In Houdini, I usually assign color to primitives (though Houdini defaults to assigning it to “points”). However, if you want Redshift to recognize color attributes (using RSUserDataColor), you need to promote the Cd attribute to points or vertices, as Redshift doesn’t interpret it directly on polygons.

Promoting Cd to points will result in color blending when you subdivide the model, which can create blurred colors. To maintain sharp color boundaries, promote Cd to vertices instead, as Redshift can understand vertex-level color attributes clearly.

While everyone is arguing what AI is best to keep people lying on the grass (Stable 3.5 or Flux), I’m using Pony Diffusion to grab some souls for this Halloween and form a “Cult of Ai”.

Was made with AI in ComfyUI on Windows. But you can build similar graph in Colab. Just need to customize the input and output folder paths.

I had to bake some texture maps in Redshift inside Houdini. Haven’t seen any clear tutorials on how to do that. So here is short guide.
Let say I created complex material mixing different texures, adjusting them with color corrections and gradients, noises. I’m happy how it looks in the Redshift renderer. And want to pass geometry to 3ds Max and setup materials with Corona.
General ideas is that you need to create custom AOVs to bake all those textures. Link to documentation about custom AOVs:
https://help.maxon.net/r3d/houdini/en-us/#html/Custom+AOVs.html

Here is how a test material network looks like:

Just for visual reference I’m adding black nulls to know what maps I want to bake. And connecting here those nulls to red nodes (StoreColorToAOV or StoreIntegerToAOV). Sadly you can’t use `opinput(“.”,0)` to get the name of connected node in MAT context like you can in SOP. So you’ll need to copy paste names from nulls.

Create separate Redshift render node. In RenderMaps tab set Renders Maps Baking Enable.
If during testing you want to switch fast between textures resolution (from 512x512px to 1024, 2048, 4096) add an integer slider (with range from 0 to 3) to the inteface of RenderMaps tab (I called it indra_res_mult) and in the Output resolution add:

512*pow(2, ch("indra_res_mult"))

If it is black and white texture like roughness or mask use data type scalar. And it will be saved as 8 bit greyscale image in this case. They need to be with gamma 1. But if you render them in Redshift in png it will save in gamma 2.2. So if you want gamma 1 you need to save in tif. And for channels like base color use png.

Things to remember:

1. No tessellation on obj level. It took me more than 1 hour to figure out why my maps were looking strange and it was just this one checkbox.
2. No overlapping uvs.
3. Faces has to be coplanar. I personally didn’t have a problem with this. But in this video for C4D it is recommended to triangulate.

Tips:

1. If you have assigned groups to geometry and want to use it inside redshift materials: you need to promote it to vertices on SOP level and switch on “Output as Integer Attribute”. You don’t need to create node for each group. Just use GRP_* in group name field. (I usually start names of all groups that I want to keep with GRP_ in the beginning). Then read it inside materaials with “RS Integer User Data” node. Just writing “GRP_group_name” or “group:GRP_group_name” will not work. That’s why we need convert group to integer attribute.
2. To write those masks you need to use “RS Store Integer to AOV”. StoreColorToAOV will not work.

How do you assign random colors from a specific set to objects and keep the setup flexible for changes with Houdini and Redshift?
Let’s say we have several plastic cups in a scene and 4 specific colors from a client.

1. Create a class attribute with a connectivity node (you can name it whatever you like).
2. Promote it to the vertex level with an attribute promote.
3. In the shader tree, use an RS Integer User Data node to bring in the attribute named “class” (or any other name that you gave it earlier).
4. Connect it to an RS Jitter node (name it “max_variations_01”) and select “User Data ID” in Input ID Mode. In “integer jitter,” set the min to 0 and the max to 3, so we will have 4 variations. With this node, we only control the number of variations.
5. Create another RS Jitter node (name it “lightness_range_01”). We will use it to create lightness variations. Keep the color to black and set Saturation Variation Max to 0. Now, with the Value Seed, you can control the randomness.
6. Create an RS Color Ramp (name it “recolor_01”) with 4 colors from your client and set the interpolation to constant.
7. After adjusting the seed on the “lightness_range_01” node, you will need to move the colors a little bit on “recolor_01” so each of them will end up in a range generated by “lightness_range_01.”

