Safe Haskell | None |
---|---|
Language | Haskell2010 |
Name
VK_QCOM_render_pass_transform - device extension
VK_QCOM_render_pass_transform
- Name String
VK_QCOM_render_pass_transform
- Extension Type
- Device extension
- Registered Extension Number
- 283
- Revision
- 1
- Extension and Version Dependencies
- Requires Vulkan 1.0
- Requires
VK_KHR_swapchain
- Requires
VK_KHR_surface
- Contact
Other Extension Metadata
- Last Modified Date
- 2020-10-15
- Interactions and External Dependencies
- This extension requires
VK_KHR_swapchain
- This extension interacts with
VK_EXT_fragment_density_map
- This extension requires
- Contributors
- Jeff Leger, Qualcomm Technologies, Inc.
- Brandon Light, Qualcomm Technologies, Inc.
Description
This extension provides a mechanism for applications to enable driver support for render pass transform.
Mobile devices can be rotated and mobile applications need to render properly when a device is held in a landscape or portrait orientation. When the current orientation differs from the device’s native orientation, a rotation is required so that the "up" direction of the rendered scene matches the current orientation.
If the Display Processing Unit (DPU) doesnt natively support rotation, the Vulkan presentation engine can handle this rotation in a separate composition pass. Alternatively, the application can render frames "pre-rotated" to avoid this extra pass. The latter is preferred to reduce power consumption and achieve the best performance because it avoids tasking the GPU with extra work to perform the copy/rotate operation.
Unlike OpenGL ES, the burden of pre-rotation in Vulkan falls on the application. To implement pre-rotation, applications render into swapchain images matching the device native aspect ratio of the display and "pre-rotate" the rendering content to match the device’s current orientation. The burden is more than adjusting the Model View Projection (MVP) matrix in the vertex shader to account for rotation and aspect ratio. The coordinate systems of scissors, viewports, derivatives and several shader built-ins may need to be adapted to produce the correct result.
It is difficult for some game engines to manage this burden; many chose to simply accept the performance/power overhead of performing rotation in the presentation engine.
This extension allows applications to achieve the performance benefits of pre-rotated rendering by moving much of the above-mentioned burden to the graphics driver. The following is unchanged with this extension:
- Applications create a swapchain matching the native orientation of
the display. Applications must also set the
SwapchainCreateInfoKHR
::preTransform
equal to thecurrentTransform
as returned bygetPhysicalDeviceSurfaceCapabilitiesKHR
.
The following is changed with this extension:
- At
cmdBeginRenderPass
, the application provides extension structRenderPassTransformBeginInfoQCOM
specifying the render pass transform parameters. - At
beginCommandBuffer
for secondary command buffers, the application provides extension structCommandBufferInheritanceRenderPassTransformInfoQCOM
specifying the render pass transform parameters. - The
renderArea
, viewPorts and scissors are all provided in the current (non-rotated) coordinate system. The implementation will transform those into the native (rotated) coordinate system. - The implementation is responsible for transforming shader built-ins
(
FragCoord
,PointCoord
,SamplePosition
, interpolateAt(), dFdx, dFdy, fWidth) into the rotated coordinate system. - The implementation is responsible for transforming
position
to the rotated coordinate system.
New Structures
New Enum Constants
QCOM_RENDER_PASS_TRANSFORM_SPEC_VERSION
Extending
RenderPassCreateFlagBits
:Extending
StructureType
:
Issues
1) Some early Adreno drivers (October 2019 through March 2020) advertised support for this extension but expected VK_STRUCTURE_TYPE values different from those in the vukan headers. To cover all Adreno devices on the market, applications need to detect the driver version and use the appropriate VK_STRUCTURE_TYPE values from the table below.
The driver version reported in VkPhysicalDeviceProperties.driverVersion
is a uint32_t
type. You can decode the uint32_t
value into a
major.minor.patch version as shown below:
uint32_t major = ((driverVersion) >> 22); uint32_t minor = ((driverVersion) >> 12) & 0x3ff); uint32_t patch = ((driverVersion) & 0xfff);
If the Adreno major.minor.patch version is greater than or equal to to 512.469.0, then simply use the VK_STRUCTURE_TYPE values as defined in vulkan_core.h. If the version is less than or equal to to 512.468.0, then use the alternate values for the two VK_STRUCTURE_TYPEs in the table below.
Adreno Driver Version | ||
---|---|---|
512.468.0 and earlier | 512.469.0 and later | |
VK_STRUCTURE_TYPE_ RENDER_PASS_TRANSFORM_BEGIN_INFO_QCOM | 1000282000 | 1000282001 |
VK_STRUCTURE_TYPE_ COMMAND_BUFFER_INHERITANCE_RENDER_PASS_TRANSFORM_INFO_QCOM | 1000282001 | 1000282000 |
Adreno
Driver Requirements
2) Should the extension support only rotations (e.g. 90, 180, 270-degrees), or also mirror transforms (e.g. vertical flips)? Mobile use-cases only require rotation. Other display systems such as projectors might require a flipped transform.
