#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>

#define WINDSIZEX 100
#define WINDSIZEY 100
#define TEXSIZE 2


void
init (void)
{
    int i;
    GLfloat white[] = { 1.0, 1.0, 1.0, 1.0 };

    glClearColor (0.0, 0.0, 0.0, 1.0);
    glColor4fv (white);
    glDisable (GL_DITHER);

    // Check if GL_EXT_framebuffer_object is supported
    if (!strstr (glGetString (GL_EXTENSIONS), "GL_EXT_framebuffer_object"))
    {
        printf ("GL_EXT_framebuffer_object is not supported\n");
	exit(0);
    }
    else
    {
        printf ("GL_EXT_framebuffer_object is supported\n");
    }
}

#define CHECK_FRAMEBUFFER_STATUS()                            \
{                                                           \
        GLenum status;                                            \
        status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT); \
        switch(status) {                                          \
          case GL_FRAMEBUFFER_COMPLETE_EXT:                       \
            printf("GL_FRAMEBUFFER_COMPLETE_EXT\n");              \
            break;                                                \
          case GL_FRAMEBUFFER_UNSUPPORTED_EXT:                    \
            printf("GL_FRAMEBUFFER_UNSUPPORTED_EXT\n");           \
            /* choose different formats */                        \
            break;                                                \
          case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT:          \
            printf("GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT\n"); \
            break;                                                \
          case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT:          \
            printf("GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT\n"); \
            break;                                                \
          case GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT:             \
            printf("GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT\n");    \
            break;                                                \
          case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT:         \
            printf("%d:GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT\n", __LINE__);\
            break;                                                \
          case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT:         \
            printf("GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT\n");\
            break;                                                \
          default:                                                \
            /* programming error; will fail on all hardware */    \
            printf("programming error\n");                        \
            break;                                                \
        }                                                         \
}


static void
test (void)
{
    GLfloat red[] = { 1.0, 0.0, 0.0, 1.0 };
    GLfloat white[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat green[] = { 0.0, 1.0, 0.0, 1.0 };
    GLuint fbs[8];
    GLuint textures[8];
    GLint t[TEXSIZE * TEXSIZE * 3];
    int i, j;
    int maxColorAttachment;

    glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS_EXT,
                                      &maxColorAttachment);
    printf("maxColorAttachment = %d\n", maxColorAttachment);
    


    glGenFramebuffersEXT (1, fbs);
    glGenTextures (1, textures);
    glBindTexture (GL_TEXTURE_2D, textures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
              TEXSIZE, TEXSIZE, 0, GL_RGB,
              GL_INT, NULL);

    printf ("%s\n", gluErrorString (glGetError ()));
 
    for (i=0; i<maxColorAttachment; i++)
    {
	printf("i = %d\n", i);
	glBindFramebufferEXT (GL_FRAMEBUFFER_EXT, fbs[0]);
	printf ("%s\n", gluErrorString (glGetError ()));
	glFramebufferTexture2DEXT (GL_FRAMEBUFFER_EXT,
                                   GL_COLOR_ATTACHMENT0_EXT+i,
                                   GL_TEXTURE_2D, textures[0], 0);
	printf ("%s\n", gluErrorString (glGetError ()));
	glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT+i);
	printf ("%s\n", gluErrorString (glGetError ()));
	glReadBuffer(GL_COLOR_ATTACHMENT0_EXT+i);
	printf ("%s\n", gluErrorString (glGetError ()));
    	CHECK_FRAMEBUFFER_STATUS ();
    }


    glFlush ();
    glDeleteTextures(1, textures);
    glDeleteFramebuffersEXT(1, fbs);
}

void
display (void)
{
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    gluOrtho2D (0, WINDSIZEX, 0, WINDSIZEX);
    test ();
}

int
main (int argc, char **argv)
{
    glutInit (&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGBA);
    glutInitWindowSize (WINDSIZEX, WINDSIZEY);
    glutInitWindowPosition (100, 100);
    glutCreateWindow (argv[0]);
    init ();
    glutDisplayFunc (display);
    glutMainLoop ();
    return 0;

}