Add : Amplify Environment template에 NiloToon char shadow receiver 지원

NiloToonEnvironment.shader 본체와 동일한 self-shadow 수신 기능을 ASE
template에도 이식. ASE로 환경 셰이더를 작성한 머티리얼도 캐릭터의
NiloToon 셀프 섀도우를 바닥/벽에 받을 수 있게 됨.

- Properties: [Toggle(_RECEIVE_NILOTOON_CHAR_SHADOW)] 토글 + Shadow
  Strength slider 추가 (기본 off, 기존 머티리얼 호환)
- Pragma: shader_feature_local_fragment _RECEIVE_NILOTOON_CHAR_SHADOW
  + multi_compile_fragment _ _NILOTOON_RECEIVE_SELF_SHADOW
- Per-material CBUFFER에 _NiloToonCharShadowStrength 추가
- 두 키워드 모두 활성 시: 텍스처/샘플러/매트릭스 uniform과
  SampleNiloToonCharSelfShadow 함수 선언
- frag에서 UniversalFragmentPBR 직후·shadow border tint 직전에 적용
  (NiloToonEnvironment_LitForwardPass.hlsl과 동일한 위치)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Assets/External/AmplifyShaderEditor/Plugins/EditorResources/Templates/URP/NiloToonEnvironment.shader

@@ -22,6 +22,10 @@ Shader /*ase_name*/ "Hidden/Universal/NiloToonEnvironment" /*end*/
 		_ScreenSpaceOutlineIntensity("Screen Space Outline Intensity", Range(0,1)) = 1
 		[HDR]_ScreenSpaceOutlineColor("Screen Space Outline Color", Color) = (1,1,1,1)
 		_ScreenSpaceOutlineWidth("Screen Space Outline Width", Float) = 1
+
+		// NiloToon Character Self Shadow Receiver (off by default to keep parity with original ASE template)
+		[Toggle(_RECEIVE_NILOTOON_CHAR_SHADOW)] _ReceiveNiloToonCharShadow("Receive NiloToon Char Shadow", Float) = 0
+		_NiloToonCharShadowStrength("    Shadow Strength", Range(0, 1)) = 1.0
 	}
 
 	SubShader
@@ -198,6 +202,10 @@ Shader /*ase_name*/ "Hidden/Universal/NiloToonEnvironment" /*end*/
 			#pragma shader_feature_local_fragment _ENVIRONMENTREFLECTIONS_OFF
 			#pragma shader_feature_local_fragment _SPECULAR_SETUP
 
+			// NiloToon Character Self Shadow keywords
+			#pragma shader_feature_local_fragment _RECEIVE_NILOTOON_CHAR_SHADOW
+			#pragma multi_compile_fragment _ _NILOTOON_RECEIVE_SELF_SHADOW
+
 			// -------------------------------------
 			// Universal Pipeline keywords
 			#pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
@@ -307,6 +315,8 @@ Shader /*ase_name*/ "Hidden/Universal/NiloToonEnvironment" /*end*/
 			half3 _ScreenSpaceOutlineColor;
 			float _ScreenSpaceOutlineWidth;
 			float _Surface;
+			// NiloToon Character Self Shadow per-material strength
+			float _NiloToonCharShadowStrength;
 			/*ase_srp_batcher*/
 			CBUFFER_END
 
@@ -326,6 +336,56 @@ Shader /*ase_name*/ "Hidden/Universal/NiloToonEnvironment" /*end*/
 			half3 _GlobalScreenSpaceOutlineTintColorForEnvi;
 			float _CurrentCameraFOV;
 
