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();
}

Commencez par exécuter le sketch fourni avec P2D à s = 600 et s = 1, puis comparez-le sans P2D. Suivez la gestion par P2D et P3D des extrémités et des raccords de trait ROUND, en vous concentrant sur la manière dont le nombre de points de l’arc utilise strokeWeight et scale. C’est terminé lorsque les traits réduits conservent des extrémités et des raccords arrondis, lisses et visibles.