/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 *               1993, 1994 Microsoft Corporation
 *
 * ALL RIGHTS RESERVED
 *
 * Please refer to OpenGL/readme.txt for additional information
 *
 */

/*  texgen.c
 *  This program draws a texture mapped teapot with 
 *  automatically generated texture coordinates.  The
 *  texture is rendered as stripes on the teapot.
 */
#include "glos.h"

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>

void myinit(void);
void makeStripeImage(void);
void CALLBACK display(void);
void CALLBACK myReshape(GLsizei w, GLsizei h);

#define stripeImageWidth 32
GLubyte stripeImage[3*stripeImageWidth];

void makeStripeImage(void)
{
    int j;
    
    for (j = 0; j < stripeImageWidth; j++) {
        stripeImage[3*j] = (j<=4) ? 255 : 0;
        stripeImage[3*j+1] = (j>4) ? 255 : 0;
        stripeImage[3*j+2] = 0;
    }
}

/* glTexGen stuff: */

GLfloat sgenparams[] = {1.0, 1.0, 1.0, 0.0};

void myinit(void)
{
    glClearColor (0.0, 0.0, 0.0, 0.0);

    makeStripeImage();
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexImage1D(GL_TEXTURE_1D, 0, 3, stripeImageWidth, 0,
         GL_RGB, GL_UNSIGNED_BYTE, stripeImage);

    glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
    glTexGenfv(GL_S, GL_OBJECT_PLANE, sgenparams);

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    glEnable(GL_TEXTURE_GEN_S);
    glEnable(GL_TEXTURE_1D);
    glEnable(GL_CULL_FACE);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_AUTO_NORMAL);
    glEnable(GL_NORMALIZE);
    glFrontFace(GL_CW);
    glCullFace(GL_BACK);
    glMaterialf (GL_FRONT, GL_SHININESS, 64.0);
}

void CALLBACK display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix ();
    glRotatef(45.0, 0.0, 0.0, 1.0);
    auxSolidTeapot(2.0);
    glPopMatrix ();
    glFlush();
}

void CALLBACK myReshape(GLsizei w, GLsizei h)
{
    h = (h == 0) ? 1 : h;
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
    glOrtho (-3.5, 3.5, -3.5*(GLfloat)h/(GLfloat)w, 
        3.5*(GLfloat)h/(GLfloat)w, -3.5, 3.5);
    else
    glOrtho (-3.5*(GLfloat)w/(GLfloat)h, 
        3.5*(GLfloat)w/(GLfloat)h, -3.5, 3.5, -3.5, 3.5);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB | AUX_DEPTH16);
    auxInitPosition (0, 0, 200, 200);
    auxInitWindow ("Texture Map");
    myinit();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return(0);
}
