zig-raylib-engine/src/EntitySystem.zig

const std = @import("std");
const Etyp = @import("EntitySystemTypes.zig");

//Variables Entity

const EntityIDs: std.TailQueue(u32) = init: {
    var temp = std.TailQueue(u32);
    var i = 0;
    while(i < Etyp.MAXEntitys){
        temp.append(i);
        i += 1;
    }
    break :init temp;
};
var EntityAmount: u32 = 0;

const Signatures: [Etyp.MAXEntitys]Etyp.Signature = undefined;

//Entity System

pub fn CreateEntity() !Etyp.entity {
    if(EntityAmount >= Etyp.MAXEntitys)
    {
        return error{};
    }
    EntityAmount += 1;
    return EntityIDs.popFirst();
}

pub fn DestroyEntity(entity: Etyp.entity) void {
    Signatures[entity] = null;
    EntityIDs.append(entity);
    EntityAmount -= 1;
}

pub fn SetSignature(entity: Etyp.entity, signature: Etyp.Signature) void {
    Signatures[entity] = signature;
}

pub fn GetSignature(entity: Etyp.entity) Etyp.signature {
    return Signatures[entity];
}

const ComponentArray = struct {
    Components: [Etyp.MAXEntitys]type,
    Entity2Array: [usize]EntityIDs,
    Array2Entity: [EntityIDs]usize,
    sizeM: usize,

    pub fn AddComponent(self: ComponentArray, entity: Etyp.entity, comp: type) void{
        var newidx: usize = self.sizeM;
        self.Entity2Array[entity] = newidx;
        self.Entity2Array[newidx] = entity;
        self.Components[newidx] = comp;
        self.sizeM += 1;
    }
    pub fn Removedata(self: ComponentArray, entity: Etyp.entity) void{
        var remidx: usize = self.Entity2Array[entity];
        var lastidx: usize = self.sizeM-1;
        self.Components[remidx] = self.Components[lastidx];

        var lastentity: Etyp.entity = self.Array2Entity[lastidx];
        self.Entity2Array[lastentity] = remidx;
        self.Array2Entity[remidx] = lastentity;

        self.Entity2Array[entity] = null;
        self.Array2Entity[lastentity] = null;

        self.sizeM -= 1;
    }
};