Function createDynamicTexture

Create a blank, immediately-sampleable DynamicTexture2D of width × height whose pixels are pushed on demand with updateDynamicTexture. Reads as transparent black until the first update.

The texture is created with TEXTURE_BINDING | COPY_DST | RENDER_ATTACHMENT usage — copyExternalImageToTexture (used by the update helper) requires both COPY_DST and RENDER_ATTACHMENT on the destination, and the render attachment is also what the mipmap-blit pass writes into.