479 lines
11 KiB
C
479 lines
11 KiB
C
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/*
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* This program demonstrates how to do "off-screen" rendering using
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* the GLX pixel buffer extension.
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*
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* Written by Brian Paul for the "OpenGL and Window System Integration"
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* course presented at SIGGRAPH '97. Updated on 5 October 2002.
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*
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* Usage:
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* pbuffers width height imgfile
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* Where:
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* width is the width, in pixels, of the image to generate.
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* height is the height, in pixels, of the image to generate.
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* imgfile is the name of the PPM image file to write.
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*
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*
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* This demo draws 3-D boxes with random orientation. A pbuffer with
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* a depth (Z) buffer is prefered but if such a pbuffer can't be created
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* we use a non-depth-buffered config.
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*
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* On machines such as the SGI Indigo you may have to reconfigure your
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* display/X server to enable pbuffers. Look in the /usr/gfx/ucode/MGRAS/vof/
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* directory for display configurationswith the _pbuf suffix. Use
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* setmon -x <vof> to configure your X server and display for pbuffers.
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*
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* O2 systems seem to support pbuffers well.
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*
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* IR systems (at least 1RM systems) don't have single-buffered, RGBA,
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* Z-buffered pbuffer configs. BUT, they DO have DOUBLE-buffered, RGBA,
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* Z-buffered pbuffers. Note how we try four different fbconfig attribute
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* lists below!
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*/
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#include <assert.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <X11/Xlib.h>
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#include "pbutil.h"
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/* Some ugly global vars */
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static Display *gDpy = NULL;
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static int gScreen = 0;
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static FBCONFIG gFBconfig = 0;
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static PBUFFER gPBuffer = 0;
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static int gWidth, gHeight;
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static GLXContext glCtx;
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/*
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* Create the pbuffer and return a GLXPbuffer handle.
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*
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* We loop over a list of fbconfigs trying to create
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* a pixel buffer. We return the first pixel buffer which we successfully
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* create.
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*/
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static PBUFFER
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MakePbuffer( Display *dpy, int screen, int width, int height )
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{
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#define NUM_FB_CONFIGS 4
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const char fbString[NUM_FB_CONFIGS][100] = {
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"Single Buffered, depth buffer",
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"Double Buffered, depth buffer",
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"Single Buffered, no depth buffer",
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"Double Buffered, no depth buffer"
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};
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int fbAttribs[NUM_FB_CONFIGS][100] = {
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{
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/* Single buffered, with depth buffer */
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GLX_RENDER_TYPE, GLX_RGBA_BIT,
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GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
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GLX_RED_SIZE, 1,
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GLX_GREEN_SIZE, 1,
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GLX_BLUE_SIZE, 1,
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GLX_DEPTH_SIZE, 1,
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GLX_DOUBLEBUFFER, 0,
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GLX_STENCIL_SIZE, 0,
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None
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},
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{
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/* Double buffered, with depth buffer */
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GLX_RENDER_TYPE, GLX_RGBA_BIT,
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GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
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GLX_RED_SIZE, 1,
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GLX_GREEN_SIZE, 1,
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GLX_BLUE_SIZE, 1,
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GLX_DEPTH_SIZE, 1,
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GLX_DOUBLEBUFFER, 1,
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GLX_STENCIL_SIZE, 0,
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None
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},
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{
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/* Single bufferd, without depth buffer */
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GLX_RENDER_TYPE, GLX_RGBA_BIT,
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GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
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GLX_RED_SIZE, 1,
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GLX_GREEN_SIZE, 1,
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GLX_BLUE_SIZE, 1,
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GLX_DEPTH_SIZE, 0,
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GLX_DOUBLEBUFFER, 0,
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GLX_STENCIL_SIZE, 0,
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None
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},
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{
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/* Double bufferd, without depth buffer */
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GLX_RENDER_TYPE, GLX_RGBA_BIT,
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GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
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GLX_RED_SIZE, 1,
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GLX_GREEN_SIZE, 1,
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GLX_BLUE_SIZE, 1,
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GLX_DEPTH_SIZE, 0,
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GLX_DOUBLEBUFFER, 1,
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GLX_STENCIL_SIZE, 0,
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None
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}
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};
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Bool largest = True;
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Bool preserve = False;
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FBCONFIG *fbConfigs;
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PBUFFER pBuffer = None;
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int nConfigs;
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int i;
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int attempt;
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for (attempt=0; attempt<NUM_FB_CONFIGS; attempt++) {
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/* Get list of possible frame buffer configurations */
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fbConfigs = ChooseFBConfig(dpy, screen, fbAttribs[attempt], &nConfigs);
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if (nConfigs==0 || !fbConfigs) {
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printf("Error: glXChooseFBConfig failed\n");
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XCloseDisplay(dpy);
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return 0;
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}
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#if 0 /*DEBUG*/
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for (i=0;i<nConfigs;i++) {
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printf("Config %d\n", i);
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PrintFBConfigInfo(dpy, screen, fbConfigs[i], 0);
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}
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#endif
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/* Create the pbuffer using first fbConfig in the list that works. */
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for (i=0;i<nConfigs;i++) {
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pBuffer = CreatePbuffer(dpy, screen, fbConfigs[i], width, height, preserve, largest);
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if (pBuffer) {
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gFBconfig = fbConfigs[i];
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gWidth = width;
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gHeight = height;
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break;
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}
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}
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if (pBuffer!=None) {
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break;
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}
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}
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if (pBuffer) {
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printf("Using: %s\n", fbString[attempt]);
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}
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XFree(fbConfigs);
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return pBuffer;
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#undef NUM_FB_CONFIGS
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}
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/*
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* Do all the X / GLX setup stuff.
