优化回声描边逻辑

unity/Assets/Materials/tree4_GroundClipMat.mat

@@ -13,6 +13,7 @@ Material:
   m_ModifiedSerializedProperties: 0
   m_ValidKeywords: []
   m_InvalidKeywords:
+  - _CASTSHADOW_ON
   - _ENABLECLIP_ON
   m_LightmapFlags: 4
   m_EnableInstancingVariants: 0
@@ -30,9 +31,13 @@ Material:
         m_Offset: {x: 0, y: 0}
     m_Ints: []
     m_Floats:
+    - _CastShadow: 1
     - _ClipSoftness: 0.05
     - _EnableClip: 1
     - _GroundHeight: 0
+    - _ShadowOffset: -0.1
+    - _ShadowOpacity: 0.5
     m_Colors:
     - _Color: {r: 1, g: 1, b: 1, a: 1}
+    - _ShadowColor: {r: 0, g: 0, b: 0, a: 0.5}
   m_BuildTextureStacks: []