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

#define WINDSIZEX 100
#define WINDSIZEY 100


   GLint texID;

void init(void)
{
   int i, j;
   GLfloat   texImage0[4][4][4];
   GLfloat   texImage1[2][2][4];
   GLfloat   texImage2[1][1][4];

   for (i = 0; i < 4; i++)
   {
      for (j = 0; j < 4; j++)
      {
            texImage0[i][j][0] = 1.0;
            texImage0[i][j][1] = 0.0;
            texImage0[i][j][2] = 0.0;
            texImage0[i][j][3] = 0.0;
      }
   }

   for (i = 0; i < 2; i++)
   {
      for (j = 0; j < 2; j++)
      {
            texImage1[i][j][0] = 0.0;
            texImage1[i][j][1] = 1.0;
            texImage1[i][j][2] = 0.0;
            texImage1[i][j][3] = 0.0;
      }
   }

   
            texImage2[1][1][0] = 0.0;
            texImage2[1][1][1] = 0.0;
            texImage2[1][1][2] = 1.0;
            texImage2[1][1][3] = 0.0;


   glGenTextures(1, &texID);

   glBindTexture(GL_TEXTURE_2D, texID);

   glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, //GL_NEAREST);
                                   GL_NEAREST_MIPMAP_NEAREST);
   glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 4, 4, 0, GL_RGBA, GL_FLOAT,
         texImage0);
   glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 2, 2, 0, GL_RGBA, GL_FLOAT,
         texImage1);
   glTexImage2D(GL_TEXTURE_2D, 2, GL_RGBA, 1, 1, 0, GL_RGBA, GL_FLOAT,
         texImage2);

   glEnable(GL_TEXTURE_2D);
   /*glTexEnvf(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);
 
   glEnable(GL_POINT_SPRITE);

   GLfloat maxSize;
   glGetFloatv(GL_POINT_SIZE_MAX, &maxSize);
   printf ("max point size: %f\n", maxSize);
*/
}

#define TEX_WIDTH 2
static void test(void)
{    
   GLfloat buf[(TEX_WIDTH+2)*(TEX_WIDTH+2)*3];
   int i, j;

   glClear(GL_COLOR_BUFFER_BIT);
   glBindTexture(GL_TEXTURE_2D, texID);
/*
   glPointSize(TEX_WIDTH);
   glBegin(GL_POINTS);
      glVertex2f(TEX_WIDTH/2+1, TEX_WIDTH/2+1);
   glEnd();
*/
   int size = 2;
   glBegin(GL_QUADS);
   glTexCoord2f(0.0, 0.0); glVertex2f(12.0, 12.0);
   glTexCoord2f(0.0, 1.0); glVertex2f(12.0, 12.0+size);
   glTexCoord2f(1.0, 1.0); glVertex2f(12.0+size, 12.0+size);
   glTexCoord2f(1.0, 0.0); glVertex2f(12.0+size, 12.0);
   glEnd();
   glFlush();



   glReadPixels(11, 11, 4, 4, GL_RGB, GL_FLOAT, buf);
   //glReadPixels(11, 11, TEX_WIDTH+2, TEX_WIDTH+2, GL_RGB, GL_FLOAT, buf);
   for (i=0; i<TEX_WIDTH+2; i++)
   {
      printf ("row %d: ", i);
      for (j=0; j<TEX_WIDTH+2; j++){
          printf("(%f %f %f)  ", buf[(i*(TEX_WIDTH+2)+j)*3], buf[(i*(TEX_WIDTH+2)+j)*3+1], buf[(i*(TEX_WIDTH+2)+j)*3+2]);
      }
      printf("\n");
   }
}

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

    test();
}

int main(int argc, char** argv)
{
   printf ("Please check the support to point_sprite yourself!\n");

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