71 lines
3.3 KiB
D
71 lines
3.3 KiB
D
/************************************************************************************************************************
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*Entity module.
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*/
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module ecs.entity;
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import ecs.system;
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import ecs.manager;
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/************************************************************************************************************************
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*Entity ID structure. Used as reference to Entity. Pointer to entity should be ever used to store entity reference!
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*/
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struct EntityID
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{
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///Index to entity in IDManager.
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uint id;
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///Counter required for reusing ID.
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uint counter;
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}
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/************************************************************************************************************************
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*Structure of Entity. It's have only ID, but have full konwlege to get to components memory (If pointer to it is proper).
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*/
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struct Entity
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{
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///Entity ID.
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EntityID id;
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/************************************************************************************************************************
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*Get specified component. If component doesn't exist function retun null. Pointer is valid only before next "commit()", "begin()" or "end()"
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*function is called. Returned pointer shouldn't be used to store reference to entity data.
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*/
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T* getComponent(T)() const
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{
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EntityManager.EntitiesBlock* block = gEM.getMetaData(&this);
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EntityManager.EntityInfo* info = block.type_info;
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if (T.component_id >= info.deltas.length || info.deltas[T.component_id] == 0)
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return null;
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static if (EntityID.sizeof == 8)
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uint ind = cast(uint)((cast(void*)&this - block.dataBegin()) >> 3);
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else
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uint ind = cast(uint)((cast(void*)&this - block.dataBegin()) / EntityID.sizeof());
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return cast(T*)(cast(void*)block + info.deltas[T.component_id] + ind * T.sizeof);
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}
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}
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/************************************************************************************************************************
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*Entity template structure.
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*Entity contain whole information needed to create new entity. Allocating EntityTemplate is considered as more expensive operation
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*than adding entity. Whole components memory is stored in EntityTemplate and is copyied to newly added entity.
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*If you want to place several entity with small difference in data then you should take pointer to component and change it before every
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*entity addition.
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*There is no restriction about number of allocated templates. Single template can be used from multiple threads, but if you
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*want to changes some components data before add entity (entity position for example) it's better to use multiple templates.
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*/
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export struct EntityTemplate
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{
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///Entity components data
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ubyte[] entity_data;
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///Pointer to entity type info.
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EntityManager.EntityInfo* info;
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/************************************************************************************************************************
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*Get specified component. If component doesn't exist function return null. Returned pointer is valid during EntityTemplate lifetime.
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*/
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T* getComponent(T)() nothrow @nogc
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{
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if(T.component_id >= info.tmpl_deltas.length || info.tmpl_deltas[T.component_id] == ushort.max)return null;
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return cast(T*)(entity_data.ptr + info.tmpl_deltas[T.component_id]);
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}
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}
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