openFrameworks - open file system dialog // get texture from video

open file system dialog

https://forum.openframeworks.cc/t/how-do-i-mix-the-alpha-channel-of-one-video-with-another/18771

ofApp.h file

#pragma once

#include "ofMain.h"

class ofApp : public ofBaseApp{

	public:
		void setup();
		void update();
		void draw();

	ofVideoPlayer video, maskVideo;
	bool bVideosLoaded = false;
};
ofApp.cpp file:

#include "ofApp.h"
//--------------------------------------------------------------
void ofApp::setup(){

	auto r = ofSystemLoadDialog("Select video file"); // use the load dialog to find the video on your 
//computer. if you already know the path and/or dont want to have the load dialog popping up just 
//manually specify the file path to the video file. 
	if(r.bSuccess){
		bVideosLoaded = video.load(r.getPath());
		cout << r.getPath() << endl; // just print the video path.
	}
	if(bVideosLoaded){
		r = ofSystemLoadDialog("Select masking video file");
		if(r.bSuccess){
			bVideosLoaded = maskVideo.load(r.getPath());
			cout << r.getPath() << endl;
		}
	}	
	if(bVideosLoaded){ //Checking that both videos loaded properly		
		video.play();
		maskVideo.play();
	}
}

//--------------------------------------------------------------
void ofApp::update(){
	if(bVideosLoaded){
		video.update();
		maskVideo.update();
		if(video.isFrameNew() || maskVideo.isFrameNew()){
			video.getTexture().setAlphaMask(maskVideo.getTexture());	// THIS IS THE MAGIC LINE!
		}
	}
}

//--------------------------------------------------------------
void ofApp::draw(){
	if(bVideosLoaded){
		video.draw(0,0);
		maskVideo.draw(video.getWidth(), 0);
	}
}