Update instanced buffer attributes array breaks in webGPU

[Samsy]

Description

1 ) Create an instancedgeometry

2 ) fill it with instancedattributes

3 ) update with new values later

This works in WebGL, but not in WebGPU

This is exactly the break :

OperationError: Failed to execute 'writeBuffer' on 'GPUQueue': Number of bytes to write is too large

My guess is, once the buffer is created, it cannot be replaced ?

Live example

Live fiddle

Uncomment the line 81

Version

last

Device

Desktop

Browser

Chrome

OS

MacOS

[holtsetio]

The issue is this function call in WebGPUAttributeUtils.js:

device.queue.writeBuffer(
	buffer,
	0,
	array,
	range.start * array.BYTES_PER_ELEMENT,
	range.count * array.BYTES_PER_ELEMENT
);

According to the WebGPU API, the writeBuffer command treats the last two arguments (dataOffset and size) as number of elements if the array is a TypedArray, not as number of bytes. So the multiplication by array.BYTES_PER_ELEMENT is wrong and causes the error.

As a dirty workaround until it is fixed you can just not specify an update range or divide the start and count by array.BYTES_PER_ELEMENT.

[RenaudRohlinger]

Fixed with #29967.

Thanks!