Another thing that you can do is to offset UVs for each object. So when you add textures for roughness, they will not repeat obviously. To do this, after the connectivity node, add an attribute wrangle node (Run over Vertices) with this:

@uv.x+=rand(@class);

Before:

After:

Timelapse of modeling low poly pirate ship in 3d using Houdini, Zbrush, Substance Painter, RizomUV and Redshift:

If you prefer video on youtube with chapters you can watch it here.

Small concept drawing that you see in timelaps I found on pinterest quite a while ago. Sadly I don’t know the author.
You can rotate model in your browser here:

I also passed geometry to Meta Spark Studio to make an IG filter.
Here is link to open filter in Instagram:

If you want to do that there are couple of things to remember:

If you want to search and replace paths in multiple locations use Windows -> Hscript Textport window

and write:

opchange \$DOWNLOADS"/wetransfer" \$JOB"/geo"

Backslash before variables will allow you to keep variables ($JOB and $DOWNLOADS in this case) and not expand them to full path.

Another case: you imported FBX with materials. You can move them to mat context and change path with this:

opchange ../../materials /mat

Another example: on windows machine for some reason textures are using absolute paths and I want to change them all to the root of the job project:

opchange "C:/Users/user_name/Dropbox/Work/project_name" \$JOB

Documentation:
https://www.sidefx.com/docs/houdini/commands/opchange.html

If you ever wondered why during polymodeling in zbrush you keep selecting several polygroups by CTRL+Shift clicking on only one:
Zbrush for most of brushes and selections uses vertices. And if your polygon doesn’t have any other polygon in same polygroup next to vertex that you clicked – it just selects also next polygoup.

So in this case you can use Select Lasso tool and click on one edge to hide full polygon loop. And then invert the visibility by CTRL+Shift dragging outside of mesh:

Still getting used to Modeler 2022 plugin in Houdini.

WIP:

I was trying to optimize my coloring process for a project. And here is where I got right now:

Coloring process:

1. Get palette that I want as a screenshot from here:
   https://paletton.com/#uid=60B0u0kllzcboPZgUH4pEuxt-pp
2. Convert image to Utility-Texture_sRGB with target color space ACEScg using PYCO ColorSpace converter. (I still need to make some more test on this part by using this .exrs files as emission texute to compare colors with reference).
   https://pyco.gumroad.com/l/pycocs
   Free with the code free at checkout.
3. From github you can install Color Palette Ramp – a Houdini HDA that creates a ramp based on a color palette from an image.
   https://github.com/jamesrobinsonvfx/colorpaletteramp
4. In Houdini using that HDA (colorpaletteramp) on SOP level create a ramp. If I got image from Paletton webpage then I use Stops -> 20. But something around 10 works great for other images.

5. With OD Tools you can right click on result and “Palletize Ramp [OD]” to make colors separation constant and look more like palette instead or gradient. You can get OD Houdini Shelf Tools 2021 for $100 here:
   https://origamidigital.com/cart/index.php?route=product/product&manufacturer_id=11&product_id=66

6. You can save this ramp in your OD Asset library for future use.

7. To color geometry based on disconnected pieces: first use “Connectivity” node on points to create integer attribute called id. Then use “Attribute Adjust Color” node with Adjustment Value -> Pattern type set to Random. Randomization By -> Custom attribute. Custom Attribute -> id. Then with changing seed parameter you can get random options of color combinations.

Results from 3 different ramps:

Small personal project that I made in Houdini testing Axiom GPU solver. Idea is that we always hunting for likes and “hearts”, setting traps with hot topics.
Looped video with music:

Work in progress:

Stills: