Rework layers

[Jondolf]

Objective

Fixes #322 (among other things).

Improve and simplify the API used for CollisionLayers and SpatialQueryFilter.

Solution

Add a LayerMask struct that stores a bitmask used for collision layers. The groups and masks properties have also been renamed to memberships and filters, because "groups" and "layers" sound like the same thing, and "masks" might be confusing since it's a single bitmask (just like groups/memberships). The new naming is also what Rapier uses.

A LayerMask can be created from a u32, a type implementing PhysicsLayer, or an array of layers. CollisionLayers::new now takes impl Into<LayerMask>. All of the following work:

let layers = CollisionLayers::new(0b00010, 0b0111);
let layers = CollisionLayers::new(GameLayer::Player, [GameLayer::Enemy, GameLayer::Ground]);
let layers = CollisionLayers::new(LayerMask(0b0001), LayerMask::ALL);

LayerMask also allows us to reduce the number of CollisionLayers methods. contains_group/contains_mask, add_group/add_mask and so on have been removed in favor of simply calling methods like add or remove on the actual properties.

layers.memberships.remove(GameLayer::Environment);
layers.filters.add([GameLayer::Environment, GameLayer::Tree]);

// Bitwise ops also work since we're accessing the bitmasks/layermasks directly
layers.memberships |= GameLayer::Player; // or bitmask directly, e.g. 0b0010

The methods mutate in place instead of returning a copy, which fixes #322.

SpatialQueryFilter also now uses LayerMask for its masks, and its constructors have been improved. new has been removed for redundancy, with_mask_from_bits has been removed, and instead it has the methods from_mask, from_excluded_entities, with_mask, and with_excluded_entities.

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Changelog

Added

• LayerMask struct
• SpatialQueryFilter::from_mask
• SpatialQueryFilter::from_excluded_entities

Changed

CollisionLayers

• groups and masks of CollisionLayers are now called memberships and filters
• CollisionLayers stores LayerMasks for memberships and filters
• Methods that took impl IntoIterator<Item = impl PhysicsLayer> now take impl Into<LayerMask>
• Change CollisionLayers::all() to constant CollisionLayers::ALL
• Change CollisionLayers::none() to constant CollisionLayers::NONE
• Change CollisionLayers::all_groups() to constant CollisionLayers::ALL_MEMBERSHIPS
• Change CollisionLayers::all_masks() to constant CollisionLayers::ALL_FILTERS

SpatialQueryFilter

• SpatialQueryFilter stores a LayerMask for collision masks
• SpatialQueryFilter::with_mask now takes impl Into<LayerMask>
• Rename SpatialQueryFilter::without_entities to with_excluded_entities for consistency

Removed

• CollisionLayers::add_group and CollisionLayers::add_mask
• CollisionLayers::remove_group and CollisionLayers::remove_mask
• CollisionLayers::contains_group and CollisionLayers::contains_mask
• CollisionLayers::groups_bits and CollisionLayers::masks_bits (you could get e.g. layers.groups.0 instead)
• SpatialQueryFilter::new
• SpatialQueryFilter::with_masks_from_bits

Migration Guide

• Replace e.g. every layers.add_group(...) with layers.memberships.add(...) and so on, and similarly for masks/filters
• Change CollisionLayers::all() to CollisionLayers::ALL
• Change CollisionLayers::none() to CollisionLayers::NONE
• Change CollisionLayers::all_groups() to CollisionLayers::ALL_MEMBERSHIPS
• Change CollisionLayers::all_masks() to CollisionLayers::ALL_FILTERS
• Change SpatialQueryFilter::new() to SpatialQueryFilter::default() or use the SpatialQueryFilter::from_mask or SpatialQueryFilter::from_excluded_entities constructors
• Change SpatialQueryFilter::without_entities to with_excluded_entities
• Change CollisionLayers::groups_bits() and CollisionLayers::masks_bits() to layers.memberships.0 and layers.filters.0