Channels

Channel in Ucupaint

A channel in Ucupaint represents a pair consisting of an input and an output within the Ucupaint node.

The Ucupaint channels input and output (I/O) on the actual node

Each channel has at least one input and one output, but the Normal channel can have multiple inputs and outputs (read Displacement Setup).

The base color or value of the channel is the default input of the node, as shown in the GIF below.

The base color or value of a channel corresponds to the node’s default input

All inputs and outputs can be freely connected, allowing the Ucupaint node to work with your custom node setups.

In the channels list panel, you can perform basic actions such as adding, moving up/down, or removing channels.

Channels list panel

Adding a New Channel

To add a new channel, use the + button next to the channel list. The video below demonstrates how to create an Emission channel in Ucupaint.

After creating a new channel, the Ucupaint node will display new input and output sockets corresponding to that channel.

Channel Types

There are three channel types in Ucupaint: RGB, Value, and Normal.

RGB Channel Type

An RGB channel consists of three color values: red, green, and blue. You can also enable alpha to add transparency, which makes the base color transparent by default..

RGB channel options

If alpha is enabled, your material will automatically switch to Alpha Dithered method in Eevee. The default alpha value is 0.0, making the background fully transparent. If you create a layer with a mix blend, it will be placed on top of the transparent background. This can be useful for cases like creating hair planes or vegetation.

Value Channel Type

Value channels consist of a single value.

Value channel options

Normal Channel Type

Normal channels consist of a normal vector. You can have only one normal channel per Ucupaint node.

Normal channel options

The Height Tweak option is to multiply the value maximum displacement/bump height. It's useful for tweaking the total displacement/bump height without manually adjusting the height for each layer one by one.

Displacement Setup

Enabling the Displacement Setup will add extra input and output sockets to the Ucupaint node: Height, Max Height, and Vector Displacement. These outputs are connected to displacement nodes, which are automatically created when the Displacement Setup is enabled for the first time. While you can connect them to other nodes if needed, they are mainly intended to be used with the given displacement nodes.

Multiple Normal Inputs and Outputs when Displacement Setup is active

Enabling Displacement Setup also does the following:

• Adds a Subdivision Surface modifier to all objects using the same material
• Converts bump maps from Ucupaint layers into real displacement (unless Write Height is enabled on that layer, which disables displacement for it)

The Max Polygons value controls how much the object is subdivided. It’s measured in thousands; for example, a value of 1000 means up to 1 million polygons.

If you enable Adaptive Subdivision (Cycles only), Ucupaint will:

• Enable the Experimental feature set for Cycles render
• Automatically configure adaptive subdivision, which adjusts detail based on the camera view

Adaptive subdivision improves displacement details when you're using Cycles renderer, but may increase load time when entering render view.

The video below demonstrates how to set up Ucupaint for drawing with displacement

Experimental Features

To access Experimental Features, go to: Edit → Preferences → Add-ons → Ucupaint, then enable the Show Experimental Features option in the Ucupaint settings.

Enable Experimental Features

Experimental features will add more options to the Normal channel, which are Smoother Bump and Parallax.

Smoother Bump (Experimental)

This feature is only useful for Blender 2.7x. Smooth Bump makes your bump map appear smoother than Blender’s default, but this comes at the cost of some precision and performance.

Smooth Bump comparison

Parallax (Experimental)

The Parallax option lets you create parallax effects when using bump maps. It only works after you bake the normal channel. Please save your file before enabling it, as it may cause Blender to freeze. Note that parallax effects only work in perspective view.

Parallax comparison