[d3d9] Don't perform clipping in FF if disabled

Avoids unnecessary matrix multiplications in the shader, given this isn't as cheap as it is for programmable.

src/d3d9/d3d9_device.cpp

@@ -1668,6 +1668,8 @@ namespace dxvk {
     bool changed = states[State] != Value;
 
     if (likely(changed)) {
+      const bool oldClipPlaneEnabled = IsClipPlaneEnabled();
+
       const bool oldDepthBiasEnabled = IsDepthBiasEnabled();
 
       const bool oldATOC = IsAlphaToCoverageEnabled();
@@ -1836,9 +1838,15 @@ namespace dxvk {
           m_flags.set(D3D9DeviceFlag::DirtyRasterizerState);
           break;
 
-        case D3DRS_CLIPPLANEENABLE:
+        case D3DRS_CLIPPLANEENABLE: {
+          const bool clipPlaneEnabled = IsClipPlaneEnabled();
+
+          if (clipPlaneEnabled != oldClipPlaneEnabled)
+            m_flags.set(D3D9DeviceFlag::DirtyFFVertexShader);
+
           m_flags.set(D3D9DeviceFlag::DirtyClipPlanes);
           break;
+        }
 
         case D3DRS_ALPHAREF:
           UpdatePushConstant<D3D9RenderStateItem::AlphaRef>();
@@ -5946,6 +5954,8 @@ namespace dxvk {
         key.Data.Contents.VertexBlendCount   = m_state.renderStates[D3DRS_VERTEXBLEND] & 0xff;
       }
 
+      key.Data.Contents.VertexClipping = IsClipPlaneEnabled();
+
       EmitCs([
         this,
         cKey     = key,

src/d3d9/d3d9_device.h

@@ -776,6 +776,10 @@ namespace dxvk {
       return m_state.renderStates[D3DRS_ZENABLE] && m_state.depthStencil != nullptr;
     }
 
+    inline bool IsClipPlaneEnabled() {
+      return m_state.renderStates[D3DRS_CLIPPLANEENABLE] != 0;
+    }
+
     void BindMultiSampleState();
     
     void BindBlendState();

src/d3d9/d3d9_fixed_function.cpp

@@ -1163,6 +1163,7 @@ namespace dxvk {
     uint32_t pointSize = m_module.opFClamp(m_floatType, pointInfo.defaultValue, pointInfo.min, pointInfo.max);
     m_module.opStore(m_vs.out.POINTSIZE, pointSize);
 
+    if (m_vsKey.Data.Contents.VertexClipping)
       emitVsClipping(vtx);
   }
 

src/d3d9/d3d9_fixed_function.h

@@ -107,6 +107,8 @@ namespace dxvk {
         uint32_t VertexBlendMode    : 2;
         uint32_t VertexBlendIndexed : 1;
         uint32_t VertexBlendCount   : 3;
+
+        uint32_t VertexClipping     : 1;
       } Contents;
 
       uint32_t Primitive[4];