Name Strings
SPV_NV_viewport_array2
Contact
To report problems with this extension, please open a new issue at:
Contributors
-
Daniel Koch, NVIDIA
Status
-
Complete
Version
Last Modified Date |
2017-02-15 |
Revision |
2 |
Dependencies
This extension is written against the SPIR-V Specification, Version 1.1 Revision 4.
This extension requires SPIR-V 1.0.
Overview
This extension adds new capabilities to support the OpenGL GL_ARB_shader_viewport_layer_array and GL_NV_viewport_array2 extensions, as well as the Vulkan VK_NV_viewport_array2 extension in SPIR-V.
The new ShaderViewportIndexLayerNV capability allows the Layer and ViewportIndex builtin variables to be exported from Vertex or Tessellation shaders, in addition to Geometry shaders. This is functionality added by both GL_ARB_shader_viewport_layer_array and GL_NV_viewport_array2, and separately by GL_AMD_vertex_shader_layer, and GL_AMD_vertex_shader_viewport_index.
The new ShaderViewportMaskNV capability adds a new ViewportMaskNV builtin variable which can be exported from Vertex, Tessellation, or Geometry shaders. This corresponds to the gl_ViewportMask variable in GLSL. It also adds a new ViewportRelativeNV decoration that corresponds to the viewport_relative layout qualifier that can be applied to the gl_Layer shader output variable in GLSL.
Extension Name
To use this extension within a SPIR-V module, the following OpExtension must be present in the module:
OpExtension "SPV_NV_viewport_array2"
New Capabilities
This extension introduces two new capabilities:
ShaderViewportIndexLayerNV ShaderViewportMaskNV
New Decorations
Decoration added under the ShaderViewportMaskNV capability:
ViewportRelativeNV
New Builtins
A new builtin is added as an ouput for the Vertex, Tessellation, and Geometry Execution Models under the ShaderViewportMaskNV capability:
ViewportMaskNV
The existing Layer and ViewportIndex builtins are extended and may also be used as outputs in the Vertex and Tessellation Execution Models under the ShaderViewportIndexLayerNV capability.
New Instructions
None.
Token Number Assignments
ViewportRelativeNV |
5252 |
ViewportMaskNV |
5253 |
ShaderViewportIndexLayerNV |
5254 |
ShaderViewportMaskNV |
5255 |
Modifications to the SPIR-V Specification, Version 1.1
- (Modify Section 3.20, Decoration, adding a row to the Decoration table)
-
Decoration Enabling Capabilities Extra Operands 5252
ViewportRelativeNV
Apply to a variable. Indicates that the value of the variable decorated with ViewportIndex is added to this variable. Only valid for the Output Storage Class.ShaderViewportMaskNV
- (Modify Section 3.21, BuiltIn)
-
(add a new row to the Builtin table)
BuiltIn Enabling Capabilities 5253
ViewportMaskNV
Output viewport mask in Vertex, Tessellation, or Geometry Execution Model. See Vulkan or OpenGL API specifications for more detail.ShaderViewportMaskNV
(Modify the definition of Layer and ViewportIndex as follows, allowing them to be outputs from Vertex and Tessellation shaders)
BuiltIn Enabling Capabilities 9
Layer
Layer selection for multi-layer framebuffer. See Vulkan or OpenGL API specification for more detail.Layer output by a Geometry Execution Model, input to a Fragment Execution Model.
Geometry
Layer output by a Vertex or Tessellation Execution Model.
ShaderViewportIndexLayerNV
10
ViewportIndex
Viewport selection for viewport transformation when using multipe viewports. See Vulkan or OpenGL API specification for more detail.Viewport Index output by a Geometry Execution Model, input to a Fragment Execution Model.
MultiViewport
Viewport Index output by a Vertex or Tessellation Execution Model.
ShaderViewportIndexLayerNV
- (Modify Section 3.31, Capability, adding new rows to the Capability table)
-
Capability Depends On Enabled by Extension 5254
ShaderViewportIndexLayerNV
MultiViewport
SPV_NV_viewport_array2
5255
ShaderViewportMaskNV
ShaderViewportIndexLayerNV
SPV_NV_viewport_array2
Validation Rules
An OpExtension must be added to the SPIR-V for validation layers to check legal use of this extension:
OpExtension "SPV_NV_viewport_array2"
Issues
None yet!
Revision History
| Rev | Date | Author | Changes |
|---|---|---|---|
1 |
2016-11-25 |
Daniel Koch |
Initial draft |
2 |
2017-02-15 |
Daniel Koch |
Mark Complete, add mention of Vulkan extension |