This reverts commit d0d7270fcc.
Revert "More sample count cleanup:"
This reverts commit d653cac70e.
Revert "Add new GrContext queries for imagability, surfacability, and max sample count of color types"
This reverts commit 85ae7159c9.
Need to understand NVPR perf changes before relanding
Change-Id: I0db075fb42438ef2a1f9885df184dce52892ac4b
Reviewed-on: https://skia-review.googlesource.com/102780
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Fixes gpu config default samples to be 1 and updates config parsing test accordingly.
This reverts commit c1ce2f7966.
Bug: skia:
Change-Id: I456973b1f52ced85a2011ea10fc49449bfc5846f
Reviewed-on: https://skia-review.googlesource.com/102147
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
This reverts commit 48825b11ad.
Reason for revert: nanobench
Original change's description:
> Redefine the meaning of sample counts in GPU backend.
>
> Old: 0 -> nonMSAA
> 1+ -> MSAA
>
> New:
> 0 -> error/unsupported
> 1 -> nonMSAA
> 2+ -> MSAA
>
> We still allow 0 to mean nonMSAA in three sets of public APIs for backwards compatibility:
>
> 1) SkSurface factories
> 2) GrBackendRenderTarget constructors
> 3) GrCaps::getSampleCnt()'s requestedCount parameter
>
> However, we immediately clamp to 1 and treat 0 as invalid/non-renderable internally.
>
> This also changes the behavior when using a large sample count. We now fail in that case rather than using the largest sample available sample count. GrCaps::getSampleCount() will return 0 in this case.
>
>
> Bug: skia:
> Change-Id: Ida22c6b22c1365e563c9046b611e88bf5eb3ff33
> Reviewed-on: https://skia-review.googlesource.com/101560
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>
TBR=egdaniel@google.com,bsalomon@google.com
Change-Id: Ic257619a8a5ee9ac15419ecf10259e42daed7f82
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/102662
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Old: 0 -> nonMSAA
1+ -> MSAA
New:
0 -> error/unsupported
1 -> nonMSAA
2+ -> MSAA
We still allow 0 to mean nonMSAA in three sets of public APIs for backwards compatibility:
1) SkSurface factories
2) GrBackendRenderTarget constructors
3) GrCaps::getSampleCnt()'s requestedCount parameter
However, we immediately clamp to 1 and treat 0 as invalid/non-renderable internally.
This also changes the behavior when using a large sample count. We now fail in that case rather than using the largest sample available sample count. GrCaps::getSampleCount() will return 0 in this case.
Bug: skia:
Change-Id: Ida22c6b22c1365e563c9046b611e88bf5eb3ff33
Reviewed-on: https://skia-review.googlesource.com/101560
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
This prepares us to share this with other effects (most notably maskfilters)
Bug: skia:
Change-Id: I12530fdf10c4e5f2a9ab6d394bf9e87c54ea60c4
Reviewed-on: https://skia-review.googlesource.com/97062
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Some pathological cases don't converge to a reasonable number of points
when using uniform linearization of quadratic points. Cap them to the
maximum which GrPathUtils supports.
Add reduced test case from crbug-762369.
BUG=762369
Change-Id: Icc744018e5c01a0e0fe2ec00613bdb25e49614e9
Reviewed-on: https://skia-review.googlesource.com/92721
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
With some large values, intersection for bevelling will fail.
These should just skip the point, not assert.
BUG=798912
Change-Id: Ie5c8cc3c9387055e1e31480321a231f0e6ff153b
Reviewed-on: https://skia-review.googlesource.com/91141
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
If input points are near-infinite, they may become inf or NaN when
stroked. Before converting the results of intersection from double
to float, clamp them to the [-FLT_MAX/FLT_MAX] range.
