From da96550d3941cb794a799c73506a1c5b695c70a1 Mon Sep 17 00:00:00 2001 From: Jim Van Verth Date: Tue, 11 Apr 2017 15:29:14 -0400 Subject: Add perspective shadows Bug: skia: Change-Id: I1972f85f593828c982ea08143e1ed7eb70345eaa Reviewed-on: https://skia-review.googlesource.com/10296 Commit-Queue: Jim Van Verth Reviewed-by: Robert Phillips --- src/utils/SkInsetConvexPolygon.h | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) (limited to 'src/utils/SkInsetConvexPolygon.h') diff --git a/src/utils/SkInsetConvexPolygon.h b/src/utils/SkInsetConvexPolygon.h index 3ab7558a25..1d5a19c176 100755 --- a/src/utils/SkInsetConvexPolygon.h +++ b/src/utils/SkInsetConvexPolygon.h @@ -8,20 +8,49 @@ #ifndef SkInsetConvexPolygon_DEFINED #define SkInsetConvexPolygon_DEFINED +#include + #include "SkTDArray.h" #include "SkPoint.h" - /** +/** * Generates a polygon that is inset a given distance from the boundary of a given convex polygon. * * @param inputPolygonVerts Array of points representing the vertices of the original polygon. * It should be convex and have no coincident points. * @param inputPolygonSize Number of vertices in the original polygon. - * @param insetDistance How far we wish to inset the polygon. This should be a positive value. + * @param insetDistanceFunc How far we wish to inset the polygon for a given index in the array. + * This should return a positive value. * @param insetPolygon The resulting inset polygon, if any. * @return true if an inset polygon exists, false otherwise. */ bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, - SkScalar insetDistance, SkTDArray* insetPolygon); + std::function insetDistanceFunc, + SkTDArray* insetPolygon); + +inline bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize, + SkScalar inset, + SkTDArray* insetPolygon) { + return SkInsetConvexPolygon(inputPolygonVerts, inputPolygonSize, + [inset](int) { return inset; }, + insetPolygon); +} + +/** + * Offset a segment by the given distance at each point. + * Uses the outer tangents of two circles centered on each endpoint. + * See: https://en.wikipedia.org/wiki/Tangent_lines_to_circles + * + * @param p0 First endpoint. + * @param p1 Second endpoint. + * @param d0 Offset distance from first endpoint. + * @param d1 Offset distance from second endpoint. + * @param side Indicates whether we want to offset to the left (1) or right (-1) side of segment. + * @param offset0 First endpoint of offset segment. + * @param offset1 Second endpoint of offset segment. + * @return true if an offset segment exists, false otherwise. + */ +bool SkOffsetSegment(const SkPoint& p0, const SkPoint& p1, SkScalar d0, SkScalar d1, + int side, SkPoint* offset0, SkPoint* offset1); #endif -- cgit v1.2.3