Struct InstanceContext 

pub struct InstanceContext<'a> {
    pub world: Scope<'a>,
    pub entity: Entity,
    pub world_from_local: Affine3A,
    joints: &'a mut Vec<JointMatrix>,
    morph_weights: &'a mut Vec<f32>,
}

Everything a family may read – and the frame arrays it may append to – while it writes one instance record.

The record is the family’s own: the built-in lit family builds a MeshInstance, while a caller’s family writes whatever its pipeline’s instance-step attributes declare, reading the components it needs from the world. Culling resolved only the entity and its placement; what else a draw carries, the family decides here.

Skin poses and morph weights are two independent things, each with its own frame array and its own pack method. A family that reads neither calls neither; a family that needs one packs only that one.

Fields

world: Scope<'a>

The scope the entity is drawn through, for per-entity components.

It is the drawing source’s own scope, so a family reads the components of the subtree that source owns rather than of the whole world.

entity: Entity

The entity the record is for.

world_from_local: Affine3A

The entity’s world transform, resolved by culling.

joints: &'a mut Vec<JointMatrix>

The frame’s joint matrices, appended to by Self::pack_joints.

morph_weights: &'a mut Vec<f32>

The frame’s morph weights, appended to by Self::pack_morph_weights.

Implementations

impl<'a> InstanceContext<'a>

pub(crate) fn new( world: Scope<'a>, entity: Entity, world_from_local: Affine3A, joints: &'a mut Vec<JointMatrix>, morph_weights: &'a mut Vec<f32>, ) -> Self

Build a context for one entity from the frame’s two growing arrays.

pub fn pack_joints(&mut self) -> u32

Append this entity’s joint matrices to the frame’s array and return the index its slice starts at.

The matrices come from the SkinPose of the entity this one names with a SkinBinding. A family calls this only for a skinned mesh, and puts the returned base into the record field its shader reads.

Panics

If the entity names no pose entity, if that entity carries no SkinPose, or if the pose is empty.

pub fn pack_morph_weights(&mut self, targets: u32) -> u32

Append this entity’s morph weights to the frame’s array and return the index its slice starts at.

The weights come from the MorphWeights of the entity this one names with a MorphBinding. targets is the mesh’s target count, which the weights must match. A family calls this only for a morphed mesh, and puts the returned base into the record field its shader reads.

Panics

If the entity names no weights entity, if that entity carries no MorphWeights, or if the weight count does not match targets.