BUG=798679
Change-Id: I7d61130dd26147a9b7cfd38aa96567e3867b5c3e
Reviewed-on: https://skia-review.googlesource.com/90983
Commit-Queue: Stephen White <senorblanco@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
This CL implements two major changes to the AA tessellating path
renderer:
1) Fix inverted edges after stroke and simplify. Instead of detecting
and fixing edges which invert on stroking during the stroking pass, we
run the full simplify pass on both inner and outer contours, then
create edge collapse events for the overlap regions. We then process
the edge events in a priority queue and process them in order of decreasing
alpha (this is the "edge event" part of the straight skeleton
algorithm). By doing it after simplification, we ensure that
there's a full-alpha intersection vertex to join the collapse edge
to (which may have <1 alpha), so no spurious gradients appear in
the rendered path.
2) "Pointy" vertices (defined as those which meet at an acute angle less
than 14 degrees) are now properly bevelled off during stroking.
This removes antialiasing artifacts which extend beyond the path
boundary.
Some ancillary changes:
The extracted boundaries which are input to stroking have their line
equations pre-normalized, and multiplied by winding. This simplifies
a lot of code which was performing this computation on the fly.
The workaround for the "intruding vertex" problem was removed, since the
straight skeleton now moves the intruding vertex before it can cause
problems.
Bug: 756823
Change-Id: I271ed32be6847da55273b387e8c04bbf9b512b70
Reviewed-on: https://skia-review.googlesource.com/87341
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Also fixes some bugs involved with creating mipped SkSurfaces.
Bug: skia:
Change-Id: I6e0109000eadd2bdee4a907d3ee2231104528165
Reviewed-on: https://skia-review.googlesource.com/65063
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
Also to SkColorTo(Premul|Unpremul)GrColor4f.
This can avoid cache lookups to find GrColorSpaceXforms as the xform pointer is stored in GrColorSpaceInfo after the first lookup.
Also uses GrColorSpaceInfo to construct GrTextUtils::Paint.
Bug: skia:
Change-Id: Idf19d512a60d2269e6921c7fb54d93aee499a70d
Reviewed-on: https://skia-review.googlesource.com/63660
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Gives the convex and tessellating renderers first claim on larger
paths, and the distance field renderer first claim on complex,
non-volatile paths. This also requires plumbing the clip bounds
through GrPathRenderer::CanDrawPathArgs.
Bug: skia:
Change-Id: I16e1d35ad5ee63251e33f113b1579cbba60456da
Reviewed-on: https://skia-review.googlesource.com/42224
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
This is then used when need to update GPU only buffers with data of size
greater than 65536. We create a temporary transfer buffer and then copy
that buffer into our GPU buffer.
Bug: skia:
Change-Id: I4bb9cb660f2ac1ccbbd1b508bb4ca6876342136f
Reviewed-on: https://skia-review.googlesource.com/38725
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
NaNs can't be correctly sorted.
Don't run the unit test on VK backend, since it requires large (>64K bytes) vertex buffer uploads.
Bug: 757650
Change-Id: I667693f135a090a5d9076bb7a2ec6879fc06d645
Reviewed-on: https://skia-review.googlesource.com/37484
Commit-Queue: Stephen White <senorblanco@chromium.org>
Reviewed-by: Greg Daniel <egdaniel@google.com>
NaNs can't be correctly sorted.
Bug: 757650
Change-Id: Id1ca2fe1d1de7884da2a64ceef9491b1da7e8e77
Reviewed-on: https://skia-review.googlesource.com/37220
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Change 3b5a3fa8b1 introduced support
for out-of-range intersections, which is necessary when the top and
bottom vertices of an edge differ by only one ULP in the primary sort
order and can't be split in-order.
However, some out-of-range intersections produce edges which cancel
each other out on splitting, in particular when the intersection is
collinear with the newly-computed edge. This undoes the effect of the
split. The tessellator then rewinds, re-detects the intersection, resplits,
an infinite loop.
The fix is to check for out-of-range intersections which are also
collinear, and ignore them. This is ok, because these are not
the cases we care about it change 3b5a3f above, which are
never collinear.
