format ...

.vscode/compile_commands.json

@@ -0,0 +1,16 @@
+[
+{
+  "directory": "/home/simon/Programmation/GPUCompute",
+  "arguments": ["/usr/bin/g++", "-c", "-m64", "-isystem", "/usr/include/X11/dri", "-isystem", "/home/simon/.xmake/packages/g/glad/v0.1.36/9e3539cb78a3425b96246554411a0b79/include", "-isystem", "/home/simon/.xmake/packages/g/glm/1.0.2/f8fba32531124eb38c4833bdc558de88/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include/stb", "-o", "build/.objs/App/linux/x86_64/release/src/Shader.cpp.o", "src/Shader.cpp"],
+  "file": "src/Shader.cpp"
+},
+{
+  "directory": "/home/simon/Programmation/GPUCompute",
+  "arguments": ["/usr/bin/g++", "-c", "-m64", "-isystem", "/usr/include/X11/dri", "-isystem", "/home/simon/.xmake/packages/g/glad/v0.1.36/9e3539cb78a3425b96246554411a0b79/include", "-isystem", "/home/simon/.xmake/packages/g/glm/1.0.2/f8fba32531124eb38c4833bdc558de88/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include/stb", "-o", "build/.objs/App/linux/x86_64/release/src/Renderer.cpp.o", "src/Renderer.cpp"],
+  "file": "src/Renderer.cpp"
+},
+{
+  "directory": "/home/simon/Programmation/GPUCompute",
+  "arguments": ["/usr/bin/g++", "-c", "-m64", "-isystem", "/usr/include/X11/dri", "-isystem", "/home/simon/.xmake/packages/g/glad/v0.1.36/9e3539cb78a3425b96246554411a0b79/include", "-isystem", "/home/simon/.xmake/packages/g/glm/1.0.2/f8fba32531124eb38c4833bdc558de88/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include", "-isystem", "/home/simon/.xmake/packages/s/stb/2025.03.14/67005fc11486400896028eb775a57270/include/stb", "-o", "build/.objs/App/linux/x86_64/release/src/Main.cpp.o", "src/Main.cpp"],
+  "file": "src/Main.cpp"
+}]

README.md

@@ -1,5 +1,5 @@
-# Real Time Fractal
+# GPU Compute
-Generate random fractals in 3D using chaos game.
+Simple app to run compute shaders using OpenGL.
 
 ## Building
 Just run xmake and build. Here's an example:

Shaders/Vertex.glsl

@@ -1,11 +1,18 @@
 #version 460 core
 
+layout(std430, binding = 3) buffer layoutName
+{
+    float data_SSBO[];
+};
+
 layout(location = 0) uniform mat4 viewMatrix;
 layout(location = 1) uniform mat4 projectionMatrix;
 
-layout(location = 0) in vec3 position;
+vec3 unpack(uint index) {
+	return vec3(data_SSBO[index * 3], data_SSBO[index * 3 + 1], data_SSBO[index * 3 + 2]);
+}
 
 void main()
 {
-	gl_Position = projectionMatrix * viewMatrix * vec4(position, 1.0);
+	gl_Position = projectionMatrix * viewMatrix * vec4(unpack(gl_InstanceID), 1.0);
 }

src/Main.cpp

@@ -17,7 +17,7 @@ constexpr int SWAP_INTERVAL = 1;
 constexpr int TRANSFORMATION_COUNT = 3;
 
 constexpr float ANIMATION_TIME = 2;
-constexpr float ANIMATION_STILL_TIME = .5f;
+constexpr float ANIMATION_STILL_TIME = 1;
 
 class Timer {
   public:
@@ -169,22 +169,31 @@ static void KeyCallback(GLFWwindow* window, int key, int scancode, int action, i
 	}
 }
 
-
+static GLuint CreateDummyVAO() {
-static std::tuple<GLuint, GLuint> CreateVAO() {
 	GLuint vertexArray;
 	glCreateVertexArrays(1, &vertexArray);
 
