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

#define MAX_TEXTURES 8
#define WINDSIZEX 100
#define WINDSIZEY 100

int         imgWidth = 2,  imgHeight = 2; 
GLuint         texobj;            // Texture object ID.
GLfloat *outrgb;

GLfloat input[] =
{0.0967741907, 1, 0.193548381, 0.806451559, 0.129032254, 0.387096763, 
   0.838709652, 0.612903237, 0.290322572, 0.806451559, 0.129032254, 
   0.387096763};

GLboolean checkExt(char *extName){
   return gluCheckExtension(extName, glGetString(GL_EXTENSIONS));
}

void init(void)
{
   int i, j;

   // Check for presence of texture compression extension. 
   if (! checkExt("GL_ARB_texture_compression")) {
      exit(2);
   }
   if (checkExt("GL_3DFX_texture_compression_FXT1") == GL_FALSE){
      exit(2);
   }

   glHint (GL_TEXTURE_COMPRESSION_HINT_ARB, GL_NICEST);

   glDisable(GL_DITHER);
   glClearColor(1,1,1,1);

   glEnable (GL_TEXTURE_2D);
   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

   glGenTextures(1, &texobj);
   glBindTexture (GL_TEXTURE_2D, texobj);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); 
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

   outrgb   = malloc (3 * WINDSIZEX * WINDSIZEY * sizeof(GLfloat));

   printf("imgWidth is %d, imgHeight is %d\n", imgWidth, imgHeight);

   for (i=0; i<2; i++)
      for(j=0; j<2; j++)
      {
	 int index2 = (j*2+i)*3;
	 printf("%d, %d   origin img: %f %f %f\n", i, j, input[index2], input[index2+1], input[index2+2]);
      }

   printf("image format is : GL_COMPRESSED_RGB_FXT1_3DFX\n");
   glTexImage2D (GL_TEXTURE_2D, 0,
	 GL_COMPRESSED_RGB_FXT1_3DFX, 2, 2,
	 0, GL_RGB, GL_FLOAT, input);
}

void display(void)
{
   int i, j;

   glViewport(0, 0, WINDSIZEX, WINDSIZEY);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluOrtho2D(0, WINDSIZEX, 0, WINDSIZEY);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();

   glGetTexImage (GL_TEXTURE_2D, 0, GL_RGB, GL_FLOAT, outrgb);

   for (i=0; i<2; i++)
      for(j=0; j<2; j++)
      {
	 int index1 = (j*2+i)*3;
	 printf("(%d, %d) get img: %f %f %f\n", i, j, outrgb[index1], outrgb[index1+1], outrgb[index1+2]);
	 printf("         origin img: %f %f %f\n", input[index1], input[index1+1], input[index1+2]);
      }

   free(outrgb);
   glDeleteTextures(1, &texobj); 
   printf("PASS!\n");
   exit(0);
}

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