From 2f63ff0f5ea33068466293f514ec726e7ee99916 Mon Sep 17 00:00:00 2001
From: Persson-dev <sim16.prib@gmail.com>
Date: Sun, 16 Nov 2025 11:56:07 +0100
Subject: [PATCH] remove memory fetch of vertex shader

---
 Shaders/Vertex.glsl | 11 ++---------
 src/Main.cpp        | 36 ++++++++++++++----------------------
 2 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/Shaders/Vertex.glsl b/Shaders/Vertex.glsl
index 165d3f2..7eb59e5 100644
--- a/Shaders/Vertex.glsl
+++ b/Shaders/Vertex.glsl
@@ -1,18 +1,11 @@
 #version 460 core
 
-layout(std430, binding = 3) buffer layoutName
-{
-    float data_SSBO[];
-};
-
 layout(location = 0) uniform mat4 viewMatrix;
 layout(location = 1) uniform mat4 projectionMatrix;
 
-vec3 unpack(uint index) {
-	return vec3(data_SSBO[index * 3], data_SSBO[index * 3 + 1], data_SSBO[index * 3 + 2]);
-}
+layout(location = 0) in vec3 position;
 
 void main()
 {
-	gl_Position = projectionMatrix * viewMatrix * vec4(unpack(gl_InstanceID), 1.0);
+	gl_Position = projectionMatrix * viewMatrix * vec4(position, 1.0);
 }
\ No newline at end of file
diff --git a/src/Main.cpp b/src/Main.cpp
index 21bd67f..ccb10a3 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -169,31 +169,22 @@ 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);
 
-	// Buffer with just one point
-	float vertices[] = {0.0f, 0.0f, 0.0f};
-	glNamedBufferData(vertexBuffer, sizeof(vertices), vertices, GL_STATIC_DRAW);
+	glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(float) * PARTICLE_COUNT * 3, nullptr, GL_DYNAMIC_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;
-}
-
-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.
+	return {vertexArray, vertexBuffer};
 }
 
 static std::vector<glm::mat4> GetTransformMatrixBlended(float dt) {
@@ -264,9 +255,7 @@ int main() {
 	if (!window)
 		return -1;
 
-	auto vertexArray = CreateDummyVAO();
-
-	CreateGpuBuffer();
+	auto [vertexArray, vertexBuffer] = CreateVAO();
 
 	float lastTime = (float)glfwGetTime();
 
@@ -274,14 +263,17 @@ 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");
 
@@ -311,14 +303,14 @@ 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);
 
-		glDrawArraysInstanced(GL_POINTS, 0, 1, PARTICLE_COUNT);
+		glDrawArrays(GL_POINTS, 0, PARTICLE_COUNT);
 
 		glfwSwapBuffers(window);
 		glfwPollEvents();