CHECKER.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/*  checker.c 
 *  This program texture maps a checkerboard image onto 
 *  two rectangles.  This program clamps the texture, if 
 *  the texture coordinates fall outside 0.0 and 1.0. 
 */ 
#include "glos.h" 
 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glaux.h> 
 
void myinit(void); 
void makeCheckImage(void); 
void CALLBACK myReshape(GLsizei w, GLsizei h); 
void CALLBACK display(void); 
 
/*  Create checkerboard texture */ 
#define checkImageWidth 64 
#define checkImageHeight 64 
GLubyte checkImage[checkImageWidth][checkImageHeight][3]; 
 
void makeCheckImage(void) 
{ 
    int i, j, c; 
     
    for (i = 0; i < checkImageWidth; i++) { 
    for (j = 0; j < checkImageHeight; j++) { 
        c = ((((i&0x8)==0)^((j&0x8))==0))*255; 
        checkImage[i][j][0] = (GLubyte) c; 
        checkImage[i][j][1] = (GLubyte) c; 
        checkImage[i][j][2] = (GLubyte) c; 
    } 
    } 
} 
 
void myinit(void) 
{     
    glClearColor (0.0, 0.0, 0.0, 0.0); 
    glEnable(GL_DEPTH_TEST); 
    glDepthFunc(GL_LESS); 
 
    makeCheckImage(); 
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1); 
    glTexImage2D(GL_TEXTURE_2D, 0, 3, checkImageWidth,  
    checkImageHeight, 0, GL_RGB, GL_UNSIGNED_BYTE,  
    &checkImage[0][0][0]); 
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); 
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); 
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); 
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); 
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); 
    glEnable(GL_TEXTURE_2D); 
    glShadeModel(GL_FLAT); 
} 
 
void CALLBACK display(void) 
{ 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glBegin(GL_QUADS); 
    glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0); 
    glTexCoord2f(0.0, 1.0); glVertex3f(-2.0, 1.0, 0.0); 
    glTexCoord2f(1.0, 1.0); glVertex3f(0.0, 1.0, 0.0); 
    glTexCoord2f(1.0, 0.0); glVertex3f(0.0, -1.0, 0.0); 
 
    glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0); 
    glTexCoord2f(0.0, 1.0); glVertex3f(1.0, 1.0, 0.0); 
    glTexCoord2f(1.0, 1.0); glVertex3f(2.41421, 1.0, -1.41421); 
    glTexCoord2f(1.0, 0.0); glVertex3f(2.41421, -1.0, -1.41421); 
    glEnd(); 
    glFlush(); 
} 
 
void CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if (!h) return; 
    glViewport(0, 0, w, h); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    gluPerspective(60.0, 1.0*(GLfloat)w/(GLfloat)h, 1.0, 30.0); 
    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity(); 
    glTranslatef(0.0, 0.0, -3.6); 
} 
 
int main(int argc, char** argv) 
{ 
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB | AUX_DEPTH16); 
    auxInitPosition (0, 0, 500, 500); 
    auxInitWindow ("Texture Map"); 
    myinit(); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}