+			// NiloToon Character Self Shadow uniforms + sampling function
+			// (mirrors NiloToonEnvironment_LitForwardPass.hlsl. Both keywords required:
+			//  _RECEIVE_NILOTOON_CHAR_SHADOW = per-material toggle, _NILOTOON_RECEIVE_SELF_SHADOW = global runtime keyword set by C# pass.)
+			#if defined(_RECEIVE_NILOTOON_CHAR_SHADOW) && defined(_NILOTOON_RECEIVE_SELF_SHADOW)
+			TEXTURE2D(_NiloToonCharSelfShadowMapRT);
+			SAMPLER_CMP(sampler_NiloToonCharSelfShadowMapRT_LinearClampCompare);
+			SAMPLER(sampler_NiloToonCharSelfShadowMapRT_Linear_Clamp);
+			float4x4 _NiloToonSelfShadowWorldToClip;
+			float4 _NiloToonSelfShadowParam;
+			float3 _NiloToonSelfShadowLightDirection;
+			float _GlobalReceiveNiloToonSelfShadowMap;
+			float _NiloToonSelfShadowRange;
+			float _NiloToonSelfShadowUseNdotLFix;
+
+			half SampleNiloToonCharSelfShadow(float3 positionWS, float3 normalWS, float linearEyeDepth)
+			{
+				float4 positionSelfShadowCS = mul(_NiloToonSelfShadowWorldToClip, float4(positionWS, 1));
+				float3 positionSelfShadowNDC = positionSelfShadowCS.xyz;
+
+				float2 shadowMapUV = positionSelfShadowNDC.xy * 0.5 + 0.5;
+				float ndcZCompareValue = positionSelfShadowNDC.z;
+				ndcZCompareValue = UNITY_NEAR_CLIP_VALUE < 0 ? ndcZCompareValue * 0.5 + 0.5 : ndcZCompareValue;
+
+				#if UNITY_UV_STARTS_AT_TOP
+				shadowMapUV.y = 1 - shadowMapUV.y;
+				#endif
+
+				if(shadowMapUV.x < 0 || shadowMapUV.x > 1 || shadowMapUV.y < 0 || shadowMapUV.y > 1)
+					return 1;
+
+				float shadowMapRawDepth = SAMPLE_TEXTURE2D_LOD(_NiloToonCharSelfShadowMapRT,
+											sampler_NiloToonCharSelfShadowMapRT_Linear_Clamp,
+											shadowMapUV, 0).r;
+				if(shadowMapRawDepth < 0.0001)
+					return 1;
+
+				half shadow = SAMPLE_TEXTURE2D_SHADOW(_NiloToonCharSelfShadowMapRT,
+								sampler_NiloToonCharSelfShadowMapRT_LinearClampCompare,
+								float3(shadowMapUV, ndcZCompareValue));
+
+				float fadeTotalDistance = 1.0;
+				shadow = lerp(shadow, 1, saturate((1.0 / fadeTotalDistance) * (linearEyeDepth - (_NiloToonSelfShadowRange - fadeTotalDistance))));
+
+				if(_NiloToonSelfShadowUseNdotLFix > 0.5)
+					shadow *= smoothstep(0.1, 0.2, saturate(dot(normalWS, _NiloToonSelfShadowLightDirection)));
+
+				return shadow;
+			}
+			#endif
+
 			#ifdef SCENEPICKINGPASS
 				float4 _SelectionID;
 			#endif
@@ -531,6 +591,17 @@ Shader /*ase_name*/ "Hidden/Universal/NiloToonEnvironment" /*end*/
 				#endif
 
 				Light mainLight = GetMainLight(inputData.shadowCoord, inputData.positionWS, nilotoonShadowMask);
+
+				// NiloToon Character Self Shadow (matches order in NiloToonEnvironment_LitForwardPass.hlsl: applied before shadow border tint)
+				#if defined(_RECEIVE_NILOTOON_CHAR_SHADOW) && defined(_NILOTOON_RECEIVE_SELF_SHADOW)
+				{
+					float linearEyeDepth = abs(mul(UNITY_MATRIX_V, float4(input.positionWS, 1)).z);
+					half charSelfShadow = SampleNiloToonCharSelfShadow(input.positionWS, inputData.normalWS, linearEyeDepth);
+					charSelfShadow = lerp(1, charSelfShadow, _NiloToonCharShadowStrength * _GlobalReceiveNiloToonSelfShadowMap);
+					color.rgb *= charSelfShadow;
+				}
+				#endif
+
 				float isShadowEdge = 1-abs(mainLight.shadowAttenuation-0.5)*2;
 				color.rgb = lerp(color.rgb, color.rgb * _NiloToonGlobalEnviShadowBorderTintColor.rgb, isShadowEdge * _NiloToonGlobalEnviShadowBorderTintColor.a);