Hi, I wonder if there’s any solution to draw a shape clipped inside the other shape just like this image.
It is drawing an ofCircle in side ofRectRounded.
I used stencil buffer to do this but unfortunately, stencil doesn’t seem to work on mobile devices.
So I’m wondering if there’s other solution to do this. Thank you.
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Using shaders, draw your rounded rectangle and create a stencil map in an ofFbo, then with another shader you can choose to paint only where you have the stencil set (inside the rectangle).
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also, ofTexture has “setAlphaMask” where you can add a second texture that will be the alpha channel on the underlying texture, – in this case, the square could be an FBO and you could add an alpha mask for the rounded corners of the square. happy to make a small example if it helps.
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Thank you so much! I would really appreciate it 
in h file:
ofFbo originalFbo;
ofFbo mask;
in cpp file
#include "ofApp.h"
//--------------------------------------------------------------
void ofApp::setup(){
originalFbo.allocate(200,200);
mask.allocate(200,200);
mask.begin();
ofClear(0,0,0);
ofSetColor(255);
ofDrawRectRounded( 0,0,200,200, 50);
mask.end();
}
//--------------------------------------------------------------
void ofApp::update(){
originalFbo.begin();
ofClear(0,255,0, 255);
ofSetColor(255,0,0);
ofCircle(100 + 100 * sin(ofGetElapsedTimef()), 100, 50);
originalFbo.end();
}
//--------------------------------------------------------------
void ofApp::draw(){
mask.draw(0,0);
// disable the alpha mask to see what this FBO looks like unmasked
originalFbo.getTexture().disableAlphaMask();
originalFbo.draw(300,0);
originalFbo.getTexture().setAlphaMask(mask.getTexture());
originalFbo.draw(600,0);
}
output:
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Wow. That’s exactly what I wanted to achieve.
I learned a lot from your code. Thank you so much Zach!