Houdini Resources

Updated on Sept 1  2022


copyright © Deborah R. Fowler


Deborah R. Fowler



Houdini UVs

Posted Dec 13  2017
Updated May 4  2020
Updated Jan 30  2024 - optimized images

In Houdini UVs are no better and no worse than in Maya imho.
One of the easiest ways to UV simple objects is by using the UV Project or UV Texture node

UV Project for example:

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This node will project a texture in Orthographic, Polar, Cylindrical among other. Here I will use it in an Orthographic projection.

There are two tabs:


Note that uv's should occur at the base level of the geometry, that is, before it is transformed or deformed so that they "stick" properly.

The outline in blue indicates the current uvs. It will display when you have the manipulator button selected as well as the uv node.

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Here a principled shader is assigned in the material node. The texture is referenced in the shader.

Note we are using one of the given texture which are located in the program files ( $HFS, much the same way your local file is $HIP)

In the principled shader under the Textures tab the texture parameter is specified

$HFS/houdini/pic/Mandril.rat

rat
stands for random access texture and is optimized for the mantra renderer

Example file gridImage.hipnc



If you are using your own texture, the path will be more like this:

$HIP/textures/ScreenSaver.jpg

This is refered to as a relative path. Do not use absolute paths. Since the file is relative to the hipnc file it will be able to find your textures as long as the folder structure with the hipnc is kept intact.

In the classicshader, use map flag is under each tab rather than a central tab as in the above example.

Finally, it is important to use Groups. Groups allow a great deal of versatility when shading your objects.

Here I have taken that same grid, selected and grouped (by selected in the viewport, pressing tab and typing group) some faces. These are then assigned a different shader that the other primitives of the grip. Note that only one material node is required to assign the shaders to the different groups.

Example file gridImageGroups.hipnc


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The same technique can be used on any geometry, for example, in this case the groups were also used to set the uv attributes for the faces.

The top green face is uv'd in uvProjectTop

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The front yellow face is uv'd in uvProjectFront

These then can be used to assign the materials to these groups and their uv attributes will be specific for that group.
Example file usingGroupForCubeFaces.hipnc




An example from H18 for uv'ing walls using both the uvproject and the uvtexture node quickTextureForWalls.hipnc
Note that the uv nodes are simply adding an attribute, DO NOT MERGE or it duplicates geometry.