Make shadow example runnable on iOS Android devices (#2433)

wgpu/examples/shadow/main.rs

@@ -292,9 +292,17 @@ impl framework::Example for Example {
 
  let entity_uniform_size = mem::size_of::<EntityUniforms>() as wgpu::BufferAddress;
  let num_entities = 1 + cube_descs.len() as wgpu::BufferAddress;
- let uniform_alignment =
- device.limits().min_uniform_buffer_offset_alignment as wgpu::BufferAddress;
- assert!(entity_uniform_size <= uniform_alignment);
+ // Make the `uniform_alignment` >= `entity_uniform_size` and aligned to `min_uniform_buffer_offset_alignment`.
+ let uniform_alignment = {
+ let alignment =
+ device.limits().min_uniform_buffer_offset_alignment as wgpu::BufferAddress;
+ let rem = entity_uniform_size % alignment;
+ if rem != 0 {
+ entity_uniform_size + alignment - rem
+ } else {
+ entity_uniform_size
+ }
+ };
  // Note: dynamic uniform offsets also have to be aligned to `Limits::min_uniform_buffer_offset_alignment`.
  let entity_uniform_buf = device.create_buffer(&wgpu::BufferDescriptor {
  label: None,