curve drawing algorithm for quadratic curves is replaced by Bezier se…

…gment. It should improve performance on iPad (see #103)
phetsims · Mar 18, 2017 · 5278d7e · 5278d7e
1 parent d2a33cc
commit 5278d7e
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/js/curve-fitting/view/GraphAreaNode.js b/js/curve-fitting/view/GraphAreaNode.js
@@ -115,6 +115,13 @@ define( function( require ) {
         if ( order === 1 ) {
           curveShape.lineTo( xMax, curve.getYValueAt( xMax ) );
         }
+        else if ( order === 2 ) {
+          // use bezier curve : must determine the control points
+          // note that the curve will not go through the control point.
+          var cpx = (xMin + xMax) / 2;
+          var cpy = (b * xMin + c / 2) * (xMax - xMin) + curve.getYValueAt( xMin );
+          curveShape.quadraticCurveTo( cpx, cpy, xMax, curve.getYValueAt( xMax ) );
+        }
         else {
           for ( x = xMin; x < xMax; x += PLOT_STEP ) {
             curveShape.lineTo( x, curve.getYValueAt( x ) );