250 lines
15 KiB
C
250 lines
15 KiB
C
// haloopdy - 2024
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// A super simple, all macro-driven ecs implementation.
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// Macros create a struct and associated functions to build
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// a simple, lightweight ecs implementation
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#ifndef __HALOO3D_ECS2_H
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#define __HALOO3D_ECS2_H
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// Note: you can get rid of string.h as a requirement if you
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// redo that memset to be a loop (up to you)
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#include <string.h>
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#ifndef ECS_MAXENTITIES
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#define ECS_MAXENTITIES 1024
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#endif
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// We reserve one slot to automatically point back to the ecs system.
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// This is the unusable 64th ID = 63 (your ids should start from 0)
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#define ECS_MAXCTYPES 63
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// The self flag is an ID that will get you back a component that is
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// the ecs system itself. It is ALSO used to identify if an entity is
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// valid, as ALL entities will implicitly have the ECS component
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#define ECS_SELFFLAG (1ULL << ECS_MAXCTYPES)
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typedef unsigned long long ecs_cid;
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typedef int ecs_eid;
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#define ECS_START(name) \
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typedef struct name name; \
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struct name { \
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ecs_cid entities[ECS_MAXENTITIES]; \
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ecs_eid entitytop; \
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name *c_##name[ECS_MAXENTITIES];
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#define ECS_END(name) \
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} \
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; \
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const ecs_cid name##_fl = ECS_SELFFLAG;
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// NOTE: these generate functions individually because some systems might
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// not allow unused functions and you may not need them all
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#define ECS_FN_INIT(name) \
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/* Always initialize the ecs system when you create a new one! */ \
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static void name##_init(name *_ecs) { memset(_ecs, 0, sizeof(name)); }
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#define ECS_FN_NEWENTITY(name) \
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/* Create an entity with the given base components (usually 0) */ \
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static ecs_eid name##_newentity(name *_ecs, ecs_cid basecomponents) { \
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for (int i = 0; i < ECS_MAXENTITIES; i++) { \
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ecs_eid id = _ecs->entitytop; \
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_ecs->entitytop = (_ecs->entitytop + 1) % ECS_MAXENTITIES; \
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if (_ecs->entities[id] == 0) { \
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_ecs->entities[id] = ECS_SELFFLAG | basecomponents; \
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_ecs->c_##name[id] = _ecs; \
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return id; \
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} \
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} \
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return -1; \
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}
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#define ECS_FN_DELETEENTITY(name) \
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/* Delete an entity by eid from the given ecs sys */ \
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static void name##_deleteentity(name *_ecs, ecs_eid eid) { \
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if (eid >= 0 && eid < ECS_MAXENTITIES) \
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_ecs->entities[eid] = 0; \
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}
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#define ECS_FN_QUERY(name) \
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/* Whether an entity matches a given list of components by flag */ \
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static int name##_match(name *_ecs, ecs_eid _eid, ecs_cid _comps) { \
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ecs_cid _realcomps = ECS_SELFFLAG | _comps; \
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return (_ecs->entities[_eid] & _realcomps) == _realcomps; \
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} \
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/* fill given list with eids of entities that match. careful with size */ \
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static int name##_query(name *_ecs, ecs_cid _comps, ecs_eid *out) { \
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int count = 0; \
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for (int i = 0; i < ECS_MAXENTITIES; i++) { \
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if (name##_match(_ecs, i, _comps)) { \
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out[count++] = i; \
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} \
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} \
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return count; \
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}
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#define ECS_FN_EID(name) \
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/* Calculate the eid from a double ecs pointer. Useful to get eid in sys */ \
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static ecs_eid name##_eid(name **_ecs) { \
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return (ecs_eid)(_ecs - (*_ecs)->c_##name); \
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}
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// Create an ECS component within an ECS struct
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#define ECS_COMPONENT(type) type c_##type[ECS_MAXENTITIES];
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#define ECS_GETCOMPONENT(_ecs, eid, type) (_ecs)->c_##type[eid]
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// Define the CIDs necessary to access a component (each component MUST
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// have a unique id and I can't do that inside a macro without requiring
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// extensions)
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#define ECS_CID(type, id) \
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const int type##_id = id; \
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const ecs_cid type##_fl = (1ULL << id);
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// Set the given entity to have the given component (by type). Follow this
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// macro immediately with the struct initializer
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#define ECS_SETCOMPONENT(_ecs, eid, type) \
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(_ecs)->entities[eid] |= type##_fl; \
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(_ecs)->c_##type[eid] = (type)
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// Internal-use loop for ECS_RUNSYSTEM
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#define _ECS_RSLOOP(_i, _ecs, _comps) \
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for (int _i = 0; _i < ECS_MAXENTITIES; _i++) \
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if (((_ecs)->entities[_i] & _comps) == _comps)
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// A shortcut to run a system against all matching components. You could also
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// define systems using ECS_SYSTEM1 etc. and call them per entity.
