An example of using GpuArrayBuffer to support platforms without storage buffers (ex: WebGL2)

example.rs

#[derive(Clone, ShaderType)]
struct MyType {
    x: f32,
}

// Create a GPU array buffer
let mut buffer = GpuArrayBuffer::<MyType>::new(&render_device.limits());

// Push some items into it
for i in 0..N {
    // indices is a GpuArrayBufferIndex<MyType> which contains a NonMaxU32
    // index into the array and an Option<NonMaxU32> dynamic offset. If storage
    // buffers are supported, it will be None, else Some with the dynamic
    // offset that needs to be used when binding the bind group. indices should
    // be stored somewhere for later lookup, often associated with an Entity.
    let indices = buffer.push(MyType { x: i as f32 });
}

// Queue writing the buffer contents to VRAM
buffer.write_buffer(&render_device, &render_queue);

// The bind group layout entry to use when creating the pipeline
let binding = 0;
let visibility = ShaderStages::VERTEX;
let bind_group_layout_entry = buffer.binding_layout(
    binding,
    visibility,
    &render_device,
);

// Get the binding resource to make a bind group entry to use when creating the
// bind group
let buffer_binding_resource = buffer.binding()?;

// Get the batch size. This will be None if storage buffers are supported, else
// it is the maximum number of elements that could fit in a batch
let buffer_batch_size = GpuArrayBuffer::<MyType>::batch_size(&render_device.limits());

// Set a shader def with the buffer batch size
if let Some(buffer_batch_size) = buffer_batch_size {
    shader_defs.push(ShaderDefVal::UInt(
        "BUFFER_BATCH_SIZE".into(),
        buffer_batch_size,
    ));
}

some_shader.wgsl

#import bevy_render::instance_index get_instance_index

struct MyType {
    x: f32,
}

// Declare the buffer binding
#ifdef BUFFER_BATCH_SIZE
@group(2) @binding(0) var<uniform> data: array<MyType, #{BUFFER_BATCH_SIZE}u>;
#else
@group(2) @binding(0) var<storage> data: array<MyType>;
#endif

// Access an instance
let my_type = data[get_instance_index(in.instance_index)];

Authored by @superdump