| /* |
| * Copyright 2008 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "include/core/SkPoint.h" |
| #include "include/core/SkScalar.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/base/SkFloatingPoint.h" |
| #include "src/core/SkPointPriv.h" |
| |
| #include <cmath> |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| void SkPoint::scale(SkScalar scale, SkPoint* dst) const { |
| SkASSERT(dst); |
| dst->set(fX * scale, fY * scale); |
| } |
| |
| bool SkPoint::normalize() { |
| return this->setLength(fX, fY, SK_Scalar1); |
| } |
| |
| bool SkPoint::setNormalize(SkScalar x, SkScalar y) { |
| return this->setLength(x, y, SK_Scalar1); |
| } |
| |
| bool SkPoint::setLength(SkScalar length) { |
| return this->setLength(fX, fY, length); |
| } |
| |
| /* |
| * We have to worry about 2 tricky conditions: |
| * 1. underflow of mag2 (compared against nearlyzero^2) |
| * 2. overflow of mag2 (compared w/ isfinite) |
| * |
| * If we underflow, we return false. If we overflow, we compute again using |
| * doubles, which is much slower (3x in a desktop test) but will not overflow. |
| */ |
| template <bool use_rsqrt> bool set_point_length(SkPoint* pt, float x, float y, float length, |
| float* orig_length = nullptr) { |
| SkASSERT(!use_rsqrt || (orig_length == nullptr)); |
| |
| // our mag2 step overflowed to infinity, so use doubles instead. |
| // much slower, but needed when x or y are very large, other wise we |
| // divide by inf. and return (0,0) vector. |
| double xx = x; |
| double yy = y; |
| double dmag = sqrt(xx * xx + yy * yy); |
| double dscale = sk_ieee_double_divide(length, dmag); |
| x *= dscale; |
| y *= dscale; |
| // check if we're not finite, or we're zero-length |
| if (!sk_float_isfinite(x) || !sk_float_isfinite(y) || (x == 0 && y == 0)) { |
| pt->set(0, 0); |
| return false; |
| } |
| float mag = 0; |
| if (orig_length) { |
| mag = sk_double_to_float(dmag); |
| } |
| pt->set(x, y); |
| if (orig_length) { |
| *orig_length = mag; |
| } |
| return true; |
| } |
| |
| SkScalar SkPoint::Normalize(SkPoint* pt) { |
| float mag; |
| if (set_point_length<false>(pt, pt->fX, pt->fY, 1.0f, &mag)) { |
| return mag; |
| } |
| return 0; |
| } |
| |
| SkScalar SkPoint::Length(SkScalar dx, SkScalar dy) { |
| float mag2 = dx * dx + dy * dy; |
| if (SkScalarIsFinite(mag2)) { |
| return sk_float_sqrt(mag2); |
| } else { |
| double xx = dx; |
| double yy = dy; |
| return sk_double_to_float(sqrt(xx * xx + yy * yy)); |
| } |
| } |
| |
| bool SkPoint::setLength(float x, float y, float length) { |
| return set_point_length<false>(this, x, y, length); |
| } |
| |
| bool SkPointPriv::SetLengthFast(SkPoint* pt, float length) { |
| return set_point_length<true>(pt, pt->fX, pt->fY, length); |
| } |
| |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| SkScalar SkPointPriv::DistanceToLineBetweenSqd(const SkPoint& pt, const SkPoint& a, |
| const SkPoint& b, |
| Side* side) { |
| |
| SkVector u = b - a; |
| SkVector v = pt - a; |
| |
| SkScalar uLengthSqd = LengthSqd(u); |
| SkScalar det = u.cross(v); |
| if (side) { |
| SkASSERT(-1 == kLeft_Side && |
| 0 == kOn_Side && |
| 1 == kRight_Side); |
| *side = (Side) SkScalarSignAsInt(det); |
| } |
| SkScalar temp = sk_ieee_float_divide(det, uLengthSqd); |
| temp *= det; |
| // It's possible we have a degenerate line vector, or we're so far away it looks degenerate |
| // In this case, return squared distance to point A. |
| if (!SkScalarIsFinite(temp)) { |
| return LengthSqd(v); |
| } |
| return temp; |
| } |
| |
| SkScalar SkPointPriv::DistanceToLineSegmentBetweenSqd(const SkPoint& pt, const SkPoint& a, |
| const SkPoint& b) { |
| // See comments to distanceToLineBetweenSqd. If the projection of c onto |
| // u is between a and b then this returns the same result as that |
| // function. Otherwise, it returns the distance to the closer of a and |
| // b. Let the projection of v onto u be v'. There are three cases: |
| // 1. v' points opposite to u. c is not between a and b and is closer |
| // to a than b. |
| // 2. v' points along u and has magnitude less than y. c is between |
| // a and b and the distance to the segment is the same as distance |
| // to the line ab. |
| // 3. v' points along u and has greater magnitude than u. c is not |
| // not between a and b and is closer to b than a. |
| // v' = (u dot v) * u / |u|. So if (u dot v)/|u| is less than zero we're |
| // in case 1. If (u dot v)/|u| is > |u| we are in case 3. Otherwise |
| // we're in case 2. We actually compare (u dot v) to 0 and |u|^2 to |
| // avoid a sqrt to compute |u|. |
| |
| SkVector u = b - a; |
| SkVector v = pt - a; |
| |
| SkScalar uLengthSqd = LengthSqd(u); |
| SkScalar uDotV = SkPoint::DotProduct(u, v); |
| |
| // closest point is point A |
| if (uDotV <= 0) { |
| return LengthSqd(v); |
| // closest point is point B |
| } else if (uDotV > uLengthSqd) { |
| return DistanceToSqd(b, pt); |
| // closest point is inside segment |
| } else { |
| SkScalar det = u.cross(v); |
| SkScalar temp = sk_ieee_float_divide(det, uLengthSqd); |
| temp *= det; |
| // It's possible we have a degenerate segment, or we're so far away it looks degenerate |
| // In this case, return squared distance to point A. |
| if (!SkScalarIsFinite(temp)) { |
| return LengthSqd(v); |
| } |
| return temp; |
| } |
| } |