The copyTextureToBuffer() method of the GPUCommandEncoder interface encodes a command that copies data from a GPUTexture to a GPUBuffer.

source

An object defining the texture to copy the data from. Combined with copySize, defines the region of the source texture subresource. source can take the following properties:

aspect Optional

An enumerated value defining which aspects of the texture to copy the data from. Possible values are:

"all"

All available aspects of the texture format will be copied from, which can mean all or any of color, depth, and stencil, depending on what kind of format you are dealing with.

"depth-only"

Only the depth aspect of a depth-or-stencil format will be copied from.

"stencil-only"

Only the stencil aspect of a depth-or-stencil format will be copied from.

If omitted, aspect takes a value of "all".

mipLevel Optional

A number representing the mip-map level of the texture to copy the data from. If omitted, mipLevel defaults to 0.

origin Optional

An object or array specifying the origin of the copy — the minimum corner of the texture region to copy the data from. Together with size, this defines the full extent of the region to copy from. The x, y, and z values default to 0 if any of all of origin is omitted.

What follows is a sample array:

js

[0, 0, 0];

The object equivalent would look like this:

js

{
  x: 0,
  y: 0,
  z: 0
}

texture

A GPUTexture object representing the texture to copy the data from.

destination

An object that defines the buffer to write to, plus the layout of the data to write to the buffer. Combined with copySize, it defines the region of the destination buffer. source can take the following properties:

buffer

The GPUBuffer to write to.

offset Optional

The offset, in bytes, from the beginning of data to the start position to write the copied data to. If omitted, offset defaults to 0.

bytesPerRow Optional

A number representing the stride, in bytes, between the start of each block row (i.e. a row of complete texel blocks) and the subsequent block row. This is required if there are multiple block rows (i.e. the copy height or depth is more than one block).

rowsPerImage Optional

The number of block rows per single image inside the data. bytesPerRow × rowsPerImage will give you the stride, in bytes, between the start of each complete image. This is required if there are multiple images to copy.

copySize

An object or array specifying the width, height, and depth/array layer count of the copied data. The width value must always be specified, while the height and depth/array layer count values are optional and will default to 1 if omitted.

What follows is a sample copySize array:

js

[16, 16, 2];

The object equivalent would look like this:

js

{
  width: 16,
  height: 16,
  depthOrArrayLayers: 2
}

None (Undefined).

The following criteria must be met when calling copyTextureToBuffer(), otherwise a GPUValidationError is generated and the GPUCommandEncoder becomes invalid.

For the source:

• mipLevel is less than the GPUTexture.mipLevelCount.
• origin.x is a multiple of the texel block width of the GPUTexture.format.
• origin.y is a multiple of the texel block height of the GPUTexture.format.
• If the GPUTexture.format is a depth-or-stencil format or GPUTexture.sampleCount is more than 1, the subresource size is equal to size.
• The source's GPUTexture.usage includes the GPUTextureUsage.COPY_SRC flag.
• The source's GPUTexture.sampleCount is 1.
• source.aspect refers to a single aspect of the GPUTexture.format.
• That aspect is a valid image copy source according to depth-or-stencil formats.
• The source is compatible with the copySize.

For the destination:

• destination.bytesPerRow is a multiple of 256.
• The destination.buffer's GPUBuffer.usage includes the GPUBufferUsage.COPY_DST flag.

• The WebGPU API