| Name |
| |
| ANGLE_metal_shared_event_sync |
| |
| Name Strings |
| |
| EGL_ANGLE_metal_shared_event_sync |
| |
| Contributors |
| |
| Dan Glastonbury, Apple |
| |
| Contacts |
| |
| Dan Glastonbury, Apple (djg 'at' apple.com) |
| |
| Status |
| |
| Draft |
| |
| Version |
| |
| Version 2, 2022-09-08 |
| |
| Number |
| |
| EGL Extensions XXX |
| |
| Extension Type |
| |
| EGL display extension |
| |
| Dependencies |
| |
| This extension is written against the wording of the EGL 1.5 |
| Specification. |
| |
| Overview |
| |
| This extension enables the creation of EGL fence sync objects that are |
| associated with a native Metal event object. The EGL fence sync objects |
| have nearly identical semantics to those sync objects defined by the |
| EGL 1.5 Specification, except that they have an additional attribute |
| storing the id<MTLSharedEvent> referring to the metal event object and |
| the integer value to signal the event with. |
| |
| New Types |
| |
| None. |
| |
| New Procedures and Functions |
| |
| void* eglCopyMetalSharedEventANGLE( |
| EGLDisplay dpy, |
| EGLSync sync); |
| |
| New Tokens |
| |
| Accepted by the <type> parameter of eglCreateSync, and returned |
| in <value> when eglGetSyncAttrib is called with <attribute> |
| EGL_SYNC_TYPE: |
| |
| EGL_SYNC_METAL_SHARED_EVENT_ANGLE 0x34D8 |
| |
| Accepted by the <attrib_list> parameter of eglCreateSync: |
| |
| EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE 0x34D9 |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNAL_VALUE_LO_ANGLE 0x34DA |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNAL_VALUE_HI_ANGLE 0x34DB |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNALED_ANGLE 0x34DC |
| |
| Additions to the EGL Specification |
| |
| Add the following after the first paragraph of Section 3.8.1.1 (Creating |
| Fence Sync Objects), |
| |
| "If <type> is EGL_SYNC_METAL_SHARED_EVENT_ANGLE, an EGL metal event sync |
| object is created. In this case the |
| EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE, |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNAL_VALUE_LO_ANGLE, |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNAL_VALUE_HI_ANGLE, and |
| EGL_SYNC_CONDITION may be specified. |
| |
| If EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE attribute is specified, it must |
| be set to a pointer to a valid id<MTLSharedEvent>, or to a NULL pointer. If |
| EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE is not specified, or is a NULL |
| pointer, the EGL implementation will create a Metal event |
| object. Additionally, the EGL implementation assumes ownership of the Metal |
| event object and will follow Objective-C behavior and increase the Metal |
| event object's retain count. |
| |
| EGL_SYNC_METAL_SHARED_EVENT_SIGNAL_VALUE_LO_ANGLE and |
| EGL_SYNC_METAL_SHARED_EVENT_HI_ANGLE are optional attributes specifying the |
| low and high 32-bit parts of an unsigned 64-bit value to be set when the |
| event is signaled. If these attributes are unspecified, the event is |
| signaled with one more than the event's signaledValue property at the time |
| of EGLSync creation. The signal value will wrap to 0 if the initial |
| signaledValue is the maximum value for uint64_t. |
| |
| If EGL_SYNC_CONDITION attribute is specified, it must be either |
| EGL_SYNC_PRIOR_COMMANDS_COMPLETE or EGL_SYNC_METAL_SHARED_EVENT_SIGNALED_ANGLE. |
| The EGL_SYNC_METAL_SHARED_EVENT_SIGNALED_ANGLE condition is satisfied by the |
| signaling of the MTLSharedEvent referred to by the |
| EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE attribute. When this happens any |
| eglClientWaitSync commands blocking on <sync> unblock. |
| |
| The default values for the EGL metal event sync object attributes are as |
| follows: |
| |
| Attribute Name Initial Attribute Value(s) |
| -------------- -------------------------- |
| EGL_SYNC_TYPE EGL_SYNC_METAL_SHARED_EVENT_ANGLE |
| EGL_SYNC_STATUS EGL_UNSIGNALED |
| EGL_SYNC_CONDITION EGL_SYNC_PRIOR_COMMANDS_COMPLETE |
| |
| Modify the list of eglCreateSync errors in Section 3.8.1.2 (Creating OpenCL |
| Event Sync Objects) |
| |
| "Errors |
| ------ |
| ..." |
| |
| Modify the second paragraph of Section 3.8.1.1 (Creating Fence Sync Objects), |
| |
| When a fence sync object is created or when an EGL metal shared event sync |
| object is created with the EGL_SYNC_CONDITION attribute set to |
| EGL_SYNC_PRIOR_COMMANDS_COMPLETE, eglCreateSync also inserts a fence command |
| into the command stream of the bound client API’s current context (i.e., the |
| context returned by eglGetCurrentContext), and associates it with the newly |
| created sync object. |
| |
| Add the following after the last paragraph of Section 3.8.1 (Sync Objects): |
| |
| "The command |
| |
| void* eglCopyMetalSharedEventANGLE( |
| EGLDisplay dpy, |
| EGLSync sync); |
| |
| increases the retain count of the id<MTLSharedEvent> stored in the |
| EGL_SYNC_METAL_SHARED_EVENT_OBJECT_ANGLE attribute of an EGL metal shared |
| event sync object and returns a pointer to the event as a void* pointer. If |
| this returns a non-null value, the caller is responsible for releasing the |
| MTLSharedEvent once after calling this function." |
| |
| Issues |
| |
| 1. What should the name be? METAL_EVENT_ANGLE? MTL or METAL? |
| |
| Revision History |
| |
| Version 1, 2022-05-17 |
| - Initial draft |
| Version 2, 2022-09-08 |
| - Add eglCopyMetalSharedEventANGLE function |
| Version 3, 2023-03-06 |
| - Add EGL_SYNC_METAL_SHARED_EVENT_SIGNALED_ANGLE |
| |
