Left Toolbar > Math Nodes > Rgbo Apply Opacity
The RGBO Apply Opacity node multiplies or divides the red green blue components of the Rgbo value by the opacity Remove: If checked, the red green blue components are divided by the opacity. If unchecked, the red green blue are multiplied by the opacity. This operation is known as pre-multiply.
On the left toolbar choose Point Nodes > Rgbo Apply Opacity
Drag the Rgbo Apply Opacity icon into the Node Graph.
Connect the Output .
rgbo A RGBO type.
amount A number type.
result A RGBO type.
These attributes are exposed as input by default. Right-click the Node to hide the attribute as input and set the point values manually. Default R:0.0, G:0.0, B:0.0, O:1.0