stencil.c

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/*
 * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the name of
 * Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Silicon Graphics.
 *
 * THE SOFTWARE IS PROVIDED "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 BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <string.h>
#include <math.h>
#include "gltk.h"


GLenum directRender;


static void Init(void)
{

    glClearColor(0.0, 0.0, 0.0, 0.0);

    glClearStencil(0);
    glStencilMask(1);
    glEnable(GL_STENCIL_TEST);
}

static void Reshape(int width, int height)
{

    glViewport(0, 0, (GLint)width, (GLint)height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
    glMatrixMode(GL_MODELVIEW);
}

static GLenum Key(int key, GLenum mask)
{

    switch (key) {
      case TK_ESCAPE:
	tkQuit();
    }
    return GL_FALSE;
}

static void Draw(void)
{

    glClear(GL_COLOR_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);

    glStencilFunc(GL_ALWAYS, 1, 1);
    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);

    glColor3ub(200, 0, 0);
    glBegin(GL_POLYGON);        
	glVertex3i(-4, -4, 0);
	glVertex3i( 4, -4, 0);
	glVertex3i( 0,  4, 0);
    glEnd();

    glStencilFunc(GL_EQUAL, 1, 1);
    glStencilOp(GL_INCR, GL_KEEP, GL_DECR);

    glColor3ub(0, 200, 0);
    glBegin(GL_POLYGON);
	glVertex3i(3, 3, 0);
	glVertex3i(-3, 3, 0);
	glVertex3i(-3, -3, 0);
	glVertex3i(3, -3, 0);
    glEnd();

    glStencilFunc(GL_EQUAL, 1, 1);
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

    glColor3ub(0, 0, 200);
    glBegin(GL_POLYGON);
	glVertex3i(3, 3, 0);
	glVertex3i(-3, 3, 0);
	glVertex3i(-3, -3, 0);
	glVertex3i(3, -3, 0);
    glEnd();

    glFlush();
}

static GLenum Args(int argc, char **argv)
{
    GLint i;

    directRender = GL_TRUE;

    for (i = 1; i < argc; i++) {
	if (strcmp(argv[i], "-dr") == 0) {
	    directRender = GL_TRUE;
	} else if (strcmp(argv[i], "-ir") == 0) {
	    directRender = GL_FALSE;
	} else {
	    printf("%s (Bad option).\n", argv[i]);
	    return GL_FALSE;
	}
    }
    return GL_TRUE;
}

void main(int argc, char **argv)
{
    GLenum type;

    if (Args(argc, argv) == GL_FALSE) {
	tkQuit();
    }

    tkInitPosition(0, 0, 300, 300);

    type = TK_RGB | TK_SINGLE | TK_STENCIL;
    type |= (directRender) ? TK_DIRECT : TK_INDIRECT;
    tkInitDisplayMode(type);

    if (tkInitWindow("Stencil Test") == GL_FALSE) {
	tkQuit();
    }

    Init();

    tkExposeFunc(Reshape);
    tkReshapeFunc(Reshape);
    tkKeyDownFunc(Key);
    tkDisplayFunc(Draw);
    tkExec();
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.