Unhooking Metal shadows from the lighting system

The D3D9 shadow system would manipulate lights to properly cast shadows. This change decouples Metal shadows from the lighting system and instead passes the required variables directly to the shadow renderer. This allows Metal to avoid expensive light changes to require shadows. Also includes a fix for high shadow strength causing shadows to be too dark. The Metal pipeline was not clamping the output diffuse color into a valid range.
H-uru · Jan 1, 2025 · ba6607b · ba6607b
1 parent c4cbb98
commit ba6607b
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Showing 3 changed files with 4 additions and 31 deletions.
diff --git a/Sources/Plasma/FeatureLib/pfMetalPipeline/ShaderSrc/FixedPipelineShaders.metal b/Sources/Plasma/FeatureLib/pfMetalPipeline/ShaderSrc/FixedPipelineShaders.metal
@@ -623,8 +623,6 @@ vertex ColorInOut shadowCastVertexShader(Vertex in
 
     float4 position = (float4(in.position, 1.f) * uniforms.localToWorldMatrix);
     const float3 Ndirection = normalize(float4(in.normal, 0.f) * uniforms.localToWorldMatrix).xyz;
-    // Shadow casting uses the diffuse material color to control opacity
-    const half4 MDiffuse = uniforms.diffuseCol;
 
     //w is attenation
     float4 direction;
@@ -640,7 +638,8 @@ vertex ColorInOut shadowCastVertexShader(Vertex in
     }
 
     const float3 dotResult = dot(Ndirection, direction.xyz);
-    const half3 diffuse = MDiffuse.rgb * half3(max(0.h, dotResult)) * shadowState.power;
+    // Post lighting diffuse color needs to be clamped to the 0..1 range even though >1.f is valid.
+    const half3 diffuse = clamp(shadowState.opacity * half3(max(0.h, dotResult)) * shadowState.power, 0.f, 1.f);
     out.vtxColor = half4(diffuse, 1.f);
 
     const float4 vCamPosition = position * uniforms.worldToCameraMatrix;

diff --git a/Sources/Plasma/FeatureLib/pfMetalPipeline/plMetalPipeline.cpp b/Sources/Plasma/FeatureLib/pfMetalPipeline/plMetalPipeline.cpp
@@ -3202,9 +3202,6 @@ bool plMetalPipeline::IPushShadowCastState(plShadowSlave* slave)
     if (!slave->SetupViewTransform(this))
         return false;
 
-    // Set texture to U_LUT
-    fCurrentRenderPassUniforms->specularSrc = 0.0;
-
     // if( !ref->fTexture )
     //{
     //     if( ref->fData )
@@ -3759,6 +3756,7 @@ void plMetalPipeline::IRenderShadowsOntoSpan(const plRenderPrimFunc& render, con
             // The shadow light isn't used in generating the shadow map, it's used
             // in projecting the shadow map onto the scene.
             plShadowState shadowState;
+            shadowState.opacity = first? mat->GetLayer(0)->GetOpacity() : 1.f;
             ISetupShadowState(fShadows[i], shadowState);
 
             struct plMetalFragmentShaderDescription passDescription{};
@@ -3846,9 +3844,6 @@ void plMetalPipeline::ISetupShadowRcvTextureStages(hsGMaterial* mat)
     // same one.
     fForceMatHandle = true;
 
-    // Set the D3D lighting/material model
-    ISetShadowLightState(mat);
-
     // Zbuffering on read-only
 
     if (fState.fCurrentDepthStencilState != fDevice.fNoZWriteStencilState) {
@@ -3885,26 +3880,6 @@ void plMetalPipeline::ISetupShadowRcvTextureStages(hsGMaterial* mat)
     fDevice.CurrentRenderCommandEncoder()->setFragmentBytes(&layerIndex, sizeof(int), FragmentShaderArgumentShadowCastAlphaSrc);
 }
 
-// ISetShadowLightState //////////////////////////////////////////////////////////////////
-// Set the D3D lighting/material model for projecting the shadow map onto this material.
-void plMetalPipeline::ISetShadowLightState(hsGMaterial* mat)
-{
-    fCurrLightingMethod = plSpan::kLiteShadow;
-
-    if (mat && mat->GetNumLayers() && mat->GetLayer(0))
-        fCurrentRenderPassUniforms->diffuseCol.r = fCurrentRenderPassUniforms->diffuseCol.g = fCurrentRenderPassUniforms->diffuseCol.b = mat->GetLayer(0)->GetOpacity();
-    else
-        fCurrentRenderPassUniforms->diffuseCol.r = fCurrentRenderPassUniforms->diffuseCol.g = fCurrentRenderPassUniforms->diffuseCol.b = 1.f;
-    fCurrentRenderPassUniforms->diffuseCol.a = 1.f;
-
-    fCurrentRenderPassUniforms->diffuseSrc = 1.0f;
-    fCurrentRenderPassUniforms->emissiveSrc = 1.0f;
-    fCurrentRenderPassUniforms->emissiveCol = 0.0f;
-    fCurrentRenderPassUniforms->specularSrc = 0.0f;
-    fCurrentRenderPassUniforms->ambientSrc = 0.0f;
-    fCurrentRenderPassUniforms->globalAmb = 0.0f;
-}
-
 // IDisableLightsForShadow ///////////////////////////////////////////////////////////
 // Disable any lights that are enabled. We'll only want the shadow light illuminating
 // the surface.

diff --git a/Sources/Plasma/FeatureLib/pfMetalPipeline/plMetalPipeline.h b/Sources/Plasma/FeatureLib/pfMetalPipeline/plMetalPipeline.h
@@ -232,8 +232,7 @@ class plMetalPipeline : public pl3DPipeline<plMetalDevice>
     hsGDeviceRef*          SharedRenderTargetRef(plRenderTarget* share, plRenderTarget* owner);
     void                   IRenderShadowsOntoSpan(const plRenderPrimFunc& render, const plSpan* span, hsGMaterial* mat, plMetalVertexBufferRef* vRef);
     void                   ISetupShadowRcvTextureStages(hsGMaterial* mat);
-    void                   ISetupShadowSlaveTextures(plShadowSlave* slave);
-    void                   ISetShadowLightState(hsGMaterial* mat);
+    void                   ISetupShadowSlaveTextures(plShadowSlave* slave); 
     void                   ISetupShadowState(plShadowSlave* slave, plShadowState& shadowState);
     void                   IDisableLightsForShadow();
     void                   IReleaseRenderTargetPools();