gl-profiling

instructions

Get a glad header (4.6 core): https://gen.glad.sh/
Build with: `gcc prof.c -o prof -lSDL2`

prof.c

#include <SDL2/SDL.h>

#define GLAD_GL_IMPLEMENTATION
#include "./gl.h"

#define GPU_PROFILE_BLOCK(Name, NSAMPLES, CodeBlock)                          \
do {                                                                          \
    static GLuint query = 0;                                                  \
    static double hist[NSAMPLES] = {0};                                       \
    static int count = 0, index = 0;                                          \
                                                                              \
    if (!query) glGenQueries(1, &query);                                      \
                                                                              \
    glBeginQuery(GL_TIME_ELAPSED, query);                                     \
    do { CodeBlock } while(0);                                                \
    glEndQuery(GL_TIME_ELAPSED);                                              \
                                                                              \
    GLuint64 ns = 0;                                                          \
    glGetQueryObjectui64v(query, GL_QUERY_RESULT, &ns);                       \
    double ms = ns / 1e6;                                                     \
                                                                              \
    hist[index] = ms;                                                         \
    index = (index + 1) % NSAMPLES;                                           \
    if (count < NSAMPLES) count++;                                            \
                                                                              \
    if (count == NSAMPLES) {                                                  \
        double sum = 0.0;                                                     \
        for (int i = 0; i < NSAMPLES; i++) sum += hist[i];                    \
        printf("[GPU] %s avg(%d) = %.3f ms\n", Name, NSAMPLES, sum/NSAMPLES); \
        count = 0;                                                            \
    }                                                                         \
} while(0)

int main(int argc, char** argv)
{
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        SDL_Log("SDL init failed: %s", SDL_GetError());
        return -1;
    }

    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 6);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

    SDL_Window* win = SDL_CreateWindow(
        "GPU Profiler Example",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
        800, 600,
        SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN
    );

    if (!win) {
        SDL_Log("Window creation failed: %s", SDL_GetError());
        SDL_Quit();
        return -1;
    }

    SDL_GLContext ctx = SDL_GL_CreateContext(win);
    if (!ctx) {
        SDL_Log("GL context failed: %s", SDL_GetError());
        SDL_DestroyWindow(win);
        SDL_Quit();
        return -1;
    }

    if (!gladLoadGL((GLADloadfunc)SDL_GL_GetProcAddress)) {
        SDL_Log("Failed to init GLAD");
        SDL_DestroyWindow(win);
        SDL_Quit();
        return -1;
    }

    int running = 1;
    while (running) {
        SDL_Event e;
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_QUIT) running = 0;
        }

        GPU_PROFILE_BLOCK("ClearScreen", 32, {
            glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
            glClear(GL_COLOR_BUFFER_BIT);
        });

        SDL_GL_SwapWindow(win);
    }

    SDL_GL_DeleteContext(ctx);
    SDL_DestroyWindow(win);
    SDL_Quit();
    return 0;
}