//========================================================================
// Fullscreen multisampling anti-aliasing test
// Copyright (c) Camilla Berglund <elmindreda@elmindreda.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 renders two high contrast, slowly rotating quads, one aliased
// and one (hopefully) anti-aliased, thus allowing for visual verification
// of whether FSAA is indeed enabled
//
//========================================================================

#include <GL/glfw3.h>

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

#ifndef GL_ARB_multisample
#define GL_MULTISAMPLE_ARB 0x809D
#endif

static void window_size_callback(GLFWwindow window, int width, int height)
{
    glViewport(0, 0, width, height);
}

int main(void)
{
    int samples;
    GLFWwindow window;

    if (!glfwInit())
    {
        fprintf(stderr, "Failed to initialize GLFW: %s\n", glfwErrorString(glfwGetError()));
        exit(EXIT_FAILURE);
    }

    glfwOpenWindowHint(GLFW_FSAA_SAMPLES, 4);

    window = glfwOpenWindow(400, 400, GLFW_WINDOWED, "Aliasing Detector", NULL);
    if (!window)
    {
        glfwTerminate();

        fprintf(stderr, "Failed to open GLFW window: %s\n", glfwErrorString(glfwGetError()));
        exit(EXIT_FAILURE);
    }

    glfwSetWindowSizeCallback(window_size_callback);
    glfwSwapInterval(1);

    samples = glfwGetWindowParam(window, GLFW_FSAA_SAMPLES);
    if (samples)
        printf("Context reports FSAA is supported with %i samples\n", samples);
    else
        printf("Context reports FSAA is unsupported\n");

    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.f, 1.f, 0.f, 1.f);

    while (glfwIsWindow(window))
    {
        GLfloat time = (GLfloat) glfwGetTime();

        glClear(GL_COLOR_BUFFER_BIT);

        glLoadIdentity();
        glTranslatef(0.5f, 0.f, 0.f);
        glRotatef(time, 0.f, 0.f, 1.f);

        glEnable(GL_MULTISAMPLE_ARB);
        glColor3f(1.f, 1.f, 1.f);
        glRectf(-0.25f, -0.25f, 0.25f, 0.25f);

        glLoadIdentity();
        glTranslatef(-0.5f, 0.f, 0.f);
        glRotatef(time, 0.f, 0.f, 1.f);

        glDisable(GL_MULTISAMPLE_ARB);
        glColor3f(1.f, 1.f, 1.f);
        glRectf(-0.25f, -0.25f, 0.25f, 0.25f);

        glfwSwapBuffers();
        glfwPollEvents();
    }

    glfwTerminate();
    exit(EXIT_SUCCESS);
}