Create a spider diagram material mask

I am trying to create a material of domain UI and blend mode translucent. I want to set a solid color for the background and then input a set of numbers, let’s say three for starters that will form a spider diagram mask that only lets the desired amount of color through.

For instance, lets go with three axis and a 0-1 scale for min-max. If I use values of 1 | 0.5 | 0.75, I want to have the spider diagram (which in this case would be a pyramid) to have one side reaching all the way to the top, then one side that is 360 / 3 =120 degrees angled go half way to the edge of the material and the third edge which would be at 240 degrees angle should go 3/4 of the way to the edge of the material.

This should be a hard transition for completely transparent inside the pyramid and completely blacked out outside the pyramid.

For reference I’d like to make something like this

I’ve tried gradients but don’t seem quite able to produce anything with multiple values and hard edges.

EDIT: After some more experimenting I got the Draw Line 2d node to draw a triangle and plug that into the opacity output but that does not fill the area that the triangle creates, it just allows the lines to be seen.