/*
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* Copyright 2014 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkMatrix22_DEFINED
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#define SkMatrix22_DEFINED
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#include "SkPoint.h"
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class SkMatrix;
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/** Find the Givens matrix G, which is the rotational matrix
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* that rotates the vector h to the positive hoizontal axis.
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* G * h = [hypot(h), 0]
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*
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* This is equivalent to
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*
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* SkScalar r = h.length();
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* SkScalar r_inv = r ? SkScalarInvert(r) : 0;
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* h.scale(r_inv);
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* G->setSinCos(-h.fY, h.fX);
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*
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* but has better numerical stability by using (partial) hypot,
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* and saves a multiply by not computing r.
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*/
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void SkComputeGivensRotation(const SkVector& h, SkMatrix* G);
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#endif
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