Module building_blocks_storage::access_traits[−][src]

Expand description

Traits defining different ways to access data from generic lattice maps.

Strided Iteration

The fastest way to iterate over data in an Array is with a simple for loop over array indices, we call them “stride“s:

use building_blocks_core::prelude::*;
use building_blocks_storage::prelude::*;

let extent = Extent3i::from_min_and_shape(Point3i::ZERO, Point3i::fill(100));
let mut map = Array3x1::fill(extent, 0);

for i in 0..extent.num_points() {
    // Use the `GetMut<Stride>` trait impl of the map.
    *map.get_mut(Stride(i)) = 1;
}

But this may require understanding the array layout.

`ForEach` over Extent

Often, you only want to iterate over a sub-extent of the map. This can also be done at similar speeds using the ForEach and ForEachMut traits:

let subextent = Extent3i::from_min_and_shape(Point3i::fill(1), Point3i::fill(98));
// Use the `ForEachMut<[i32; 3], Stride>` trait.
map.for_each_mut(&subextent, |_s: Stride, value| { *value = 2 });

Arrays also implement ForEach*<PointN<N>> and ForEach*<(PointN<N>, Stride)>. ChunkMap only implements ForEach*<PointN<N>>, because it’s ambiguous which chunk a Stride would apply to.

Copy an Extent

If you need to copy data between lattice maps, you should use the copy_extent function. Copies can be done efficiently because the ReadExtent and WriteExtent traits allow lattice maps to define how they would like to be written to or read from.

// Create another map to copy to/from. We use a `ChunkHashMap`, but any map that implements
// `WriteExtent` can be a copy destination, and any map that implements `ReadExtent` can be a
// copy source.
let chunk_shape = Point3i::fill(16);
let builder = ChunkMapBuilder3x1::new(chunk_shape, 0);
let mut other_map = builder.build_with_hash_map_storage();
copy_extent(&subextent, &map, &mut other_map.lod_view_mut(0));
copy_extent(&subextent, &other_map.lod_view(0), &mut map);

// You can even copy from a `Fn(Point3i) -> T`.
copy_extent(&subextent, &Func(|p: Point3i| p.x()), &mut map);