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

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();
}

Inizia eseguendo lo sketch fornito con P2D a s = 600 e s = 1, quindi confrontalo senza P2D. Traccia la gestione da parte di P2D e P3D delle estremità e delle giunzioni del tratto ROUND, concentrandoti su come il conteggio dei punti dell’arco usa strokeWeight e scale. Il lavoro è completato quando i tratti ridotti mantengono estremità e giunzioni arrotondate, lisce e visibili.