Visually show when 2 pshape lines cross - transparency?

Hi, I’m simply drawing lines for a schematic program using PShapes, and I want some visual indication when lines cross. I’d like to do this by controlling the transparency of the PShape lines so that a crossing would show darker at the at location.

I’ve looked at a lot of threads, talking about tints, alpha, etc, but nothing is what I’m looking for or I’m missing something simple.

Suggestions? Thanks!

Can you please show your code or relevant part

Hi Chrisir,
It’s not very exciting code, I’ll just post a fragment here. As the user draws, it adds sections to the “hose” in grey, then when done, it turns blue.

 void addHose(int lastX, lastY, endY){
    hose = createShape(LINE,lastX, lastY, lastX, endY);
    hose.setStroke(128);      // draw in gray as hoses are added
    created = true;
  void finish(){
    stroke(0,0,150);       // draw in blue once completed all hoses

You can work with smaller opacity - see fill in the reference

Also look at blendMode() in the reference

Thanks, I’ll check out blendMode(), also I just got alpha to work with stroke().