mirror of https://github.com/vitalif/openscad
245 lines
6.6 KiB
C++
245 lines
6.6 KiB
C++
/*
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Create an OpenGL context without creating an OpenGL Window. for Linux.
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See Also
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glxgears.c by Brian Paul from mesa-demos (mesa3d.org)
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http://cgit.freedesktop.org/mesa/demos/tree/src/xdemos?id=mesa-demos-8.0.1
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http://www.opengl.org/sdk/docs/man/xhtml/glXIntro.xml
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http://www.mesa3d.org/brianp/sig97/offscrn.htm
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http://glprogramming.com/blue/ch07.html
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OffscreenContext.mm (Mac OSX version)
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*/
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#include "OffscreenContext.h"
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#include "printutils.h"
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#include "imageutils.h"
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#include "system-gl.h"
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#include "fbo.h"
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#include <GL/gl.h>
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#include <GL/glx.h>
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using namespace std;
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struct OffscreenContext
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{
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GLXContext openGLContext;
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Display *xdisplay;
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Window xwindow;
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int width;
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int height;
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fbo_t *fbo;
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};
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void offscreen_context_init(OffscreenContext &ctx, int width, int height)
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{
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ctx.width = width;
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ctx.height = height;
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ctx.openGLContext = NULL;
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ctx.xdisplay = NULL;
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ctx.xwindow = (Window)NULL;
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ctx.fbo = NULL;
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}
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static XErrorHandler original_xlib_handler = (XErrorHandler) NULL;
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static bool XCreateWindow_failed = false;
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static int XCreateWindow_error(Display *dpy, XErrorEvent *event)
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{
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cerr << "XCreateWindow failed: XID: " << event->resourceid
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<< " request: " << (int)event->request_code
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<< " minor: " << (int)event->minor_code << "\n";
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char description[1024];
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XGetErrorText( dpy, event->error_code, description, 1023 );
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cerr << " error message: " << description << "\n";
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XCreateWindow_failed = true;
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return 0;
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}
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bool create_glx_dummy_window(OffscreenContext &ctx)
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{
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/*
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create a dummy X window without showing it. (without 'mapping' it)
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and save information to the ctx.
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This purposely does not use glxCreateWindow, to avoid crashes,
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"failed to create drawable" errors, and Mesa "WARNING: Application calling
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GLX 1.3 function when GLX 1.3 is not supported! This is an application bug!"
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This function will alter ctx.openGLContext and ctx.xwindow if successfull
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*/
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int attributes[] = {
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GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
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GLX_RENDER_TYPE, GLX_RGBA_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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None
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};
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Display *dpy = ctx.xdisplay;
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int num_returned = 0;
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GLXFBConfig *fbconfigs = glXChooseFBConfig( dpy, DefaultScreen(dpy), attributes, &num_returned );
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if ( fbconfigs == NULL ) {
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cerr << "glXChooseFBConfig failed\n";
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return false;
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}
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XVisualInfo *visinfo = glXGetVisualFromFBConfig( dpy, fbconfigs[0] );
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if ( visinfo == NULL ) {
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cerr << "glXGetVisualFromFBConfig failed\n";
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XFree( fbconfigs );
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return false;
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}
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// can't depend on xWin==NULL at failure. use a custom Xlib error handler instead.
