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/* Copyright (c) Mark J. Kilgard, 1994. */
/*
* (c) Copyright 1993, 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 in all copies and that both the copyright notice
* and this permission notice appear in supporting documentation, and that
* the name of Silicon Graphics, Inc. not be used in advertising
* or publicity pertaining to distribution of the software without specific,
* written prior permission.
*
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor
* clauses in the FAR or the DOD or NASA FAR Supplement.
* Unpublished-- rights reserved under the copyright laws of the
* United States. Contractor/manufacturer is Silicon Graphics,
* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
*
* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
*/
/* stencil.c
* This program draws two rotated tori in a window.
* A diamond in the center of the window masks out part
* of the scene. Within this mask, a different model
* (a sphere) is drawn in a different color.
*/
/*
* !!! NOTE !!!
*
* This demo is poorly written. The stencil buffer should be
* redrawn in display(), not in the myReshape() function.
* The reason is if the window gets "damaged" then the stencil buffer
* contents will be in an undefined state (myReshape is not called when
* a window is damaged and needs to be redrawn). If the stencil buffer
* contents are undefined, the results of display() are unpredictable.
*
* -Brian
*/
#include <stdlib.h>
#include <GL/glut.h>
#define YELLOWMAT 1
#define BLUEMAT 2
void myinit (void)
{
GLfloat yellow_diffuse[] = { 0.7, 0.7, 0.0, 1.0 };
GLfloat yellow_specular[] = { 1.0, 1.0, 1.0, 1.0 };
GLfloat blue_diffuse[] = { 0.1, 0.1, 0.7, 1.0 };
GLfloat blue_specular[] = { 0.1, 1.0, 1.0, 1.0 };
GLfloat position_one[] = { 1.0, 1.0, 1.0, 0.0 };
glNewList(YELLOWMAT, GL_COMPILE);
glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, yellow_specular);
glMaterialf(GL_FRONT, GL_SHININESS, 64.0);
glEndList();
glNewList(BLUEMAT, GL_COMPILE);
glMaterialfv(GL_FRONT, GL_DIFFUSE, blue_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, blue_specular);
glMaterialf(GL_FRONT, GL_SHININESS, 45.0);
glEndList();
glLightfv(GL_LIGHT0, GL_POSITION, position_one);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHTING);
glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);
glClearStencil(0x0);
glEnable(GL_STENCIL_TEST);
}
/* Draw a sphere in a diamond-shaped section in the
* middle of a window with 2 tori.
*/
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);
/* draw blue sphere where the stencil is 1 */
glStencilFunc (GL_EQUAL, 0x1, 0x1);
glCallList (BLUEMAT);
glutSolidSphere (0.5, 15, 15);
/* draw the tori where the stencil is not 1 */
glStencilFunc (GL_NOTEQUAL, 0x1, 0x1);
glPushMatrix();
glRotatef (45.0, 0.0, 0.0, 1.0);
glRotatef (45.0, 0.0, 1.0, 0.0);
glCallList (YELLOWMAT);
glutSolidTorus (0.275, 0.85, 15, 15);
glPushMatrix();
glRotatef (90.0, 1.0, 0.0, 0.0);
glutSolidTorus (0.275, 0.85, 15, 15);
glPopMatrix();
glPopMatrix();
glFlush();
glutSwapBuffers();
}
/* Whenever the window is reshaped, redefine the
* coordinate system and redraw the stencil area.
*/
void myReshape(int w, int h)
{
glViewport(0, 0, w, h);
glClear(GL_STENCIL_BUFFER_BIT);
/* create a diamond shaped stencil area */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-3.0, 3.0, -3.0, 3.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glStencilFunc (GL_ALWAYS, 0x1, 0x1);
glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE);
glBegin(GL_QUADS);
glVertex3f (-1.0, 0.0, 0.0);
glVertex3f (0.0, 1.0, 0.0);
glVertex3f (1.0, 0.0, 0.0);
glVertex3f (0.0, -1.0, 0.0);
glEnd();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0, (GLfloat) w/(GLfloat) h, 3.0, 7.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -5.0);
}
static void
key(unsigned char k, int x, int y)
{
switch (k) {
case 27: /* Escape */
exit(0);
break;
default:
return;
}
glutPostRedisplay();
}
/* Main Loop
* Open window with initial window size, title bar,
* RGBA display mode, and handle input events.
*/
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH | GLUT_STENCIL);
glutInitWindowSize (400, 400);
glutCreateWindow (argv[0]);
myinit ();
glutReshapeFunc (myReshape);
glutDisplayFunc(display);
glutKeyboardFunc(key);
glutMainLoop();
return 0; /* ANSI C requires main to return int. */
}
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