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

#define WINDSIZEX 100
#define WINDSIZEY 100

#define TEXSIZEX  8
#define TEXSIZEY  64

GLfloat *buf;

GLfloat colorMap[][3] = {
   {
      1.0, 0.0, 0.0
   },
   {   
      0.0, 1.0, 0.0 
   },      
   {       
      0.0, 0.0, 1.0
   },
   {
      1.0, 1.0, 0.0
   },
   {
      1.0, 0.0, 1.0
   },
   {
      0.0, 1.0, 1.0
   },
   {
      1.0, 1.0, 1.0
   }
};


static void makeMipmap(GLsizei sizeX, GLsizei sizeY)
{
   GLfloat *ptr;
   GLint level, i;

   level = 0;
   while (sizeX > 0 || sizeY > 0) {
      ptr = buf;
      for (i = 0; i < ((sizeX==0)?1:sizeX) * ((sizeY==0)?1:sizeY); i++) {
	 *ptr++ = colorMap[level][0];
	 *ptr++ = colorMap[level][1];
	 *ptr++ = colorMap[level][2];
      }
      glTexImage2D(GL_TEXTURE_2D, level++, GL_RGB, (sizeX==0)?1:sizeX,
	    (sizeY==0)?1:sizeY, 0, GL_RGB, GL_FLOAT,
	    (unsigned char *)buf);
      sizeX /= 2;
      sizeY /= 2;
   }
}

void Draw(GLfloat sizeX, GLfloat sizeY)
{
   GLfloat x, y;

      x =  (1.0 / sizeX);
      y = (1.0 / sizeY) / 16;
     
     printf ("x, y: %f %f\n", x, y);
         glBegin(GL_POLYGON);
         glTexCoord2f(0.0, 0.0);
         glVertex2f(0, 0);
         glTexCoord2f(x, 0.0);
         glVertex2f(0+1.0, 0);
         glTexCoord2f(x, y);
         glVertex2f(0+1.0, 1.0);
         glTexCoord2f(0.0, y);
         glVertex2f(0, 1.0);
         glEnd();
}


void init(void)
{
   glClearColor(0.0, 0.0, 0.0, 0.0);
   glDisable(GL_DITHER);
   glEnable(GL_TEXTURE_2D);
   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

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

   makeMipmap(TEXSIZEX, TEXSIZEY);
}

static void test(void)
{    
   int drawCount;

//   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
//   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); 
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 

   glClear(GL_COLOR_BUFFER_BIT);
   glColor3f(0.5, 0.5, 0.5);
   Draw(TEXSIZEX, TEXSIZEY);

   glReadPixels(0, 0, 1, 1, GL_RGB, GL_FLOAT, buf);
   printf("buf: %f, %f, %f\n", buf[0], buf[1], buf[2]);
   printf("it should be: 1.0, 0.0, 0.0\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)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize(WINDSIZEX, WINDSIZEY);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   init();
   glutDisplayFunc(display);
   glutMainLoop();
   return 0; 
}