Add Grid gizmos

[lynn-lumen]

Objective

• Implement grid gizmos, suggestion of Tracking issue: Amazing Gizmos #9400

Solution

• Added gizmos.grid(...) and gizmos.grid_2d(...)
• The grids may be configured using .outer_edges(...) to specify whether to draw the outer border/edges of the grid and .skew(...)to specify the skew of the grid along the x or y directions.

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Changelog

• Added a grid module to bevy_gizmos containing gizmos.grid(...) and gizmos.grid_2d(...) as well as assorted items.
• Updated the 2d_gizmos and 3d_gizmos examples to use grids.

Additional

The 2D and 3D examples now look like this:

[afonsolage]

I ran the examples and they are fine and I'm not a math guy, but the implementation seems fine too, my only point is about grid_2d since to me both grids are 2d, since a grid_3d would means, at least to me, a "cubic grid" not a "square grid".

IMO we should have only grid and showcase how to use them in 2d_gizmos and 3d_gizmos.

[lynn-lumen]

I get the confusion, but this follows the naming conventions for other gizmos like .rect() and .rect_2d. The basic idea is to provide a gizmo to 2D users who don't want to engage with quaternions just for the sake of drawing gizmos. I have not seen a 'cubic grid' (gizmo) used anywhere so far, but if there is interest I will add it.

[afonsolage]

Sorry if I wasn't clear, but my point is I don't think we need a gizmos_2d just gizmos is enough.

[lynn-lumen]

Yes, this would still provide all the functionality, but isn't approachable for new users. Imagine someone building a 2D game: they have only dealt with Vec2 positions and f32 rotations. If they want to draw a gizmo, they should continue to be fine with that and not be forced to learn about quaternions just for gizmos.

[pablo-lua]

In reality, would be good to have a cubic grid IMO. And one could find good to be able to change the space between X lines and Y lines. (In the cubic grid example, we would have Z lines)

[pablo-lua]

Can we maybe change the color of the grid lines in the example? It was a bit hard to me to see at first. Maybe we can use white?

[lynn-lumen]

And one could find good to be able to change the space between X lines and Y lines.

I'm not sure I understand this . You can have different spacings for x and y lines already. Simply pass something like Vec2::new(2., 1.) as the spacing argument. Am I missing something?

[pablo-lua]

And one could find good to be able to change the space between X lines and Y lines.

I'm not sure I understand this . You can have different spacings for x and y lines already. Simply pass something like Vec2::new(2., 1.) as the spacing argument. Am I missing something?

Not really, I'm saying thats good, sorry, wasn't clear.
The only thing that I think deserves to be there is the cubic grid in reality, as Users can find good use in it for debug purposes

[afonsolage]

And one could find good to be able to change the space between X lines and Y lines.

I'm not sure I understand this . You can have different spacings for x and y lines already. Simply pass something like Vec2::new(2., 1.) as the spacing argument. Am I missing something?

Not really, I'm saying thats good, sorry, wasn't clear.
The only thing that I think deserves to be there is the cubic grid in reality, as Users can find good use in it for debug purposes

But as follow-up PR, right? Because I think a cubic-grid is out of scope of this PR, since this can be controversial, since the implementation can be trick IMO.

[lynn-lumen]

Can we maybe change the color of the grid lines in the example? It was a bit hard to me to see at first. Maybe we can use white?

White was a bit overwhelming, but it should be better now.

[pablo-lua]

But as follow-up PR, right? Because I think a cubic-grid is out of scope of this PR, since this can be controversial, since the implementation can be trick IMO.

Yea, we can track this in #9400

[lynn-lumen]

But as follow-up PR, right?

I think I could add this here, if that is ok. It would be just adding another axis to the existing implementation and something like gizmos.cubic_grid(...)

[pablo-lua]

I think I could add this here, if that is ok. It would be just adding another axis to the existing implementation and something like gizmos.cubic_grid(...)

If we implement in the same way that is now, I think that's okay, but might be good keep this as uncontroversial as possible and do this in a follow-up? Not sure.
About the cubic_grid part, wouldn't be better call it "grid_3d" or only "grid" to keep the convention?

[lynn-lumen]

If we implement in the same way that is now, I think that's okay, but might be good keep this as uncontroversial as possible and do this in a follow-up? Not sure. About the cubic_grid part, wouldn't be better call it "grid_3d" or only "grid" to keep the convention?

Ok, fair enough. As for the name, we already have .grid which we could just extend to include a third axis or we could do something like .lattice? I don't think grid_3d would be a good idea though, as it suggests (at least to me) that it is the same shape as .grid although it is different/more general.

[pablo-lua]

Keeping .grid(...) to do that function is better IMO.

[lynn-lumen]

Keeping .grid(...) to do that function is better IMO.

Ok, so we will add that functionality to .grid in a future PR, right?

[pablo-lua]

The math behind this looks fine to me, and nothing to say about the grid itself. All good

[MiniaczQ]

New to gizmos, so seeing Drop used for finalizing the builder was interesting

Looks good

[alice-i-cecile]

The Drop pattern is a little too clever for my taste, and doesn't appear to be used elsewhere in gizmos. Can we find a simpler solution?

[MiniaczQ]

The Drop pattern is a little too clever for my taste, and doesn't appear to be used elsewhere in gizmos. Can we find a simpler solution?

oh, I thought it was a standard for gizmos so I didn't question it
In that case agreed

[pablo-lua]

I'm a little confused, isn't the drop pattern used in multiple gizmos builders? Or is there something different here? For starters, arc builders use this

[lynn-lumen]

isn't the drop pattern used in multiple gizmos builders?

Yes, the Drop pattern is used for all primitives, ellipses and arcs.

[alice-i-cecile]

Ah my apologies, I did a search for impl Drop, which didn't reveal anything because of the intervening generics.

[alice-i-cecile]

@solis-lumine-vorago can you rebase (the examples got moved) and I'll give this a final pass before merging?

[lynn-lumen]

@solis-lumine-vorago can you rebase (the examples got moved) and I'll give this a final pass before merging?

Yeah sure, it appears that Color was renamed but it should be all good now.

[lynn-lumen]

@alice-i-cecile Could you enable Auto-merge again, please :)

[lynn-lumen]

thx :D