processing / processing/processing4

Add `beginClip()` and `endClip()` masking functions

Open
#1,191 4 comments 2 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
Java
Stars
494
Forks
183
Avg merge
4h 39m
Merged PRs (30d)
3

Description

Relevant sub-area for this feature?

Core/Environment/Rendering

Feature details
Feature description

Add beginClip() and endClip() to define clipping masks using drawing commands. Shapes drawn between these calls become the mask. An optional invert flag enables inverse masking.

Benefits
  • More intuitive and less verbose than mask()
  • Matches p5.js API and reduces cognitive load when switching from one to the other
Challenges
  • Not sure
Additional context

See https://p5js.org/reference/p5/beginClip/

Example code

This mask() code...

  // Create pattern graphics
  pattern = createGraphics(width, height);
  pattern.beginDraw();
  pattern.background(255);
  pattern.stroke(0);
  pattern.strokeWeight(2);
  for (int x = 0; x < width; x += 10) {
    pattern.line(x, 0, x, height);
  }
  pattern.endDraw();

  // Create mask graphics (white circle on black)
  maskImg = createGraphics(width, height);
  maskImg.beginDraw();
  maskImg.background(0);
  maskImg.noStroke();
  maskImg.fill(255);
  maskImg.ellipse(width/2, height/2, 200, 200);
  maskImg.endDraw();

  // Apply mask to pattern
  pattern.mask(maskImg);

... becomes this using beginClip()/endClip():

  // Define clipping region
  beginClip();
  ellipse(width/2, height/2, 200, 200);
  endClip();

  // Draw pattern inside the clip
  stroke(0);
  strokeWeight(2);
  for (int x = 0; x < width; x += 10) {
    line(x, 0, x, height);
  }
Would you like to help implement this feature?

No, I’m just suggesting the feature

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start in the Core/Environment/Rendering area by reading the existing mask() behavior and the linked p5.js beginClip() reference. Define how beginClip(), endClip(), and the optional invert flag should work, then verify that drawing commands between the calls produce the expected normal and inverse clipping behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
computer-graphics
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.