Bug: 753867
Change-Id: I590231e0e6f19c98f1ccf46cb7acc8a63ba35a9d
Reviewed-on: https://skia-review.googlesource.com/34925
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Change-Id: I985e54a071338e99292a5aa2f42c92bc115b4008
Reviewed-on: https://skia-review.googlesource.com/32760
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
The only substantive changes are the removal of GrProxy instantiation in:
SkGpuBlurUtils::GaussianBlur
GrSimpleTextureEffect::Make*
Change-Id: I10970609693bd6ff5b3a3c21b41d82642bb277bc
Reviewed-on: https://skia-review.googlesource.com/19965
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
If a point in the path rounds to +inf/-inf, the intersection code can
produce NaN, which is unsortable. Fix: ignore non-finite intersections.
Quadratic interpolation can sometimes produce NaN, which will never
satisfy the flatness criterion. Abort if any of the interpolated points
are non-finite.
Bug:732023
Change-Id: If5881796e589c75b8f74459f42d00918619713a2
Reviewed-on: https://skia-review.googlesource.com/19467
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Change-Id: Iaded9025a1518d8c69dbe366deb1035e0bd4295b
Reviewed-on: https://skia-review.googlesource.com/19289
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Handle the case where the an intersection falls not only above both
edge endpoints, but above the first vertex in the mesh. This requires
passing the mesh into check_for_intersection(), in order to modify the
head. We also need to rewind the mesh after insertion, since we need
to rewind to the newly-inserted vertex.
This also cleans up vertex ID computation a little (for logging), so
that vertices before the first vertex or after the last have a
reasonable ID. It also cleans up the intersection-on-endpoint
special cases by refactoring the calls to split_edge().
BUG=730687
Change-Id: Idea736eca7b7c3c5d8a470b1373a16ad8e649e80
Reviewed-on: https://skia-review.googlesource.com/19069
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
In rare cases, a single edge can become collinear with two adjacent
neighbour edges after it's split. The solution is to continue to merge
until no collinear edges are found.
BUG=722000
Change-Id: Ia5dd212b7acfb40ed1d6c74ebfa9e4a4746fe40a
Reviewed-on: https://skia-review.googlesource.com/17963
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Introduce a private base class (SkShaderBase), to hide
implementation details from the public interface (SkShader).
Change-Id: Ib1d76cde880bd51868b97408710f8bb38128e536
Reviewed-on: https://skia-review.googlesource.com/17925
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
Introduce a private base class (SkShaderBase), to hide
implementation details from the public interface (SkShader).
Change-Id: If3ec26ca6abc9da20e3f139c11fdc023bdd85176
Reviewed-on: https://skia-review.googlesource.com/17241
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
If a previously-enclosing edge coincides exactly with the current
vertex, there are no two adjacent edges which enclose the vertex.
Since find_enclosing_edges() ensures that the left enclosing edge
is to the left of the vertex, the fix is to split the right
enclosing edge on the current vertex and restart intersection
tests.
Bug: 716720
Change-Id: Id26c5b92a6d6139f348e99554638cded37e81a8e
Reviewed-on: https://skia-review.googlesource.com/15261
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
This reverts commit 02242e82e4.
Reason for revert: Maybe breaking Chrome DEPS roll
Original change's description:
> Rm makeRenderTargetContext in favor of deferred version (take 2)
>
> This is a reland of: https://skia-review.googlesource.com/c/13001/ (Rm makeRenderTargetContext in favor of deferred version)
>
> Change-Id: Ife77b012d09c46895884a168fc5045bd92a4b919
> Reviewed-on: https://skia-review.googlesource.com/13196
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
>
TBR=egdaniel@google.com,bsalomon@google.com,robertphillips@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Change-Id: I2607116ed743f5d313da4a7b7f056776ed907702
Reviewed-on: https://skia-review.googlesource.com/14024
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
This reverts commit d83ec04412.
