Hi All.

I have been playing around and had no joy in trying to create a constant unshaded material using only the Material X LOPs.

I could hack this previously with a principled shader assigning a color/image to the Emission Color and turning off "emission Illuminates Objects". Does anyone know how to do this.

All the best. Mark

Use the MtlX Uniform EDF to create a constant (unshaded) shader.

https://www.sidefx.com/docs/houdini/nodes/vop/mtlxuniform_edf.html [www.sidefx.com]

There is no turning off 'emission illuminates objects', for that set the bounces to 0.

Hi. I did look at that but I need bounces on. I will see if I can override bounces per primitive though tomorrow. Best

jsmack
Use the MtlX Uniform EDF to create a constant (unshaded) shader.

https://www.sidefx.com/docs/houdini/nodes/vop/mtlxuniform_edf.html [www.sidefx.com]

There is no turning off 'emission illuminates objects', for that set the bounces to 0.

Hi,
I am quite new to Lops, how do I set the bounces to 0?

Regards,
Johan

Setting the bounces to 0 is done on the karma settings node. look for limits.

However, in the case of the original thread, setting bounces to 0 is unacceptable. To create a constant shaded object that doesn't contribute to lighting, add a render geometry settings node and set the render visibility to invisible to secondary rays.

Hi,
Thank you for your quick answer.
It works perfect. In the render geo settings, I set the shading > render visibility to "visible only to primary rays" to also avoid having the geo cast shadows.

It seems like the mtlxuniform_edf only works in the cpu engine. It would be really nice to be able to use a "constant unshaded surface" in the gpu engine, do you know if that is possible?

Petfactory
It seems like the mtlxuniform_edf only works in the cpu engine. It would be really nice to be able to use a "constant unshaded surface" in the gpu engine, do you know if that is possible?

For now, the beta XPU engine has limited shader support. It only works with standard surface and usd preview surface, and a couple others for hair/volumes. I expect support to be expanded in the future as it matures.

Thank you for the info!

jsmack
Setting the bounces to 0 is done on the karma settings node. look for limits.

However, in the case of the original thread, setting bounces to 0 is unacceptable. To create a constant shaded object that doesn't contribute to lighting, add a render geometry settings node and set the render visibility to invisible to secondary rays.

Very helpful.
Thanks!

Also check out MtlxUnlitSurface