OpenGL 3.3 PBO Code

pbo.cc

void init() {
	// Generate PBO
	glGenBuffers(1, &_pbo);
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, _pbo);
	glBufferData(GL_PIXEL_UNPACK_BUFFER, TEX_SIZE * TEX_SIZE * 3, nullptr, GL_STREAM_DRAW);
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
	
	
	// Generate a texture
	glGenTextures(1, &_texID);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, _texID);
	
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TEX_SIZE, TEX_SIZE, 0, GL_RGB, GL_UNSIGNED_BYTE, nullptr);
}

void update() {
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, _pbo);
	uint8_t* ptr = (uint8_t*)glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
	
	// Do stuff with ptr here
	
	glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
	
	glBindTexture(GL_TEXTURE_2D, _texID);
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, TEX_SIZE, TEX_SIZE, GL_RGB, GL_UNSIGNED_BYTE, nullptr);
	
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
}

void capture() {
	uint8_t* ptr = new uint8_t[w * h * 3];
	glReadPixels(0, 0, w, h, GL_RGB, GL_UNSIGNED_BYTE, ptr);
	stbi_write_png("capture.png", w, h, 1, ptr, w * 3);
	delete[] ptr;
}