| /* |
| * 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); |
| } |
| |
| // OPTIMIZE: assert if t is 0 or 1 (caller shouldn't pass only 0/1) |
| 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; |
| } |
| |
| double SkDLine::exactPoint(const SkDPoint& xy) const { |
| if (xy == fPts[0]) { // do cheapest test first |
| return 0; |
| } |
| if (xy == fPts[1]) { |
| return 1; |
| } |
| return -1; |
| } |
| |
| double SkDLine::nearPoint(const SkDPoint& xy) const { |
| if (!AlmostBetweenUlps(fPts[0].fX, xy.fX, fPts[1].fX) |
| || !AlmostBetweenUlps(fPts[0].fY, xy.fY, fPts[1].fY)) { |
| return -1; |
| } |
| // project a perpendicular ray from the point to the line; find the T on the line |
| SkDVector len = fPts[1] - fPts[0]; // the x/y magnitudes of the line |
| double denom = len.fX * len.fX + len.fY * len.fY; // see DLine intersectRay |
| SkDVector ab0 = xy - fPts[0]; |
| double numer = len.fX * ab0.fX + ab0.fY * len.fY; |
| if (!between(0, numer, denom)) { |
| return -1; |
| } |
| double t = numer / denom; |
| SkDPoint realPt = xyAtT(t); |
| SkDVector distU = xy - realPt; |
| double distSq = distU.fX * distU.fX + distU.fY * distU.fY; |
| double dist = sqrt(distSq); // OPTIMIZATION: can we compare against distSq instead ? |
| // find the ordinal in the original line with the largest unsigned exponent |
| double tiniest = SkTMin(SkTMin(SkTMin(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY); |
| double largest = SkTMax(SkTMax(SkTMax(fPts[0].fX, fPts[0].fY), fPts[1].fX), fPts[1].fY); |
| largest = SkTMax(largest, -tiniest); |
| if (!AlmostEqualUlps(largest, largest + dist)) { // is the dist within ULPS tolerance? |
| return -1; |
| } |
| t = SkPinT(t); |
| SkASSERT(between(0, t, 1)); |
| return t; |
| } |
| |
| double SkDLine::ExactPointH(const SkDPoint& xy, double left, double right, double y) { |
| if (xy.fY == y) { |
| if (xy.fX == left) { |
| return 0; |
| } |
| if (xy.fX == right) { |
| return 1; |
| } |
| } |
| return -1; |
| } |
| |
| double SkDLine::NearPointH(const SkDPoint& xy, double left, double right, double y) { |
| if (!AlmostEqualUlps(xy.fY, y)) { |
| return -1; |
| } |
| if (!AlmostBetweenUlps(left, xy.fX, right)) { |
| return -1; |
| } |
| double t = (xy.fX - left) / (right - left); |
| t = SkPinT(t); |
| SkASSERT(between(0, t, 1)); |
| return t; |
| } |
| |
| double SkDLine::ExactPointV(const SkDPoint& xy, double top, double bottom, double x) { |
| if (xy.fX == x) { |
| if (xy.fY == top) { |
| return 0; |
| } |
| if (xy.fY == bottom) { |
| return 1; |
| } |
| } |
| return -1; |
| } |
| |
| double SkDLine::NearPointV(const SkDPoint& xy, double top, double bottom, double x) { |
| if (!AlmostEqualUlps(xy.fX, x)) { |
| return -1; |
| } |
| if (!AlmostBetweenUlps(top, xy.fY, bottom)) { |
| return -1; |
| } |
| double t = (xy.fY - top) / (bottom - top); |
| t = SkPinT(t); |
| SkASSERT(between(0, t, 1)); |
| return t; |
| } |