CODEWITHSUNDEEP
vulkan
Aedoro
Aedoro

Reputation: 898

Reading and writing the same (depth) attachment in a subpass

I am trying to use light volumes for my deferred renderer. But i come across a problem with stencil operations. Right now i am using a depth/stencil attachment with format VK_FORMAT_D32_SFLOAT_S8_UINT. In the lighting subpass i need to read the depth to reconstruct position, and read and write the stencil to mask the light volume. To the lighting subpass I want to add the depth/stencil as an input attachment, and as a depth attachment, but these require different layout which are obviously not possible at the same time.

Right now i am referring to the same attachment both as an input attachment and a depth attachment in the same subpass. As input attachment the layout is VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL and as depth attachment the layout is VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL (giving no validation errors?), and my stencil operations are not executed.

Now i could create two different attachments for depth and stencil, but that would possibly use more memory, which is not great either. So my question is, how do you setup a subpass where you can read and write the same depth/stencil attachment? (within a single pipeline as well)

Upvotes: 2

Views: 1286

Answers (1)

Nicol Bolas
Nicol Bolas

Reputation: 474506

but these require different layout

Nonsense; that's what the GENERAL layout is for. The specification even explicitly brings that up:

An attachment used as both an input attachment and depth/stencil attachment must be in either the VK_IMAGE_LAYOUT_GENERAL or VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL layout

Obviously the latter is not helpful for you ;)

Upvotes: 3

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