Make sure the theta is correctly represented and incoming polygon is CW for shadow.
Now the theta = 0 should be on +x axis.
And cos(theta) should correctly represent x value.
Without this fix, the poly theta (from atan2) can be wrongly rotated 90 degrees.
Also, make sure the incoming polygon is CW for the shadow system.
This fix visual artifacts in recent regression for spot shadows.
bug:13553955
Change-Id: I9bbf54db094e7f133326da4dae4610962da849c1
diff --git a/libs/hwui/ShadowTessellator.cpp b/libs/hwui/ShadowTessellator.cpp
index 4d0edfb..ee60a63 100644
--- a/libs/hwui/ShadowTessellator.cpp
+++ b/libs/hwui/ShadowTessellator.cpp
@@ -169,5 +169,67 @@
return centroid;
}
+/**
+ * Test whether the polygon is order in clockwise.
+ *
+ * @param polygon the polygon as a Vector2 array
+ * @param len the number of points of the polygon
+ */
+bool ShadowTessellator::isClockwise(const Vector2* polygon, int len) {
+ double sum = 0;
+ double p1x = polygon[len - 1].x;
+ double p1y = polygon[len - 1].y;
+ for (int i = 0; i < len; i++) {
+
+ double p2x = polygon[i].x;
+ double p2y = polygon[i].y;
+ sum += p1x * p2y - p2x * p1y;
+ p1x = p2x;
+ p1y = p2y;
+ }
+ return sum < 0;
+}
+
+bool ShadowTessellator::isClockwisePath(const SkPath& path) {
+ SkPath::Iter iter(path, false);
+ SkPoint pts[4];
+ SkPath::Verb v;
+
+ Vector<Vector2> arrayForDirection;
+ while (SkPath::kDone_Verb != (v = iter.next(pts))) {
+ switch (v) {
+ case SkPath::kMove_Verb:
+ arrayForDirection.add(Vector2(pts[0].x(), pts[0].y()));
+ break;
+ case SkPath::kLine_Verb:
+ arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
+ break;
+ case SkPath::kQuad_Verb:
+ arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
+ arrayForDirection.add(Vector2(pts[2].x(), pts[2].y()));
+ break;
+ case SkPath::kCubic_Verb:
+ arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
+ arrayForDirection.add(Vector2(pts[2].x(), pts[2].y()));
+ arrayForDirection.add(Vector2(pts[3].x(), pts[3].y()));
+ break;
+ default:
+ break;
+ }
+ }
+
+ return isClockwise(arrayForDirection.array(), arrayForDirection.size());
+}
+
+void ShadowTessellator::reverseVertexArray(Vertex* polygon, int len) {
+ int n = len / 2;
+ for (int i = 0; i < n; i++) {
+ Vertex tmp = polygon[i];
+ int k = len - 1 - i;
+ polygon[i] = polygon[k];
+ polygon[k] = tmp;
+ }
+}
+
}; // namespace uirenderer
}; // namespace android