rendering: unify builtin forward and depth-style shaders

engine/assets/builtin/shaders/shadow-caster/shadow-caster.shader

@@ -6,26 +6,67 @@ Shader "Builtin Shadow Caster"
         _Cutoff ("Alpha Cutoff", Range) = 0.5 [Semantic(AlphaCutoff)]
         _MainTex ("Base Map", 2D) = "white" [Semantic(BaseColorTexture)]
     }
+    HLSLINCLUDE
+    cbuffer PerObjectConstants : register(b0)
+    {
+        float4x4 gProjectionMatrix;
+        float4x4 gViewMatrix;
+        float4x4 gModelMatrix;
+    };
+
+    cbuffer MaterialConstants : register(b1)
+    {
+        float4 gBaseColorFactor;
+        float4 gAlphaCutoffParams;
+    };
+
+    Texture2D BaseColorTexture : register(t0);
+    SamplerState LinearClampSampler : register(s0);
+
+    struct VSInput
+    {
+        float3 position : POSITION;
+        float3 normal : NORMAL;
+        float2 texcoord : TEXCOORD0;
+    };
+
+    struct PSInput
+    {
+        float4 position : SV_POSITION;
+        float2 texcoord : TEXCOORD0;
+    };
+
+    PSInput MainVS(VSInput input)
+    {
+        PSInput output;
+        const float4 positionWS = mul(gModelMatrix, float4(input.position, 1.0f));
+        const float4 positionVS = mul(gViewMatrix, positionWS);
+        output.position = mul(gProjectionMatrix, positionVS);
+        output.texcoord = input.texcoord;
+        return output;
+    }
+
+    float MainPS(PSInput input) : SV_Depth
+    {
+    #ifdef XC_ALPHA_TEST
+        const float4 baseColor =
+            BaseColorTexture.Sample(LinearClampSampler, input.texcoord) * gBaseColorFactor;
+        clip(baseColor.a - gAlphaCutoffParams.x);
+    #endif
+        return input.position.z;
+    }
+    ENDHLSL
     SubShader
     {
         Pass
         {
             Name "ShadowCaster"
             Tags { "LightMode" = "ShadowCaster" }
-            Resources
-            {
-                PerObjectConstants (ConstantBuffer, 0, 0) [Semantic(PerObject)]
-                MaterialConstants (ConstantBuffer, 1, 0) [Semantic(Material)]
-                BaseColorTexture (Texture2D, 2, 0) [Semantic(BaseColorTexture)]
-                LinearClampSampler (Sampler, 3, 0) [Semantic(LinearClampSampler)]
-            }
             HLSLPROGRAM
+            #pragma target 4.5
             #pragma vertex MainVS
             #pragma fragment MainPS
             #pragma shader_feature_local _ XC_ALPHA_TEST
-            #pragma backend D3D12 HLSL "shadow-caster.vs.hlsl" "shadow-caster.ps.hlsl" vs_5_0 ps_5_0
-            #pragma backend OpenGL GLSL "shadow-caster.vert.glsl" "shadow-caster.frag.glsl"
-            #pragma backend Vulkan GLSL "shadow-caster.vert.vk.glsl" "shadow-caster.frag.vk.glsl"
             ENDHLSL
         }
     }