Octane equivalent of group masking to override a material Tweet

[rubberchicken]

This is a workflow I use a great deal in Modo and I'd like to work out the way to do this most efficiently in Octane. In this case, I have a black plastic material as a regular material tag, this is assigned directly on a number of polys in various mesh items as is normal. Higher on the shader tree I have an image as a group mask sitting in a group limited to the lower cap as a part selection. This group contains instances of the main diffuse colour to create a coloured arrow-shaped inset, yellow on this SKU. The box in frame shows the equivalent vray render. I use this a lot where I have a general material and then an override, usually a printed graphic or colour variation. I work like this becuase it seem most efficient to override one material where I need rather than duplicate materials and create unique variations.

[rubberchicken]

Example Modo scene.

[funk]

I replied on skype, but I'm sharing my ideas here in case someone finds them useful or has a different ways of doing things. The attached 7zip has 2 examples

1) Group Mask Override Example - edit 001.lxo

This method lets you keep all your shader tree groups/sets/parts for organisation.

For variations that override the entire material (no layer/group mask), you use instances of nodes
eg. instance your clear plastic material node and move the instance into an override in the variation (right click node > move node to...). You can then plug a different color into this instance.

For your group masks, it might be easier to use a composite material (you mix 2 materials based on a group mask texture). To do this you can COPY the base material node (right click node > copy node to...) into the widget group (so you have 1 node shared in 2 overrides), then use an instance to create the color/roughness changes etc. This doesnt seem to work for masking not textured bump values though, so Im connecting the mask as a bump too (this will need tweaking)

You could use composite/mix nodes with a single materials to do the group mask (instead of mixing 2 materials), but you'd need to mask every channel that needs changing. I can show you this if you need an example. It would be like using layer masks for each texture in the shader tree

You can also use real copies of material nodes (no instances), then use shared copies of all the inputs (eg your color, roughness etc would all be additional nodes shared in 2 overrides). It just depends what you feel is easiest for you.

2) Group Mask Override Example - edit 002.lxo

This example is using weight maps for the clear plastic, which lets you color one part differently to the other.

I actually do this when I want variations of a part, but it didn't make much sense to use this anywhere else since your other parts were in separate meshes. This might work better for other examples, but it may get too complex if you need to mask things off with textures too.

This is a lot more complicated to set up though. You need to select polygons and give them specific weights, then use a gradient node (with constant interpolation) with input values as your variations, with positions set slightly below/above those weights.