From 21666e3db410d3ab9c7e4b18a3c29ae78a04fa95 Mon Sep 17 00:00:00 2001
From: Brian Paul <brian.paul@tungstengraphics.com>
Date: Sat, 5 Oct 2002 18:30:13 +0000
Subject: pbuffer info and demo programs

---
 progs/xdemos/pbdemo.c | 477 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 477 insertions(+)
 create mode 100644 progs/xdemos/pbdemo.c

(limited to 'progs/xdemos/pbdemo.c')

diff --git a/progs/xdemos/pbdemo.c b/progs/xdemos/pbdemo.c
new file mode 100644
index 0000000000..611e7e594f
--- /dev/null
+++ b/progs/xdemos/pbdemo.c
@@ -0,0 +1,477 @@
+/* $Id: pbdemo.c,v 1.1 2002/10/05 18:30:13 brianp Exp $ */
+
+/*
+ * This program demonstrates how to do "off-screen" rendering using
+ * the GLX pixel buffer extension.
+ *
+ * Written by Brian Paul for the "OpenGL and Window System Integration"
+ * course presented at SIGGRAPH '97.  Updated on 5 October 2002.
+ *
+ * Usage:
+ *   pbuffers width height imgfile
+ * Where:
+ *   width is the width, in pixels, of the image to generate.
+ *   height is the height, in pixels, of the image to generate.
+ *   imgfile is the name of the PPM image file to write.
+ *
+ *
+ * This demo draws 3-D boxes with random orientation.  A pbuffer with
+ * a depth (Z) buffer is prefered but if such a pbuffer can't be created
+ * we use a non-depth-buffered config.
+ *
+ * On machines such as the SGI Indigo you may have to reconfigure your
+ * display/X server to enable pbuffers.  Look in the /usr/gfx/ucode/MGRAS/vof/
+ * directory for display configurationswith the _pbuf suffix.  Use
+ * setmon -x <vof> to configure your X server and display for pbuffers.
+ *
+ * O2 systems seem to support pbuffers well.
+ *
+ * IR systems (at least 1RM systems) don't have single-buffered, RGBA,
+ * Z-buffered pbuffer configs.  BUT, they DO have DOUBLE-buffered, RGBA,
+ * Z-buffered pbuffers.  Note how we try four different fbconfig attribute
+ * lists below!
+ */
+
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <X11/Xlib.h>
+#include "pbutil.h"
+
+
+/* Some ugly global vars */
+static GLXFBConfigSGIX gFBconfig = 0;
+static Display *gDpy = NULL;
+static int gScreen = 0;
+static GLXPbufferSGIX gPBuffer = 0;
+static int gWidth, gHeight;
+
+
+
+/*
+ * Create the pbuffer and return a GLXPbufferSGIX handle.
