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.
Pull Request: https://projects.blender.org/blender/blender/pulls/124407
Jeroen Bakker
ca0e1d696a