Add option for custom sort axis for 2d y-sorting

[matidfk]

Describe the project you are working on

2D bullet hell game with a unique perspective similar to RotMG. a top down camera that can rotate, and sprites will billboard to point upright

Describe the problem or limitation you are having in your project

when rotating, y-sorting remains based on each sprite's y coordinate. with a rotating camera, for things to be sorted properly, this needs to correspond to a vector.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

allow a custom sort axis setting

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Add a project (or in some other location) setting for a custom sort axis vector (or direction), based on which sprites will be sorted.
eg. the default would be (0, 1). if this vector was changed to (1, 0), now sprites that are towards the +x will be displayed on top.

If this enhancement will not be used often, can it be worked around with a few lines of script?

it can almost be worked around at the moment, by manually setting a sprites z index. however, as z index is an integer type, this loses precision and leads to flickering. additionally, it would be nice to be able to use the z index on top of a custom sort direction.

Is there a reason why this should be core and not an add-on in the asset library?

i dont think it can be implemented as an addon as i believe it requires changing engine source code?

[matidfk]

Looking into the source code, I believe it should be as simple as changing ItemYSort to compare dot products of position and the sort axis, rather than position.y. might try implement myself

[matidfk]

After trying it out, it's a bit more involved and adding the ability to change the sort axis at runtime requires modifying quite a few different parts of the code to do with rendering. I'm not at all familiar with godot's source code so maybe someone more experienced than me can take on this instead.

[pcloves]

After trying it out, it's a bit more involved and adding the ability to change the sort axis at runtime requires modifying quite a few different parts of the code to do with rendering. I'm not at all familiar with godot's source code so maybe someone more experienced than me can take on this instead.

Is it necessary to modify the sort axis at runtime? Would it be better to move this sort axis to project settings, get its value during engine initialization, and prohibit runtime modifications?

[matidfk]

After trying it out, it's a bit more involved and adding the ability to change the sort axis at runtime requires modifying quite a few different parts of the code to do with rendering. I'm not at all familiar with godot's source code so maybe someone more experienced than me can take on this instead.

Is it necessary to modify the sort axis at runtime? Would it be better to move this sort axis to project settings, get its value during engine initialization, and prohibit runtime modifications?

Yeah, as when the camera rotates, the axis needs to be updated. Maybe it could be implemented as a toggle instead that determines whether the sort axis shouls stay fixed or follow the cameras rotation?