-1 scale make stencil test not working?

Unity Engine
1

I’m working with the planar shadow,the shadow pass as below:
pass {
Tags { “LightMode” = “ForwardBase”}
Blend SrcAlpha OneMinusSrcAlpha
Stencil {
Ref 1
Comp NotEqual
Pass replace
}
//ZTest Less
Cull Back
Offset -1,-1
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include “UnityCG.cginc”
float4 vert(float4 vertex: POSITION) : SV_POSITION
{
float3 litDir = float3(-0.1,-0.2,0.2);

float4 vt = mul(_Object2World, vertex);
vt.xz=vt.xz-(vt.y/litDir.y)*litDir.xz;
vt.y=0;

vt=mul(_World2Object,vt);
return mul(UNITY_MATRIX_MVP, vt);
}
float4 frag(void) : COLOR
{
return float4(0.1,0.1,0.1,0.6);
}
ENDCG
}//

}

but when I set the object scale is (-1, 1, 1), the stencil test not working and will overdraw the shadow as the picture

1842404--118161--QQ截图20141110104718.png
1842404--118161--QQ截图20141110104718.png709×458 161 KB

2

If you have 1 (or 3) negative scaling factors, the triangles will be flipped, so you’ll have to reverse the backface culling:

Cull Front
3

Cull Front or Cull Back does not work:(, I have already tested

4

How about setting the readmask and writemask of the stencil operation to 1?

Right now you’re writing 255, but comparing with 1, so you can still have overdraw.

5

Hello z-Tree,

What version of Unity did you notice this in?

Thanks,
Scott