+ */
+static GLXPbufferSGIX
+MakePbuffer( Display *dpy, int screen, int width, int height )
+{
+#define NUM_FB_CONFIGS 4
+   char fbString[NUM_FB_CONFIGS][100] = {
+      "Single Buffered, depth buffer",
+      "Double Buffered, depth buffer",
+      "Single Buffered, no depth buffer",
+      "Double Buffered, no depth buffer"
+   };
+   int fbAttribs[NUM_FB_CONFIGS][100] = {
+      {
+         /* Single buffered, with depth buffer */
+         GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
+         GLX_DRAWABLE_TYPE_SGIX, GLX_PIXMAP_BIT_SGIX,
+         GLX_RED_SIZE, 1,
+         GLX_GREEN_SIZE, 1,
+         GLX_BLUE_SIZE, 1,
+         GLX_DEPTH_SIZE, 1,
+         GLX_DOUBLEBUFFER, 0,
+         GLX_STENCIL_SIZE, 0,
+         None
+      },
+      {
+         /* Double buffered, with depth buffer */
+         GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
+         GLX_DRAWABLE_TYPE_SGIX, GLX_PIXMAP_BIT_SGIX,
+         GLX_RED_SIZE, 1,
+         GLX_GREEN_SIZE, 1,
+         GLX_BLUE_SIZE, 1,
+         GLX_DEPTH_SIZE, 1,
+         GLX_DOUBLEBUFFER, 1,
+         GLX_STENCIL_SIZE, 0,
+         None
+      },
+      {
+         /* Single bufferd, without depth buffer */
+         GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
+         GLX_DRAWABLE_TYPE_SGIX, GLX_PIXMAP_BIT_SGIX,
+         GLX_RED_SIZE, 1,
+         GLX_GREEN_SIZE, 1,
+         GLX_BLUE_SIZE, 1,
+         GLX_DEPTH_SIZE, 0,
+         GLX_DOUBLEBUFFER, 0,
+         GLX_STENCIL_SIZE, 0,
+         None
+      },
+      {
+         /* Double bufferd, without depth buffer */
+         GLX_RENDER_TYPE_SGIX, GLX_RGBA_BIT_SGIX,
+         GLX_DRAWABLE_TYPE_SGIX, GLX_PIXMAP_BIT_SGIX,
+         GLX_RED_SIZE, 1,
+         GLX_GREEN_SIZE, 1,
+         GLX_BLUE_SIZE, 1,
+         GLX_DEPTH_SIZE, 0,
+         GLX_DOUBLEBUFFER, 1,
+         GLX_STENCIL_SIZE, 0,
+         None
+      }
+   };
+   int pbAttribs[] = {
+      GLX_LARGEST_PBUFFER_SGIX, True,
+      GLX_PRESERVED_CONTENTS_SGIX, False,
+      None
+   };
+   GLXFBConfigSGIX *fbConfigs;
+   GLXPbufferSGIX pBuffer = None;
+   int nConfigs;
+   int i;
+   int attempt;
+
+   for (attempt=0; attempt<NUM_FB_CONFIGS; attempt++) {
+
+      /* Get list of possible frame buffer configurations */
+      fbConfigs = glXChooseFBConfigSGIX(dpy, screen, fbAttribs[attempt], &nConfigs);
+      if (nConfigs==0 || !fbConfigs) {
+         printf("Error: glxChooseFBConfigSGIX failed\n");
+         XCloseDisplay(dpy);
+         return 0;
+      }
+
+#ifdef DEBUG
+      for (i=0;i<nConfigs;i++) {
+         printf("Config %d\n", i);
+         PrintFBConfigInfo(dpy, fbConfigs[i], 0);
+      }
+#endif
+
+      /* Create the pbuffer using first fbConfig in the list that works. */
+      for (i=0;i<nConfigs;i++) {
+         pBuffer = CreatePbuffer(dpy, fbConfigs[i], width, height, pbAttribs);
+         if (pBuffer) {
+            gFBconfig = fbConfigs[i];
+            gWidth = width;
+            gHeight = height;
+            break;
+         }
+      }
+
+      if (pBuffer!=None) {
+         break;
+      }
+   }
+
+   if (pBuffer) {
+      printf("Using: %s\n", fbString[attempt]);
+   }
+
+   XFree(fbConfigs);
+
+   return pBuffer;
+#undef NUM_FB_CONFIGS
+}
+
+
+
+/*
+ * Do all the X / GLX setup stuff.
