@Clément Foucault (fclem) I have tested with new engine and still does the same. Do you think this is a design limitation?

Yes this is because we are rendering in layers. The GPencil engine cannot know that something has been rendered and is transparent in front of it unless it has been written to the depth buffer.

There is no real workaround this it is a limitation of the way things works.

In T59979#857098, @Clément Foucault (fclem) wrote:

Yes this is because we are rendering in layers. The GPencil engine cannot know that something has been rendered and is transparent in front of it unless it has been written to the depth buffer.

There is no real workaround this it is a limitation of the way things works.

now over a year later is there any idea to resolve this in the long run (like rendering gp objects with eevee )?

i dont know how you composit the things in code but just know that image planes and cartoon animation belong together like siamese twins and are the gold standard in 2d animation (and will never change)

it would be sad if the tool is just left so you can never do a full animation scene (or the bulk of it at least) directly in eevee and instead plan it around using aftereffects, still.

Since alpha clipped textures are working fine with grease pencil objects,

maybe adding a compositing step and reusing the alpha buffer of the image plane's shader onto a depth buffered(alphaclipped) version/copy of the alpha blended object/material (the one you use for compositing),

and therefor at least approximate the alpha blending.

You guys also approximate the camera depth blur so maybe that would be a solution ?