Vulkan: Layer tracking during render scope #124407

Jeroen Bakker · 2024-07-09T13:35:43+02:00

Jeroen Bakker commented

2024-07-09 13:35:43 +02:00

EEVEE can bind layers of a texture that is also used as an attachment. When binding
the image layout of these specific layers can be different that the image layout of
the whole image.

This fixes the known synchronization issues inside EEVEE. wasp_bot, tree_creature and
wanderer scenes can be rendered without any synchronization issue reported by the
Vulkan validation layers.

Design task: #124214

When beginning to render the attachments are being evaluated. If there is an arrayed
texture (with multiple layers) the individual layers of that texture can be tracked
during until the rendering is ended.

When the same texture is bound to a shader it will be a different layer (otherwise
there is a feedback loop, which isn't allowed). The bound layers will typically need
a different layout the transition to the new layout is executed and recorded. When
the rendering ends, the layers are transitioned back to the layout the texture is
expected in.

It can happen that a layer is used multiple times during the same rendering. In
that case the rendering should be suspended to perform the transition. Image layout
transitions are not allowed during rendering.

There is one place where a layer needs to be transited multiple times that is when
EEVEE wants to extract the thickness from the shadow. The thickness is stored inside
the gbuffer_normal which is also used as an attachment. Eval then samples the thickness
from the gbuffer_normal as a sampler. To work around this issue we suspend the rendering
when a GPU_BARRIER_SHADER_IMAGE_ACCESS is signaled.

EEVEE can bind layers of a texture that is also used as an attachment. When binding the image layout of these specific layers can be different that the image layout of the whole image. This fixes the known synchronization issues inside EEVEE. wasp_bot, tree_creature and wanderer scenes can be rendered without any synchronization issue reported by the Vulkan validation layers. Design task: #124214 When beginning to render the attachments are being evaluated. If there is an arrayed texture (with multiple layers) the individual layers of that texture can be tracked during until the rendering is ended. When the same texture is bound to a shader it will be a different layer (otherwise there is a feedback loop, which isn't allowed). The bound layers will typically need a different layout the transition to the new layout is executed and recorded. When the rendering ends, the layers are transitioned back to the layout the texture is expected in. It can happen that a layer is used multiple times during the same rendering. In that case the rendering should be suspended to perform the transition. Image layout transitions are not allowed during rendering. There is one place where a layer needs to be transited multiple times that is when EEVEE wants to extract the thickness from the shadow. The thickness is stored inside the gbuffer_normal which is also used as an attachment. Eval then samples the thickness from the gbuffer_normal as a sampler. To work around this issue we suspend the rendering when a `GPU_BARRIER_SHADER_IMAGE_ACCESS` is signaled.

Jeroen Bakker added this to the 4.3 milestone 2024-07-09 13:35:43 +02:00

Jeroen Bakker added the

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Vulkan: Layer tracking during render scope #124407