Module sampling 

Texture bindings for the image paint.

Why every draw binds a texture

The shader is one program serving every material kind, so it declares the texture and sampler whether a given draw samples them or not. Vulkan wants every descriptor a pipeline statically uses to be bound, and “statically uses” does not care that the branch reading it is unreachable for a solid fill. The alternatives are a pipeline variant per material kind, which multiplies the cache by four to avoid one binding, or leaving the descriptor unbound, which is invalid. So a draw that samples nothing binds a one-pixel placeholder instead.

Why one sampler rather than one per tile mode

Address modes are a property of the paint, and baking them into samplers would mean a sampler per combination and a descriptor set per draw that used a different one. The shader does the wrapping arithmetic itself and the sampler stays fixed at clamp-to-edge, which also keeps repeat and decal from depending on filtering behavior at the seam.

Structs

Bindings

Descriptor sets and image views for one submission.

Functions

build

Build the bindings a batch needs from the table it was given.

create_descriptor_layout

The descriptor set layout every pipeline is built against.

create_placeholder_binding

The pool, view and set for the placeholder texture.

create_sampler

The one sampler every image draw uses.

image_binding

Which binding number the indexth texture a program declares occupies.

transition_for_sampling

Move every texture a batch samples into the layout a shader reads from.