ofDocsexamples gl threadedPixelBufferExample src ofApp.cpp
#include "ofApp.h"
#include "ofConstants.h"

// this example will probably only work in real time in release mode

//--------------------------------------------------------------
void ofApp::setup(){
	fbo.allocate(ofGetWidth(),ofGetHeight(),GL_RGB);
	pixelBufferBack.allocate(ofGetWidth()*ofGetHeight()*3,GL_DYNAMIC_READ);
	pixelBufferFront.allocate(ofGetWidth()*ofGetHeight()*3,GL_DYNAMIC_READ);
	box.set(400);
	box.setResolution(1);
	box.setPosition({ofGetWidth()*0.5, ofGetHeight()*0.5,0});
	record = false;
	firstFrame = true;
}

//--------------------------------------------------------------
void ofApp::update(){
	box.setOrientation(glm::angleAxis(ofDegToRad(ofGetElapsedTimef()*10),	glm::vec3(0,1,0))*
	                   glm::angleAxis(45.0f,glm::vec3(0,0,1))*
	                   glm::angleAxis(45.0f, glm::vec3(1,0,0)));

	ofEnableDepthTest();
	fbo.begin();
	ofClear(0,255);
	ofSetColor(100);
	box.setScale(1);
	box.draw();
	ofSetColor(255);
	box.setScale(1.001);
	box.drawWireframe();
	fbo.end();
	ofDisableDepthTest();

	if(record){
		if(!firstFrame){
			// wait for the thread to finish saving the
			// previous frame and then unmap it
			saverThread.waitReady();
			pixelBufferBack.unmap();
		}
		firstFrame = false;

		// copy the fbo texture to a buffer
		fbo.getTexture().copyTo(pixelBufferBack);

		// bind and map the buffer as PIXEL_UNPACK so it can be
		// accessed from a different thread  from the cpu
		// and send the memory address to the saver thread
		pixelBufferFront.bind(GL_PIXEL_UNPACK_BUFFER);
		unsigned char * p = pixelBufferFront.map<unsigned char>(GL_READ_ONLY);
		saverThread.save(p);

		// swap the front and back buffer so we are always
		// copying the texture to one buffer and reading
		// back from another to avoid stalls
		swap(pixelBufferBack,pixelBufferFront);
	}
}

//--------------------------------------------------------------
void ofApp::draw(){
	ofSetColor(255);
	fbo.draw(0,0);
	ofDrawBitmapString(ofGetFrameRate(),20,20);
	if(record){
		ofDrawBitmapString("'r' toggles recording (on)",20,40);
	}else{
		ofDrawBitmapString("'r' toggles recording (off)",20,40);
	}
}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){
	if(key=='r'){
		record = !record;
	}
}

//--------------------------------------------------------------
void ofApp::keyReleased(int key){

}

//--------------------------------------------------------------
void ofApp::mouseMoved(int x, int y ){

}

//--------------------------------------------------------------
void ofApp::mouseDragged(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mousePressed(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseReleased(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseEntered(int x, int y){

}

//--------------------------------------------------------------
void ofApp::mouseExited(int x, int y){

}

//--------------------------------------------------------------
void ofApp::windowResized(int w, int h){

}

//--------------------------------------------------------------
void ofApp::gotMessage(ofMessage msg){

}

//--------------------------------------------------------------
void ofApp::dragEvent(ofDragInfo dragInfo){ 

}