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solled
10-21-2001, 09:26 AM
I'm a beginner and I'm having trouble understanding/using texture mapping. Below is the code for a sphere (from the Red Book). I simply want to color part of the sphere a differnt color. I'm trying to paint an eye. Do I need to use texture mapping? I've been trying to learn texture mapping, but I don't see how to do what I want. Would you please add the code needed to the folling program. Thank you.

/*
* Copyright (c) 1993-1999, Silicon Graphics, Inc.
* ALL RIGHTS RESERVED
* Permission to use, copy, modify, and distribute this software for
* any purpose and without fee is hereby granted, provided that the above
* copyright notice appear. */

/*
* light.c
* This program demonstrates the use of the OpenGL lighting
* model. A sphere is drawn using a grey material characteristic.
* A single light source illuminates the object.
*/
#include <GL/glut.h>
#include <stdlib.h>

/* Initialize material property, light source, lighting model,
* and depth buffer.
*/
void init(void)
{
GLfloat mat_specular[] = { .5, .5, .5, 1.0 };
GLfloat mat_shininess[] = { 30.0 };
GLfloat light_position[] = { -0.4, 2.1, 3.1, 0.0 };

glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel (GL_SMOOTH);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
glLightfv(GL_LIGHT3, GL_POSITION, light_position);

glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_DEPTH_TEST);
}

void display(void)
{
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glutSolidSphere (.7, 40, 20);
glFlush ();
}

void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity();
if (w <= h)
glOrtho (-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w,
1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
else
glOrtho (-1.5*(GLfloat)w/(GLfloat)h,
1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
}
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
init ();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}