--- /dev/null
+
+/*
+ * 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.
+ *
+ * Updated on 31 January 2004 to use native GLX by
+ * Andrew P. Lentvorski, Jr. <bsder@allcaps.org>
+ *
+ * Usage:
+ * glxpbdemo 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.
+ *
+ * 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 configurations with the _pbuf suffix. Use
+ * setmon -x <vof> to configure your X server and display for pbuffers.
+ *
+ * O2 systems seem to support pbuffers well.
+ *
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <X11/Xlib.h>
+#include <GL/glx.h>
+
+/* Some ugly global vars */
+static GLXFBConfig gFBconfig = 0;
+static Display *gDpy = NULL;
+static int gScreen = 0;
+static GLXPbuffer gPBuffer = 0;
+static int gWidth, gHeight;
+
+
+/*
+ * Test for appropriate version of GLX to run this program
+ * Input: dpy - the X display
+ * screen - screen number
+ * Return: 0 = GLX not available.
+ * 1 = GLX available.
+ */
+static int
+RuntimeQueryGLXVersion(Display *dpy, int screen)
+{
+#if defined(GLX_VERSION_1_3) || defined(GLX_VERSION_1_4)
+ char *glxversion;
+
+ glxversion = (char *) glXGetClientString(dpy, GLX_VERSION);
+ if (!(strstr(glxversion, "1.3") || strstr(glxversion, "1.4")))
+ return 0;
+
+ glxversion = (char *) glXQueryServerString(dpy, screen, GLX_VERSION);
+ if (!(strstr(glxversion, "1.3") || strstr(glxversion, "1.4")))
+ return 0;
+
+ return 1;
+#else
+ return 0;
+#endif
+}
+
+
+
+/*
+ * Create the pbuffer and return a GLXPbuffer handle.
+ */
+static GLXPbuffer
+MakePbuffer( Display *dpy, int screen, int width, int height )
+{
+ GLXFBConfig *fbConfigs;
+ GLXFBConfig chosenFBConfig;
+ GLXPbuffer pBuffer = None;
+
+ int nConfigs;
+ int fbconfigid;
+
+ int fbAttribs[] = {
+ GLX_RENDER_TYPE, GLX_RGBA_BIT,
+ GLX_DEPTH_SIZE, 1,
+ GLX_DRAWABLE_TYPE, GLX_PIXMAP_BIT | GLX_PBUFFER_BIT,
+ None
+ };
+
+ int pbAttribs[] = {
+ GLX_PBUFFER_WIDTH, 0,
+ GLX_PBUFFER_HEIGHT, 0,
+ GLX_LARGEST_PBUFFER, False,
+ GLX_PRESERVED_CONTENTS, False,
+ None
+ };
+
+ pbAttribs[1] = width;
+ pbAttribs[3] = height;
+
+ fbConfigs = glXChooseFBConfig(dpy, screen, fbAttribs, &nConfigs);
+
+ if (0 == nConfigs || !fbConfigs) {
+ printf("Error: glxChooseFBConfig failed\n");
+ XCloseDisplay(dpy);
+ return 0;
+ }
+
+ chosenFBConfig = fbConfigs[0];
+
+ glXGetFBConfigAttrib(dpy, chosenFBConfig, GLX_FBCONFIG_ID, &fbconfigid);
+ printf("Chose 0x%x as fbconfigid\n", fbconfigid);
+
+ /* Create the pbuffer using first fbConfig in the list that works. */
+ pBuffer = glXCreatePbuffer(dpy, chosenFBConfig, pbAttribs);
+
+ if (pBuffer) {
+ gFBconfig = chosenFBConfig;
+ gWidth = width;
+ gHeight = height;
+ }
+
+ XFree(fbConfigs);
+
+ return pBuffer;
+}
+
+
+
+/*
+ * Do all the X / GLX setup stuff.
+ */
+static int
+Setup(int width, int height)
+{
+#if defined(GLX_VERSION_1_3) || defined(GLX_VERSION_1_4)
+ 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 GLX is available */
+ if (!RuntimeQueryGLXVersion(gDpy, gScreen)) {
+ printf("Error: GLX 1.3 or 1.4 not available\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;
+ }
+
+ /* Create GLX context */
+ glCtx = glXCreateNewContext(gDpy, gFBconfig, GLX_RGBA_TYPE, NULL, True);
+ if (glCtx) {
+ if (!glXIsDirect(gDpy, glCtx)) {
+ printf("Warning: using indirect GLXContext\n");
+ }
+ }
+ else {
+ printf("Error: Couldn't create GLXContext\n");
+ XFree(visInfo);
+ XCloseDisplay(gDpy);
+ return 0;
+ }
+
+ /* 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 version 1.3 or 1.4 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;
+ }
+
+ printf("Setup completed\n");
+ Render();
+ printf("Render completed.\n");
+ WriteFile(fileName);
+ printf("File write completed.\n");
+
+ glXDestroyPbuffer( gDpy, gPBuffer );
+ }
+ return 0;
+}
+
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