pbuffer info and demo programs
diff --git a/progs/xdemos/pbdemo.c b/progs/xdemos/pbdemo.c
new file mode 100644
index 0000000..611e7e5
--- /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;
+}
+