Custom ShadowCaster for Indirect Surface Shader

Hi, I have an "Instanced Indirect" surface shader which works fine except it is not casting shadows properly:

Spoiler: Shader Code

Shader "InstancedIndirect"
{
Properties
{
_MainTex("Albedo (RGB)", 2D) = "white" {}
}

CGINCLUDE

#ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED
StructuredBuffer<float4x4> obj2world;
StructuredBuffer<float4x4> world2obj;
#endif

void setup()
{
#ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED
unity_ObjectToWorld = obj2world[unity_InstanceID];
unity_WorldToObject = world2obj[unity_InstanceID];
#endif
}

ENDCG

SubShader
{
Tags { "Queue" = "Geometry" "RenderType" = "Opaque" "IgnoreProjector" = "True" "DisableBatching" = "True" }

CGPROGRAM

//#pragma surface surf Standard addshadow
#pragma surface surf Standard
#pragma target 4.5
#pragma multi_compile_instancing
#pragma instancing_options procedural:setup

sampler2D _MainTex;

struct Input
{
float2 uv_MainTex;
UNITY_VERTEX_INPUT_INSTANCE_ID
};

void surf(Input IN, inout SurfaceOutputStandard o)
{
o.Albedo = tex2D(_MainTex, IN.uv_MainTex);
}

ENDCG

Pass
{
Name "SHADOWCASTER"
Tags { "LightMode" = "ShadowCaster" }

CGPROGRAM

#pragma vertex vert
#pragma fragment frag
#pragma multi_compile_shadowcaster
#pragma fragmentoption ARB_precision_hint_fastest

#include "UnityCG.cginc"

struct v2f
{
V2F_SHADOW_CASTER;
};

v2f vert(appdata_base v)
{
v2f o;
TRANSFER_SHADOW_CASTER_NORMALOFFSET(o)
return o;
}

float4 frag(v2f i) : COLOR
{
SHADOW_CASTER_FRAGMENT(i)
}

ENDCG
}
}
FallBack Off
}

Basically, if I do "addshadow" in the pragma section the shadows get batched together for multiple objects and
they all overlap, as if unity was not instancing them properly. See image below:

https://imgur.com/a/X9vDbcD

One thing I am trying now is to add a custom "ShadowCaster" pass into this surface shader, but it is not working at all
for indirect instanced objects, but because it is working for normal MeshRenderers, I can guess I am in the right direction.

Can someone please let me know if there's a way to either make Unity batch the shadows properly using "addshadows"
or to make this custom pass to work? (Using Unity 2019.4.1f1)

Thank you in advance

 

Any chance this is related to this?

https://forum.unity.com/threads/dra...e-comments-and-questions.446080/#post-2995966

the workaround described there works - but I also reported an issue and they fixed it for 2021.1 and also opened backport requests for 2019.4. See https://issuetracker.unity3d.com/is...ling-drawmeshinstancedindirect-multiple-times

Just in short: try adding a materialproperty block with one unique property to each "Draw" call

 

Hi, thanks for replying but using materialproperties didn't work for me. The pass below solved the problem (I included only the relevant parts):

Code (CSharp):

1. Pass
2. {
3.     Name "ShadowCaster"
4.     Tags { "LightMode" = "ShadowCaster" }
5.  
6.     ZWrite On
7.     ZTest LEqual
8.  
9.     CGPROGRAM
10.  
11.     #pragma vertex vertShadowCaster
12.     #pragma fragment fragShadowCaster
13.  
14.     StructuredBuffer<float4x4> obj2world;
15.  
16.     struct v2f
17.     {
18.         float4 vertex : SV_POSITION;
19.         float2 uv : TEXCOORD0;
20.     };
21.  
22.     v2f vertShadowCaster(appdata_base v, uint i : SV_InstanceID)
23.     {
24.         v2f o;
25.  
26.         v.vertex = mul(obj2world[i], v.vertex);
27.         o.vertex = mul(UNITY_MATRIX_VP, v.vertex);
28.  
29.         o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
30.  
31.         return o;
32.     }
33.  
34.     float4 fragShadowCaster(v2f i) : SV_Target
35.     {      
36.         return 0;
37.     }
38.    
39.     ENDCG
40. }