rendering: add builtin alpha-test pass support

engine/assets/builtin/shaders/shadow-caster/shadow-caster.vs.hlsl

@@ -7,16 +7,19 @@ cbuffer PerObjectConstants : register(b0) {
 
 struct VSInput {
     float3 position : POSITION;
+    float2 texcoord : TEXCOORD0;
 };
 
 struct PSInput {
     float4 position : SV_POSITION;
+    float2 texcoord : TEXCOORD0;
 };
 
 PSInput MainVS(VSInput input) {
     PSInput output;
-    float4 positionWS = mul(gModelMatrix, float4(input.position, 1.0));
+    float4 positionWS = mul(gModelMatrix, float4(input.position, 1.0f));
     float4 positionVS = mul(gViewMatrix, positionWS);
     output.position = mul(gProjectionMatrix, positionVS);
+    output.texcoord = input.texcoord;
     return output;
 }