Merge pull request #384 from RagnarokResearchLab/fix-water-transparency

Fix alpha compositing for translucent water surfaces

Core/NativeClient/Renderer.lua

@@ -99,10 +99,7 @@ local Renderer = {
 
 function Renderer:InitializeWithGLFW(nativeWindowHandle)
 	Renderer:CreateGraphicsContext(nativeWindowHandle)
-
-	-- Need to compute the preferred texture format first
-	self.backingSurface:UpdateConfiguration()
-	Renderer:CompileMaterials(self.backingSurface.preferredTextureFormat)
+	Renderer:CompileMaterials(self.backingSurface.textureFormat)
 
 	Renderer:CreateUniformBuffers()
 
@@ -134,6 +131,8 @@ function Renderer:CreateGraphicsContext(nativeWindowHandle)
 
 	printf("Creating depth buffer with texture dimensions %d x %d", viewportWidth, viewportHeight)
 	self.depthStencilTexture = DepthStencilTexture(device, viewportWidth, viewportHeight)
+
+	self.backingSurface:UpdateConfiguration()
 end
 
 function Renderer:CompileMaterials(outputTextureFormat)

Core/NativeClient/WebGPU/Pipelines/GroundMeshDrawingPipeline.lua

@@ -46,6 +46,11 @@ function GroundMeshDrawingPipeline:Construct(wgpuDeviceHandle, textureFormatID)
 							dstFactor = ffi.C.WGPUBlendFactor_OneMinusSrcAlpha,
 							operation = ffi.C.WGPUBlendOperation_Add,
 						},
+						alpha = {
+							srcFactor = ffi.C.WGPUBlendFactor_One,
+							dstFactor = ffi.C.WGPUBlendFactor_OneMinusSrcAlpha,
+							operation = ffi.C.WGPUBlendOperation_Add,
+						},
 					}),
 					writeMask = ffi.C.WGPUColorWriteMask_All,
 				}),

Core/NativeClient/WebGPU/Pipelines/WaterPlaneDrawingPipeline.lua

@@ -46,6 +46,11 @@ function WaterPlaneDrawingPipeline:Construct(wgpuDeviceHandle, textureFormatID)
 							dstFactor = ffi.C.WGPUBlendFactor_OneMinusSrcAlpha,
 							operation = ffi.C.WGPUBlendOperation_Add,
 						},
+						alpha = {
+							srcFactor = ffi.C.WGPUBlendFactor_One,
+							dstFactor = ffi.C.WGPUBlendFactor_OneMinusSrcAlpha,
+							operation = ffi.C.WGPUBlendOperation_Add,
+						},
 					}),
 					writeMask = ffi.C.WGPUColorWriteMask_All,
 				}),

Core/NativeClient/WebGPU/RenderTargets/ScreenshotCaptureTexture.lua

@@ -10,7 +10,7 @@ local Device = require("Core.NativeClient.WebGPU.Device")
 local format = string.format
 
 local ScreenshotCaptureTexture = {
-	OUTPUT_TEXTURE_FORMAT = ffi.C.WGPUTextureFormat_RGBA8UnormSrgb,
+	OUTPUT_TEXTURE_FORMAT = ffi.C.WGPUTextureFormat_RGBA8Unorm,
 }
 
 function ScreenshotCaptureTexture:Construct(wgpuDevice, width, height)

Core/NativeClient/WebGPU/Shaders/BasicTriangleShader.wgsl

@@ -116,9 +116,5 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4f {
 	let materialColor = vec4f(uMaterialInstanceData.diffuseRed, uMaterialInstanceData.diffuseGreen, uMaterialInstanceData.diffuseBlue, uMaterialInstanceData.materialOpacity);
 	let finalColor = in.color * diffuseTextureColor.rgb * materialColor.rgb;
 
-	// Gamma-correction:
-	// WebGPU assumes that the colors output by the fragment shader are given in linear space
-	// When setting the surface format to BGRA8UnormSrgb it performs a linear to sRGB conversion
-	let gammaCorrectedColor = pow(finalColor.rgb, vec3f(2.2));
-	return vec4f(gammaCorrectedColor, diffuseTextureColor.a * materialColor.a + DEBUG_ALPHA_OFFSET);
+	return vec4f(finalColor, diffuseTextureColor.a * materialColor.a + DEBUG_ALPHA_OFFSET);
 }

Core/NativeClient/WebGPU/Shaders/TerrainGeometryShader.wgsl

@@ -167,10 +167,5 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4f {
 
 	// Should be a no-op if fog is disabled, since the fogFactor would be zero
 	let foggedColor = mix(fragmentColor.rgb, uPerSceneData.fogColor.rgb, in.fogFactor);
-
-	// Gamma-correction:
-	// WebGPU assumes that the colors output by the fragment shader are given in linear space
-	// When setting the surface format to BGRA8UnormSrgb it performs a linear to sRGB conversion
-	let gammaCorrectedColor = pow(foggedColor.rgb, vec3f(2.2));
-	return vec4f(gammaCorrectedColor, diffuseTextureColor.a + DEBUG_ALPHA_OFFSET);
+	return vec4f(foggedColor.rgb, diffuseTextureColor.a + DEBUG_ALPHA_OFFSET);
 }

