OpenGL strokeCap(ROUND) and strokeJoin should account for scale when computing the number of arc points

[processing-bot]

Created by: scudly

The default renderer very smoothly supports zooming in on ROUND line endcaps and joins while maintaining their roundness. P2D and P3D, however, assume that any strokeWeight less than one won't have visible endcaps even when the scale factor blows them up to many pixels in size.

The following code runs fine with s = 600, i.e., no scaling. Change to s = 1, however, and the endcaps and joins disappear. Remove the P2D and both cases will stay smooth.

float s = 600;
void setup() {
  size( 600, 600, P2D );
  noFill();
  scale( height/s );
  strokeWeight( 0.2*s );
  point( 0.3*s, 0.3*s );
  strokeJoin( ROUND );
  beginShape();
  vertex( 0.6*s, 0.2*s );
  vertex( 0.8*s, 0.8*s );
  vertex( 0.2*s, 0.6*s );
  endShape();
}

[processing-bot]

Created by: codeanticode

This one seems tricky. I haven't looked at this code in a long time but I tracked down the use of the stroke weight in the tessellation of the stroke paths in P2D to this call:

https://github.com/processing/processing4/blob/master/core/src/processing/opengl/PGraphicsOpenGL.java#L13916

But it's no as simple as just multiplying strokeWeight by a scaling factor (I did just that just to see what happens, and the entire geometry blows up).

The LinePath and LineStroker classes that do the actual work come from some even older code that we adapted to use in Processing, but never went into the inner workings of those.

So I don't think there is a quick, easy fix... but I might be wrong :-)