Transparent shader disappears with multiple objects

Question

I'm trying to write a transparent billboard shader that mimics a plane always aiming at the camera. The shader works on one object, but when two objects with the same shader are both in view they disappear at most angles.

 VertexOutput vert(VertexInput i)
 {
     VertexOutput o;
 
     float3 center = mul(_Object2World, float4(0,0,0,1));
 
     float3 eye = _WorldSpaceCameraPos - center;
     float3 right = normalize(cross(eye, float3(0, 1, 0)));
     float3 up = normalize(cross(right, eye));
 
     o.pos = float4(center, 1);
     o.pos += i.pos.x + float4(right, 0);
     o.pos += i.pos.y + float4(up, 0);
     o.pos = mul(UNITY_MATRIX_VP, o.pos);
 
     o.col = i.col;
     o.tex = i.tex;
 
     return o;
 }

After trying to debug for a while I think the part that's causing this issue is the part that updates the world position with the right and up vectors:

 o.pos += i.pos.x + float4(right, 0);
 o.pos += i.pos.y + float4(up, 0);

I would appreciate any help with this.

Answer 1

Answer by Glenn-Korver · Jul 04, 2021 at 10:11 PM

You might be running into issues due to "Dynamic Batching" being enabled (which is the default). Try disabling it. https://docs.unity3d.com/Manual/SL-SubShaderTags.html

 Shader "ExampleShader" {
     SubShader {
         Tags { "DisableBatching" = "false" }
         Pass {
             …
         }
     }
 }

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Eno-Khaon · Jul 04, 2021 at 10:56 PM 0

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For reference, your example is backwards. "DisableBatching" *IS* false by default, so you would want to make it true instead.

 Tags { /* etc. */ "DisableBatching" = "false" }

Transparent shader disappears with multiple objects

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