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42 lines
1.4 KiB
42 lines
1.4 KiB
using System; |
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using System.Runtime.InteropServices; |
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using gaemstone.Utility; |
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using static flecs_hub.flecs; |
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namespace gaemstone.ECS; |
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public static class ObserverExtensions |
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{ |
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public static unsafe EntityRef InitObserver(this EntityRef entity, |
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FilterDesc filter, Action<Iterator> callback, params Entity[] events) |
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{ |
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if (events.Length == 0) throw new ArgumentException("Must specify at least 1 event", nameof(events)); |
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if (events.Length > 8) throw new ArgumentException("Must specify at most 8 events", nameof(events)); |
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var world = entity.World; |
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using var alloc = TempAllocator.Use(); |
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var desc = new ecs_observer_desc_t { |
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entity = entity, |
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filter = filter.ToFlecs(alloc), |
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binding_ctx = (void*)CallbackContextHelper.Create((world, callback)), |
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binding_ctx_free = new() { Data = new() { Pointer = &FreeContext } }, |
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callback = new() { Data = new() { Pointer = &Callback } }, |
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}; |
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var span = desc.events; |
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for (var i = 0; i < events.Length; i++) |
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span[i] = events[i]; |
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return new(world, new(ecs_observer_init(world, &desc))); |
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} |
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[UnmanagedCallersOnly] |
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private static unsafe void Callback(ecs_iter_t* iter) |
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{ |
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var (world, callback) = CallbackContextHelper |
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.Get<(World, Action<Iterator>)>((nint)iter->binding_ctx); |
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callback(new Iterator(world, null, *iter)); |
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} |
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[UnmanagedCallersOnly] |
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private static unsafe void FreeContext(void* context) |
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=> CallbackContextHelper.Free((nint)context); |
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}
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