main.cpp

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <vector>
#include <fstream>
#include <sstream>
#include <string>

// Helper to read file content
std::string loadShaderSource(const char* filename) {
    std::ifstream file(filename);
    if (!file.is_open()) {
        std::cerr << "ERROR: Could not open shader file: " << filename << std::endl;
        return "";
    }
    std::stringstream buffer;
    buffer << file.rdbuf();
    return buffer.str();
}

int main() {
    // 1. Setup Hidden Window
    if (!glfwInit()) return -1;
    glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
    GLFWwindow* window = glfwCreateWindow(640, 480, "Hidden", NULL, NULL);
    glfwMakeContextCurrent(window);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // 2. Load Shader from File
    std::string sourceStr = loadShaderSource("compute.glsl");
    if (sourceStr.empty()) return -1;
    const char* sourceCStr = sourceStr.c_str();

    // 3. Compile Shader
    GLuint shader = glCreateShader(GL_COMPUTE_SHADER);
    glShaderSource(shader, 1, &sourceCStr, NULL);
    glCompileShader(shader);

    // Check Errors
    GLint success;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    if (!success) {
        char infoLog[512];
        glGetShaderInfoLog(shader, 512, NULL, infoLog);
        std::cout << "Shader Error: " << infoLog << std::endl;
    }

    GLuint program = glCreateProgram();
    glAttachShader(program, shader);
    glLinkProgram(program);
    glUseProgram(program);

    // 4. Data & Buffers
    std::vector<float> inputData = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f };
    size_t dataSize = inputData.size() * sizeof(float);

    GLuint ssbo;
    glGenBuffers(1, &ssbo);
    glBindBuffer(GL_SHADER_STORAGE_BUFFER, ssbo);
    glBufferData(GL_SHADER_STORAGE_BUFFER, dataSize, inputData.data(), GL_DYNAMIC_COPY);
    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, ssbo);

    // 5. Dispatch
    glDispatchCompute((GLuint)inputData.size(), 1, 1);
    glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT);

    // 6. Read Back
    float* ptr = (float*)glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_READ_ONLY);
    std::cout << "Output: ";
    for (int i = 0; i < inputData.size(); i++) std::cout << ptr[i] << " ";
    std::cout << std::endl;

    glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
    glfwTerminate();
    return 0;
}