fix(linear lighting): fix horizon seam

src/Features/LinearLighting.cpp

@@ -4,6 +4,7 @@ NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(
 	LinearLighting::Settings,
 	enableLinearLighting,
 	enableGammaCorrection,
+	clearRenderGamma,
 	lightGamma,
 	colorGamma,
 	emitColorGamma,
@@ -48,6 +49,7 @@ void LinearLighting::DrawSettings()
 	ImGui::SliderFloat("Effect Gamma", &settings.effectGamma, 0.1f, 3.0f, "%.2f");
 	ImGui::SliderFloat("Effect Transparency Gamma", &settings.effectAlphaGamma, 0.1f, 3.0f, "%.2f");
 	ImGui::SliderFloat("Sky Gamma", &settings.skyGamma, 0.1f, 3.0f, "%.2f");
+	ImGui::SliderFloat("Clear Render Gamma", &settings.clearRenderGamma, 0.1f, 3.0f, "%.2f");
 	ImGui::SliderFloat("Water Gamma", &settings.waterGamma, 0.1f, 3.0f, "%.2f");
 	ImGui::SliderFloat("Volumetric Lighting Gamma", &settings.vlGamma, 0.1f, 3.0f, "%.2f");
 
@@ -93,6 +95,61 @@ void LinearLighting::SetupResources()
 	PerGeometryCB = new ConstantBuffer(ConstantBufferDesc<PerGeometryData>());
 }
 
+void LinearLighting::EarlyPrepass()
+{
+	ConvertClearColor();
+}
+
+void LinearLighting::ReflectionsPrepass()
+{
+	ConvertClearColor();
+}
+
+void LinearLighting::ConvertClearColor()
+{
+	bool isMainLoadingMenu = globals::game::ui && (globals::game::ui->IsMenuOpen(RE::MainMenu::MENU_NAME) || globals::game::ui->IsMenuOpen(RE::LoadingMenu::MENU_NAME));
+	if (!settings.enableLinearLighting || isMainLoadingMenu)
+		return;
+
+	// Convert clear color from gamma space to linear space at the source
+	// This affects the background color visible at worldspace edges and in water reflections
+	auto renderer = globals::game::renderer;
+	if (renderer) {
+		auto& rendererData = renderer->GetRendererData();
+
+		const bool isAlreadyConverted =
+			rendererData.clearColor[0] == lastConvertedClearColor[0] &&
+			rendererData.clearColor[1] == lastConvertedClearColor[1] &&
+			rendererData.clearColor[2] == lastConvertedClearColor[2];
+
+		// Only refresh the source color when the engine has changed it
+		if (!isAlreadyConverted &&
+			(rendererData.clearColor[0] != lastOriginalClearColor[0] ||
+				rendererData.clearColor[1] != lastOriginalClearColor[1] ||
+				rendererData.clearColor[2] != lastOriginalClearColor[2])) {
+			lastOriginalClearColor[0] = rendererData.clearColor[0];
+			lastOriginalClearColor[1] = rendererData.clearColor[1];
+			lastOriginalClearColor[2] = rendererData.clearColor[2];
+		}
+
+		float gamma = std::clamp(settings.clearRenderGamma, 0.1f, 3.0f);
+		if (isAlreadyConverted && gamma == lastConvertedClearGamma) {
+			return;
+		}
+
+		rendererData.clearColor[0] = std::pow(lastOriginalClearColor[0], gamma);
+		rendererData.clearColor[1] = std::pow(lastOriginalClearColor[1], gamma);
+		rendererData.clearColor[2] = std::pow(lastOriginalClearColor[2], gamma);
+		// Alpha (clearColor[3]) typically doesn't need gamma correction
+
+		// Remember what we converted to
+		lastConvertedClearColor[0] = rendererData.clearColor[0];
+		lastConvertedClearColor[1] = rendererData.clearColor[1];
+		lastConvertedClearColor[2] = rendererData.clearColor[2];
+		lastConvertedClearGamma = gamma;
+	}
+}
+
 void LinearLighting::Prepass()
 {
 	bool isMainLoadingMenu = globals::game::ui && (globals::game::ui->IsMenuOpen(RE::MainMenu::MENU_NAME) || globals::game::ui->IsMenuOpen(RE::LoadingMenu::MENU_NAME));

src/Features/LinearLighting.h

@@ -28,6 +28,7 @@ struct LinearLighting : Feature
 	{
 		uint enableLinearLighting = false;
 		uint enableGammaCorrection = true;
+		float clearRenderGamma = 1.62f;
 		float lightGamma = 1.8f;
 		float colorGamma = 1.8f;
 		float emitColorGamma = 1.8f;
@@ -108,6 +109,9 @@ struct LinearLighting : Feature
 
 	uint isDirLightLinear = false;
 	float dirLightMult = 1.0f;
+	float lastConvertedClearColor[3] = { -1.0f, -1.0f, -1.0f };  // Track to avoid double conversion
+	float lastOriginalClearColor[3] = { -1.0f, -1.0f, -1.0f };   // Source gamma-space color
+	float lastConvertedClearGamma = -1.0f;
 
 	virtual void DrawSettings() override;
 
@@ -116,6 +120,8 @@ struct LinearLighting : Feature
 
 	virtual void RestoreDefaultSettings() override;
 
+	virtual void EarlyPrepass() override;
+	virtual void ReflectionsPrepass() override;
 	virtual void Prepass() override;
 	virtual void PostPostLoad() override;
 
@@ -127,5 +133,7 @@ struct LinearLighting : Feature
 
 	void BSLightingShader_SetupGeometry(RE::BSRenderPass* a_pass);
 
+	void ConvertClearColor();
+
 	struct Hooks;
 };