43 lines
1.1 KiB
C++
43 lines
1.1 KiB
C++
//
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// A class for affine transforms (ax + b) of scalar values
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//
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// Copyright (C) 2020-2021 Andreas Gustafsson. This file is part of
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// the Gaborator library source distribution. See the file LICENSE at
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// the top level of the distribution for license information.
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//
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#ifndef _GABORATOR_AFFINE_TRANSFORM_H
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#define _GABORATOR_AFFINE_TRANSFORM_H
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namespace gaborator {
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struct affine_transform {
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affine_transform(): a(0), b(0) { }
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affine_transform(double a_, double b_): a(a_), b(b_) { }
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affine_transform(const affine_transform &rhs): a(rhs.a), b(rhs.b) { }
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double operator()(double x) const { return a * x + b; }
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affine_transform inverse() const {
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return affine_transform(1.0 / a, -b / a);
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}
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static affine_transform identity() { return affine_transform(1, 0); }
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double a, b;
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};
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// Composition
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static inline affine_transform
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operator *(const affine_transform &a, const affine_transform &b) {
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return affine_transform(a.a * b.a, a.a * b.b + a.b);
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}
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// Equality
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static inline bool
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operator ==(const affine_transform &a, const affine_transform &b) {
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return a.a == b.a && a.b == b.b;
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}
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} // namespace
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#endif
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