+ */
+static int
+Setup(int width, int height)
+{
+#if defined(GLX_SGIX_fbconfig) && defined(GLX_SGIX_pbuffer)
+   XVisualInfo *visInfo;
+   GLXContext glCtx;
+
+   /* Open the X display */
+   gDpy = XOpenDisplay(NULL);
+   if (!gDpy) {
+      printf("Error: couldn't open default X display.\n");
+      return 0;
+   }
+
+   /* Get default screen */
+   gScreen = DefaultScreen(gDpy);
+
+   /* Test that pbuffers are available */
+   if (!QueryPbuffers(gDpy, gScreen)) {
+      printf("Error: pbuffers not available on this screen\n");
+      XCloseDisplay(gDpy);
+      return 0;
+   }
+
+   /* Create Pbuffer */
+   gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
+   if (gPBuffer==None) {
+      printf("Error: couldn't create pbuffer\n");
+      XCloseDisplay(gDpy);
+      return 0;
+   }
+
+   /* Get corresponding XVisualInfo */
+   visInfo = glXGetVisualFromFBConfigSGIX(gDpy, gFBconfig);
+   if (!visInfo) {
+      printf("Error: can't get XVisualInfo from FBconfig\n");
+      XCloseDisplay(gDpy);
+      return 0;
+   }
+
+   /* Create GLX context */
+   glCtx = glXCreateContext(gDpy, visInfo, NULL, True);
+   if (!glCtx) {
+      /* try indirect */
+      glCtx = glXCreateContext(gDpy, visInfo, NULL, False);
+      if (!glCtx) {
+         printf("Error: Couldn't create GLXContext\n");
+         XFree(visInfo);
+         XCloseDisplay(gDpy);
+         return 0;
+      }
+      else {
+         printf("Warning: using indirect GLXContext\n");
+      }
+   }
+
+   /* Bind context to pbuffer */
+   if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
+      printf("Error: glXMakeCurrent failed\n");
+      XFree(visInfo);
+      XCloseDisplay(gDpy);
+      return 0;
+   }
+
+   return 1;  /* Success!! */
+#else
+   printf("Error: GLX_SGIX_fbconfig and/or GLX_SGIX_pbuffer extensions not"
+                  " available at compile-time.\n");
+   return 0;
+#endif
+}
+
+
+
+/* One-time GL setup */
+static void
+InitGL(void)
+{
+   static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
+   glEnable(GL_LIGHTING);
+   glEnable(GL_LIGHT0);
+   glLightfv(GL_LIGHT0, GL_POSITION, pos);
+   glEnable(GL_NORMALIZE);
+   glEnable(GL_DEPTH_TEST);
+   glEnable(GL_CULL_FACE);
+
+   glViewport(0, 0, gWidth, gHeight);
+   glMatrixMode( GL_PROJECTION );
+   glLoadIdentity();
+   glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
+   glMatrixMode( GL_MODELVIEW );
+   glLoadIdentity();
+   glTranslatef( 0.0, 0.0, -15.0 );
+
+}
+
+
+/* Return random float in [0,1] */
+static float
+Random(void)
+{
+   int i = rand();
+   return (float) (i % 1000) / 1000.0;
+}
+
+
+static void
+RandomColor(void)
+{
+   GLfloat c[4];
+   c[0] = Random();
+   c[1] = Random();
+   c[2] = Random();
+   c[3] = 1.0;
+   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
+}
+
+
+/* This function borrowed from Mark Kilgard's GLUT */
+static void
+drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
+  GLfloat z0, GLfloat z1, GLenum type)
+{
+  static GLfloat n[6][3] =
+  {
+    {-1.0, 0.0, 0.0},
+    {0.0, 1.0, 0.0},
+    {1.0, 0.0, 0.0},
+    {0.0, -1.0, 0.0},
+    {0.0, 0.0, 1.0},
+    {0.0, 0.0, -1.0}
+  };
+  static GLint faces[6][4] =
+  {
+    {0, 1, 2, 3},
+    {3, 2, 6, 7},
+    {7, 6, 5, 4},
+    {4, 5, 1, 0},
+    {5, 6, 2, 1},
+    {7, 4, 0, 3}
+  };
+  GLfloat v[8][3], tmp;
+  GLint i;
+
+  if (x0 > x1) {
+    tmp = x0;
+    x0 = x1;
+    x1 = tmp;
+  }
+  if (y0 > y1) {
+    tmp = y0;
+    y0 = y1;
+    y1 = tmp;
+  }
+  if (z0 > z1) {
+    tmp = z0;
+    z0 = z1;
+    z1 = tmp;