Core/NativeClient/WebGPU/Shaders/UserInterfaceShader.wgsl

@@ -87,9 +87,5 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4f {
 	// Currently the same buffer is used when RML assigns the same texture, which won't work
 	let finalColor = in.color * diffuseTextureColor * vec4f(1.0, 1.0, 1.0, 1.0);
 
-	// Gamma-correction:
-	// WebGPU assumes that the colors output by the fragment shader are given in linear space
-	// When setting the surface format to BGRA8UnormSrgb it performs a linear to sRGB conversion
-	let gammaCorrectedColor = vec4f(pow(finalColor.rgb, vec3f(2.2)), finalColor.w);
-	return vec4f(gammaCorrectedColor);
+	return vec4f(finalColor);
 }

Core/NativeClient/WebGPU/Shaders/WaterSurfaceShader.wgsl

@@ -170,9 +170,5 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4f {
 	let materialColor = vec4f(uMaterialInstanceData.diffuseRed, uMaterialInstanceData.diffuseGreen, uMaterialInstanceData.diffuseBlue, uMaterialInstanceData.materialOpacity);
 	let finalColor = in.color * diffuseTextureColor.rgb * materialColor.rgb;
 
-	// Gamma-correction:
-	// WebGPU assumes that the colors output by the fragment shader are given in linear space
-	// When setting the surface format to BGRA8UnormSrgb it performs a linear to sRGB conversion
-	let gammaCorrectedColor = pow(finalColor.rgb, vec3f(2.2));
-	return vec4f(gammaCorrectedColor, diffuseTextureColor.a * materialColor.a + DEBUG_ALPHA_OFFSET);
+	return vec4f(finalColor.rgb, diffuseTextureColor.a * materialColor.a + DEBUG_ALPHA_OFFSET );
 }

Core/NativeClient/WebGPU/Surface.lua

@@ -16,6 +16,7 @@ local Surface = {
 		BACKING_SURFACE_OUTDATED = "The backing surface is outdated and can't be used (window resized or moved?)",
 		BACKING_SURFACE_TIMEOUT = "The backing surface couldn't be accessed in time (CPU or GPU too busy?)",
 	},
+	textureFormat = ffi.C.WGPUTextureFormat_BGRA8Unorm,
 }
 
 function Surface:Construct(wgpuInstance, wgpuAdapter, wgpuDevice, glfwWindow)
@@ -33,23 +34,16 @@ function Surface:Construct(wgpuInstance, wgpuAdapter, wgpuDevice, glfwWindow)
 end
 
 function Surface:UpdateConfiguration()
-	local preferredTextureFormat = webgpu.bindings.wgpu_surface_get_preferred_format(self.wgpuSurface, self.wgpuAdapter)
-	self.preferredTextureFormat = preferredTextureFormat -- Required to create the render pipeline
-	assert(
-		preferredTextureFormat == ffi.C.WGPUTextureFormat_BGRA8UnormSrgb,
-		"Only sRGB texture formats are currently supported"
-	)
-
 	local textureViewDescriptor = self.wgpuTextureViewDescriptor
 	textureViewDescriptor.dimension = ffi.C.WGPUTextureViewDimension_2D
-	textureViewDescriptor.format = preferredTextureFormat
+	textureViewDescriptor.format = self.textureFormat
 	textureViewDescriptor.mipLevelCount = 1
 	textureViewDescriptor.arrayLayerCount = 1
 	textureViewDescriptor.aspect = ffi.C.WGPUTextureAspect_All
 
 	local surfaceConfiguration = self.wgpuSurfaceConfiguration
 	surfaceConfiguration.device = self.wgpuDevice
-	surfaceConfiguration.format = preferredTextureFormat
+	surfaceConfiguration.format = self.textureFormat
 	surfaceConfiguration.usage = ffi.C.WGPUTextureUsage_RenderAttachment
 
 	-- The underlying framebuffer may be different if DPI scaling is applied, but let's ignore that for now
@@ -62,12 +56,14 @@ function Surface:UpdateConfiguration()
 
 	webgpu.bindings.wgpu_surface_configure(self.wgpuSurface, surfaceConfiguration)
 
+	local preferredTextureFormat = webgpu.bindings.wgpu_surface_get_preferred_format(self.wgpuSurface, self.wgpuAdapter)
 	printf(
 		"Surface configuration changed: Frame buffer size is now %dx%d (preferred texture format: %d)",
 		viewportWidth,
 		viewportHeight,
 		tonumber(preferredTextureFormat)
 	)
+	self.preferredTextureFormat = preferredTextureFormat
 end
 
 function Surface:AcquireTextureView()

Core/NativeClient/WebGPU/Texture.lua

@@ -10,7 +10,7 @@ local new = ffi.new
 local math_floor = math.floor
 
 local Texture = {
-	DEFAULT_TEXTURE_FORMAT = ffi.C.WGPUTextureFormat_RGBA8Unorm, -- TBD: WGPUTextureFormat_BGRA8UnormSrgb ?
+	DEFAULT_TEXTURE_FORMAT = ffi.C.WGPUTextureFormat_RGBA8Unorm,
 	MAX_TEXTURE_DIMENSION = 4096,
 	ERROR_DIMENSIONS_NOT_POWER_OF_TWO = "Texture dimensions should always be a power of two",
 	ERROR_DIMENSIONS_EXCEEDING_LIMIT = "Texture dimensions must not exceed the configured GPU limit",