From d26b4d865ac57d1b5ef810dd4408d8cc147b3460 Mon Sep 17 00:00:00 2001 From: Stephen White Date: Thu, 26 Jul 2018 10:02:27 -0400 Subject: GrTessellator: fix for collinear edge merging. In some cases, two edges can be collinear when tested on one side (e.g., left top vs right edge), but non-collinear when tested on the other (e.g., right top vs left edge). We were actually merging based on one criterion, but assserting based on the other. The safest fix is to merge if either condition is true, and then assert that both conditions are false. Bug: 866319 Change-Id: Ia1be330caf62f6d7961746752f73993ca098d0a3 Reviewed-on: https://skia-review.googlesource.com/143501 Reviewed-by: Robert Phillips Commit-Queue: Stephen White --- src/gpu/GrTessellator.cpp | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) (limited to 'src') diff --git a/src/gpu/GrTessellator.cpp b/src/gpu/GrTessellator.cpp index 944471a076..72a3bc8bf1 100644 --- a/src/gpu/GrTessellator.cpp +++ b/src/gpu/GrTessellator.cpp @@ -1051,30 +1051,40 @@ void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Vertex** } } +bool top_collinear(Edge* left, Edge* right) { + if (!left || !right) { + return false; + } + return left->fTop->fPoint == right->fTop->fPoint || + !left->isLeftOf(right->fTop) || !right->isRightOf(left->fTop); +} + +bool bottom_collinear(Edge* left, Edge* right) { + if (!left || !right) { + return false; + } + return left->fBottom->fPoint == right->fBottom->fPoint || + !left->isLeftOf(right->fBottom) || !right->isRightOf(left->fBottom); +} + void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Vertex** current, Comparator& c) { for (;;) { - const SkPoint& top = edge->fTop->fPoint; - const SkPoint& bottom = edge->fBottom->fPoint; - if (edge->fPrevEdgeAbove && (edge->fPrevEdgeAbove->fTop->fPoint == top || - !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { + if (top_collinear(edge->fPrevEdgeAbove, edge)) { merge_edges_above(edge->fPrevEdgeAbove, edge, activeEdges, current, c); - } else if (edge->fNextEdgeAbove && (edge->fNextEdgeAbove->fTop->fPoint == top || - !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { + } else if (top_collinear(edge, edge->fNextEdgeAbove)) { merge_edges_above(edge->fNextEdgeAbove, edge, activeEdges, current, c); - } else if (edge->fPrevEdgeBelow && (edge->fPrevEdgeBelow->fBottom->fPoint == bottom || - !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { + } else if (bottom_collinear(edge->fPrevEdgeBelow, edge)) { merge_edges_below(edge->fPrevEdgeBelow, edge, activeEdges, current, c); - } else if (edge->fNextEdgeBelow && (edge->fNextEdgeBelow->fBottom->fPoint == bottom || - !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { + } else if (bottom_collinear(edge, edge->fNextEdgeBelow)) { merge_edges_below(edge->fNextEdgeBelow, edge, activeEdges, current, c); } else { break; } } - SkASSERT(!edge->fPrevEdgeAbove || edge->fPrevEdgeAbove->isLeftOf(edge->fTop)); - SkASSERT(!edge->fPrevEdgeBelow || edge->fPrevEdgeBelow->isLeftOf(edge->fBottom)); - SkASSERT(!edge->fNextEdgeAbove || edge->fNextEdgeAbove->isRightOf(edge->fTop)); - SkASSERT(!edge->fNextEdgeBelow || edge->fNextEdgeBelow->isRightOf(edge->fBottom)); + SkASSERT(!top_collinear(edge->fPrevEdgeAbove, edge)); + SkASSERT(!top_collinear(edge, edge->fNextEdgeAbove)); + SkASSERT(!bottom_collinear(edge->fPrevEdgeBelow, edge)); + SkASSERT(!bottom_collinear(edge, edge->fNextEdgeBelow)); } bool split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Vertex** current, Comparator& c, -- cgit v1.2.3