 	GLuint vertexBuffer;
 	glCreateBuffers(1, &vertexBuffer);
 
-	glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+	// Buffer with just one point
-	glBufferData(GL_ARRAY_BUFFER, sizeof(float) * PARTICLE_COUNT * 3, nullptr, GL_DYNAMIC_DRAW);
+	float vertices[] = {0.0f, 0.0f, 0.0f};
+	glNamedBufferData(vertexBuffer, sizeof(vertices), vertices, GL_STATIC_DRAW);
 	glVertexArrayVertexBuffer(vertexArray, 0, vertexBuffer, 0, sizeof(float) * 3);
 	glEnableVertexArrayAttrib(vertexArray, 0);
 	glVertexArrayAttribFormat(vertexArray, 0, 3, GL_FLOAT, GL_FALSE, 0);
 	glVertexArrayAttribBinding(vertexArray, 0, 0);
 
-	return {vertexArray, vertexBuffer};
+	return vertexArray;
+}
+
+static void CreateGpuBuffer() {
+	GLuint ssbo;
+	glGenBuffers(1, &ssbo);
+	glBindBuffer(GL_SHADER_STORAGE_BUFFER, ssbo);
+	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, ssbo);
+	glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(float) * 3 * PARTICLE_COUNT, nullptr,
+		GL_DYNAMIC_COPY);  // sizeof(data) only works for statically sized C/C++ arrays.
 }
 
 static std::vector<glm::mat4> GetTransformMatrixBlended(float dt) {
@@ -240,7 +249,7 @@ static GLFWwindow* InitWindow() {
 		return nullptr;
 	}
 
-	auto viewMatrix = glm::lookAt(glm::vec3{1, 1.5, 1.5}, {0, 0, 0}, {0, 1, 0});
+	auto viewMatrix = glm::lookAt(glm::vec3{1, 2, 2}, {0, 0, 0}, {0, 1, 0});
 	auto projectionMatrix = glm::perspective(70.0f, 2.0f, 0.01f, 10.0f);
 
 	glUseProgram(s_GraphicsShader);
@@ -255,7 +264,9 @@ int main() {
 	if (!window)
 		return -1;
 
-	auto [vertexArray, vertexBuffer] = CreateVAO();
+	auto vertexArray = CreateDummyVAO();
+
+	CreateGpuBuffer();
 
 	float lastTime = (float)glfwGetTime();
 
@@ -263,17 +274,14 @@ int main() {
 	float secondsTimer = 0.0f;
 	float animationTimer = 0.0f;
 
+	glBindVertexArray(vertexArray);
+
 	// ApplyTransforms(SIERPINSKI_TRIANGLE);
 	s_T1 = GenRandomFractal();
 	s_T2 = GenRandomFractal();
 
 	glClearColor(0.4f, 0.4f, 0.4f, 1.0f);
 
-	glBindBuffer(GL_SHADER_STORAGE_BUFFER, vertexBuffer);
-	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, vertexBuffer);
-
-	glBindVertexArray(vertexArray);
-
 	while (!glfwWindowShouldClose(window)) {
 		// ScopedTimer timer("Main Loop");
 
@@ -303,14 +311,14 @@ int main() {
 		glUniformMatrix4fv(1, matricies.size(), false, glm::value_ptr(matricies[0]));
 
 		glDispatchCompute(PARTICLE_COUNT / WORK_GROUP_SIZE, 1, 1);
-		
+
 		// Ensure all writes to the image are complete
 		glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
-		
+
 		// Graphics
 		glUseProgram(s_GraphicsShader);
 
-		glDrawArrays(GL_POINTS, 0, PARTICLE_COUNT);
+		glDrawArraysInstanced(GL_POINTS, 0, 1, PARTICLE_COUNT);
 
 		glfwSwapBuffers(window);
 		glfwPollEvents();