101 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C#
		
	
			
		
		
	
	
			101 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C#
		
	
/******************************************************************************
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 * Spine Runtimes Software License v2.5
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 *
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 * Copyright (c) 2013-2016, Esoteric Software
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 * All rights reserved.
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 *
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 * You are granted a perpetual, non-exclusive, non-sublicensable, and
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 * non-transferable license to use, install, execute, and perform the Spine
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 * Runtimes software and derivative works solely for personal or internal
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 * use. Without the written permission of Esoteric Software (see Section 2 of
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 * the Spine Software License Agreement), you may not (a) modify, translate,
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 * adapt, or develop new applications using the Spine Runtimes or otherwise
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 * create derivative works or improvements of the Spine Runtimes or (b) remove,
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 * delete, alter, or obscure any trademarks or any copyright, trademark, patent,
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 * or other intellectual property or proprietary rights notices on or in the
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 * Software, including any copy thereof. Redistributions in binary or source
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 * form must include this license and terms.
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 *
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 * THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE "AS IS" AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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 * EVENT SHALL ESOTERIC SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, BUSINESS INTERRUPTION, OR LOSS OF
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 * USE, DATA, OR PROFITS) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 * POSSIBILITY OF SUCH DAMAGE.
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 *****************************************************************************/
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using System;
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namespace Spine {
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	public static class MathUtils {
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		public const float PI = 3.1415927f;
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		public const float PI2 = PI * 2;
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		public const float RadDeg = 180f / PI;
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		public const float DegRad = PI / 180;
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		const int SIN_BITS = 14; // 16KB. Adjust for accuracy.
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		const int SIN_MASK = ~(-1 << SIN_BITS);
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		const int SIN_COUNT = SIN_MASK + 1;
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		const float RadFull = PI * 2;
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		const float DegFull = 360;
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		const float RadToIndex = SIN_COUNT / RadFull;
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		const float DegToIndex = SIN_COUNT / DegFull;
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		static float[] sin = new float[SIN_COUNT];
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		static MathUtils () {
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			for (int i = 0; i < SIN_COUNT; i++)
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				sin[i] = (float)Math.Sin((i + 0.5f) / SIN_COUNT * RadFull);
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			for (int i = 0; i < 360; i += 90)
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				sin[(int)(i * DegToIndex) & SIN_MASK] = (float)Math.Sin(i * DegRad);
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		}
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		/// <summary>Returns the sine in radians from a lookup table.</summary>
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		static public float Sin (float radians) {
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			return sin[(int)(radians * RadToIndex) & SIN_MASK];
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		}
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		/// <summary>Returns the cosine in radians from a lookup table.</summary>
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		static public float Cos (float radians) {
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			return sin[(int)((radians + PI / 2) * RadToIndex) & SIN_MASK];
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		}
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		/// <summary>Returns the sine in radians from a lookup table.</summary>
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		static public float SinDeg (float degrees) {
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			return sin[(int)(degrees * DegToIndex) & SIN_MASK];
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		}
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		/// <summary>Returns the cosine in radians from a lookup table.</summary>
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		static public float CosDeg (float degrees) {
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			return sin[(int)((degrees + 90) * DegToIndex) & SIN_MASK];
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		}
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		/// <summary>Returns atan2 in radians, faster but less accurate than Math.Atan2. Average error of 0.00231 radians (0.1323
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		/// degrees), largest error of 0.00488 radians (0.2796 degrees).</summary>
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		static public float Atan2 (float y, float x) {
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			if (x == 0f) {
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				if (y > 0f) return PI / 2;
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				if (y == 0f) return 0f;
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				return -PI / 2;
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			}
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			float atan, z = y / x;
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			if (Math.Abs(z) < 1f) {
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				atan = z / (1f + 0.28f * z * z);
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				if (x < 0f) return atan + (y < 0f ? -PI : PI);
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				return atan;
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			}
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			atan = PI / 2 - z / (z * z + 0.28f);
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			return y < 0f ? atan - PI : atan;
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		}
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		static public float Clamp (float value, float min, float max) {
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			if (value < min) return min;
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			if (value > max) return max;
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			return value;
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		}
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	}
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}
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