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// Functions shared by OffscreenContext[platform].cc (or .mm)
// #include directly after definition of struct OffscreenContext.
void bind_offscreen_context(OffscreenContext *ctx)
{
if (ctx) fbo_bind(ctx->fbo);
}
/*
Capture framebuffer from OpenGL and write it to the given filename as PNG.
*/
bool save_framebuffer(OffscreenContext *ctx, const char *filename)
{
std::ofstream fstream(filename);
if (!fstream.is_open()) {
std::cerr << "Can't open file " << filename << " for writing";
return false;
} else {
save_framebuffer(ctx, fstream);
fstream.close();
}
return true;
}
/*!
Capture framebuffer from OpenGL and write it to the given ostream.
Called by save_framebuffer() from platform-specific code.
*/
bool save_framebuffer_common(OffscreenContext *ctx, std::ostream &output)
{
if (!ctx) return false;
int samplesPerPixel = 4; // R, G, B and A
vector<GLubyte> pixels(ctx->width * ctx->height * samplesPerPixel);
glReadPixels(0, 0, ctx->width, ctx->height, GL_RGBA, GL_UNSIGNED_BYTE, &pixels[0]);
// Flip it vertically - images read from OpenGL buffers are upside-down
int rowBytes = samplesPerPixel * ctx->width;
unsigned char *flippedBuffer = (unsigned char *)malloc(rowBytes * ctx->height);
if (!flippedBuffer) {
std::cerr << "Unable to allocate flipped buffer for corrected image.";
return 1;
}
flip_image(&pixels[0], flippedBuffer, samplesPerPixel, ctx->width, ctx->height);
bool writeok = write_png(output, flippedBuffer, ctx->width, ctx->height);
free(flippedBuffer);
return writeok;
}
// Called by create_offscreen_context() from platform-specific code.
OffscreenContext *create_offscreen_context_common(OffscreenContext *ctx)
{
if (!ctx) return NULL;
GLenum err = glewInit(); // must come after Context creation and before FBO c$
if (GLEW_OK != err) {
cerr << "Unable to init GLEW: " << glewGetErrorString(err) << "\n";
return NULL;
}
//cerr << glew_dump(0);
ctx->fbo = fbo_new();
if (!fbo_init(ctx->fbo, ctx->width, ctx->height)) {
return NULL;
}
return ctx;
}
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