## C Specification

Information about the layout of the image subresource is returned in a VkSubresourceLayout structure:

typedef struct VkSubresourceLayout {
VkDeviceSize    offset;
VkDeviceSize    size;
VkDeviceSize    rowPitch;
VkDeviceSize    arrayPitch;
VkDeviceSize    depthPitch;
} VkSubresourceLayout;

## Members

• offset is the byte offset from the start of the image or the plane where the image subresource begins.

• size is the size in bytes of the image subresource. size includes any extra memory that is required based on rowPitch.

• rowPitch describes the number of bytes between each row of texels in an image.

• arrayPitch describes the number of bytes between each array layer of an image.

• depthPitch describes the number of bytes between each slice of 3D image.

## Description

If the image is linear, then rowPitch, arrayPitch and depthPitch describe the layout of the image subresource in linear memory. For uncompressed formats, rowPitch is the number of bytes between texels with the same x coordinate in adjacent rows (y coordinates differ by one). arrayPitch is the number of bytes between texels with the same x and y coordinate in adjacent array layers of the image (array layer values differ by one). depthPitch is the number of bytes between texels with the same x and y coordinate in adjacent slices of a 3D image (z coordinates differ by one). Expressed as an addressing formula, the starting byte of a texel in the image subresource has address:

// (x,y,z,layer) are in texel coordinates
address(x,y,z,layer) = layer*arrayPitch + z*depthPitch + y*rowPitch + x*elementSize + offset

For compressed formats, the rowPitch is the number of bytes between compressed texel blocks in adjacent rows. arrayPitch is the number of bytes between compressed texel blocks in adjacent array layers. depthPitch is the number of bytes between compressed texel blocks in adjacent slices of a 3D image.

// (x,y,z,layer) are in compressed texel block coordinates
address(x,y,z,layer) = layer*arrayPitch + z*depthPitch + y*rowPitch + x*compressedTexelBlockByteSize + offset;

The value of arrayPitch is undefined for images that were not created as arrays. depthPitch is defined only for 3D images.

If the image has a single-plane color format and its tiling is VK_IMAGE_TILING_LINEAR , then the aspectMask member of VkImageSubresource must be VK_IMAGE_ASPECT_COLOR_BIT.

If the image has a depth/stencil format and its tiling is VK_IMAGE_TILING_LINEAR , then aspectMask must be either VK_IMAGE_ASPECT_DEPTH_BIT or VK_IMAGE_ASPECT_STENCIL_BIT. On implementations that store depth and stencil aspects separately, querying each of these image subresource layouts will return a different offset and size representing the region of memory used for that aspect. On implementations that store depth and stencil aspects interleaved, the same offset and size are returned and represent the interleaved memory allocation.

If the image has a multi-planar format and its tiling is VK_IMAGE_TILING_LINEAR , then the aspectMask member of VkImageSubresource must be VK_IMAGE_ASPECT_PLANE_0_BIT, VK_IMAGE_ASPECT_PLANE_1_BIT, or (for 3-plane formats only) VK_IMAGE_ASPECT_PLANE_2_BIT. Querying each of these image subresource layouts will return a different offset and size representing the region of memory used for that plane. If the image is disjoint, then the offset is relative to the base address of the plane. If the image is non-disjoint, then the offset is relative to the base address of the image.

If the image’s tiling is VK_IMAGE_TILING_DRM_FORMAT_MODIFIER_EXT, then the aspectMask member of VkImageSubresource must be one of VK_IMAGE_ASPECT_MEMORY_PLANE_i_BIT_EXT, where the maximum allowed plane index i is defined by the drmFormatModifierPlaneCount associated with the image’s format and modifier. The memory range used by the subresource is described by offset and size. If the image is disjoint, then the offset is relative to the base address of the memory plane. If the image is non-disjoint, then the offset is relative to the base address of the image. If the image is non-linear, then rowPitch, arrayPitch, and depthPitch have an implementation-dependent meaning.