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Amiga Format CD 52
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Amiga Format AFCD52 (Issue 136, May 2000).iso
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mesa
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book.aux
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alpha.c
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2000-02-23
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/*
* (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* Unpublished-- rights reserved under the copyright laws of the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.
*/
/*
* alpha.c
* This program draws several overlapping filled polygons
* to demonstrate the effect order has on alpha blending results.
*/
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdlib.h>
#include <GL/glaux.h>
/*
* Initialize alpha blending function.
*/
void myinit(void)
{
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glShadeModel(GL_FLAT);
glClearColor(0.0, 0.0, 0.0, 0.0);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glColor4f(1.0, 1.0, 0.0, 0.75);
glRectf(0.0, 0.0, 0.5, 1.0);
glColor4f(0.0, 1.0, 1.0, 0.75);
glRectf(0.0, 0.0, 1.0, 0.5);
/*
* draw colored polygons in reverse order in upper right
*/
glColor4f(0.0, 1.0, 1.0, 0.75);
glRectf(0.5, 0.5, 1.0, 1.0);
glColor4f(1.0, 1.0, 0.0, 0.75);
glRectf(0.5, 0.5, 1.0, 1.0);
glFlush();
}
void myReshape(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w <= h)
gluOrtho2D(0.0, 1.0, 0.0, 1.0 * (GLfloat) h / (GLfloat) w);
else
gluOrtho2D(0.0, 1.0 * (GLfloat) w / (GLfloat) h, 0.0, 1.0);
glMatrixMode(GL_MODELVIEW);
}
/*
* Main Loop
* * Open window with initial window size, title bar,
* * RGBA display mode, and handle input events.
*/
int main(int argc, char **argv)
{
auxInitDisplayMode(AUX_SINGLE | AUX_RGB);
auxInitPosition(0, 0, 500, 500);
if (!auxInitWindow(argv[0]))
auxQuit();
myinit();
auxReshapeFunc(myReshape);
auxMainLoop(display);
return 0;
}