UVW Randomizer rotation

[thomas_kaufmann]

Hello,

currently, I am experimenting with the UVWRandomizer in Vray 5 and 6.
There are a few things the documentation seems to neglect, hence this post.

1. Is there any documentation around which point the rotation of the Variance UV Rotation is calculated? Currently, this is causing my decal textures to get in touch with the edges and be cut off)
2. what do the units in the scaling/offsets refer to scene units, pixels or percentage of image?
3. is there a general documentation considering the order of operations done inside this node ?

reason for asking:
my current project involves a few lovely materials that would benefit from this information, currently the areas marked in red are getting cut off.

Thanks
Thomas

[vladimir_krastev]

Hi, thanks for posting. Could you share a bit more details about your project? Please add screengrabs and if possible a scene. If you want to keep the project confidential you can use the support contact form. If you choose the contact form, please add a link to this tread so we can handle you issue faster.

[hermit.crab]

1. Not sure what you mean here. The center point is dependent on the UVWRandomizer's mode. After that - the texture's center.
2. Percentage.
3. Why would that matter?

[thomas_kaufmann]

1. I am using the stochastic randomizer as I basically do have planes/cubes as base objects with low resolution geometry
2. good to know
3. well.. in my scenario it is important, because: if you rotate a centered decal first and move it after, no issue. Moving it and then rotating it around the center of the virtual new image means you are not rotating it around its center anymore.


Scene scenario is as follows:
simple centered sprite ( a stone with alpha) -> needs to be randmized and placed to create a layer of terazzo structure.
Will attach a scene later tonight demonstrating the issue.

[hermit.crab]

Ok, let me get this straight. You basically wish for the cut texture to be whole right? If so, I found out this is called "texture bombing" and works differently than the VRayUVWRandomizer. However, there is a 3ds Max native OSL shader (written by Zap Andersson), which does precisely that. It's called RandomizedBitmap. It comes with 3ds Max, but I will attach it here. I played around with it and it seems to work in Maya too (through a VRayTexOSL). Check the attached scene and screencap of the result. Is this what you're after?

[thomas_kaufmann]

Funny.. I was investigating an OSL solution parallel to this thread

The basic idea is correct, except that I do need to have the option for either overlapping or not. That was why I wanted the randomizer node.
From testing with a single image and planar uvs in 0,0, 1,1 I played with only the rotation and it is not rotating around the center of the space, causing the cut off behaviour in the first place.

[hermit.crab]

The provided OSL (RandomizedBitmaps) does have an option for overlapping.

[matthew999]

Zap Anderson, that a blast on the mental ray past..... Didn't he have a patent on mental ray implementation of round corners. Sorry to hijack