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original_xlib_handler = XSetErrorHandler( XCreateWindow_error );
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Window xWin = XCreateSimpleWindow( dpy, DefaultRootWindow(dpy), 0,0,10,10, 0,0,0 );
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XSync( dpy, false );
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if ( XCreateWindow_failed ) {
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XFree( visinfo );
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XFree( fbconfigs );
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return false;
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}
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XSetErrorHandler( original_xlib_handler );
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// Most programs would call XMapWindow here. But we don't, to keep the window hidden
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// XMapWindow( dpy, xWin );
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GLXContext context = glXCreateNewContext( dpy, fbconfigs[0], GLX_RGBA_TYPE, NULL, True );
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if ( context == NULL ) {
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cerr << "glXCreateNewContext failed\n";
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XDestroyWindow( dpy, xWin );
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XFree( visinfo );
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XFree( fbconfigs );
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return false;
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}
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//GLXWindow glxWin = glXCreateWindow( dpy, fbconfigs[0], xWin, NULL );
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if (!glXMakeContextCurrent( dpy, xWin, xWin, context )) {
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//if (!glXMakeContextCurrent( dpy, glxWin, glxWin, context )) {
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cerr << "glXMakeContextCurrent failed\n";
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glXDestroyContext( dpy, context );
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XDestroyWindow( dpy, xWin );
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XFree( visinfo );
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XFree( fbconfigs );
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return false;
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}
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ctx.openGLContext = context;
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ctx.xwindow = xWin;
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XFree( visinfo );
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XFree( fbconfigs );
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return true;
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}
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Bool create_glx_dummy_context(OffscreenContext &ctx)
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{
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// This will alter ctx.openGLContext and ctx.xdisplay and ctx.xwindow if successfull
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int major;
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int minor;
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Bool result = False;
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ctx.xdisplay = XOpenDisplay( NULL );
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if ( ctx.xdisplay == NULL ) {
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cerr << "Unable to open a connection to the X server\n";
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return False;
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}
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// glxQueryVersion is not always reliable. Use it, but then
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// also check to see if GLX 1.3 functions exist
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glXQueryVersion(ctx.xdisplay, &major, &minor);
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if ( major==1 && minor<=2 && glXGetVisualFromFBConfig==NULL ) {
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cerr << "Error: GLX version 1.3 functions missing. "
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<< "Your GLX version: " << major << "." << minor << endl;
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} else {
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result = create_glx_dummy_window(ctx);
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}
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if (!result) XCloseDisplay( ctx.xdisplay );
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return result;
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}
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OffscreenContext *create_offscreen_context(int w, int h)
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{
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OffscreenContext *ctx = new OffscreenContext;
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offscreen_context_init( *ctx, w, h );
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// before an FBO can be setup, a GLX context must be created
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// this call alters ctx->xDisplay and ctx->openGLContext
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// and ctx->xwindow if successfull
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if (!create_glx_dummy_context( *ctx )) {
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return NULL;
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}
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// glewInit must come after Context creation and before FBO calls.
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GLenum err = glewInit();
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if (GLEW_OK != err) {
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cerr << "Unable to init GLEW: " << glewGetErrorString(err) << endl;
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return NULL;
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}
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glew_dump();
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ctx->fbo = fbo_new();
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if (!fbo_init(ctx->fbo, w, h)) {
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cerr << "GL Framebuffer Object init failed; dumping GLEW info" << endl;
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return NULL;
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}
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return ctx;
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}
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bool teardown_offscreen_context(OffscreenContext *ctx)
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{
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if (ctx) {
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fbo_unbind(ctx->fbo);
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fbo_delete(ctx->fbo);
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XDestroyWindow( ctx->xdisplay, ctx->xwindow );
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glXDestroyContext( ctx->xdisplay, ctx->openGLContext );
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XCloseDisplay( ctx->xdisplay );
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return true;
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}
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return false;
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}
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/*!
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Capture framebuffer from OpenGL and write it to the given filename as PNG.
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*/
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bool save_framebuffer(OffscreenContext *ctx, const char *filename)
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{
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if (!ctx || !filename) return false;
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int samplesPerPixel = 4; // R, G, B and A
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GLubyte pixels[ctx->width * ctx->height * samplesPerPixel];
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glReadPixels(0, 0, ctx->width, ctx->height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
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// Flip it vertically - images read from OpenGL buffers are upside-down
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int rowBytes = samplesPerPixel * ctx->width;
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unsigned char *flippedBuffer = (unsigned char *)malloc(rowBytes * ctx->height);
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if (!flippedBuffer) {
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std::cerr << "Unable to allocate flipped buffer for corrected image.";
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return 1;
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}
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flip_image(pixels, flippedBuffer, samplesPerPixel, ctx->width, ctx->height);
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bool writeok = write_png(filename, flippedBuffer, ctx->width, ctx->height);
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free(flippedBuffer);
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return writeok;
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}
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void bind_offscreen_context(OffscreenContext *ctx)
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{
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if (ctx) fbo_bind(ctx->fbo);
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}
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