Derivative Normal Map Material Function

[Deadlineproof]

Made a fast test(far from production ready) to check derivative maps in unreal engine by material editor.

Number of instructions against the same shader with tangent space normal mapping is a bit highter actually.
I’m completely unaware of what is happening under the hood (es if engine is animating tangents and passing them as interpolator if shader compiler optimizes out the z calculation of the normal and so on).
Character also mixes both normal map for the head and derivative for the body(i didn’t have head derivative map at the moment).It might be or not be relevant as far as optimization is concerned.
It will require more investigation, but probably to have an optimized implementation some engine tweakings are required.

Actually I’m testing it with normal texture exported from xnormal and compressing with TC_Normalmap(default compression doesn’t seem to give good quality results even on derivative maps).
TC_Normalmap also gives just scaled and biased result to just plug in the function so, If you use different compression, you have to scale and bias manually.

Pic is a little test mixing tangent and derivative normal maps on characters bodies (mostly right side char are derivative), heads are all tanget space.

The difference is almost unrecognizable but overally tangent space achieve clean uv seams while on derivative map they are slightly visible, but less than what you can normally see in thousand of shipped games and possibly due to my eyeballed parameters.Neck Seam between tangent and derivative mapped body part is negligible too.

Normal map issues here and there are due to sculpting and normal map calculation errors on my character that is still in early wip.
Character sculpting is not final, nor topology and textures.

p.s. This character will be modular with different body shapes, clothing and themed equipment and I hope to finish and to release it soon to the community.

in case you want to test it here is the material function. The scale factor for my texture is x256 and y -256 for the default xnormal derivative map settings,
but i just eyeballed it to match tangent space one.different scale gives more or less bumpiness(for free).

Begin Object Class=MaterialFunction Name="DerivativeNormalPerturb"
   Begin Object Class=MaterialExpressionAdd Name="MaterialExpressionAdd_16"
   End Object
   Begin Object Class=MaterialExpressionAdd Name="MaterialExpressionAdd_17"
   End Object
   Begin Object Class=MaterialExpressionAdd Name="MaterialExpressionAdd_18"
   End Object
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   End Object
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   End Object
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   End Object
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   End Object
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   End Object
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   Begin Object Class=MaterialExpressionMultiply Name="MaterialExpressionMultiply_69"
   End Object
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   End Object
   Begin Object Class=MaterialExpressionNormalize Name="MaterialExpressionNormalize_8"
   End Object
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   End Object
   Begin Object Class=MaterialExpressionVertexNormalWS Name="MaterialExpressionVertexNormalWS_5"
   End Object
   Begin Object Class=MaterialExpressionWorldPosition Name="MaterialExpressionWorldPosition_3"
   End Object
   Begin Object Class=SceneThumbnailInfoWithPrimitive Name="SceneThumbnailInfoWithPrimitive_2"
   End Object
   Begin Object Class=MaterialExpressionComponentMask Name="MaterialExpressionComponentMask_2"
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   End Object
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   End Object
   Begin Object Class=MaterialExpressionDDY Name="MaterialExpressionDDY_3"
   End Object
   Begin Object Class=MaterialExpressionDDY Name="MaterialExpressionDDY_4"
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   Begin Object Class=MaterialExpressionVertexNormalWS Name="MaterialExpressionVertexNormalWS_1"
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   End Object
   Begin Object Class=MaterialExpressionWorldPosition Name="MaterialExpressionWorldPosition_1"
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   End Object
   Begin Object Class=MaterialExpressionSubtract Name="MaterialExpressionSubtract_1"
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   End Object
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   Begin Object Class=MaterialExpressionFunctionInput Name="MaterialExpressionFunctionInput_9"
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   Begin Object Name="MaterialExpressionAdd_16"
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      Function=MaterialFunction'"DerivativeNormalPerturb"'
   End Object
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      MaterialExpressionGuid=1A35D3394300FE9224BFD787964005FB
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      Input=(Expression=MaterialExpressionFunctionInput'MaterialExpressionFunctionInput_1')
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      MaterialExpressionGuid=1A35D3394300FE9224BFD787964005FB
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      MaterialExpressionGuid=C568B7644B5C281FE8D3B793F7834F06
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      MaterialExpressionGuid=F3B744FB49C889C2E6DF068ABA9F4DFE
      Function=MaterialFunction'"DerivativeNormalPerturb"'
      Desc="fDet"
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      MaterialExpressionGuid=59842F404960EE46F6E8F6BBBF25D7B9
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      Id=8AD637A74080AC1550617A8C6CEEF77B
      InputType=FunctionInput_Vector2
      MaterialExpressionEditorX=-1504
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      MaterialExpressionGuid=59842F404960EE46F6E8F6BBBF25D7B9
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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      InputName="DerivativeMap_R"
      Description="Require Scale and Biased Value"
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      InputType=FunctionInput_Scalar
      SortPriority=1
      MaterialExpressionEditorX=-1504
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      MaterialExpressionGuid=18EE169546DE45117B4932B2A03906B8
      Function=MaterialFunction'"DerivativeNormalPerturb"'
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[Jambax]

For some reason I found that posted image hilarious… this is the only industry where such an image would be accepted as ‘normal’ (no pun intended).

Interesting results… I don’t see much use in DeriveNormalZ if you’re using TC_NormalMap compression unless I’m missing something. Perhaps it is useful if you’re combining lots of normal maps in the material, but just using the R and G channels and getting the overall B channel.

[Deadlineproof]

For some reason I found that posted image hilarious… this is the only industry where such an image would be accepted as ‘normal’ (no pun intended).

Random tests + wip things usually come with even more hilarious results.
animation is from engine and with no gun just looks quite weird expecially on this naked big gim there.
It has been used as i was testing the new skin shader too and put many of them to try out performance on my pc.

TC_Normalmap is supposed to compress r and g in DXGI_FORMAT_BC5_SNORM ( I have not checked but it is quite reasonable) so possibly the blue is just calculated to be displayed on screen as engine expects a tangent space normal, This doesn’t change it is the most efficient format for derivative too.
I have no idea if it calculates b in my shader but I suppose it will get optimized out in any case during compilation, but I don’t like to just suppose I hoped someone could confirm that.

I think that another use of derivative maps could be with morph targets es I planned to have a base thin body shape and encode a heavy body shape in vertex color without the need to store/calculate tangents/binormals.
However some more or less specific use may require engine to be modified so for now I will put this in pause as long as no proper use emerges.

[Archiechoke]

@TheJamsh;167622

For some reason I found that posted image hilarious… this is the only industry where such an image would be accepted as ‘normal’ (no pun intended).

Interesting results… I don’t see much use in DeriveNormalZ if you’re using TC_NormalMap compression unless I’m missing something. Perhaps it is useful if you’re combining lots of normal maps in the material, but just using the R and G channels and getting the overall B channel.

Same here. First thing that came to my mind was Machinima Skyrim Gamer **** :- https://www.youtube.com/watch?v=ZPllpzxmM5k#t=135

[Deadlineproof]

Reminder : Use just clothed models in proof of concepts or at least invite some women to the “party”
I admit the pic is quite misleading, my fault, but from now on stay on the derivative normal map topic please.