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

从 Core/Environment/Rendering 区域开始，阅读现有的 mask() 行为以及链接的 p5.js beginClip() 参考。定义 beginClip()、endClip() 和可选的 invert 标志应如何工作，然后验证两次调用之间的绘图命令是否产生预期的正常和反向裁剪行为。

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