vraydisplacement mod, texture channel

[super gnu]

im using nested maps to drive displacement,with masks between them. some of them use mapping channel 2, some use mapping channel 4.

how does this work when you have to specify a single mapping channel in the displacement modifier -more to the point, why do you have to specify it there? surely each map has its texture channel defined in the bitmap loader etc.?


also, i was considering using "use object mtl" is that supposed to play nicely with multiple blended vraymaterials in a vrayblendmtl, if each has its own displacement map (with different uv map channels) and mask texture...? i got some quite odd results..

[Vizioen]

im using nested maps to drive displacement,with masks between them. some of them use mapping channel 2, some use mapping channel 4.

how does this work when you have to specify a single mapping channel in the displacement modifier -more to the point, why do you have to specify it there? surely each map has its texture channel defined in the bitmap loader etc.?


also, i was considering using "use object mtl" is that supposed to play nicely with multiple blended vraymaterials in a vrayblendmtl, if each has its own displacement map (with different uv map channels) and mask texture...? i got some quite odd results..

I don't think it works like this. You're input needs to be a single 'map' if you have multiple displacement maps in your blend materials you will need to consolidate them in one map (by using composites or comptex or something). And use that map to drive your 3D displacement.

Also:

Texture chan – The UVW channel that will be used for displacement mapping. This must match the texture channel specified in the texture map itself, if it uses explicit UVW mapping. This is ignored if the Use object mtl option is enabled.

You make a valid point though about the different mapping channels so I tested it out because I was curious. And my tests point out that texture chan is also ignored when using 3D displacement instead of 2D. Someone of Chaos please correct me if this is wrong. If true this should be pointed out in the docs (and maybe this option should be greyed out when using 3D and use object mtl) although pretty obvious it can be confusing.

[hermit.crab]

The VRayDisplacementMod's 'Texture chan' parameter works in a similar fashion as texture map channels - it takes the UVW coordinates from the selected channel. For example, in the scenario where you have an object with two UVW modifiers, set as map channels 1 and 2, the parameter lets you choose which of the coordinates to be used. This mainly concerns 2D mapping displacement, since when using 3d mapping only the first texture channel is respected. Regarding the 'use object mtl' option - the texture is taken from the base material of, for example, a VRayBlendMtl.

[vlado]

The texture channel is indeed used for 2D displacement only; we should probably grey it out when using the other modes.

Best regards,
Vlado

[super gnu]

I don't think it works like this. You're input needs to be a single 'map' if you have multiple displacement maps in your blend materials you will need to consolidate them in one map (by using composites or comptex or something). And use that map to drive your 3D displacement.

that is what im doing. using comptex and mix maps to combine several bitmaps into a single displacement map.. however there are 3 bitmaps, and each uses a different mapping channel.

in any case, im using 3d mapping, so as noted, this setting does nothing anyway.

[super gnu]

Regarding the 'use object mtl' option - the texture is taken from the base material of, for example, a VRayBlendMtl.

so, if we have multiple materials with displacement maps, in a blend mtl, with masks mixing one with another, you will NOT get properly blended displacement? it will just use the displacement from the base material?

workflow-wise this is terrible, if so. you would have to manually re-create the blended displacement maps by hand, which would be unlikely to give a correct result.

can we have a "use object mtl" which works correctly with blended materials?