Struct DeformerDesc 

pub struct DeformerDesc {
    pub name: &'static str,
    pub stage: DeformStage,
    pub priority: i32,
    pub wgsl_body: String,
    pub per_vertex_stride: u32,
}

Description of a deformer to register against the mesh shader family.

wgsl_body defines:

fn <name>_deform(v: DeformVertex, ctx: DeformContext) -> DeformVertex { ... }

The composer prefixes every top-level identifier it finds inside wgsl_body with <name>__ to keep multiple deformers independent. The body may read deform_data / deform_instance_data via the deform_read_* helpers in deform.wgsl, and read its slot’s parameter region via deform_header.slot_params[ctx.slot * 4 + k].

Hook contract

The shipped deform.wgsl declares:

struct DeformVertex {
    position: vec3<f32>,
    normal: vec3<f32>,
    vertex_index: u32,
};

struct DeformContext {
    model: mat4x4<f32>,
    object_origin: vec3<f32>,
    time_seconds: f32,
    flags: u32,
    slot: u32,
};

These signatures are stable: additive changes only. Existing fields will not be renamed, retyped, or removed. New fields may be appended; bodies compiled against an older view continue to work because the WGSL struct init they don’t touch is filled by the caller.

position is object-space on entry to an ObjectSpace body and world-space on entry to a WorldSpace body. vertex_index is the @builtin(vertex_index) from the vertex stage. ctx.slot is the slot the registry assigned to this deformer; use it to address deform_data and deform_instance_data rather than baking in a literal.

Composition order

Deformers run in two stages: every DeformStage::ObjectSpace body first, then every DeformStage::WorldSpace body. Within a stage, bodies execute in ascending priority (lower runs first); ties break by name. The in-crate skinning deformer registers at DEFORM_PRIORITY_SKINNING = -1000 so morph-class deformers registered at the default priority of 0 run after it. This ordering is part of the contract: a body that wants to run before skinning must register with a priority strictly less than -1000.

Pass scope

Every registered deformer runs in every mesh-family pass: the main solid and transparent passes, the OIT accumulate pass, the instanced and instanced-OIT pipelines, the shadow pass, and the outline-mask pass. A deformer cannot opt out of a single pass; the composed pipeline is shared across them.

In particular: shadows always deform. A skinned or wind-swept mesh casts a shadow that matches its deformed silhouette. The outline mask follows the deformed silhouette for the same reason. GPU picking, which uses the same mesh family, picks the deformed mesh.

Bodies that have nothing to do for a draw (no slot data attached, flag bit clear) are gated off by the per-slot flag branch the composer wraps the call in, so the cost on undeformed draws is the branch predicate, not the body.

Fields

name: &'static str

Deformer name. Must be a valid WGSL identifier and unique across the registry. The composer uses it as the prefix for every top-level declaration spliced from wgsl_body.

stage: DeformStage

Which side of the model transform the body runs on.

priority: i32

Execution order within the stage; lower runs first. Ties break by name.

wgsl_body: String

WGSL body defining fn <name>_deform(v: DeformVertex, ctx: DeformContext) -> DeformVertex plus any helper declarations. All top-level identifiers in this body are prefixed with <name>__ at composition time.

per_vertex_stride: u32

Bytes per vertex in the slot storage buffer (validated on attach).

Trait Implementations

impl Clone for DeformerDesc

fn clone(&self) -> DeformerDesc

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DeformerDesc

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.