c-project/libs/glfw-3.3.2/tests/empty.c

//========================================================================
// Empty event test
// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================
//
// This test is intended to verify that posting of empty events works
//
//========================================================================

#include "tinycthread.h"

#include <glad/gl.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

static volatile int running = GLFW_TRUE;

static void error_callback(int error, const char* description)
{
    fprintf(stderr, "Error: %s\n", description);
}

static int thread_main(void* data)
{
    struct timespec time;

    while (running)
    {
        clock_gettime(CLOCK_REALTIME, &time);
        time.tv_sec += 1;
        thrd_sleep(&time, NULL);

        glfwPostEmptyEvent();
    }

    return 0;
}

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GLFW_TRUE);
}

static float nrand(void)
{
    return (float) rand() / (float) RAND_MAX;
}

int main(void)
{
    int result;
    thrd_t thread;
    GLFWwindow* window;

    srand((unsigned int) time(NULL));

    glfwSetErrorCallback(error_callback);

    if (!glfwInit())
        exit(EXIT_FAILURE);

    window = glfwCreateWindow(640, 480, "Empty Event Test", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glfwMakeContextCurrent(window);
    gladLoadGL(glfwGetProcAddress);
    glfwSetKeyCallback(window, key_callback);

    if (thrd_create(&thread, thread_main, NULL) != thrd_success)
    {
        fprintf(stderr, "Failed to create secondary thread\n");

        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    while (running)
    {
        int width, height;
        float r = nrand(), g = nrand(), b = nrand();
        float l = (float) sqrt(r * r + g * g + b * b);

        glfwGetFramebufferSize(window, &width, &height);

        glViewport(0, 0, width, height);
        glClearColor(r / l, g / l, b / l, 1.f);
        glClear(GL_COLOR_BUFFER_BIT);
        glfwSwapBuffers(window);

        glfwWaitEvents();

        if (glfwWindowShouldClose(window))
            running = GLFW_FALSE;
    }

    glfwHideWindow(window);
    thrd_join(thread, &result);
    glfwDestroyWindow(window);

    glfwTerminate();
    exit(EXIT_SUCCESS);
}