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();
}

まず、提供されたスケッチを P2D で s = 600 と s = 1 にして実行し、その後 P2D なしの場合と比較します。P2D と P3D における ROUND のストローク端点と接合部の処理を追跡し、円弧の点数が strokeWeight と scale をどのように使用しているかに注目します。縮小されたストロークでも、見やすく滑らかな丸い端点と接合部が維持されれば完了です。