#16 Enable new stroke code

And fix rendering artifacts in testBasic

Author: wtholliday

Sources/vger/sdf.h

@@ -505,18 +505,23 @@ inline float2 bezier(float2 A, float2 B, float2 C, float t) {
     return (1 - t) * (1 - t) * A + 2 * (1 - t) * t * B + t * t * C;
 }
 
-inline bool lineTest(float2 p, float2 A, float2 B) {
-
-    int cs = (A.y < p.y) * 2 + (B.y < p.y);
-
-    if(cs == 0 or cs == 3) return false; // trivial reject
+inline bool side(float2 p, float2 A, float2 B) {
 
     auto v = B - A;
 
     // Intersect line with x axis.
     float t = (p.y-A.y)/v.y;
 
     return (A.x + t*v.x) > p.x;
+}
+
+inline bool lineTest(float2 p, float2 A, float2 B) {
+
+    int cs = (A.y < p.y) * 2 + (B.y < p.y);
+
+    if(cs == 0 or cs == 3) return false; // trivial reject
+
+    return side(p, A, B);
 
 }
 
@@ -530,8 +535,17 @@ inline bool bezierTest(float2 p, float2 A, float2 B, float2 C) {
     float s = (v2.x * v1.y - v1.x * v2.y) / det;
     float t = (v0.x * v2.y - v2.x * v0.y) / det;
 
-    if(s < 0 or t < 0 or (1-s-t) < 0) {
-        return false; // outside triangle
+    // Concave or convex?
+    // Try to be consistent with lineTest so we don't
+    // double-flip the inside/outside in edge cases.
+    if (side(B, A, C)) {
+        if(s <= 0 or t < 0 or (1-s-t) < 0) {
+            return false; // outside triangle
+        }
+    } else {
+        if(s < 0 or t < 0 or (1-s-t) < 0) {
+            return false; // outside triangle
+        }
     }
 
     // Transform to canonical coordinte space.

Sources/vger/vger.mm

@@ -250,7 +250,7 @@ void vgerStrokeBezier(vgerContext vg, vgerBezierSegment s, float width, vgerPain
 
     if(!vg->checkPaint(paint)) return;
 
-#if 0
+#if 1
     // Improve quality of beziers by rendering as fills.
 
     // 90 degrees CCW
@@ -272,7 +272,7 @@ void vgerStrokeBezier(vgerContext vg, vgerBezierSegment s, float width, vgerPain
     vgerFill(vg, paint);
 #endif
 
-#if 1
+#if 0
 
     // Are the points degenerate?
     // This may not work in general because these are pre-transformed coordinates.