81 lines
2.9 KiB
C#
81 lines
2.9 KiB
C#
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using Godot;
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using System;
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using Rokojori.Extensions;
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namespace Rokojori
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{
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/** Blend modes for a TextureStackLayer.
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The first four are *native* modes: BlitMaterial carries them as a runtime
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blend_mode, so they need no shader at all and no ping-pong buffer - the
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hardware blends the layer straight onto the accumulation. The remaining
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six have no hardware equivalent and are computed in
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TextureStackComposite.gdshader, which needs the accumulation handed in as
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a source texture (see TextureStackCompositor.NeedsCompositeShader).
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The formulas mirror the CPU predecessor in
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Procedural/Textures/TextureCombiner ( TextureCombinerBlendMode /
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TextureCombinerBlendModeAlgorithm / ColorX.Blend* ). Two copies of the
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same math exist on purpose - see the note in TextureStack.gdshaderinc -
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so a fix to one belongs in the other as well.
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Order matches the int values the composite shader switches on. Do not
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renumber without updating TextureStack.gdshaderinc.
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*/
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public enum TextureStackBlendMode
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{
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// Native - BlitMaterial.BlendModeEnum, no shader needed.
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Mix = 0,
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Add = 1,
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Sub = 2,
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Multiply = 3,
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// In-shader only, require the accumulation as a source.
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Screen = 4,
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Overlay = 5,
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HardLight = 6,
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SoftLight = 7,
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Color = 8,
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Hue = 9
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}
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public static class TextureStackBlendModeX
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{
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/** True for the four modes BlitMaterial can do in hardware.
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Note this says nothing about whether the *layer* can take the native
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path - a mask, clip-to-below or a non-trivial alpha requirement still
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forces the composite shader. TextureStackCompositor decides that.
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*/
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public static bool IsNative( this TextureStackBlendMode mode )
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{
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return mode == TextureStackBlendMode.Mix
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|| mode == TextureStackBlendMode.Add
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|| mode == TextureStackBlendMode.Sub
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|| mode == TextureStackBlendMode.Multiply;
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}
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/** Spike finding G5/constraint 2: the hardware blend applies to alpha too,
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so Add and Sub drive the target's alpha somewhere unintended even with a
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fully opaque source. Only safe where the target's alpha does not matter.
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*/
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public static bool NativePreservesAlpha( this TextureStackBlendMode mode )
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{
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return mode == TextureStackBlendMode.Mix;
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}
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public static BlitMaterial.BlendModeEnum ToBlitBlendMode( this TextureStackBlendMode mode )
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{
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switch ( mode )
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{
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case TextureStackBlendMode.Mix: return BlitMaterial.BlendModeEnum.Mix;
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case TextureStackBlendMode.Add: return BlitMaterial.BlendModeEnum.Add;
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case TextureStackBlendMode.Sub: return BlitMaterial.BlendModeEnum.Sub;
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case TextureStackBlendMode.Multiply: return BlitMaterial.BlendModeEnum.Mul;
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}
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return BlitMaterial.BlendModeEnum.Mix;
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}
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}
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}
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