## C Specification

Bits which can be set in VkSubpassDescription::flags, specifying usage of the subpass, are:

typedef enum VkSubpassDescriptionFlagBits {
VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX = 0x00000001,
VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX = 0x00000002,
VK_SUBPASS_DESCRIPTION_FRAGMENT_REGION_BIT_QCOM = 0x00000004,
} VkSubpassDescriptionFlagBits;

## Description

• VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX specifies that shaders compiled for this subpass write the attributes for all views in a single invocation of each vertex processing stage. All pipelines compiled against a subpass that includes this bit must write per-view attributes to the *PerViewNV[] shader outputs, in addition to the non-per-view (e.g. Position) outputs.

• VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX specifies that shaders compiled for this subpass use per-view positions which only differ in value in the x component. Per-view viewport mask can also be used.

• VK_SUBPASS_DESCRIPTION_FRAGMENT_REGION_BIT_QCOM specifies that the framebuffer region is the fragment region, that is, the minimum region dependencies are by pixel rather than by sample, such that any fragment shader invocation can access any sample associated with that fragment shader invocation.

• VK_SUBPASS_DESCRIPTION_SHADER_RESOLVE_BIT_QCOM specifies that the subpass performs shader resolve operations.

 Note Shader resolve operations allow for custom resolve operations, but overdrawing pixels may have a performance and/or power cost. Furthermore, since the contents of any depth stencil attachment or color attachment is undefined at the begining of a shader resolve subpass, any depth testing, stencil testing, or blending which sources these undefined values are also undefined.
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