path ops -- rewrite angle sort
This is a major change resulting from a minor
tweak. In the old code, the intersection point
of two curves was shared between them, but the
intersection points and end points of sorted edges was
computed directly from the intersection T value.
In this CL, both intersection points and sorted points
are the same, and intermediate control points are computed
to preserve their slope.
The sort itself has been completely rewritten to be more
robust and remove 'magic' checks, conditions that empirically
worked but couldn't be rationalized.
This CL was triggered by errors generated computing the clips
of SKP files. At this point, all 73M standard tests work and
at least the first troublesome SKPs work.
Review URL: https://codereview.chromium.org/15338003
git-svn-id: http://skia.googlecode.com/svn/trunk@9432 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pathops/SkPathOpsQuad.cpp b/src/pathops/SkPathOpsQuad.cpp
index 685f49e..ce89469 100644
--- a/src/pathops/SkPathOpsQuad.cpp
+++ b/src/pathops/SkPathOpsQuad.cpp
@@ -4,6 +4,7 @@
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
+#include "SkIntersections.h"
#include "SkLineParameters.h"
#include "SkPathOpsCubic.h"
#include "SkPathOpsQuad.h"
@@ -220,12 +221,53 @@
return dst;
}
+void SkDQuad::align(int endIndex, SkDPoint* dstPt) const {
+ if (fPts[endIndex].fX == fPts[1].fX) {
+ dstPt->fX = fPts[endIndex].fX;
+ }
+ if (fPts[endIndex].fY == fPts[1].fY) {
+ dstPt->fY = fPts[endIndex].fY;
+ }
+}
+
SkDPoint SkDQuad::subDivide(const SkDPoint& a, const SkDPoint& c, double t1, double t2) const {
+ SkASSERT(t1 != t2);
SkDPoint b;
+#if 0
+ // this approach assumes that the control point computed directly is accurate enough
double dx = interp_quad_coords(&fPts[0].fX, (t1 + t2) / 2);
double dy = interp_quad_coords(&fPts[0].fY, (t1 + t2) / 2);
b.fX = 2 * dx - (a.fX + c.fX) / 2;
b.fY = 2 * dy - (a.fY + c.fY) / 2;
+#else
+ SkDQuad sub = subDivide(t1, t2);
+ SkDLine b0 = {{a, sub[1] + (a - sub[0])}};
+ SkDLine b1 = {{c, sub[1] + (c - sub[2])}};
+ SkIntersections i;
+ i.intersectRay(b0, b1);
+ if (i.used() == 1) {
+ b = i.pt(0);
+ } else {
+ SkASSERT(i.used() == 2 || i.used() == 0);
+ b = SkDPoint::Mid(b0[1], b1[1]);
+ }
+#endif
+ if (t1 == 0 || t2 == 0) {
+ align(0, &b);
+ }
+ if (t1 == 1 || t2 == 1) {
+ align(2, &b);
+ }
+ if (precisely_subdivide_equal(b.fX, a.fX)) {
+ b.fX = a.fX;
+ } else if (precisely_subdivide_equal(b.fX, c.fX)) {
+ b.fX = c.fX;
+ }
+ if (precisely_subdivide_equal(b.fY, a.fY)) {
+ b.fY = a.fY;
+ } else if (precisely_subdivide_equal(b.fY, c.fY)) {
+ b.fY = c.fY;
+ }
return b;
}