Shader Connections Not Shaded?

[richie-m]

Hi guys,

Got a problem connecting shading node to a mesh. I've written some code in the API, heres what it does:

create lambert node using MFnDependencyNodeFn.create(...)
create shadingEngine node using MFnDependencyNodeFn.create(...)

get all relevent plugs for connections:
outColor of lambert
surfaceShader of shadingEngine
instObjGroups of mesh
dagSetMembers of shadingEngine

and i connect them - as you can see the hypershade view attached:

the funny thing is, the geometry (created in API) isnt shaded at all even though the shader network is connected. Am i meant to update something???

Hope you can help! Thanks!

[joojaa]

Well is your mesh in grouping[0]

[jamespiechota]

Is it only unshaded in the viewport? Or also when you render? If it is shaded correctly when you render then you might be missing a connection to a materialInfo node. For more information create a shading network and assign it to an object using the regular Maya UI. Then do a listConnections on the material (e.g. lambert2), you should see a materialInfo node listed - check if a similar node and connection exists in your network. (the materialInfo nodes don't show up in the hypershade or hypergraph)

Also when assigning a shape to a shadingGroup it can sometimes be safer to use the MFnSet function set and treat the shadingGroup as a set. This is not always necessary, though, just something else to try.

Yeah, and what Joojaa said too. The iog connections can get complicated particularly if you're doing face-level shading assignments or your shape is instanced.

[richie-m]

hey joojaa!

im not quite sure what you mean, but i checked using
[codebox]
listConnections -p 1 -s 1 -c 1 tshirt2_SG
[/codebox]

the result is

[codebox]
// Result: tshirt2_SG.dagSetMembers[0] tshirtShape2.instObjGroups tshirt2_SG.surfaceShader tshirt2_SN.outColor tshirt2_SG.message lightLinker1.link[9].object //
[/codebox]

do you mean that the insObjGroups connection is not right? it should be instObjGroups[0]??? it appears fine in the connection editor???

[richie-m]

hey James! thanks for your reply! i already replied by the time i got it.

I will try what you said. will let you know what happens!

edit: oh, and sorry, yeah it unshaded in both render and viewport

[richie-m]

ah! it seems to be the problem that materialInfo node is missing...

im gonna implement that now nad let you know what happens!

thanks for replies!

[richie-m]

bugger! its not working!

i forgot to mention that the materials dont show up in the hypershade, only the shading groups do...

if i force input and output connections then the shader shows in the hypershade...

see screenshot, you can see that the lambert nodes dont show in the mateirials section???

weird right?

ive created a materialInfo node and connected the following:

[codebox]
lambert.message -> materialInfo.material
lambertSG.message -> materialInfo.shadingGroup
[/codebox]

whats wrong here?

[joojaa]

Ok let me recreate this in mel for you (you should prototype these things in mel btw im showing the reasoning here):

createNode -n mylamb1 lambert;
createNode -n myset shadingEngine;
connectAttr -f mylamb1.outColor myset.surfaceShader;

this si what your doing.Observe what maya does:

shadingNode -n mylamb1 -asShader lambert;
sets -renderable true -noSurfaceShader true -empty -name myset;
connectAttr -f mylamb1.outColor myset.surfaceShader;

Very basic mel and api programming fundamentals to ask maya first , now these 2 go into the heart of the matter. Set are a bit special so with this knowledge you should be probably using MFnSet. However back to the original. let use compare the 2.

using list conections:

myset
mylamb1

well the later gives this

materialInfo1 defaultShaderList1 myset
lightLinker1 materialInfo1 lightLinker1 renderPartition mylamb1

Obviously theres still a tad to do... Anyway it wont work well.

Still one problem well see i said to you to use MFnSet well i mean it because otherwise the corresponding group might not come to existence into the meshes data. Off course all maya made meshes have but thats no guarantee for the api.

However might be even smarter to use MFnLambertShader instead of al the hastle

[jamespiechota]

Regarding the materials missing from the hypershade, in order to be marked as a shader, a node needs to be connected to the defaultShaderList1. Do a listConnections on a material created through the Maya UI to see what I mean. If you create materials using the "shadingNode -asShader" command instead of the createNode command, Maya will add this connection for you (and the necessary connections for textures, utilities, etc...). You can make it yourself, too, if you'd like.

Using MFnLambertShader to create a lambert may also make all the necessary extra connections, but I haven't tried. Usually if I have to set up a shading network I do it in MEL, even if this means using MGlobal::executeCommand to run the script that creates the network. It has saved me a lot of headaches in the past (undo/redo for free, no mucking around with MPlugs, etc...), and usually the performance impact was not noticeable.

Unfortunately I don't think these missing connections are the problem. Joojaa's post, though, may have the solution: ShadingEngines are special types of sets and should be created with the "sets -renderable true" MEL command or the MFnSet::create(...) method setting the restriction to kRenderableOnly. If a shading engine is created using MFnDependencyCreate::create(...) or the createNode command I'm not sure it will be marked as a renderable set and may not function correctly.

[richie-m]

Hey guys!

Thanks for the replies! Very helpful! Well, im creating my shading networking using the API - i suppose MEL would be easier! I was thinking the performance hit might not be too great.

I suppose, like you said James, it wont be that much of an issue - i mean its only a couple of commands right!

thanks guys! will get back to you!