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*/
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static int
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Setup(int width, int height)
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{
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int pbSupport;
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XVisualInfo *visInfo;
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/* Open the X display */
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gDpy = XOpenDisplay(NULL);
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if (!gDpy) {
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printf("Error: couldn't open default X display.\n");
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return 0;
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}
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/* Get default screen */
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gScreen = DefaultScreen(gDpy);
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/* Test that pbuffers are available */
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pbSupport = QueryPbuffers(gDpy, gScreen);
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if (pbSupport == 1) {
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printf("Using GLX 1.3 Pbuffers\n");
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}
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else if (pbSupport == 2) {
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printf("Using SGIX Pbuffers\n");
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}
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else {
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printf("Error: pbuffers not available on this screen\n");
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XCloseDisplay(gDpy);
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return 0;
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}
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/* Create Pbuffer */
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gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
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if (gPBuffer==None) {
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printf("Error: couldn't create pbuffer\n");
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XCloseDisplay(gDpy);
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return 0;
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}
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/* Get corresponding XVisualInfo */
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visInfo = GetVisualFromFBConfig(gDpy, gScreen, gFBconfig);
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if (!visInfo) {
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printf("Error: can't get XVisualInfo from FBconfig\n");
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XCloseDisplay(gDpy);
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return 0;
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}
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/* Create GLX context */
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glCtx = glXCreateContext(gDpy, visInfo, NULL, True);
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if (!glCtx) {
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/* try indirect */
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glCtx = glXCreateContext(gDpy, visInfo, NULL, False);
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if (!glCtx) {
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printf("Error: Couldn't create GLXContext\n");
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XFree(visInfo);
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XCloseDisplay(gDpy);
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return 0;
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}
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else {
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printf("Warning: using indirect GLXContext\n");
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}
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}
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/* Bind context to pbuffer */
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if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
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printf("Error: glXMakeCurrent failed\n");
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XFree(visInfo);
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XCloseDisplay(gDpy);
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return 0;
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}
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return 1; /* Success!! */
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}
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/* One-time GL setup */
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static void
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InitGL(void)
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{
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static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
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glEnable(GL_LIGHTING);
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glEnable(GL_LIGHT0);
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glLightfv(GL_LIGHT0, GL_POSITION, pos);
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glEnable(GL_NORMALIZE);
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glEnable(GL_DEPTH_TEST);
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glEnable(GL_CULL_FACE);
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glViewport(0, 0, gWidth, gHeight);
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glMatrixMode( GL_PROJECTION );
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glLoadIdentity();
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glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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glTranslatef( 0.0, 0.0, -15.0 );
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}
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/* Return random float in [0,1] */
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static float
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Random(void)
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{
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int i = rand();
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return (float) (i % 1000) / 1000.0;
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}
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static void
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RandomColor(void)
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{
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GLfloat c[4];
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c[0] = Random();
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c[1] = Random();
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c[2] = Random();
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c[3] = 1.0;
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glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
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}
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/* This function borrowed from Mark Kilgard's GLUT */
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static void
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drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
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GLfloat z0, GLfloat z1, GLenum type)
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{
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static GLfloat n[6][3] =
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{
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{-1.0, 0.0, 0.0},
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{0.0, 1.0, 0.0},
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{1.0, 0.0, 0.0},
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{0.0, -1.0, 0.0},
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{0.0, 0.0, 1.0},
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{0.0, 0.0, -1.0}
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};
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static GLint faces[6][4] =
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{
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{0, 1, 2, 3},
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{3, 2, 6, 7},
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{7, 6, 5, 4},
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{4, 5, 1, 0},
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{5, 6, 2, 1},
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{7, 4, 0, 3}
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};
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GLfloat v[8][3], tmp;
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GLint i;
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if (x0 > x1) {
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tmp = x0;
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x0 = x1;
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x1 = tmp;
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}
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if (y0 > y1) {
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tmp = y0;
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y0 = y1;
