1include::meta/VK_EXT_conservative_rasterization.txt[] 2 3*Last Modified Data*:: 4 2017-08-28 5*Contributors*:: 6 - Daniel Koch, NVIDIA 7 - Daniel Rakos, AMD 8 - Jeff Bolz, NVIDIA 9 - Slawomir Grajewski, Intel 10 - Stu Smith, Imagination Technologies 11 12This extension adds a new rasterization mode called conservative 13rasterization. 14There are two modes of conservative rasterization; overestimation and 15underestimation. 16 17When overestimation is enabled, if any part of the primitive, including its 18edges, covers any part of the rectangular pixel area, including its sides, 19then a fragment is generated with all coverage samples turned on. 20This extension allows for some variation in implementations by accounting 21for differences in overestimation, where the generating primitive size is 22increased at each of its edges by some sub-pixel amount to further increase 23conservative pixel coverage. 24Implementations can allow the application to specify an extra overestimation 25beyond the base overestimation the implementation already does. 26It also allows implementations to either cull degenerate primitives or 27rasterize them. 28 29When underestimation is enabled, fragments are only generated if the 30rectangular pixel area is fully covered by the generating primitive. 31If supported by the implementation, when a pixel rectangle is fully covered 32the fragment shader input variable builtin called FullyCoveredEXT is set to 33true. 34The shader variable works in either overestimation or underestimation mode. 35 36Implementations can process degenerate triangles and lines by either 37discarding them or generating conservative fragments for them. 38Degenerate triangles are those that end up with zero area after the 39rasterizer quantizes them to the fixed-point pixel grid. 40Degenerate lines are those with zero length after quantization. 41 42=== New Object Types 43 44None. 45 46=== New Enum Constants 47 48 * Extending elink:VkStructureType: 49 50 ** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_CONSERVATIVE_RASTERIZATION_PROPERTIES_EXT 51 ** ename:VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_CONSERVATIVE_STATE_CREATE_INFO_EXT 52 53=== New Enums 54 55 * elink:VkPipelineRasterizationConservativeStateCreateFlagsEXT 56 * elink:VkConservativeRasterizationModeEXT 57 58=== New Structures 59 60 * slink:VkPhysicalDeviceConservativeRasterizationPropertiesEXT 61 * slink:VkPipelineRasterizationConservativeStateCreateInfoEXT 62 63=== New Functions 64 65None. 66 67=== Issues 68 69None. 70 71=== Version History 72 73 * Revision 1, 2017-08-28 (Piers Daniell) 74 - Internal revisions 75