Reason for revert: various bot failures
Original change's description:
> Rm makeRenderTargetContext in favor of deferred version
>
> Change-Id: Ifdf67453607256ba7cdb0837263377bd83907212
> Reviewed-on: https://skia-review.googlesource.com/13001
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
>
TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Change-Id: I4e67a20cbe658b24725dcf386ac8bfdd127647ea
Reviewed-on: https://skia-review.googlesource.com/13131
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
BUG=skia:
Change-Id: I4aa3c2707811ece3a63d161035e316c3bbc1cd15
Reviewed-on: https://skia-review.googlesource.com/9482
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
This is pulled out of: https://skia-review.googlesource.com/c/6680/ (Make SkImage_Gpu be deferred) and is only tangentially related to the goal of that CL.
Change-Id: I6b6db4869597070f85ab3b9fea178fc88c104f87
Reviewed-on: https://skia-review.googlesource.com/9106
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Add a null-check on geometry processor creation.
Add a test which exercises it: AA tessellator, with a non-invertible
matrix and a fragment processor which needs local coords (e.g., linear
gradient).
BUG=691902
Change-Id: I005b893aed58d3ad2500c41501045ac94b0b4b95
Reviewed-on: https://skia-review.googlesource.com/8462
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
This makes GrPaints usable only once. In some places we must make copies in order to issue draws with the same paint state.
Change-Id: Ie816e5185ce93a064111cad64c6880e1e21184c2
Reviewed-on: https://skia-review.googlesource.com/6844
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
This reverts commit a8f80de2bc.
Reason for revert: nanobench failing on windows bots, possibly others
Change-Id: Iacb8c650064a28654c165665be057377ffb02ba5
Reviewed-on: https://skia-review.googlesource.com/6802
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
All GrXPFactory instances are static constexpr.
Change-Id: If1086b08534166201e53b3fd9379104e361eb5e6
Reviewed-on: https://skia-review.googlesource.com/6701
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Change-Id: I6410eae41f051ce38bef6f38d670924c3483c325
Reviewed-on: https://skia-review.googlesource.com/6163
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Fixes a bad merge.
This reverts commit 073285c059.
Change-Id: I5e92339d9b33d3a6dc58b9fcd2a1b3a5684e8f8a
Reviewed-on: https://skia-review.googlesource.com/5774
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
This reverts commit 3944484020.
Reason for revert: Merges badly with a recent change. Will rebase and reland.
Original change's description:
> Reland "Remove antialiasing control from GrPaint."
>
> This contains fixes for GLPrograms test and mixed samples rendering.
>
> This reverts commit 419d81eed4.
>
> BUG=skia:
>
> Change-Id: If8f002fbfaaaab6d1607403f2b15ccc7f1e17e87
> Reviewed-on: https://skia-review.googlesource.com/5763
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
>
TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org
BUG=skia:
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Change-Id: Iff9657041e28604a845bc5a9acec7c9b248c53bd
Reviewed-on: https://skia-review.googlesource.com/5772
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
This contains fixes for GLPrograms test and mixed samples rendering.
This reverts commit 419d81eed4.
BUG=skia:
Change-Id: If8f002fbfaaaab6d1607403f2b15ccc7f1e17e87
Reviewed-on: https://skia-review.googlesource.com/5763
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
This adds an additional param (of new enum type GrAA) to draws that can antialias and a new enum GrAAType to indicate the AA technique (none, fragment shader computed coverage, msaa).
Some GMs change due to this:
1) In some places we weren't disabling MSAA when the draw was supposed to be unantialiased.
2) Some bounding rect draws that use GrFragmentProcessors were unnecessarily turning on antialiasing, by disabling it a very small number of pixel LSBs change.
