1, -1, 1)
+	};
+	for (auto v: quadToTriangles(back))
+		vertices[i++] = v;
+
+
+	const array<glm::vec3, 4> top = {
+		glm::vec3(1, 1, -1),
+		glm::vec3(-1, 1, -1),
+		glm::vec3(-1, 1, 1),
+		glm::vec3(1, 1, 1)
+	};
+	for (auto v: quadToTriangles(top))
+		vertices[i++] = v;
+
+	const array<glm::vec3, 4> bottom = {
+		glm::vec3(1, -1, 1),
+		glm::vec3(-1, -1, 1),
+		glm::vec3(-1, -1, -1),
+		glm::vec3(1, -1, -1)
+	};
+	for (auto v: quadToTriangles(bottom))
+		vertices[i++] = v;
+
+	const array<glm::vec3, 4> left = {
+		glm::vec3(-1, 1, 1),
+		glm::vec3(-1, 1, -1),
+		glm::vec3(-1, -1, -1),
+		glm::vec3(-1, -1, 1)
+	};
+	for (auto v: quadToTriangles(left))
+		vertices[i++] = v;
+
+	const array<glm::vec3, 4> right = {
+		glm::vec3(1, 1, -1),
+		glm::vec3(1, 1, 1),
+		glm::vec3(1, -1, 1),
+		glm::vec3(1, -1, -1)
+	};
+	for (auto v: quadToTriangles(right))
+		vertices[i++] = v;
+
+	return vertices;
+}
+
+constexpr array<glm::vec3, 36> cubeArray() {
 	int i = 0;
 	array<glm::vec3, 36> vertices;
 	
@@ -112,7 +177,72 @@ constexpr glm::vec3 pyramid[18] = {
 	glm::vec3(1, -1, 1)
 };
 
-// TODO: Add a sphere
-/* constexpr std::vector<glm::vec3> sphere() { */
+// taken from http://www.songho.ca/opengl/gl_sphere.html
+#define SECTOR_COUNT 16
+#define STACK_COUNT 16
+inline std::vector<glm::vec3> sphere(float radius = 1) {
+	float sectorStep = 2 * M_PI / SECTOR_COUNT;
+	float stackStep = M_PI / STACK_COUNT;
+
+	std::vector<glm::vec3> vertices;
+
+	for(int i = 0; i <= STACK_COUNT; i++) {
+		float stackAngle = M_PI / 2 - i * stackStep;        // starting from pi/2 to -pi/2
+		float xy = radius * cosf(stackAngle);             // r * cos(u)
+		float z = radius * sinf(stackAngle);              // r * sin(u)
+
+		// add (sectorCount+1) vertices per stack
+		// the first and last vertices have same position and normal, but different tex coords
+		for(int j = 0; j <= SECTOR_COUNT; j++)
+		{
+			float sectorAngle = j * sectorStep;           // starting from 0 to 2pi
+
+			// vertex position (x, y, z)
+			float x = xy * cosf(sectorAngle);             // r * cos(u) * cos(v)
+			float y = xy * sinf(sectorAngle);             // r * cos(u) * sin(v)
+			vertices.push_back({x, y, z});
+
+			// normalized vertex normal (nx, ny, nz)
+			/* nx = x * lengthInv; */
+			/* ny = y * lengthInv; */
+			/* nz = z * lengthInv; */
+			/* normals.push_back(nx); */
+			/* normals.push_back(ny); */
+			/* normals.push_back(nz); */
+
+		}
+	}
+	return vertices;
+}
+
+inline std::vector<unsigned int> sphereIndices() {
+	// generate CCW index list of sphere triangles
+	vector<unsigned int> indices;
+	int k1, k2;
+	for(int i = 0; i < STACK_COUNT; ++i)
+	{
+		k1 = i * (SECTOR_COUNT + 1);     // beginning of current stack
+		k2 = k1 + SECTOR_COUNT + 1;      // beginning of next stack
+
+		for(int j = 0; j < SECTOR_COUNT; ++j, ++k1, ++k2)
+		{
+			// 2 triangles per sector excluding first and last stacks
+			// k1 => k2 => k1+1
+			if(i != 0)
+			{
+				indices.push_back(k1);
+				indices.push_back(k2);
+				indices.push_back(k1 + 1);
+			}
 
-/* } */
+			// k1+1 => k2 => k2+1
+			if(i != (STACK_COUNT-1))
+			{
+				indices.push_back(k1 + 1);
+				indices.push_back(k2);
+				indices.push_back(k2 + 1);
+			}
+		}
+	} 
+	return indices;
+}