RESOLVED: In this version of the extension, the functionality is restricted to 90, 180, and 270-degree rotations to address mobile use-cases.
3) How does this extension interact with VK_EXT_fragment_density_map?
RESOLVED Some implementations may not be able to support a render pass that enables both renderpass transform and fragment density maps. For simplicity, this extension disallows enabling both features within a single render pass.
4) What should this extension be named?
We considered names such as "rotated_rendering", "pre_rotation" and others. Since the functionality is limited to a render pass, it seemed the name should include "render_pass". While the current extension is limited to rotations, it could be extended to other transforms (like mirror) in the future.
RESOLVED The name "render_pass_transform" seems like the most accurate description of the introduced functionality.
Version History
- Revision 1, 2020-02-05 (Jeff Leger)
See Also
CommandBufferInheritanceRenderPassTransformInfoQCOM
,
RenderPassTransformBeginInfoQCOM
Document Notes
For more information, see the Vulkan Specification
This page is a generated document. Fixes and changes should be made to the generator scripts, not directly.
Synopsis
- data RenderPassTransformBeginInfoQCOM = RenderPassTransformBeginInfoQCOM {}
- data CommandBufferInheritanceRenderPassTransformInfoQCOM = CommandBufferInheritanceRenderPassTransformInfoQCOM {}
- type QCOM_RENDER_PASS_TRANSFORM_SPEC_VERSION = 1
- pattern QCOM_RENDER_PASS_TRANSFORM_SPEC_VERSION :: forall a. Integral a => a
- type QCOM_RENDER_PASS_TRANSFORM_EXTENSION_NAME = "VK_QCOM_render_pass_transform"
- pattern QCOM_RENDER_PASS_TRANSFORM_EXTENSION_NAME :: forall a. (Eq a, IsString a) => a
- newtype SurfaceTransformFlagBitsKHR where
- SurfaceTransformFlagBitsKHR Flags
- pattern SURFACE_TRANSFORM_IDENTITY_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_ROTATE_90_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_ROTATE_180_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_ROTATE_270_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_HORIZONTAL_MIRROR_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_90_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_180_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_270_BIT_KHR :: SurfaceTransformFlagBitsKHR
- pattern SURFACE_TRANSFORM_INHERIT_BIT_KHR :: SurfaceTransformFlagBitsKHR
- type SurfaceTransformFlagsKHR = SurfaceTransformFlagBitsKHR
Documentation
data RenderPassTransformBeginInfoQCOM Source #
VkRenderPassTransformBeginInfoQCOM - Structure describing transform parameters of a render pass instance
Valid Usage
-
transform
must beSURFACE_TRANSFORM_IDENTITY_BIT_KHR
,SURFACE_TRANSFORM_ROTATE_90_BIT_KHR
,SURFACE_TRANSFORM_ROTATE_180_BIT_KHR
, orSURFACE_TRANSFORM_ROTATE_270_BIT_KHR
- The
renderpass
must have been created withRenderPassCreateInfo
::flags
containingRENDER_PASS_CREATE_TRANSFORM_BIT_QCOM
Valid Usage (Implicit)
-
sType
must beSTRUCTURE_TYPE_RENDER_PASS_TRANSFORM_BEGIN_INFO_QCOM
See Also
RenderPassTransformBeginInfoQCOM | |
|
Instances
data CommandBufferInheritanceRenderPassTransformInfoQCOM Source #
VkCommandBufferInheritanceRenderPassTransformInfoQCOM - Structure describing transformed render pass parameters command buffer
Description
When the secondary is recorded to execute within a render pass instance
using cmdExecuteCommands
, the
render pass transform parameters of the secondary command buffer must
be consistent with the render pass transform parameters specified for
the render pass instance. In particular, the transform
and
renderArea
for command buffer must be identical to the transform
and renderArea
of the render pass instance.
Valid Usage (Implicit)
See Also
CommandBufferInheritanceRenderPassTransformInfoQCOM | |
|
Instances
pattern QCOM_RENDER_PASS_TRANSFORM_SPEC_VERSION :: forall a. Integral a => a Source #
type QCOM_RENDER_PASS_TRANSFORM_EXTENSION_NAME = "VK_QCOM_render_pass_transform" Source #
pattern QCOM_RENDER_PASS_TRANSFORM_EXTENSION_NAME :: forall a. (Eq a, IsString a) => a Source #
newtype SurfaceTransformFlagBitsKHR Source #
VkSurfaceTransformFlagBitsKHR - presentation transforms supported on a device
See Also
CommandBufferInheritanceRenderPassTransformInfoQCOM
,
CopyCommandTransformInfoQCOM
,
DisplaySurfaceCreateInfoKHR
,
RenderPassTransformBeginInfoQCOM
,
SurfaceCapabilities2EXT
,
SurfaceCapabilitiesKHR
, SurfaceTransformFlagsKHR
,
SwapchainCreateInfoKHR