Introduce AlphaCompositing.darken

breki · May 23, 2024 · 3443c96 · 3443c96
1 parent 7323f9e
commit 3443c96
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Showing 7 changed files with 48 additions and 57 deletions.
diff --git a/Demeton.Tests/Aw3d/AW3D experiments.fs b/Demeton.Tests/Aw3d/AW3D experiments.fs
@@ -91,8 +91,9 @@ let fetchAw3dHeightsArray _ =
 [<Fact(Skip = "downloads the tile so it takes too long")>]
 let ``Generate hillshading from AW3D`` () =
     let pixelShader =
-        HighwireHillshader.shadePixel
+        IgorHillshader.shadePixel
             { SunAzimuth = IgorHillshader.DefaultSunAzimuth
+              ShadingColor = 0u
               HeightsArrayIndex = 0 }
 
     let createShaderFunction _ =

diff --git a/Demeton.Tests/WorldCover/WorldCover experiments.fs b/Demeton.Tests/WorldCover/WorldCover experiments.fs
@@ -38,8 +38,8 @@ let StepNameXcTracerWaterBodies = "XCTracer-water-bodies"
 let StepNameXcTracerWaterBodiesOutline = "XCTracer-water-bodies-outline"
 
 let hillshadingStep =
-    Demeton.Shaders.Pipeline.Common.ShadingStep.HighwireHillshading
-        Demeton.Shaders.HighwireHillshader.defaultParameters
+    Demeton.Shaders.Pipeline.Common.ShadingStep.IgorHillshading
+        IgorHillshader.defaultParameters
 
 let waterBodiesStep = Pipeline.Common.CustomShading StepNameXcTracerWaterBodies
 

diff --git a/Demeton/Commands/TileShadeCommand.fs b/Demeton/Commands/TileShadeCommand.fs
@@ -341,17 +341,17 @@ let run (options: Options) : Result<unit, string> =
     let igorHillshadingStep =
         ShadingStep.IgorHillshading IgorHillshader.defaultParameters
 
-    let highwireHillshadingStep =
-        ShadingStep.HighwireHillshading HighwireHillshader.defaultParameters
+    let igorHillshadingStep =
+        ShadingStep.IgorHillshading IgorHillshader.defaultParameters
 
     let slopeShadingStep =
         ShadingStep.SlopeShading SlopeShader.defaultParameters
 
     let hillshadingStep =
         Compositing(
-            highwireHillshadingStep,
+            igorHillshadingStep,
             slopeShadingStep,
-            CompositingFuncIdOver
+            CompositingFuncIdAlphaDarken
         )
 
     let rootShadingStep =

diff --git a/Demeton/Demeton.fsproj b/Demeton/Demeton.fsproj
@@ -80,7 +80,6 @@
         <Compile Include="Shaders\SlopeShader.fs"/>
         <Compile Include="Shaders\AspectShader.fs"/>
         <Compile Include="Shaders\IgorHillshader.fs"/>
-        <Compile Include="Shaders\HighwireHillshader.fs"/>
         <Compile Include="Shaders\Pipeline\Common.fs"/>
         <Compile Include="Shaders\Pipeline\Parsing.fs"/>
         <Compile Include="Shaders\Pipeline\Building.fs"/>

diff --git a/Demeton/Png/AlphaCompositing.fs b/Demeton/Png/AlphaCompositing.fs
@@ -93,3 +93,39 @@ let imageOver: CompositingFunc =
         |> ignore
 
         dest
+
+let darken: CompositingFunc =
+    fun
+        (imageWidth: int)
+        (imageHeight: int)
+        (source: RawImageData)
+        (dest: RawImageData) ->
+        Parallel.For(
+            0,
+            imageHeight,
+            fun y ->
+                for x in 0 .. imageWidth - 1 do
+                    let sourceDarknessRatio =
+                        Rgba8Bit.pixelAt source imageWidth x y
+                        |> Rgba8Bit.a
+                        |> byteToRatio
+
+                    let destDarknessRatio =
+                        Rgba8Bit.pixelAt dest imageWidth x y
+                        |> Rgba8Bit.a
+                        |> byteToRatio
+
+                    let outDarknessRatio =
+                        1.
+                        - ((1. - sourceDarknessRatio) * (1. - destDarknessRatio))
+
+                    let outAlpha = ratioToByte outDarknessRatio
+
+                    // todo 5: use source RGB value instead of always black
+                    let outPixel = Rgba8Bit.rgbaColor 0uy 0uy 0uy outAlpha
+
+                    Rgba8Bit.setPixelAt dest imageWidth x y outPixel
+        )
+        |> ignore
+
+        dest
diff --git a/Demeton/Shaders/HighwireHillshader.fs b/Demeton/Shaders/HighwireHillshader.fs
diff --git a/Demeton/Shaders/Pipeline/Common.fs b/Demeton/Shaders/Pipeline/Common.fs
@@ -23,19 +23,22 @@ type ShadingStep =
     | IgorHillshading of IgorHillshader.ShaderParameters
     | SlopeShading of SlopeShader.ShaderParameters
     | AspectShading of AspectShader.ShaderParameters
-    | HighwireHillshading of HighwireHillshader.ShaderParameters
     | CustomShading of ShadingFuncId
     | Compositing of (ShadingStep * ShadingStep * CompositingFuncId)
 
 [<Literal>]
 let CompositingFuncIdOver = "over"
 
+[<Literal>]
+let CompositingFuncIdAlphaDarken = "alpha-darken"
+
 let createShadingFuncById shadingFuncId =
     invalidOp "we currently do not support custom shading functions"
 
 let createCompositingFuncById compositingFuncId =
     match compositingFuncId with
     | CompositingFuncIdOver -> AlphaCompositing.imageOver
+    | CompositingFuncIdAlphaDarken -> AlphaCompositing.darken
     | _ -> invalidOp "Unknown compositing function."
 
 
@@ -130,12 +133,6 @@ let rec executeShadingStep
                 Hillshading.shadeRaster
                     parameters.HeightsArrayIndex
                     (SlopeShader.shadePixel parameters)
-            | HighwireHillshading parameters ->
-                Log.info "Running highwire hillshading step..."
-
-                Hillshading.shadeRaster
-                    parameters.HeightsArrayIndex
-                    (HighwireHillshader.shadePixel parameters)
             | CustomShading shadingFuncId -> shadingFuncFactory shadingFuncId
             | _ -> invalidOp "Unsupported shading step"