Tutorial: Insert Alpha Channel

This documentation is for update 2.0+, applied to 5.4+.

This guide provides a detailed walkthrough for using the Insert Alpha Channel job. This is a simple but essential utility that allows you to take the color information from one texture and combine it with the transparency information from another, creating a single texture with a new alpha channel.

1. What is an Alpha Channel?

An alpha channel is an extra channel in an image (in addition to Red, Green, and Blue) that stores transparency information. It's used for effects like cutouts, decals, and translucency. This tool is perfect for when you have your main color texture (RGB) and a separate grayscale mask (like an opacity mask) and you want to combine them into a single RGBA texture file.

2. Setting Up the Job

1. In the main Texture Tools window, click the Add Job button.

2. From the dropdown menu, select Job: Insert Alpha Channel.

3. A new "Insert Alpha Channel" job will be added to the job queue. Select it to see its properties in the Details panel.

3. Providing Input Textures

The Insert Alpha Channel job requires two inputs, which you can provide in the Input viewport on the left side of the tool.

• INPUT BASE TEXTURE: This is the texture that provides the Red, Green, and Blue color channels for the final output.

• INPUT ALPHA MASK: This is the texture that provides the transparency information. It is typically a grayscale mask where white is fully opaque and black is fully transparent.

Drag and drop your textures from the Content Browser into these two slots.

4. Configuring the Alpha Insertion

All the settings for this job are located in the Input Settings category in the Details panel.

• Mask Channel: This dropdown lets you select which channel from the Input Alpha Mask to use as the source for the new alpha channel.

  • R, G, B: If your mask is a standard grayscale image, you can select any of these, as all three channels will contain the same information.

  • A (Alpha): If your mask texture already has an alpha channel you want to use, select this option.

Add the separate Opacity Texture into the Diffuse Texture to combine

5. Generating the Final Texture

1. Once you have provided your base texture and alpha mask, ensure the Insert Alpha Channel job is selected in the job queue.

2. Click the main Run Selected Job button.

3. The tool will combine the RGB channels from the base texture with the selected channel from the alpha mask. The new texture asset will be saved to the path specified in the Generate Settings category with the _Alpha suffix.