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Add inner loop geometry to miter join for toy stroker

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Now the miter join matches SkStroke, adding the extra inner loop
geometry always. Next will be the harder part, which is figuring out how
to get rid of it!

Also fixed a CW/CCW rotation inconsistency to match SkStroke

Change-Id: Ie3d164053fd5683f3b678bb80f8421dc6dc48cd7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/304809
Reviewed-by: Tyler Denniston <tdenniston@google.com>
Auto-Submit: Tyler Denniston <tdenniston@google.com>
Commit-Queue: Tyler Denniston <tdenniston@google.com>
This commit is contained in:
Tyler Denniston 2020-07-21 16:16:55 -04:00 committed by Skia Commit-Bot
parent 324578b553
commit f219aadebc
1 changed files with 13 additions and 2 deletions
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15
samplecode/SampleSimpleStroker.cpp
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@ -17,7 +17,7 @@ namespace {
//////////////////////////////////////////////////////////////////////////////
static SkPoint rotate90(const SkPoint& p) { return {-p.fY, p.fX}; }
static SkPoint rotate90(const SkPoint& p) { return {p.fY, -p.fX}; }
static SkPoint rotate180(const SkPoint& p) { return p * -1; }
static SkPoint setLength(SkPoint p, float len) {
if (!p.setLength(len)) {
@ -161,7 +161,9 @@ void SkPathStroker2::endcap(CapLocation loc) {
void SkPathStroker2::join(const PathSegment& prev, const PathSegment& curr) {
const auto miterJoin = [this](const PathSegment& prev, const PathSegment& curr) {
// Common path endpoint of the two segments is the midpoint of the miter line.
const SkPoint miterMidpt = curr.fPoints[0];
SkPoint before = unitNormal(prev, 1);
SkPoint after = unitNormal(curr, 0);
@ -193,8 +195,17 @@ void SkPathStroker2::join(const PathSegment& prev, const PathSegment& curr) {
const float halfMiterLength = fRadius / sinHalfTheta;
miterVec.setLength(halfMiterLength); // TODO: miter length limit
// Outer: connect to the miter point, and then to t=0 (on outside) of next segment.
const SkPoint dest = setLength(after, fRadius);
outer->lineTo(miterMidpt + miterVec);
inner->lineTo(miterMidpt - miterVec);
outer->lineTo(miterMidpt + dest);
// Inner: we're already at t=1 (on inside) of 'prev'.
// Connect to the miter midpoint (common path endpoint of the two segments),
// and then to t=0 (on inside) of the next segment. This adds an interior "loop" of
// geometry that in many cases is unnecessary, but handles several edge cases.
inner->lineTo(miterMidpt);
inner->lineTo(miterMidpt - dest);
};
switch (fJoin) {