Merge pull request #387 from RagnarokResearchLab/reduced-color-textures

Implement color banding for diffuse texture images

Core/FileFormats/RagnarokMap.lua

@@ -4,6 +4,7 @@ local RagnarokGRF = require("Core.FileFormats.RagnarokGRF")
 local RagnarokRSW = require("Core.FileFormats.RagnarokRSW")
 
 local C_Resources = require("Core.NativeClient.C_Resources")
+local Texture = require("Core.NativeClient.WebGPU.Texture")
 
 local NormalsVisualization = require("Core.NativeClient.DebugDraw.NormalsVisualization")
 
@@ -100,6 +101,8 @@ function RagnarokMap:LoadTerrainGeometry(mapID)
 		local textureImageBytes = self:FetchResourceByID(normalizedTextureImagePath)
 		local rgbaImageBytes, width, height = C_ImageProcessing.DecodeFileContents(textureImageBytes)
 
+		rgbaImageBytes, width, height = Texture:CreateReducedColorImage(rgbaImageBytes, width, height)
+
 		printf(
 			"[RagnarokMap] Loading GND ground mesh section %d with diffuse texture %s (%d x %d)",
 			sectionID,

Core/NativeClient/WebGPU/Texture.lua

@@ -209,6 +209,45 @@ function Texture:CreateTextureView(wgpuTexture, wgpuTextureViewDescriptor)
 	return webgpu.bindings.wgpu_texture_create_view(wgpuTexture, wgpuTextureViewDescriptor)
 end
 
+-- Should probably be replaced with an optimized version (via the ImageProcessing API)?
+function Texture:CreateReducedColorImage(inputImageBytes, width, height, posterizationLevel)
+	posterizationLevel = posterizationLevel or 3
+
+	local numBytesWritten = 0
+	local rgbaImageBytes = buffer.new(width * height * 4)
+	local bufferStartPointer = rgbaImageBytes:reserve(width * height * 4)
+	local inputPixels = buffer.new():put(inputImageBytes):ref()
+	for pixelV = 0, height - 1, 1 do
+		for pixelU = 0, width - 1, 1 do
+			local writableAreaStartIndex = (pixelV * width + pixelU) * 4
+			local red = inputPixels[writableAreaStartIndex + 0]
+			local green = inputPixels[writableAreaStartIndex + 1]
+			local blue = inputPixels[writableAreaStartIndex + 2]
+			local alpha = inputPixels[writableAreaStartIndex + 3]
+
+			local posterizedRed = bit.rshift(red, posterizationLevel)
+			local posterizedGreen = bit.rshift(green, posterizationLevel)
+			local posterizedBlue = bit.rshift(blue, posterizationLevel)
+			local posterizedAlpha = bit.rshift(alpha, posterizationLevel)
+			posterizedRed = bit.lshift(posterizedRed, posterizationLevel)
+			posterizedGreen = bit.lshift(posterizedGreen, posterizationLevel)
+			posterizedBlue = bit.lshift(posterizedBlue, posterizationLevel)
+			posterizedAlpha = bit.lshift(posterizedAlpha, posterizationLevel)
+
+			bufferStartPointer[writableAreaStartIndex + 0] = posterizedRed
+			bufferStartPointer[writableAreaStartIndex + 1] = posterizedGreen
+			bufferStartPointer[writableAreaStartIndex + 2] = posterizedBlue
+			bufferStartPointer[writableAreaStartIndex + 3] = posterizedAlpha
+
+			numBytesWritten = numBytesWritten + 4
+		end
+	end
+
+	rgbaImageBytes:commit(numBytesWritten)
+
+	return rgbaImageBytes, width, height
+end
+
 Texture.__call = Texture.Construct
 Texture.__index = Texture
 setmetatable(Texture, Texture)

Tests/FileFormats/RagnarokMap.spec.lua

@@ -5,6 +5,16 @@ local RagnarokRSW = require("Core.FileFormats.RagnarokRSW")
 
 local Texture = require("Core.NativeClient.WebGPU.Texture")
 
+local openssl = require("openssl")
+local digest = openssl.digest.digest
+
+local function assertImageChecksumMatches(actualImageBytes, expectedImageBytes)
+	local checksum = digest("sha256", tostring(actualImageBytes))
+	expectedImageBytes = Texture:CreateReducedColorImage(expectedImageBytes, 256, 256)
+	local expectedChecksum = digest("sha256", tostring(expectedImageBytes))
+	assertEquals(checksum, expectedChecksum)
+end
+
 local function makeFileSystem(name)
 	local testFileSystem = {
 		ROOT_DIR = path.join("Tests", "Fixtures", "Borftopia"),
@@ -80,15 +90,15 @@ describe("RagnarokMap", function()
 			assertEquals(#map.meshes, 2 + 1)
 			assertEquals(#map.meshes, #groundMeshSections + #waterPlanes)
 
-			assertEquals(map.meshes[1].diffuseTextureImage.rgbaImageBytes, gradientTexture)
+			assertImageChecksumMatches(map.meshes[1].diffuseTextureImage.rgbaImageBytes, gradientTexture)
 			assertEquals(map.meshes[1].diffuseTextureImage.width, 256)
 			assertEquals(map.meshes[1].diffuseTextureImage.height, 256)
 			assertEquals(map.meshes[1].vertexPositions, groundMeshSections[1].vertexPositions)
 			assertEquals(map.meshes[1].vertexColors, groundMeshSections[1].vertexColors)
 			assertEquals(map.meshes[1].triangleConnections, groundMeshSections[1].triangleConnections)
 			assertEquals(map.meshes[1].diffuseTextureCoords, groundMeshSections[1].diffuseTextureCoords)
 
-			assertEquals(map.meshes[2].diffuseTextureImage.rgbaImageBytes, gridTexture)
+			assertImageChecksumMatches(map.meshes[2].diffuseTextureImage.rgbaImageBytes, gridTexture)
 			assertEquals(map.meshes[2].diffuseTextureImage.width, 256)
 			assertEquals(map.meshes[2].diffuseTextureImage.height, 256)
 			assertEquals(map.meshes[2].vertexPositions, groundMeshSections[2].vertexPositions)

Tests/NativeClient/WebGPU/Texture.spec.lua

@@ -204,4 +204,15 @@ describe("Texture", function()
 			end, Texture.ERROR_DIMENSIONS_EXCEEDING_LIMIT)
 		end)
 	end)
+
+	describe("CreateReducedColorImage", function()
+		it("should reduce the color depth of the texture image", function()
+			local testImage = "\255\192\128\000" .. "\007\007\007\007"
+			local reducedColorImage, width, height = Texture:CreateReducedColorImage(testImage, 2, 1)
+			local expectedimageBytes = "\248\192\128\000\000\000\000\000"
+			assertEquals(width, 2)
+			assertEquals(height, 1)
+			assertEquals(tostring(reducedColorImage), expectedimageBytes)
+		end)
+	end)
 end)