1# gl_ClipDistance extension support in Metal back-end 2 3OpenGL GLSL's `gl_ClipDistance` is equivalent to `[[clip_distance]]` attribute in the Metal Shading 4Language. However, OpenGL supports disabling/enabling individual `gl_ClipDistance[i]` on the API 5level side. Writing to `gl_ClipDistance[i]` in shader will be ignored if it is disabled. Metal 6doesn't have any equivalent API to disable/enable the writing, though writing to a `clip_distance` 7variable automatically enables it. 8 9To emulate this enabling/disabling API, the Metal back-end uses a similar implementation as what 10[Vulkan back-end does](../../vulkan/doc/APPLE_clip_distance.md). Please refer to that document for 11more details. 12