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#include "OffscreenContext.h"
#include "imageutils.h"
#include "fbo.h"
#import <AppKit/AppKit.h> // for NSOpenGL...
#define REPORTGLERROR(task) { GLenum tGLErr = glGetError(); if (tGLErr != GL_NO_ERROR) { std::cout << "OpenGL error " << tGLErr << " while " << task << "\n"; } }
struct OffscreenContext
{
NSOpenGLContext *openGLContext;
NSAutoreleasePool *pool;
int width;
int height;
fbo_t *fbo;
};
OffscreenContext *create_offscreen_context(int w, int h)
{
OffscreenContext *ctx = new OffscreenContext;
ctx->width = w;
ctx->height = h;
ctx->pool = [NSAutoreleasePool new];
// Create an OpenGL context just so that OpenGL calls will work.
// Will not be used for actual rendering.
NSOpenGLPixelFormatAttribute attributes[] = {
NSOpenGLPFAPixelBuffer,
NSOpenGLPFANoRecovery,
NSOpenGLPFAAccelerated,
NSOpenGLPFADepthSize, 24,
(NSOpenGLPixelFormatAttribute) 0
};
NSOpenGLPixelFormat *pixFormat = [[[NSOpenGLPixelFormat alloc] initWithAttributes:attributes] autorelease];
// Create and make current the OpenGL context to render with (with color and depth buffers)
ctx->openGLContext = [[NSOpenGLContext alloc] initWithFormat:pixFormat shareContext:nil];
if (!ctx->openGLContext) {
std::cerr << "Unable to create NSOpenGLContext\n";
return NULL;
}
[ctx->openGLContext makeCurrentContext];
glewInit();
#ifdef DEBUG
cout << "GLEW version " << glewGetString(GLEW_VERSION) << "\n";
cout << (const char *)glGetString(GL_RENDERER) << "(" << (const char *)glGetString(GL_VENDOR) << ")\n"
<< "OpenGL version " << (const char *)glGetString(GL_VERSION) << "\n";
cout << "Extensions: " << (const char *)glGetString(GL_EXTENSIONS) << "\n";
if (GLEW_ARB_framebuffer_object) {
cout << "ARB_FBO supported\n";
}
if (GLEW_EXT_framebuffer_object) {
cout << "EXT_FBO supported\n";
}
if (GLEW_EXT_packed_depth_stencil) {
cout << "EXT_packed_depth_stencil\n";
}
#endif
ctx->fbo = fbo_new();
if (!fbo_init(ctx->fbo, w, h)) {
return NULL;
}
return ctx;
}
bool teardown_offscreen_context(OffscreenContext *ctx)
{
fbo_unbind(ctx->fbo);
fbo_delete(ctx->fbo);
/*
* Cleanup
*/
[ctx->openGLContext clearDrawable];
[ctx->openGLContext release];
[ctx->pool release];
return true;
}
/*!
Capture framebuffer from OpenGL and write it to the given filename as PNG.
*/
bool save_framebuffer(OffscreenContext *ctx, const char *filename)
{
// Read pixels from OpenGL
int samplesPerPixel = 4; // R, G, B and A
int rowBytes = samplesPerPixel * ctx->width;
unsigned char *bufferData = (unsigned char *)malloc(rowBytes * ctx->height);
if (!bufferData) {
std::cerr << "Unable to allocate buffer for image extraction.";
return 1;
}
glReadPixels(0, 0, ctx->width, ctx->height, GL_RGBA, GL_UNSIGNED_BYTE,
bufferData);
REPORTGLERROR("reading pixels from framebuffer");
// Flip it vertically - images read from OpenGL buffers are upside-down
unsigned char *flippedBuffer = (unsigned char *)malloc(rowBytes * ctx->height);
if (!flippedBuffer) {
std::cout << "Unable to allocate flipped buffer for corrected image.";
return 1;
}
flip_image(bufferData, flippedBuffer, samplesPerPixel, ctx->width, ctx->height);
bool writeok = write_png(filename, flippedBuffer, ctx->width, ctx->height);
free(flippedBuffer);
free(bufferData);
return writeok;
}
void bind_offscreen_context(OffscreenContext *ctx)
{
fbo_bind(ctx->fbo);
}
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