palette crush effect

Effects/HLSL/PaletteCrushEffect.fx

@@ -0,0 +1,66 @@
+#include "Macros.fxh"
+
+#define FLT_MAX 3.402823466e+38
+
+DECLARE_TEXTURE(Texture, 0);
+DECLARE_TEXTURE(Palette, 1);
+
+BEGIN_CONSTANTS
+
+	int PaletteWidth   _ps(c0)   _cb(c0);
+
+END_CONSTANTS
+
+struct VertexInput
+{
+	float4 Position : POSITION;
+	float2 TexCoord : TEXCOORD;
+};
+
+struct PixelInput
+{
+	float4 Position : SV_POSITION;
+	float2 TexCoord : TEXCOORD0;
+};
+
+PixelInput main_vs(VertexInput input)
+{
+	PixelInput output;
+
+	output.Position = input.Position;
+	output.TexCoord = input.TexCoord;
+
+	return output;
+}
+
+float4 main_ps(PixelInput input) : SV_TARGET0
+{
+	float4 sampled = SAMPLE_TEXTURE(Texture, input.TexCoord);
+
+	float3 sampled_color = sampled.rgb;
+	
+	float3 closest_color = float3(0, 0, 0);
+	float closest_dist = FLT_MAX;
+
+	for (int i = 0; i < PaletteWidth; i++)
+	{
+		float3 palette_color = SAMPLE_TEXTURE(Palette, float2(i / (float)PaletteWidth, 0));
+		float dist = distance(palette_color, sampled_color);
+		if (dist < closest_dist)
+		{
+			closest_dist = dist;
+			closest_color = palette_color;
+		}
+	}
+
+	return float4(closest_color, sampled.a);
+}
+
+Technique PaletteCrush
+{
+	Pass
+	{
+		VertexShader = compile vs_3_0 main_vs();
+		PixelShader = compile ps_3_0 main_ps();
+	}
+}

Effects/PaletteCrushEffect.cs

@@ -0,0 +1,51 @@
+using Microsoft.Xna.Framework.Graphics;
+
+namespace Kav
+{
+    public class PaletteCrushEffect : Effect
+    {
+        EffectParameter textureParam;
+        EffectParameter paletteParam;
+        EffectParameter paletteWidthParam;
+
+        Texture2D texture;
+        Texture2D palette;
+
+        int paletteWidth;
+
+        public Texture2D Texture
+        {
+            get { return texture; }
+            set 
+            { 
+                texture = value;
+                textureParam.SetValue(texture); 
+            }
+        }
+
+        public Texture2D Palette
+        {
+            get { return palette; }
+            set
+            {
+                palette = value;
+                paletteWidth = palette.Width;
+                paletteParam.SetValue(palette);
+                paletteWidthParam.SetValue(paletteWidth);
+            }
+        }
+
+        public PaletteCrushEffect(GraphicsDevice graphicsDevice) : base(graphicsDevice, Resources.PaletteCrushEffect)
+        {
+            CacheEffectParameters();
+        }
+
+        void CacheEffectParameters()
+        {
+            textureParam = Parameters["Texture"];
+            paletteParam = Parameters["Palette"];
+
+            paletteWidthParam = Parameters["PaletteWidth"];
+        }
+    }
+}

Kav.Core.csproj

@@ -58,6 +58,9 @@
     <EmbeddedResource Include="Effects\FXB\DiffuseLitSpriteEffect.fxb">
       <LogicalName>Kav.Resources.DiffuseLitSpriteEffect.fxb</LogicalName>
 		</EmbeddedResource>
+    <EmbeddedResource Include="Effects\FXB\PaletteCrushEffect.fxb">
+      <LogicalName>Kav.Resources.PaletteCrushEffect.fxb</LogicalName>
+		</EmbeddedResource>
     <EmbeddedResource Include="Models\UnitCube.glb">
       <LogicalName>Kav.Resources.UnitCube.glb</LogicalName>
 		</EmbeddedResource>

Kav.Framework.csproj

@@ -58,6 +58,9 @@
     <EmbeddedResource Include="Effects\FXB\DiffuseLitSpriteEffect.fxb">
       <LogicalName>Kav.Resources.DiffuseLitSpriteEffect.fxb</LogicalName>
 		</EmbeddedResource>
+    <EmbeddedResource Include="Effects\FXB\PaletteCrushEffect.fxb">
+      <LogicalName>Kav.Resources.PaletteCrushEffect.fxb</LogicalName>
+		</EmbeddedResource>
     <EmbeddedResource Include="Models\UnitCube.glb">
       <LogicalName>Kav.Resources.UnitCube.glb</LogicalName>
 		</EmbeddedResource>

Renderer.cs

@@ -26,7 +26,7 @@ namespace Kav
         private Effect ToneMapEffect { get; }
         private SkyboxEffect SkyboxEffect { get; }
         private DiffuseLitSpriteEffect DiffuseLitSpriteEffect { get; }
-
+        
         private Kav.Model UnitCube { get; }
 
         public Renderer(
@@ -180,7 +180,7 @@ namespace Kav
             }
         }
 
-        private IEnumerable<(MeshSprite, Matrix)> BillboardTransforms(
+        private static IEnumerable<(MeshSprite, Matrix)> BillboardTransforms(
             PerspectiveCamera camera,
             IEnumerable<(MeshSprite, SpriteBillboardConstraint, Matrix)> meshSpriteBillboardTransforms
         ) {

Resources.cs

@@ -171,6 +171,18 @@ namespace Kav
             }
         }
 
+        public static byte[] PaletteCrushEffect
+        {
+            get
+            {
+                if (paletteCrushEffect == null)
+                {
+                    paletteCrushEffect = GetResource("PaletteCrushEffect.fxb");
+                }
+                return paletteCrushEffect;
+            }
+        }
+
         public static byte[] UnitCubeModel
         {
             get
@@ -197,6 +209,7 @@ namespace Kav
         private static byte[] linearDepthEffectInstanced;
         private static byte[] skyboxEffect;
         private static byte[] diffuseLitSpriteEffect;
+        private static byte[] paletteCrushEffect;
 
         private static byte[] unitCubeModel;