Change-Id: I7d8d8793dda70bcd373d09055beb9949c1a8a4d0
Reviewed-on: https://skia-review.googlesource.com/5608
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
This is in preparation for GrTextureContext and GrSurfaceContext
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4030
Change-Id: Ie58c93052e68f3f1f5fe8d15d63760de274a6fbd
Reviewed-on: https://skia-review.googlesource.com/4030
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
In rare cases, floating point error causes the tesselator to add the
same Vertex to more than one Poly on the same side. This was not a big
problem when we were allocating new vertices when constructing Polys,
but after https://codereview.chromium.org/2029243002 it causes more serious
issues, since each Edge can only belong to two Polys, and violating this
condition messes up the linked list of Edges used for left & right Polys
and the associated estimated vertex count.
The fix is to simply let the first Poly win, and skip that vertex for
subsequent Polys. Since this only occurs in cases where vertices are very
close to each other, it should have little visual effect.
This is also exercised by Nebraska-StateSeal.svg.
BUG=skia:5636
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2259493002
Review-Url: https://codereview.chromium.org/2259493002
Converts GrClip to an abstract base class and adds a "GrFixedClip"
implementation. GrFixedClip denotes a clip implemented with fixed-
function hardware. GrFixedClip allows us to remove the stateful
"fClipMode" member from GrClipMaskManager, and in the future will
be able to nicely encapsulate window rectangles.
After this change GrClipMaskManager is just a wrapper around
GrDrawTarget. We may want to consider removing it altogether.
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1971343002
Review-Url: https://codereview.chromium.org/1971343002
Initialize glGenTexture, glGenBuffer call id buffer items to zero before
calls. Otherwise it's not easy to check if the call succeeded or not.
Assert the rule in debug gl context.
Make TesselatingPathRendererTests use debug gl context. It exercises
some of the GenBuffers call sites.
Review URL: https://codereview.chromium.org/1514033002
Use DEF_GPUTEST_FOR_*_CONTEXT macros to obtain the
test GPU context.
Makes changing the context -related classes easier,
since not all tests need to be changed.
BUG=skia:2992
Review URL: https://codereview.chromium.org/1448873002
This shouldn't really make any difference but allocating and holding on to a GrRenderTarget for each test target generates image differences for Mali GPUs. This CL allows an existing render target to be used for the test target.
TBR=bsalomon@google.com
Review URL: https://codereview.chromium.org/1447113002
Move line dashing logic from GrContext::drawPath to
GrDashLinePathRenderer. This makes it possible to let path renderers render arbitrary dashed paths.
End goal is to implement dashing in GrStencilAndCoverPathRenderer.
Review URL: https://codereview.chromium.org/1100073003
More nullptr checks for factories I have added.
Other checks more Yoda-like I have made. (Skia style this is.)
BUG=skia:
Review URL: https://codereview.chromium.org/1086393004
Sometimes, the intersection returned by check_intersection() is
out-of-bounds for both edges (above both tops or below both bottoms)
due to floating-point inaccuracy. This causes split_edge() to create a
tiny negative-length edge on one side (which would then assert).
Although we could safely remove this assert and allow the negative
length edge to be removed, it's faster/safer to simply avoid its
creation in the first place by adjusting one edge to the other edge's
endpoint.
Added a new unit test to exercise this case.
Review URL: https://codereview.chromium.org/968993002
This path renderer converts paths to linear contours, resolves intersections via Bentley-Ottman, implements a trapezoidal decomposition a la Fournier and Montuno to produce triangles, and renders those with a single draw call. It does not currently do antialiasing, so it must be used in conjunction with multisampling.
A fair amount of the code is to handle floating point edge cases in intersections. Rather than perform exact computations (which would require arbitrary precision arithmetic), we reconnect the mesh to reflect the intersection points. For example, intersections can occur above the current vertex, and force edges to be merged into the current vertex, requiring a restart of the intersections. Splitting edges for intersections can also force them to merge with formerly-distinct edges in the same polygon, or to violate the ordering of the active edge list, or the active edge state of split edges.
BUG=skia:
Review URL: https://codereview.chromium.org/855513004
