Re: Problem with normalmap

On 27.07.2013 01:49, Naman Gupta wrote:
>   res, was CS/data/shader-snippet/tcoffset2-perturb-normal.xml left
> incomplete?
>   was it suppose to pass "z killed normal" in simple float3 ?

I don't think so. Z is zeroed out in the tcoffset2-perturb-normal-cam
snippet because a transformation from tangent to camera space will take
place; with a non-zero Z this could result in unwanted (I think) extra
distortions when the camera is tilted.

>    Phew, I finally figured why the normal maps in weaver was showing
> such weird results.
>
>    It's because normal,tangent and bitangents are NOT provided by the
> watermesh plugin and I failed to see in the "outer" code as it is
> triggered by coercion.
>
>   The way I see it to work around with this problem is to alter
> tcoffset snippet. or maybe...
>

Well, or you provide tangents and bitangents.
Though that probably means getting them must move out of the coercion
library… the position snippet looks like an appropriate place.
There's some precedent for a value generated by the position snippet but
consumed by coercion snippet; specifically, it's the object-to-world
transform. For general meshes, it's passed in a shader var, but for
instanced meshes it has to be computed per instance. So, the position
snippet stores that transform in a global variable, and the coercion
snippets needing object2world take it from there – and it doesn't matter
whether the mesh is instanced or not.
If the same was done for tangent & bitangent, you could write a “water”
position snippet that computes them in the shader.

-f.r.

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