Disable color blending between specific objects


I’m not sure what I’m about to ask is at all possible, but:
How can you disable color blending between a set of objects, while allowing color blending between those objects and others (like the background, for example)?

This question arises from seeing this example:

Like the example shown, I want to take a set of 2D shapes rendered with an orthographic camera and, because each bigger shape “contains” the smaller ones, I’ve been using the z coordinate to render them in such a way that the bigger objects are rendered behind smaller ones.

That works. However, I want to disable the color blending as if I wasn’t drawing full objects everytime but instead drawing its increments/decrements like the example above. Additionally, I want each to blend with the existing contents, like the background or the map shown in the example above.

Thank you in advance for any help.


Maybe makes sense to use THREE.Shape(), where previous/inner shape is a hole for the current one?