Vulkan Compatibility

[msiglreith]

Meta issue about the current missing features of gfx-rs compared to Vulkan (Core) API:

• Physical Device Physical Device Information #1671:

  • Adapter limits and features (easy): Adapter features #1553
    Expose all limits from Vulkan and improve implementation for other backends.

  • Adapter Info (easy):
    Add missing fields from PhysicalDeviceInfo

  • Physical device limits (med) Allow device information acquisition on physical devices #1682:
    Move Limits from Device into AdapterInfo following Vulkan.
    Depending on adapter limits implementation.
    OpenGL only exposes single adapter so we can just create a context here, depending on Place of GL backend in the new low-level world #1539 (comment)
    DX12 might require temporarily create and destroy device again.

  • Queue families (easy):
    Add missing queue family properties (timestampValidBits, minImageTransferGranularity)
    minImageTransferGranularity arbitrary for transfer (0, 0, 0) for whole mipmaps
    (1, 1, 1) for Compute or Graphics -> compute shader required for DX12 (metal?)

• Support queue priorities (easy) hal: Custom queue priorities #1618

• Support more formats (easy?) Refactor formats and tweak buffer-image copies #1700

• Query supported formats for device (easy-med) Physical Device Information #1671
  Might depend a bit on how other physical device/device queries are implemented

• Command Buffers

  • Secondary command buffers (hard):
    Expose buffer level Reusable and Secondary command buffers #1712
    Inheritance info on buffer begin
    cmd_execute_commands Reusable and Secondary command buffers #1712

  • Buffer usage flags: Reusable and Secondary command buffers #1712
    OneTimeSubmit (Easy)
    Simultaneous usage (Hard?)
    RenderPassContinue (Easy)

• Blit command (hard)
  Requires emulation via shaders

• Synchronization

  • (Memory barriers (hard)) [ll] Memory Barriers portability #1498
    Difficult for global memory barriers due to RESOURCE_STATES not changing, issue?
    Queue ownership transfer

  • Query fence status (Easy?) [hal][Vulkan][Metal][Empty] Add get_fence_status method to Device trait #1635

  • Events Add Events API and implement for Vulkan backend #2806

  • Subpass self-dependencies (med)

  • Queue wait idle (med) Add wait_idle #1773

• Renderpass

  • Renderpass image resolves (med)

  • Renderpass implicit subpass dependencies:
    Depends on global memory barriers (hard)

  • Query render area granularity (easy?) Query optimal renderpass area #1558
    Lacks a bit of information on this topic
    Might require a bit of research in kind of exposed values on different devices (discrete, integrated, tilers)

• Pipeline

  • Geometry/Tessellation support (hard)

  • Early fragment test (med) HLSL: Support early_fragment_tests attribute KhronosGroup/SPIRV-Cross#337

  • Pipeline caches (hard)

  • Pipeline derives (med) Pipeline deriving #1620

  • Pipeline specialization constants (hard) Specialization constants #1634
    Might require SPIR-V inspection and SPIRV-Cross support

  • Disable pipeline optimization (easy) Pipeline deriving #1620

  • Graphics pipeline dynamic states (med) Dynamic Pipeline States #1567

  • Concurrent pipeline bind points (hard) d3d12: Refactor pipeline layouts to match Vulkan's compatibility rules. #1632
    Allow to handle graphics and compute bind points independently.
    Hard on DX12 which will overwrite pipeline bind points.
    Evaluate performance overhead/implications.

• Multisampling (hard) Multisampling support #1542

• Memory

  • Host memory allocator (hard):
    Allow registration of custom memory allocators

  • Host memory access (hard) dx12/vk: Implement vulkan based memory mapping #1718
    Vulkan allows persistent mapping of whole buffers and no nested mapping.
    Flush and invalidation for visibility for non-coherent memory types.
    Doesn't map very well to DX12 and Metal, need to find consensus by on Vulkan Portability TSG

  • Lazily allocated memory (easy?) Transient textures. #1390
    Only supported on Vulkan (?), others can just not expose it.
    Add function to query memory commitment

  • Resource sharing (hard)

• Resources

  • Compatible image view formats (med)
    DX12 has some restrictions on the supported image view formats to be compatible.
    Requires consensus by VkPortability TSG

  • (Component swizzling?)

  • Sampler states (easy-med) Support Min/Mag filter for samplers #1404
    Check all sampler configuration fields

  • Add missing descriptor types (hard)
    Dynamic descriptors and Combined image-samplers

  • Push Constants (med) Push constants! #1622 [RFC] Push constants in D3D12 #1625

• Query pools and commands (med-hard) (In progess @msiglreith) [RFC] Query resolve #1638 Query operations #1640

• Sparse resources (hard)

• Slightly unrelated

  • Readonly Storage buffers/images (med):
    Optimization for rust orientated libs and possibly gpuweb
    Allows more fine granular pipeline barriers