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// Make sure you pass int the name of YOUR system, not the "run" function (you
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// don't need the run function when using these macros)
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#define ECS_RUNSYSTEM1(_ecs, _system, type1) \
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{ \
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ecs_cid _ecsflags = ECS_SELFFLAG | type1##_fl; \
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_ECS_RSLOOP(eid, _ecs, _ecsflags) { _system((_ecs)->c_##type1 + eid); } \
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}
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// A shortcut to run a system against all matching components. You could also
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// define systems using ECS_SYSTEM2 etc. and call them per entity.
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// Make sure you pass int the name of YOUR system, not the "run" function (you
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// don't need the run function when using these macros)
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#define ECS_RUNSYSTEM2(_ecs, _system, t1, t2) \
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{ \
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ecs_cid _ecsflags = ECS_SELFFLAG | t1##_fl | t2##_fl; \
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_ECS_RSLOOP(eid, _ecs, _ecsflags) { \
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_system((_ecs)->c_##t1 + eid, (_ecs)->c_##t2 + eid); \
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} \
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}
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// A shortcut to run a system against all matching components. You could also
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// define systems using ECS_SYSTEM3 etc. and call them per entity.
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// Make sure you pass int the name of YOUR system, not the "run" function (you
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// don't need the run function when using these macros)
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#define ECS_RUNSYSTEM3(_ecs, _system, t1, t2, t3) \
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{ \
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ecs_cid _ecsflags = ECS_SELFFLAG | t1##_fl | t2##_fl | t3##_fl; \
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_ECS_RSLOOP(eid, _ecs, _ecsflags) { \
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_system((_ecs)->c_##t1 + eid, (_ecs)->c_##t2 + eid, \
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(_ecs)->c_##t3 + eid); \
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} \
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}
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// A shortcut to run a system against all matching components. You could also
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// define systems using ECS_SYSTEM4 etc. and call them per entity.
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// Make sure you pass int the name of YOUR system, not the "run" function (you
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// don't need the run function when using these macros)
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#define ECS_RUNSYSTEM4(_ecs, _system, t1, t2, t3, t4) \
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{ \
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ecs_cid _ecsflags = ECS_SELFFLAG | t1##_fl | t2##_fl | t3##_fl | t4##_fl; \
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_ECS_RSLOOP(eid, _ecs, _ecsflags) { \
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_system((_ecs)->c_##t1 + eid, (_ecs)->c_##t2 + eid, \
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(_ecs)->c_##t3 + eid, (_ecs)->c_##t4 + eid); \
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} \
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}
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// A shortcut to run a system against all matching components. You could also
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// define systems using ECS_SYSTEM5 etc. and call them per entity.
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// Make sure you pass int the name of YOUR system, not the "run" function (you
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// don't need the run function when using these macros)
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#define ECS_RUNSYSTEM5(_ecs, _system, t1, t2, t3, t4, t5) \
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{ \
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ecs_cid _ecsflags = \
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ECS_SELFFLAG | t1##_fl | t2##_fl | t3##_fl | t4##_fl | t5##_fl; \
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_ECS_RSLOOP(eid, _ecs, _ecsflags) { \
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_system(_ecs->c_##t1 + eid, _ecs->c_##t2 + eid, _ecs->c_##t3 + eid, \
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_ecs->c_##t4 + eid, _ecs->c_##t5 + eid); \
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} \
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}
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// ---------------------------------------------------------
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// YOU DON'T NEED THIS STUFF IF YOU USE ECS_RUNSYSTEM
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// ---------------------------------------------------------
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM1(ecsname, fname, type1) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = type1##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid); \
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} \
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}
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM2(ecsname, fname, type1, type2) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = type1##_fl | type2##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid); \
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} \
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}
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM3(ecsname, fname, type1, type2, type3) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = type1##_fl | type2##_fl | type3##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid, \
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_ecs->c_##type3 + eid); \
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} \
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}
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM4(ecsname, fname, type1, type2, type3, type4) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = type1##_fl | type2##_fl | type3##_fl | type4##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid, \
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_ecs->c_##type3 + eid, _ecs->c_##type4 + eid); \
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} \
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}
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM5(ecsname, fname, type1, type2, type3, type4, type5) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = \
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type1##_fl | type2##_fl | type3##_fl | type4##_fl | type5##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid, \
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_ecs->c_##type3 + eid, _ecs->c_##type4 + eid, \
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_ecs->c_##type5 + eid); \
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} \
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}
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// Add a system function which automatically calls your given function with
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// pre-pulled items from the entity component arrays. The new function is
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// named the same as the old one, just with _run appeneded
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#define ECS_SYSTEM6(ecsname, fname, type1, type2, type3, type4, type5, type6) \
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void fname##_run(ecsname *_ecs, ecs_eid eid) { \
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ecs_cid _ecsflags = type1##_fl | type2##_fl | type3##_fl | type4##_fl | \
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type5##_fl | type6##_fl; \
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if (ecsname##_match(_ecs, eid, _ecsflags)) { \
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fname(_ecs->c_##type1 + eid, _ecs->c_##type2 + eid, \
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_ecs->c_##type3 + eid, _ecs->c_##type4 + eid, \
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_ecs->c_##type5 + eid, _ecs->c_##type6 + eid); \
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} \
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}
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#endif
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