displacement and .. what?

rollin

Hi, I'm having a problem with my CG tessellation and displacement shader.

I'm doing this in unity but I'm not sure this is related to unity.




To make it short. I use the diffuse texture alpha chanel as my displacement source. I set it to 128.

I calculate displacement like that (DisplacementCenter = 0.5f)

float vHeight = (tex2Dlod(_MainTex, float4(uv,0,0)).a - _DisplacementCenter) * _DisplacementFactor;	
	vertexPosition.xyz += normal * vHeight;

So why is there a gap?!
gamma? I've set import to skip sRGB sampling. I set it to linear color space.. Nothing changes a bit. Maybe the problem it's already located in Photoshop? My color picker tells me 128. Is the alpha channel ever treated by gamma?

EarthQuake

UVs and/or hard edges are the the likely culprit. This is a common issue with realtime displacement, from what I'm aware it takes a lot of custom work to get gapless displacement shader working.

rollin

yea I made sure the normals face in the direction of the quad. So the direction of the displacement is ok. Also I made the complete alpha flat 128 to avoid uv or mipmapping issues counting in.