/*
 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * author: Jerome Glisse
 */
#define MAXFRAME        5
#define PFINISH         1
#define MAX_PARTICLES   256

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define GL_GLEXT_PROTOTYPES
#include <GL/glew.h>
#include <GL/glut.h>

static GLuint win_width = 1024;
static GLuint win_height = 1024;

static GLuint fbo;
static GLuint renderbuffers[3];
static GLuint nrenderbuffers = 0;

GLuint generate_simple_fbo(unsigned width, unsigned height)
{
    GLuint fb;
    GLenum status;
    unsigned color, stencil, depth, packed;

    color = stencil = depth = packed = 1;

#if 0
    /* texture */
    glGenTextures(1, &gears_tex);
    glBindTexture(GL_TEXTURE_2D, gears_tex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
#endif

    glGenFramebuffers(1, &fb);
    glBindFramebuffer(GL_FRAMEBUFFER, fb);


    if (color) {
#if 1
        glGenRenderbuffers(1, &renderbuffers[nrenderbuffers]);
        glBindRenderbuffer(GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        nrenderbuffers++;
#else
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gears_tex, 0);
#endif
    }

    if (stencil) {
        const GLenum format = (packed)
            ? GL_DEPTH24_STENCIL8
            : GL_STENCIL_INDEX8;
        const GLenum attachment = (packed)
            ? GL_DEPTH_STENCIL_ATTACHMENT
            : GL_STENCIL_ATTACHMENT;

        glGenRenderbuffers(1, &renderbuffers[nrenderbuffers]);
        glBindRenderbuffer(GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        glRenderbufferStorage(GL_RENDERBUFFER, format, width, height);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, attachment, GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        nrenderbuffers++;
    }

    if (!packed && depth) {
        glGenRenderbuffers(1, &renderbuffers[nrenderbuffers]);
        glBindRenderbuffer(GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderbuffers[nrenderbuffers]);
        nrenderbuffers++;
    }

    status = glGetError();
    if (status != GL_NO_ERROR) {
        fprintf(stderr, "Unexpected GL error: 0x%x\n", status);
        exit(1);
    }

    /* All of the possible combinations that we can generate are required
     * to be supported by all OpenGL 3.0 implementations, with one
     * exception.  As far as I can tell, implementations are not required
     * to support separate depth and stencil.  That one option is handled
     * specially.
     */
    status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if (status != GL_FRAMEBUFFER_COMPLETE
        && !(status == GL_FRAMEBUFFER_UNSUPPORTED && stencil && !packed)) {
        fprintf(stderr,
            "Framebuffer %s color, %s stencil (%s) was not "
            "complete: 0x%04x\n",
            color ? "with" : "without",
            stencil ? "with" : "without",
            packed ? "packed" : "separate",
            status);
        exit(1);
    }

    if (status == GL_FRAMEBUFFER_UNSUPPORTED) {
        glDeleteRenderbuffers(nrenderbuffers, renderbuffers);
        glDeleteFramebuffers(1, &fb);
        fprintf(stderr, "Unsupported framebuffer\n");
        exit(1);
    }
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

#if 0
    glClearColor(0.2, 0.4, 0.6, 1.0);
    glClearDepth(0.5);
    glClearStencil(0x7a);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
    glFinish();
#endif
    return fb;
}

void vsimple_probe(void)
{
    GLfloat *pixels = malloc(256*256*sizeof(float));
    glReadPixels(0, 0, 256, 256, GL_DEPTH_COMPONENT, GL_FLOAT, pixels);
    fprintf(stderr, "probed %f\n", pixels[100]);
    free(pixels);
}

static void draw(void)
{
    static const float first[4]  = { 0.5, 1.0, 1.0, 1.0 };
    static const float second[4] = { 0.8, 0.0, 0.0, 0.0 };

#if PFINISH
    fprintf(stderr, "EE CLEAR 0.5 -------------------------------------------------\n");
#endif
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glClearColor(0.2, 0.4, 0.6, 1.0);
    glClearDepth(0.5);
    glClearStencil(0x7a);
    glClearBufferfv(GL_DEPTH, 0, first);
#if PFINISH
    glFinish();
    fprintf(stderr, "EE CLEAR 0.5 _________________________________________________\n");
#endif

#if PFINISH
    fprintf(stderr, "EE CLEAR PROBE -----------------------------------------------\n");
#endif
    vsimple_probe();
#if PFINISH
    fprintf(stderr, "EE CLEAR PROBE _______________________________________________\n");
#endif

#if PFINISH
    fprintf(stderr, "EE CLEAR 0.8 -------------------------------------------------\n");
#endif
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glClearColor(0.2, 0.4, 0.6, 1.0);
    glClearDepth(0.8);
    glClearStencil(0x7a);
    glClearBufferfv(GL_DEPTH, 0, second);
#if PFINISH
    glFinish();
    fprintf(stderr, "EE CLEAR 0.8 _________________________________________________\n");
#endif

#if PFINISH
    fprintf(stderr, "EE CLEAR PROBE -----------------------------------------------\n");
#endif
    vsimple_probe();
#if PFINISH
    fprintf(stderr, "EE CLEAR PROBE _______________________________________________\n");
#endif

    exit(0);
}

static void idle(void)
{
}

/* new window size or exposure */
static void reshape(int width, int height)
{
    GLfloat h = (GLfloat) height / (GLfloat) width;

    glViewport(0, 0, (GLint) width, (GLint) height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef(0.0, 0.0, -40.0);

    win_width = width;
    win_height = height;
}

static void init(void)
{
    fbo = generate_simple_fbo(512, 512);
}

static void key(unsigned char k, int x, int y)
{
  switch (k) {
  case 27:  /* Escape */
      exit(0);
      break;
  default:
      return;
  }
  glutPostRedisplay();
}

int main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE | GLUT_STENCIL);
    glutInitWindowSize(win_width, win_height);
    glutCreateWindow("glgears");

    GLenum err = glewInit();
    if (GLEW_OK != err) {
        fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
        return -1;
    }

    glutKeyboardFunc(key);
    glutIdleFunc(idle);
    glutReshapeFunc(reshape);
    glutDisplayFunc(draw);

    init();
    reshape(win_width, win_height);
    glutMainLoop();
    return 0;
}