Every environment in Modo can have a variety of texture layers added to it. These are useful to add depth and complexity to the background of any scene. The layering, opacity, and blend modes all work the same between layers as they do under the render item. You can modify a layer's effect from the default settings by right-clicking the layer in the Effect column of the Shader Tree and choosing an available command.
Driver A, B, C, and D—
Allows texture layers (either a bitmap, a procedural, or a combination) to drive a gradient layer with a matching input parameter. Modo passes the mapping of the image's brightness (luminosity) onto the gradient. The gradient's keyed values replace those of the driving layers and are output as specified by the gradient layer's Effect setting.
Environment Color—
Passes all the color (and illumination information, if applicable, such as in HDR images) to Modo's render engine. This is the default setting for any texture layer added to an environment item.
Group Mask—
Masks all layers within the group to reveal any lower texture layers in the Shader Tree. The texture layer must reside within a Material Group item and be specified as a Group Mask for the brightness values of the layer to act as a mask. Black areas are completely transparent and attenuate toward white areas that are completely opaque.
Layer Mask—
Works identically as the Group Mask, but where a Group Mask affects an entire group, a layer mask only affects a single layer. When you set any texture layer as a Layer Mask, it modulates the texture layer directly below it in the Shader Tree. Black areas are completely transparent, and they attenuate toward white areas that are completely opaque.