| // Copyright (c) 2016-2018 Khronos Group. This work is licensed under a |
| // Creative Commons Attribution 4.0 International License; see |
| // http://creativecommons.org/licenses/by/4.0/ |
| |
| include::meta/VK_KHR_variable_pointers.txt[] |
| |
| *Last Modified Date*:: |
| 2017-09-05 |
| *IP Status*:: |
| No known IP claims. |
| *Interactions and External Dependencies*:: |
| - Requires the |
| https://www.khronos.org/registry/spir-v/extensions/KHR/SPV_KHR_variable_pointers.html[+SPV_KHR_variable_pointers+] |
| SPIR-V extension. |
| - Promoted to Vulkan 1.1 Core |
| *Contributors*:: |
| - John Kessenich, Google |
| - Neil Henning, Codeplay |
| - David Neto, Google |
| - Daniel Koch, Nvidia |
| - Graeme Leese, Broadcom |
| - Weifeng Zhang, Qualcomm |
| - Stephen Clarke, Imagination Technologies |
| - Jason Ekstrand, Intel |
| - Jesse Hall, Google |
| |
| The `VK_KHR_variable_pointers` extension allows implementations to indicate |
| their level of support for the +SPV_KHR_variable_pointers+ SPIR-V extension. |
| The SPIR-V extension allows shader modules to use invocation-private |
| pointers into uniform and/or storage buffers, where the pointer values can |
| be dynamic and non-uniform. |
| |
| The +SPV_KHR_variable_pointers+ extension introduces two capabilities. |
| The first, code:VariablePointersStorageBuffer, must: be supported by all |
| implementations of this extension. |
| The second, code:VariablePointers, is optional. |
| |
| === New Enum Constants |
| |
| * Extending elink:VkStructureType: |
| ** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VARIABLE_POINTER_FEATURES_KHR |
| |
| === New Structures |
| |
| * slink:VkPhysicalDeviceVariablePointerFeaturesKHR |
| |
| === New SPIR-V Capabilities |
| |
| * <<spirvenv-capabilities-table-variablepointers,VariablePointersStorageBuffer>> |
| * <<spirvenv-capabilities-table-variablepointers,VariablePointers>> |
| |
| === Promotion to Vulkan 1.1 |
| |
| All functionality in this extension is included in core Vulkan 1.1, with the |
| KHR suffix omitted, however support for the |
| <<features-features-variablePointersStorageBuffer, |
| pname:variablePointersStorageBuffer>> feature is made optional. |
| The original type, enum and command names are still available as aliases of |
| the core functionality. |
| |
| === Issues |
| |
| 1) Do we need an optional property for the SPIR-V |
| code:VariablePointersStorageBuffer capability or should it be mandatory when |
| this extension is advertised? |
| |
| *RESOLVED*: Add it as a distinct feature, but make support mandatory. |
| Adding it as a feature makes the extension easier to include in a future |
| core API version. |
| In the extension, the feature is mandatory, so that presence of the |
| extension guarantees some functionality. |
| When included in a core API version, the feature would be optional. |
| |
| 2) Can support for these capabilities vary between shader stages? |
| |
| *RESOLVED*: No, if the capability is supported in any stage it must be |
| supported in all stages. |
| |
| 3) Should the capabilities be features or limits? |
| |
| *RESOLVED*: Features, primarily for consistency with other similar |
| extensions. |
| |
| === Version History |
| |
| * Revision 1, 2017-03-14 (Jesse Hall and John Kessenich) |
| - Internal revisions |
