124 lines
4.5 KiB
C#
124 lines
4.5 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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using SFML.Graphics;
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namespace Spine.Utils
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{
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/// <summary>
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/// SFML 混合模式, 预乘模式下输入和输出的像素值都是预乘的
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/// </summary>
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public static class SFMLBlendMode
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{
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///// <summary>
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///// Normal Blend, 无预乘, 仅在 dst.a 是 1 时得到正确结果, 其余情况是有偏结果
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///// <para>当 <c>src.c < dst.c</c> 时, 结果偏大, 例如 src 是半透明纯黑, dst 是全透明纯白</para>
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///// <para>当 <c>src.c > dst.c</c> 时, 结果偏小, 例如 src 是半透明纯白, dst 是全透明纯黑</para>
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///// <code>
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///// res.c = src.c * src.a + dst.c * (1 - src.a)
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///// res.a = src.a * 1 + dst.a * (1 - src.a)
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///// </code>
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///// </summary>
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//public static readonly BlendMode Normal = new(
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// BlendMode.Factor.SrcAlpha,
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// BlendMode.Factor.OneMinusSrcAlpha,
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// BlendMode.Equation.Add,
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// BlendMode.Factor.One,
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// BlendMode.Factor.OneMinusSrcAlpha,
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// BlendMode.Equation.Add
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//);
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///// <summary>
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///// Additive Blend, 无预乘, 仅在 dst.a 是 1 时得到正确结果, 其余情况是有偏结果
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///// <para>当 <c>src.a + dst.a >= 1</c> 时, 结果偏大, 例如 src 是不透明纯黑, dst 是全透明纯白</para>
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///// <para>当 <c>src.a + dst.a < 1</c> 时, 结果偏差方式类似 <see cref="Normal"/>, 均可假设 dst 是全透明纯白进行判断</para>
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///// <code>
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///// res.c = src.c * src.a + dst.c * 1
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///// res.a = src.a * 1 + dst.a * 1
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///// </code>
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///// </summary>
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//public static readonly BlendMode Additive = new(
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// BlendMode.Factor.SrcAlpha,
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// BlendMode.Factor.One,
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// BlendMode.Equation.Add,
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// BlendMode.Factor.One,
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// BlendMode.Factor.One,
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// BlendMode.Equation.Add
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//);
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/// <summary>
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/// Normal Blend with PremultipliedAlpha
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/// <code>
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/// [res.c * res.a] = [src.c * src.a] * 1 + [dst.c * dst.a] * (1 - src.a)
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/// res.a = src.a * 1 + dst.a * (1 - src.a)
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/// </code>
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/// </summary>
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public static readonly BlendMode NormalPma = new(
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BlendMode.Factor.One,
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BlendMode.Factor.OneMinusSrcAlpha,
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BlendMode.Equation.Add,
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BlendMode.Factor.One,
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BlendMode.Factor.OneMinusSrcAlpha,
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BlendMode.Equation.Add
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);
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/// <summary>
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/// Additive Blend with PremultipliedAlpha
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/// <code>
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/// [res.c * res.a] = [src.c * src.a] * 1 + [dst.c * dst.a] * 1
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/// res.a = src.a * 1 + dst.a * 1
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/// </code>
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/// </summary>
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public static readonly BlendMode AdditivePma = new(
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BlendMode.Factor.One,
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BlendMode.Factor.One,
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BlendMode.Equation.Add,
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BlendMode.Factor.One,
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BlendMode.Factor.One,
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BlendMode.Equation.Add
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);
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/// <summary>
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/// Multiply Blend with PremultipliedAlpha
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/// <code>
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/// res.c = src.c * dst.c + dst.c * (1 - src.a)
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/// res.a = src.a * 1 + dst.a * (1 - src.a)
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/// </code>
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/// </summary>
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public static readonly BlendMode MultiplyPma = new(
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BlendMode.Factor.DstColor,
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BlendMode.Factor.OneMinusSrcAlpha,
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BlendMode.Equation.Add,
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BlendMode.Factor.One,
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BlendMode.Factor.OneMinusSrcAlpha,
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BlendMode.Equation.Add
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);
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/// <summary>
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/// Screen Blend with PremultipliedAlpha Only
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/// <code>
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/// res.c = src.c * 1 + dst.c * (1 - src.c) = 1 - [(1 - src.c)(1 - dst.c)]
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/// res.a = src.a * 1 + dst.a * (1 - src.a)
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/// </code>
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/// </summary>
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public static readonly BlendMode ScreenPma = new(
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BlendMode.Factor.One,
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BlendMode.Factor.OneMinusSrcColor,
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BlendMode.Equation.Add,
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BlendMode.Factor.One,
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BlendMode.Factor.OneMinusSrcAlpha,
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BlendMode.Equation.Add
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);
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/// <summary>
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/// 仅源像素混合模式
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/// </summary>
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public static readonly BlendMode SourceOnly = new(
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BlendMode.Factor.One,
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BlendMode.Factor.Zero
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);
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}
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}
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