101 lines
3.4 KiB
C
101 lines
3.4 KiB
C
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/*
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* (c) Copyright 1993, Silicon Graphics, Inc.
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* ALL RIGHTS RESERVED
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* Permission to use, copy, modify, and distribute this software for
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* any purpose and without fee is hereby granted, provided that the above
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* copyright notice appear in all copies and that both the copyright notice
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* and this permission notice appear in supporting documentation, and that
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* the name of Silicon Graphics, Inc. not be used in advertising
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* or publicity pertaining to distribution of the software without specific,
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* written prior permission.
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*
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* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
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* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
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* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
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* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
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* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
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* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
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* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
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* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
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* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
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* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* US Government Users Restricted Rights
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* Use, duplication, or disclosure by the Government is subject to
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* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
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* (c)(1)(ii) of the Rights in Technical Data and Computer Software
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* clause at DFARS 252.227-7013 and/or in similar or successor
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* clauses in the FAR or the DOD or NASA FAR Supplement.
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* Unpublished-- rights reserved under the copyright laws of the
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* United States. Contractor/manufacturer is Silicon Graphics,
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* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
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*
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* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
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*/
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/*
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* alpha.c
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* This program draws several overlapping filled polygons
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* to demonstrate the effect order has on alpha blending results.
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*/
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#include <windows.h>
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#include <GL/gl.h>
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#include <GL/glu.h>
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#include "glaux.h"
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/* Initialize alpha blending function.
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*/
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void myinit(void)
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{
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glEnable (GL_BLEND);
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glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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glShadeModel (GL_FLAT);
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glClearColor (0.0, 0.0, 0.0, 0.0);
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}
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void display(void)
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{
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glClear(GL_COLOR_BUFFER_BIT);
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glColor4f (1.0, 1.0, 0.0, 0.75);
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glRectf (0.0, 0.0, 0.5, 1.0);
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glColor4f (0.0, 1.0, 1.0, 0.75);
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glRectf (0.0, 0.0, 1.0, 0.5);
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/* draw colored polygons in reverse order in upper right */
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glColor4f (0.0, 1.0, 1.0, 0.75);
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glRectf (0.5, 0.5, 1.0, 1.0);
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glColor4f (1.0, 1.0, 0.0, 0.75);
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glRectf (0.5, 0.5, 1.0, 1.0);
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glFlush();
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}
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void myReshape(GLsizei w, GLsizei h)
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{
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glViewport(0, 0, w, h);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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if (w <= h)
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gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat)h/(GLfloat)w);
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else
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gluOrtho2D (0.0, 1.0*(GLfloat)w/(GLfloat)h, 0.0, 1.0);
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glMatrixMode(GL_MODELVIEW);
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}
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/* Main Loop
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* Open window with initial window size, title bar,
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* RGBA display mode, and handle input events.
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*/
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int main(int argc, char** argv)
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{
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auxInitDisplayMode (AUX_SINGLE | AUX_RGB);
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auxInitPosition (0, 0, 500, 500);
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auxInitWindow (argv[0]);
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myinit();
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auxReshapeFunc (myReshape);
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auxMainLoop(display);
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}
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