From 0c0b272ccc209ce86cb70142071ace4627eaee86 Mon Sep 17 00:00:00 2001
From: Twilrom <thejower@gmail.com>
Date: Tue, 13 Feb 2018 15:49:38 +0100
Subject: [PATCH] Update WebGL Graphics.arc to work more like on Canvas

---
 .../webgl/pipelines/FlatTintPipeline.js       | 49 +++++++++++++------
 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/src/renderer/webgl/pipelines/FlatTintPipeline.js b/src/renderer/webgl/pipelines/FlatTintPipeline.js
index c56b04db4..3f60182cf 100644
--- a/src/renderer/webgl/pipelines/FlatTintPipeline.js
+++ b/src/renderer/webgl/pipelines/FlatTintPipeline.js
@@ -796,6 +796,7 @@ var FlatTintPipeline = new Class({
         var path = null;
         var sin = Math.sin;
         var cos = Math.cos;
+        var PI2 = Math.PI * 2;
         var sr = sin(srcRotation);
         var cr = cos(srcRotation);
         var sra = cr * srcScaleX;
@@ -835,31 +836,51 @@ var FlatTintPipeline = new Class({
                     endAngle = commands[cmdIndex + 5];
                     anticlockwise = commands[cmdIndex + 6];
 
+                    if (lastPath === null)
+                    {
+                        lastPath = new Path(x + cos(startAngle) * radius, y + sin(startAngle) * radius, lineWidth, lineColor, lineAlpha);
+                        pathArray.push(lastPath);
+                        iteration += iterStep;
+                    }
+
+                    endAngle -= startAngle;
                     if (anticlockwise)
                     {
-                        ta = endAngle;
-                        endAngle = startAngle;
-                        startAngle = -ta;
+                        if (endAngle < -PI2)
+                        {
+                            endAngle = -PI2;
+                        }
+                        else if (endAngle > 0)
+                        {
+                            endAngle = -PI2 + endAngle % PI2;
+                        }
                     }
-                    
+                    else if (endAngle > PI2)
+                    {
+                        endAngle = PI2;
+                    }
+                    else if (endAngle < 0)
+                    {
+                        endAngle = PI2 + endAngle % PI2;
+                    }
+
                     while (iteration < 1)
                     {
-                        ta = (endAngle - startAngle) * iteration + startAngle;
+                        ta = endAngle * iteration + startAngle;
                         tx = x + cos(ta) * radius;
                         ty = y + sin(ta) * radius;
 
-                        if (iteration === 0)
-                        {
-                            lastPath = new Path(tx, ty, lineWidth, lineColor, lineAlpha);
-                            pathArray.push(lastPath);
-                        }
-                        else
-                        {
-                            lastPath.points.push(new Point(tx, ty, lineWidth, lineColor, lineAlpha));
-                        }
+                        lastPath.points.push(new Point(tx, ty, lineWidth, lineColor, lineAlpha));
 
                         iteration += iterStep;
                     }
+
+                    ta = endAngle + startAngle;
+                    tx = x + cos(ta) * radius;
+                    ty = y + sin(ta) * radius;
+
+                    lastPath.points.push(new Point(tx, ty, lineWidth, lineColor, lineAlpha));
+
                     cmdIndex += 6;
                     break;