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https://github.com/Ukendio/jecs.git
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61 lines
1.5 KiB
Text
61 lines
1.5 KiB
Text
local jecs = require("@jecs")
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local pair = jecs.pair
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local world = jecs.World.new()
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local Name = world:component()
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local function named(ctr, name)
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local e = ctr(world)
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world:set(e, Name, name)
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return e
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end
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local function name(e)
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return world:get(e, Name)
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end
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local Position = named(world.component, "Position") :: jecs.Entity<vector>
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local Previous = jecs.Rest
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local added = world
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:query(Position)
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:without(pair(Previous, Position))
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:cached()
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local changed = world
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:query(Position, pair(Previous, Position))
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:cached()
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local removed = world
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:query(pair(Previous, Position))
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:without(Position)
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:cached()
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local e1 = named(world.entity, "e1")
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world:set(e1, Position, vector.create(10, 20, 30))
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local e2 = named(world.entity, "e2")
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world:set(e2, Position, vector.create(10, 20, 30))
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for entity, p in added do
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print(`Added {name(entity)}: \{{p.x}, {p.y}, {p.z}}`)
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world:set(entity, pair(Previous, Position), p)
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end
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world:set(e1, Position, vector.create(999, 999, 1998))
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for _, archetype in changed:archetypes() do
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if new ~= old then
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print(`{name(e)}'s Position changed from \{{old.x}, {old.y}, {old.z}\} to \{{new.x}, {new.y}, {new.z}\}`)
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world:set(e, pair(Previous, Position), new)
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end
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end
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world:remove(e2, Position)
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for e in removed:iter() do
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print(`Position was removed from {name(e)}`)
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world:remove(e, pair(Previous, Position))
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end
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-- Output:
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-- Added 265: {10, 20, 30}
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-- Added 264: {10, 20, 30}
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-- e1's Position changed from {10, 20, 30} to {999, 999, 1998}
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-- Position was removed from e2
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