Hi.

In a modeling/shading process, i'm just creating different SOPS, appending a shader at the end of each one but when i append a mergeSOP merging all the already shaded SOP, it seems that some shaders are not computed as they were when rendering each separately ( before merging).

The MergeSOP seems to bring confusion in the shaders…
I checked my spreadsheet ( Primitive attribute pages, many faces haven't got shaders applied, but normally, Houdini uses a default shader instead).
But here the situation is abit more confuse. Has anyone already faced these problems.
To me,that the shading process ( applying a Shader SOP) can occur anywhere in the network, because it just sets primitive attribute. But what is the problem here!

Version? There used to be some problems with the merge SOP messing up attributes, but I haven't noticed anything in recent versions with the shader attribute. Use this all the time. Try to isolate things to a very simple example - it's most likely that something else in your network is affecting your shader attribute…

Cheers,

J.C.

just some things to check -
merge sop sometimes converts vertex uvs to point uvs, that can mess up yr shading in places. Fix this by applying a vertex sop after the merge ( on the affected group only) and substitute in the vertex uvs from before you merged using the second input and “Add texture” with $MAPU2, $MAPV2

merge sop doesn't like it when some inputs have explicit normals and others do not, make sure all inputs have normals by using facet sop and “compute normals”

the above may not be your problem at all, but i thought i'd point it out.

Im Having a very similar problem as well. If I want to apply different shaders to a single geometry, I would generate the shader and then select the faces of the geometry I want to apply it to. I then would guess to create another shader and select the remaing faces of that same geometry that I would like to apply a secondary texture to. This work fine aslong as you only want to see one of the shaders at the object level. When I apply a merge to these two shaders and render I get huge artefacting, as the shader are trying to map over eachother. The texture tutorial with the watermelon goes over these exercises but they never attempt to render or even leave the sop level?? What am I doing wrong? Help would be great.

Harvey