RGB masks / May 14, 2015 by Xuan Prada

We use RGB masks all the time in VFX, don't we?
They are very handy and we can save a lot of extra texture maps combining 4 channels in one single texture map RGB+A.

We use them to mix shaders in look-dev stage, or as IDs for compositing, or maybe as utility passes for things like motion blur o depth.

Let's see how I use RGB masks in my common software: Maya, Clarisse, Mari and Nuke.

Maya

I use a surface shader with a layered texture connected.
I connect all the shaders that I need to mix to the layered texture.
Then I use a remapColor node with the RGB mask connected as mask for each one of the shaders.

We need to indicate which RGB channel we want to use in each remapColor node.
Then just use the output as mask for the shaders.

Clarisse

In Clarisse I use a reorder node connected to my RGB mask.
Just indicate the desired channel in the channel order parameter.

To convert the RGB channel to alpha just type it in the channel order field.

Mari

You will only need a shuffle adjustment layer and select the required channel.

Nuke

You can use a shuffle node and select the channel.
Or maybe a keyer node and select the channel in the operation parameter. (this will place the channel only in the alpha).

Introduction to channels in Mari / July 11, 2011 by Xuan Prada

Create a new proyect in Mari.

Create a new channel called “base”.
Adjust size, color space and color.

Right click on “base channel” to import a texture bitmap as base color.

We already have our cube with the blue base color.

Create a new shader called “blueCube” and choose as texture the “base channel” created before.

Create a new channel called “underPaint”.
Adjust size, color space and color.

Right click on the “underPaint” channel to import a nice under paint texture map.

You can see it in the viewport.

Create another channel called “underPaintMask”.
Adjust size, color space and color.

Import the under paint mask texture into the “under paint channel.”

Looks awesome in the viewport.

Select the “blueCube shader” and add a “new shader module”.
Select “masked diffuse” from the list.

As base texture select “underPaint channel”.
As mask texture select “underPaintMask channel”.
Invert the mask.

Add more layers in very simple, just need to add more channels.
Create a new channel called “rust”.
Adjust the size, color space and color.

Import a rust map into the channel.

Check it in the viewport.

Add a new channel called “rustMask”.
Adjust size, color space and color.

Go back to shaders tab and select “bluCube shader”.
Add a new shader module and select “masked diffuse” from the list.

Select the “rust channel” as “base texture” and “rustMask channel” as “mask texture”.
Invert the mask.

Select the “rustMask channel” and paint with black color to create rust in desired areas.

Inverted occlusion in 3D Max / January 22, 2011 by Xuan Prada

People asked me for a step by step installation and usage of Binary Alchemy Color Ray Length shader in 3D Max.
Here we go.

Installation

Download BA Shaders for 3D Max.
Copy .dll files here -> “3ds Max 2010\mentalray\shaders_3rdparty\shaders”
Copy .mi files here -> “3ds Max 2010\mentalray\shaders_3rdparty\include”
Edit “3rdparty.mi” located here -> 3ds Max 2010\mentalray\shaders_3rdparty
Your “3rdparty.mi” must be something like this.

Usage

Create a matte/shadow shader and uncheck “receive shadows” and “use ambient occlusion”.

In the “camera mapped background” input, connect a “BA_color_raylength” shader.

Play with the “spread” to control the behaviour of the occlusion.
Once rendered you’ll have something similar to this.

Mix the “BA_color_raylength” with procedural maps or bitmaps to improve the result.

Edit: The most important parameters to play with are “spread” and “far output”.

Worn edges / January 6, 2011 by Xuan Prada

This technique is based on “worn edges techniques” by Neil Blevins.

Requirements

3D Max Scanline Render
SoulBourn Scripts
Warp Texture Script
All the objects must have a correct UV mapping

Procedure

We must complete perfectly the UV mapping of the objects, without overlappings and similar common issues.

To reach better results, we need more geometry information, especially in the corners.
For that purpose, duplicate the objects, rename them and apply them some bevels in the corners and one or two turbosmooths if necessary. (but try first only adding bevels).

Note: All the object mesh must be “Editable Poly”.
Select the object and execute “Corner edge to vertex map” script.

We will have to play with the low and high angle parameters, especially decreasing the intensity of the low angle when more complex geometry has the object.
The next step is to distort this mask created by vertex color, to give it more caotic shape and indeed, more real aspect.
We need to download the “warp texture” plugin.

In a standard material connect the warpt texture to diffuse channel.
In the target input connect a vertex color. 3D Max put by default the vertex information which we have generated previously with the corner edge to vertex script.