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y1 = tmp;
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}
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if (z0 > z1) {
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tmp = z0;
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z0 = z1;
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z1 = tmp;
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}
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v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
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v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
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v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
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v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
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v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
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v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
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for (i = 0; i < 6; i++) {
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glBegin(type);
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glNormal3fv(&n[i][0]);
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glVertex3fv(&v[faces[i][0]][0]);
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glVertex3fv(&v[faces[i][1]][0]);
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glVertex3fv(&v[faces[i][2]][0]);
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glVertex3fv(&v[faces[i][3]][0]);
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glEnd();
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}
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}
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/* Render a scene */
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static void
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Render(void)
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{
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int NumBoxes = 100;
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int i;
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glClearColor(0.2, 0.2, 0.9, 0.0);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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for (i=0;i<NumBoxes;i++) {
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float tx = -2.0 + 4.0 * Random();
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float ty = -2.0 + 4.0 * Random();
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float tz = 4.0 - 16.0 * Random();
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float sx = 0.1 + Random() * 0.4;
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float sy = 0.1 + Random() * 0.4;
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float sz = 0.1 + Random() * 0.4;
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float rx = Random();
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float ry = Random();
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float rz = Random();
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float ra = Random() * 360.0;
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glPushMatrix();
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glTranslatef(tx, ty, tz);
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glRotatef(ra, rx, ry, rz);
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glScalef(sx, sy, sz);
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RandomColor();
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drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
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glPopMatrix();
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}
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glFinish();
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}
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static void
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WriteFile(const char *filename)
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{
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FILE *f;
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GLubyte *image;
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int i;
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image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
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if (!image) {
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printf("Error: couldn't allocate image buffer\n");
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return;
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}
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glPixelStorei(GL_PACK_ALIGNMENT, 1);
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glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
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f = fopen(filename, "w");
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if (!f) {
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printf("Couldn't open image file: %s\n", filename);
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return;
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}
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fprintf(f,"P6\n");
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fprintf(f,"# ppm-file created by %s\n", "trdemo2");
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fprintf(f,"%i %i\n", gWidth, gHeight);
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fprintf(f,"255\n");
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fclose(f);
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f = fopen(filename, "ab"); /* now append binary data */
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if (!f) {
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printf("Couldn't append to image file: %s\n", filename);
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return;
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}
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for (i=0;i<gHeight;i++) {
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GLubyte *rowPtr;
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/* Remember, OpenGL images are bottom to top. Have to reverse. */
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rowPtr = image + (gHeight-1-i) * gWidth*3;
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fwrite(rowPtr, 1, gWidth*3, f);
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}
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fclose(f);
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free(image);
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printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
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}
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/*
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* Print message describing command line parameters.
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*/
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static void
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Usage(const char *appName)
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{
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printf("Usage:\n");
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printf(" %s width height imgfile\n", appName);
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printf("Where imgfile is a ppm file\n");
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}
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int
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main(int argc, char *argv[])
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{
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if (argc!=4) {
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Usage(argv[0]);
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}
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else {
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int width = atoi(argv[1]);
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int height = atoi(argv[2]);
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char *fileName = argv[3];
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if (width<=0) {
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printf("Error: width parameter must be at least 1.\n");
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return 1;
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}
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if (height<=0) {
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printf("Error: height parameter must be at least 1.\n");
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return 1;
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}
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if (!Setup(width, height)) {
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return 1;
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}
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InitGL();
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Render();
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WriteFile(fileName);
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DestroyPbuffer(gDpy, gScreen, gPBuffer);
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}
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return 0;
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}
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