include::meta/VK_EXT_line_rasterization.txt[]

*Last Modified Date*::
    2019-05-09
*IP Status*::
    No known IP claims.
*Contributors*::
  - Jeff Bolz, NVIDIA
  - Allen Jensen, NVIDIA
  - Jason Ekstrand, Intel

This extension adds some line rasterization features that are commonly used
in CAD applications and supported in other APIs like OpenGL.
Bresenham-style line rasterization is supported, smooth rectangular lines
(coverage to alpha) are supported, and stippled lines are supported for all
three line rasterization modes.

=== New Enum Constants

  * Extending elink:VkStructureType:
  ** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_LINE_RASTERIZATION_FEATURES_EXT
  ** ename:VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_LINE_STATE_CREATE_INFO_EXT

  * Extending elink:VkDynamicState:
  ** ename:VK_DYNAMIC_STATE_LINE_STIPPLE_EXT

=== New Enums

  * elink:VkLineRasterizationModeEXT

=== New Structures

  * slink:VkPhysicalDeviceLineRasterizationFeaturesEXT
  * slink:VkPipelineRasterizationLineStateCreateInfoEXT

=== New Functions

  * flink:vkCmdSetLineStippleEXT

=== Issues

 (1) Do we need to support Bresenham-style and smooth lines with more than
     one rasterization sample? i.e. the equivalent of
     glDisable(GL_MULTISAMPLE) in OpenGL when the framebuffer has more than
     one sample?

  RESOLVED: Yes.
  For simplicity, Bresenham line rasterization carries forward a few
  restrictions from OpenGL, such as not supporting per-sample shading, alpha
  to coverage, or alpha to one.

=== Version History

  * Revision 1, 2019-05-09 (Jeff Bolz)
    - Initial draft