+  }
+  v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
+  v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
+  v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
+  v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
+  v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
+  v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
+
+  for (i = 0; i < 6; i++) {
+    glBegin(type);
+    glNormal3fv(&n[i][0]);
+    glVertex3fv(&v[faces[i][0]][0]);
+    glVertex3fv(&v[faces[i][1]][0]);
+    glVertex3fv(&v[faces[i][2]][0]);
+    glVertex3fv(&v[faces[i][3]][0]);
+    glEnd();
+  }
+}
+
+
+
+/* Render a scene */
+static void
+Render(void)
+{
+   int NumBoxes = 100;
+   int i;
+
+   InitGL();
+   glClearColor(0.2, 0.2, 0.9, 0.0);
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+   for (i=0;i<NumBoxes;i++) {
+      float tx = -2.0 + 4.0 * Random();
+      float ty = -2.0 + 4.0 * Random();
+      float tz =  4.0 - 16.0 * Random();
+      float sx = 0.1 + Random() * 0.4;
+      float sy = 0.1 + Random() * 0.4;
+      float sz = 0.1 + Random() * 0.4;
+      float rx = Random();
+      float ry = Random();
+      float rz = Random();
+      float ra = Random() * 360.0;
+      glPushMatrix();
+      glTranslatef(tx, ty, tz);
+      glRotatef(ra, rx, ry, rz);
+      glScalef(sx, sy, sz);
+      RandomColor();
+      drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
+      glPopMatrix();
+   }
+
+   glFinish();
+}
+
+
+
+static void
+WriteFile(const char *filename)
+{
+   FILE *f;
+   GLubyte *image;
+   int i;
+
+   image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
+   if (!image) {
+      printf("Error: couldn't allocate image buffer\n");
+      return;
+   }
+
+   glPixelStorei(GL_PACK_ALIGNMENT, 1);
+   glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
+
+   f = fopen(filename, "w");
+   if (!f) {
+      printf("Couldn't open image file: %s\n", filename);
+      return;
+   }
+   fprintf(f,"P6\n");
+   fprintf(f,"# ppm-file created by %s\n", "trdemo2");
+   fprintf(f,"%i %i\n", gWidth, gHeight);
+   fprintf(f,"255\n");
+   fclose(f);
+   f = fopen(filename, "ab");  /* now append binary data */
+   if (!f) {
+      printf("Couldn't append to image file: %s\n", filename);
+      return;
+   }
+
+   for (i=0;i<gHeight;i++) {
+      GLubyte *rowPtr;
+      /* Remember, OpenGL images are bottom to top.  Have to reverse. */
+      rowPtr = image + (gHeight-1-i) * gWidth*3;
+      fwrite(rowPtr, 1, gWidth*3, f);
+   }
+
+   fclose(f);
+   free(image);
+
+   printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
+}
+
+
+
+/*
+ * Print message describing command line parameters.
+ */
+static void
+Usage(const char *appName)
+{
+   printf("Usage:\n");
+   printf("  %s width height imgfile\n", appName);
+   printf("Where imgfile is a ppm file\n");
+}
+
+
+
+int
+main(int argc, char *argv[])
+{
+   if (argc!=4) {
+      Usage(argv[0]);
+   }
+   else {
+      int width = atoi(argv[1]);
+      int height = atoi(argv[2]);
+      char *fileName = argv[3];
+      if (width<=0) {
+         printf("Error: width parameter must be at least 1.\n");
+         return 1;
+      }
+      if (height<=0) {
+         printf("Error: height parameter must be at least 1.\n");
+         return 1;
+      }
+      if (!Setup(width, height)) {
+         return 1;
+      }
+      Render();
+      WriteFile(fileName);
+      glXDestroyGLXPbufferSGIX( gDpy, gPBuffer );
+   }
+   return 0;
+}
+
-- 
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