122 lines
2.7 KiB
C
122 lines
2.7 KiB
C
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/* Copyright (C) 2010 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef INCLUDED_FIXED_VECTOR2D
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#define INCLUDED_FIXED_VECTOR2D
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#include "maths/Fixed.h"
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#include "maths/Sqrt.h"
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class CFixedVector2D
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{
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private:
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typedef CFixed_23_8 fixed;
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public:
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fixed X, Y;
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CFixedVector2D() { }
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CFixedVector2D(fixed X, fixed Y) : X(X), Y(Y) { }
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/// Vector equality
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bool operator==(const CFixedVector2D& v) const
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{
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return (X == v.X && Y == v.Y);
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}
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/// Vector addition
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CFixedVector2D operator+(const CFixedVector2D& v) const
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{
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return CFixedVector2D(X + v.X, Y + v.Y);
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}
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/// Vector subtraction
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CFixedVector2D operator-(const CFixedVector2D& v) const
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{
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return CFixedVector2D(X - v.X, Y - v.Y);
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}
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/// Negation
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CFixedVector2D operator-() const
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{
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return CFixedVector2D(-X, -Y);
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}
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/// Vector addition
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CFixedVector2D& operator+=(const CFixedVector2D& v)
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{
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*this = *this + v;
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return *this;
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}
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/// Vector subtraction
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CFixedVector2D& operator-=(const CFixedVector2D& v)
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{
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*this = *this - v;
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return *this;
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}
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/**
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* Returns the length of the vector.
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* Will not overflow if the result can be represented as type 'fixed'.
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*/
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fixed Length() const
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{
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// Do intermediate calculations with 64-bit ints to avoid overflows
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i64 x = (i64)X.GetInternalValue();
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i64 y = (i64)Y.GetInternalValue();
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u64 d2 = (u64)(x * x + y * y);
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u32 d = isqrt64(d2);
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fixed r;
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r.SetInternalValue((i32)d);
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return r;
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}
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/**
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* Normalize the vector so that length is close to 1.
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* If length is 0, does nothing.
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* WARNING: The fixed-point numbers only have 8-bit fractional parts, so
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* a normalized vector will be very imprecise.
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*/
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void Normalize()
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{
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fixed l = Length();
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if (!l.IsZero())
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{
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X = X / l;
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Y = Y / l;
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}
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}
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/**
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* Compute the dot product of this vector with another.
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*/
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fixed Dot(const CFixedVector2D& v)
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{
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i64 x = (i64)X.GetInternalValue() * (i64)v.X.GetInternalValue();
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i64 y = (i64)Y.GetInternalValue() * (i64)v.Y.GetInternalValue();
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i64 sum = x + y;
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fixed ret;
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ret.SetInternalValue((i32)(sum >> fixed::fract_bits));
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return ret;
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}
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};
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#endif // INCLUDED_FIXED_VECTOR2D
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