glfw-fbo.cpp

#include <cstdio>
#include <cstdlib>
#include <iostream>

using namespace std;

#include <GL/glew.h>

#define GLEW_STATIC

#include <GLFW/glfw3.h>

#include <glm/glm.hpp>
#include <glm/gtx/transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtx/rotate_vector.hpp>

using namespace glm;

void error_callback(int error, const char *message) {
    fprintf(stderr, "GLFW error: %s\n", message);
    glfwTerminate();
    exit(EXIT_FAILURE);
}

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {}
void character_callback(GLFWwindow* window, unsigned int codepoint) {}
void charmods_callback(GLFWwindow* window, unsigned int codepoint, int mods) {}
static void cursor_position_callback(GLFWwindow* window, double xpos, double ypos) {}
void cursor_enter_callback(GLFWwindow* window, int entered) {}
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) {}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) {}
void joystick_callback(int joy, int event) {}
void drop_callback(GLFWwindow* window, int count, const char** paths) {}

int main() {
    /* Create a window */
    glfwSetErrorCallback(error_callback);

    glfwInit();

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

    GLFWwindow *window = glfwCreateWindow(
            1024,
            1024,
            "test", nullptr, nullptr
    );
    glfwSetWindowPos(window, 0, 0);
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    /* Initialize OpenGL */
    glfwMakeContextCurrent(window);

    glewExperimental = GL_TRUE;
    if (glewInit() != GLEW_OK) {
        printf("Failed to initialize GLEW.\n");
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LINE_SMOOTH);
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

    // force highest FPS possible
    glfwSwapInterval(0);

    GLfloat delta = 0.0f;
    GLfloat lastFrame = 0.0f;
    int fps = 0;
    GLfloat cycleSum = 0;
    GLfloat lastFpsFrame = 0.0f;

    glfwPollEvents();


    GLuint fbo;
    glGenFramebuffers(1, &fbo);

    while (!glfwWindowShouldClose(window)) {
        GLfloat currentFrame = glfwGetTime();
        delta = currentFrame - lastFrame;
        lastFrame = currentFrame;

        if (currentFrame - lastFpsFrame > 1.0) {
            printf("%6.2f\n", cycleSum * 1000.f / fps);
            cycleSum = 0;
            fps = 0;
            lastFpsFrame = currentFrame;
        }
        cycleSum += delta;
        fps++;

#if TRUE
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
#else
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
#endif
        glfwSwapBuffers(window);
    }

    return 0;
}