#[repr(C)]
pub enum VertexStepMode {
    Vertex,
    Instance,
}
Expand description

Whether a vertex buffer is indexed by vertex or by instance.

Consider a call to RenderPass::draw like this:

render_pass.draw(vertices, instances)

where vertices is a Range<u32> of vertex indices, and instances is a Range<u32> of instance indices.

For this call, wgpu invokes the vertex shader entry point once for every possible (v, i) pair, where v is drawn from vertices and i is drawn from instances. These invocations may happen in any order, and will usually run in parallel.

Each vertex buffer has a step mode, established by the step_mode field of its VertexBufferLayout, given when the pipeline was created. Buffers whose step mode is Vertex use v as the index into their contents, whereas buffers whose step mode is Instance use i. The indicated buffer element then contributes zero or more attribute values for the (v, i) vertex shader invocation to use, based on the VertexBufferLayout’s attributes list.

You can visualize the results from all these vertex shader invocations as a matrix with a row for each i from instances, and with a column for each v from vertices. In one sense, v and i are symmetrical: both are used to index vertex buffers and provide attribute values. But the key difference between v and i is that line and triangle primitives are built from the values of each row, along which i is constant and v varies, not the columns.

An indexed draw call works similarly:

render_pass.draw_indexed(indices, base_vertex, instances)

The only difference is that v values are drawn from the contents of the index buffer—specifically, the subrange of the index buffer given by indices—instead of simply being sequential integers, as they are in a draw call.

A non-instanced call, where instances is 0..1, is simply a matrix with only one row.

Corresponds to WebGPU GPUVertexStepMode.

Variants§

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Vertex

Vertex data is advanced every vertex.

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Instance

Vertex data is advanced every instance.

Trait Implementations§

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impl Clone for VertexStepMode

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fn clone(&self) -> VertexStepMode

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for VertexStepMode

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

Formats the value using the given formatter. Read more
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impl Default for VertexStepMode

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fn default() -> VertexStepMode

Returns the “default value” for a type. Read more
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impl<'de> Deserialize<'de> for VertexStepMode

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fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl Hash for VertexStepMode

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fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl PartialEq<VertexStepMode> for VertexStepMode

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fn eq(&self, other: &VertexStepMode) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Serialize for VertexStepMode

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fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl Copy for VertexStepMode

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impl Eq for VertexStepMode

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impl StructuralEq for VertexStepMode

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impl StructuralPartialEq for VertexStepMode

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> DeserializeOwned for Twhere T: for<'de> Deserialize<'de>,