Add base types for path ops
Paths contain lines, quads, and cubics, which are
collectively curves.
To work with path intersections, intermediary curves
are constructed. For now, those intermediates use
doubles to guarantee sufficient precision.
The DVector, DPoint, DLine, DQuad, and DCubic
structs encapsulate these intermediate curves.
The DRect and DTriangle structs are created to
describe intersectable areas of interest.
The Bounds struct inherits from SkRect to create
a SkScalar-based rectangle that intersects shared
edges.
This also includes common math equalities and
debugging that the remainder of path ops builds on,
as well as a temporary top-level interface in
include/pathops/SkPathOps.h.
Review URL: https://codereview.chromium.org/12827020
git-svn-id: http://skia.googlecode.com/svn/trunk@8551 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pathops/SkPathOpsLine.cpp b/src/pathops/SkPathOpsLine.cpp
new file mode 100644
index 0000000..b7c91c9
--- /dev/null
+++ b/src/pathops/SkPathOpsLine.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkPathOpsLine.h"
+
+SkDLine SkDLine::subDivide(double t1, double t2) const {
+ SkDVector delta = tangent();
+ SkDLine dst = {{{
+ fPts[0].fX - t1 * delta.fX, fPts[0].fY - t1 * delta.fY}, {
+ fPts[0].fX - t2 * delta.fX, fPts[0].fY - t2 * delta.fY}}};
+ return dst;
+}
+
+// may have this below somewhere else already:
+// copying here because I thought it was clever
+
+// Copyright 2001, softSurfer (www.softsurfer.com)
+// This code may be freely used and modified for any purpose
+// providing that this copyright notice is included with it.
+// SoftSurfer makes no warranty for this code, and cannot be held
+// liable for any real or imagined damage resulting from its use.
+// Users of this code must verify correctness for their application.
+
+// Assume that a class is already given for the object:
+// Point with coordinates {float x, y;}
+//===================================================================
+
+// isLeft(): tests if a point is Left|On|Right of an infinite line.
+// Input: three points P0, P1, and P2
+// Return: >0 for P2 left of the line through P0 and P1
+// =0 for P2 on the line
+// <0 for P2 right of the line
+// See: the January 2001 Algorithm on Area of Triangles
+// return (float) ((P1.x - P0.x)*(P2.y - P0.y) - (P2.x - P0.x)*(P1.y - P0.y));
+double SkDLine::isLeft(const SkDPoint& pt) const {
+ SkDVector p0 = fPts[1] - fPts[0];
+ SkDVector p2 = pt - fPts[0];
+ return p0.cross(p2);
+}
+
+SkDPoint SkDLine::xyAtT(double t) const {
+ double one_t = 1 - t;
+ SkDPoint result = { one_t * fPts[0].fX + t * fPts[1].fX, one_t * fPts[0].fY + t * fPts[1].fY };
+ return result;
+}