Flatten Mix is a helpful feature that allows you to minimize resource usage when building complex mixes. Every layer added to a mix increases the resource usage of your mix. By flattening a mix, all layers are merged into the base maps of your texture set. This frees up the resources taken up by each layer.

By default, you can access flatten Mix through the Edit drop-down in the main menu.

Take a look at this Sci-Fi Barrel based on five texture sets and many layers in the layer stack. This will directly impact the performance to optimize, save a copy of your mix, and try Flatten Mix to free up resources and continue working further.

By selecting the resolution of your choice, click ‘Flatten’ to convert all layers and groups into the current texture sets. This action can easily be undone using ctrl – z.

Here is the same barrel, but you will notice no layers present in the stack, yet all the textures are still present.

If you take a look at the Texture Sets Editor, you will notice that all the layers have been baked down as base layers and are present in their corresponding texture set with the affix ‘flattened’ added to their names.