Enum wgpu_types::VertexStepMode
source · #[repr(C)]pub enum VertexStepMode {
Vertex = 0,
Instance = 1,
}
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§
Vertex = 0
Vertex data is advanced every vertex.
Instance = 1
Vertex data is advanced every instance.
Trait Implementations§
source§impl Clone for VertexStepMode
impl Clone for VertexStepMode
source§fn clone(&self) -> VertexStepMode
fn clone(&self) -> VertexStepMode
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for VertexStepMode
impl Debug for VertexStepMode
source§impl Default for VertexStepMode
impl Default for VertexStepMode
source§fn default() -> VertexStepMode
fn default() -> VertexStepMode
source§impl Hash for VertexStepMode
impl Hash for VertexStepMode
source§impl PartialEq for VertexStepMode
impl PartialEq for VertexStepMode
source§fn eq(&self, other: &VertexStepMode) -> bool
fn eq(&self, other: &VertexStepMode) -> bool
self
and other
values to be equal, and is used
by ==
.