source: trunk/sys/TinyGL/examples/texobj.c @ 17

/*
 * Example of using the 1.1 texture object functions.
 * Also, this demo utilizes Mesa's fast texture map path.
 *
 * Brian Paul   June 1996
 */

#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <GL/glx.h> 
#include <GL/gl.h> 
#include "ui.h"

static GLuint TexObj[2];
static GLfloat Angle = 0.0f;

static int cnt=0,v=0;

void 
draw(void)
{
  glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

  glColor3f(1.0, 1.0, 1.0);

  /* draw first polygon */
  glPushMatrix();
  glTranslatef(-1.0, 0.0, 0.0);
  glRotatef(Angle, 0.0, 0.0, 1.0);
  glBindTexture(GL_TEXTURE_2D, TexObj[v]);

  glEnable(GL_TEXTURE_2D);
  glBegin(GL_QUADS);
  glTexCoord2f(0.0, 0.0);
  glVertex2f(-1.0, -1.0);
  glTexCoord2f(1.0, 0.0);
  glVertex2f(1.0, -1.0);
  glTexCoord2f(1.0, 1.0);
  glVertex2f(1.0, 1.0);
  glTexCoord2f(0.0, 1.0);
  glVertex2f(-1.0, 1.0);
  glEnd();
  glDisable(GL_TEXTURE_2D);
  glPopMatrix();

  /* draw second polygon */
  glPushMatrix();
  glTranslatef(1.0, 0.0, 0.0);
  glRotatef(Angle - 90.0, 0.0, 1.0, 0.0);

  glBindTexture(GL_TEXTURE_2D, TexObj[1-v]);

  glEnable(GL_TEXTURE_2D);
  glBegin(GL_QUADS);
  glTexCoord2f(0.0, 0.0);
  glVertex2f(-1.0, -1.0);
  glTexCoord2f(1.0, 0.0);
  glVertex2f(1.0, -1.0);
  glTexCoord2f(1.0, 1.0);
  glVertex2f(1.0, 1.0);
  glTexCoord2f(0.0, 1.0);
  glVertex2f(-1.0, 1.0);
  glEnd();
  glDisable(GL_TEXTURE_2D);

  glPopMatrix();

  tkSwapBuffers();
}


/* new window size or exposure */
void 
reshape(int width, int height)
{
  glViewport(0, 0, (GLint) width, (GLint) height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  /* glOrtho( -3.0, 3.0, -3.0, 3.0, -10.0, 10.0 ); */
  glFrustum(-2.0, 2.0, -2.0, 2.0, 6.0, 20.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(0.0, 0.0, -8.0);
}


void bind_texture(int texobj,int image)
{
  static int width = 8, height = 8;
  static int color[2][3]={
    {255,0,0},
    {0,255,0},
  };
  GLubyte tex[64][3];
  static GLubyte texchar[2][8*8] = {
  {
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 1, 0, 0, 0,
    0, 0, 0, 1, 1, 0, 0, 0,
    0, 0, 0, 0, 1, 0, 0, 0,
    0, 0, 0, 0, 1, 0, 0, 0,
    0, 0, 0, 0, 1, 0, 0, 0,
    0, 0, 0, 1, 1, 1, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0},
  {
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 2, 2, 0, 0, 0,
    0, 0, 2, 0, 0, 2, 0, 0,
    0, 0, 0, 0, 0, 2, 0, 0,
    0, 0, 0, 0, 2, 0, 0, 0,
    0, 0, 0, 2, 0, 0, 0, 0,
    0, 0, 2, 2, 2, 2, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0}};

  int i,j;
  
  glBindTexture(GL_TEXTURE_2D, texobj);

  /* red on white */
  for (i = 0; i < height; i++) {
    for (j = 0; j < width; j++) {
      int p = i * width + j;
      if (texchar[image][(height - i - 1) * width + j]) {
        tex[p][0] = color[image][0];
        tex[p][1] = color[image][1];
        tex[p][2] = color[image][2];
      } else {
        tex[p][0] = 255;
        tex[p][1] = 255;
        tex[p][2] = 255;
      }
    }
  }
  glTexImage2D(GL_TEXTURE_2D, 0, 3, width, height, 0,
    GL_RGB, GL_UNSIGNED_BYTE, 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_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  /* end of texture object */
}



void 
init(void)
{
  glEnable(GL_DEPTH_TEST);

  /* Setup texturing */
  glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
  glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);

  /* generate texture object IDs */
  glGenTextures(2, TexObj);
  bind_texture(TexObj[0],0);
  bind_texture(TexObj[1],1);
  
}

void 
idle(void)
{
  
  Angle += 2.0;

  if (++cnt==5) {
    cnt=0;
    v=!v;
  }
  draw();
}

/* change view angle, exit upon ESC */
GLenum key(int k, GLenum mask)
{
   switch (k) {
      case 'q':
      case KEY_ESCAPE:
          exit(0);
   }
   return GL_FALSE;
}

int main(int argc, char **argv) 
{
    return ui_loop(argc, argv, "texobj");
}