Can this be used with an atlas?

[tobyselway]

Hi, great crate!

I'm making a top-down dungeon, where the levels are made up of tiles, and my tiles are all in a single spritesheet.
I've created a separate spritesheet with textures only representing collisions in order to be able to define which parts of each tile are wall/floor.
Is it possible to load this spritesheet into bevy_collider_gen with an index of a tile, and have it generate a polyline for that specific tile? Or will I have to split my spritesheet up into separate image files?

[shnewto]

Hello! Thank you!

If I'm understanding correctly, you can use multi_polyline_collider_translated to generate colliders for all the sprites in your image/spritesheet at once, it returns a Vec<Collider>

If I'm not understanding correctly I could use some more details and maybe a sample image 😄

[tobyselway]

This is one of the collision tiles. By placing this in a spritesheet and processing it at once, won't I get a Vec containing 3 separate colliders?

How can I then distinguish between which ones pertain to each tile?

[shnewto]

🤔 yeah you would in that case. Is the issue then not wanting 3 separate colliders for that tile? Or is distinguishing the colliders the root of it?

[tobyselway]

3 colliders for that tile makes sense. The issue is distinguishing that those 3 colliders are related to this specific tile, as they'll be in the vector alongside all the other colliders from the spritesheet.

[shnewto]

ahh okay yeah I'm understanding now, yeah that's a challenge to do with this crate as it is today.

I think there are folks achieving something similar using the crate this one depends on edges, where you can pass bytes directly to the Edges::march_edges function. You'd need to read your image then do a bit of bytes and offsets juggling to pass each tile's bytes in at a time. The physics engines this crate supports just want points in drawing order and march_edges will return that for you to pass to them directly.

I do like the idea of being able to specify things specifically in a spritesheet though and not generating colliders for entire images. I'll start thinking about how to support it without needing too much extra work from the user. If this crate did what you were hoping already, how are you imagining you'd be able to specify an individual sprite in a sprite sheet, something like specifying size, width, and offset?

[tobyselway]

Something like that, yes. Ideally an index only, the same way a SpritesheetBundle's texture is specified.
Feel free to reach out if you'd like some assistance in implementing this. I'm not currently blocked by this so there's no pressure

[shnewto]

Ah okay, that's a great pointer. I'll see if I can use the SpritesheetBundle as a reference. I'll take a pass at it and tag you in a comment and maybe you can let me know if I'm on the right track for what you're imagining.

[salam99823]

Hi, how about adding a function to get edges from bevy_math::rect::URect or adding an area argument to edges::Edges::image_edges, then adding DynamicColliderPlugin and DynamicCollider component to bevy_collider_gen.

[shnewto]

@salam99823 I think I like the idea of adding something to edges like Edges::from_grid with the same signature Bevy uses here to generate a texture atlas

Then it does get sort of tricky here in bevy_collider_gen because the caller might want more than one collider for the sprites in the atlas so we'd need to make a clean way for this crate to make it easier than just using the edges crate themselves 🤔

[shnewto]

I think you're right about something like DynamicCollider, maybe it's an object that once instantiated with an atlas, you need to specify the collider type in order to get the value at index i