zig-raylib-engine/src/EntitySystem.zig

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

//Variables Entity

var EntityIDs: std.ArrayList(usize) = undefined;
var EntityAmount: u32 = 0;

var Signatures: std.ArrayList(Etyp.Signature) = undefined;

//Entity System

fn CreateEntitysub() !Etyp.Entity {
    if (EntityAmount >= Etyp.MAXEntitys) {
        return error.GenericError;
    }
    EntityAmount += 1;
    return EntityIDs.pop();
}

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

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

fn GetSignature(entity: Etyp.Entity) Etyp.Signature {
    return Signatures.items[entity];
}

//Component Manager variables

var ComponentTypeList: std.StringArrayHashMap(Etyp.Component) = std.StringArrayHashMap(Etyp.Component).init(std.heap.page_allocator);

var ComponentArrays = undefined;
var String2CompArr: std.StringArrayHashMap(usize) = std.StringArrayHashMap(usize).init(std.heap.page_allocator);

var NextComponent: Etyp.Component = 0;

//component manager

fn RegisterComponentsub(comptime in: anytype) !void {
    var name = @typeName(in);
    try ComponentTypeList.put(name, NextComponent);
    ComponentArrays = Etyp.ComponentArray(in).init();
    try String2CompArr.put(name, ComponentArrays.len);
}

fn GetComponentArray(comptime in: type) type {
    return ComponentArrays[@typeName(in)]();
}
fn GetComponentTypesub(comptime in: type) Etyp.Component{
    return ComponentTypeList[@typeName(in)];
}
fn AddComponentsub(Entity: Etyp.Entity, comptime Component: type) void{
    GetComponentArray(Component).AddComponent(Entity, Component);
}
fn RemoveComponentsub(Entity: Etyp.Entity, comptime in: anytype) void{
    GetComponentArray(in).Removedata(Entity);
}
fn GetComponentsub(Entity: Etyp.Entity, comptime in: type) type{
    return GetComponentArray(in).GetData(Entity);
}
fn EntityDestroyed(Entity: Etyp.Entity) void{
    for(ComponentArrays.values())|val|{
        val.EntityDestroyed(Entity);
    } 
}

//THE MASTER
pub fn Init() !void{
    EntityIDs = init: {
        var temp = try std.ArrayList(usize).initCapacity(std.heap.page_allocator, Etyp.MAXEntitys);
        var i = Etyp.MAXEntitys;
        while (i > 0) {
            temp.appendAssumeCapacity(i);
            i -= 1;
        }
        break :init temp;
    };
    Signatures = try std.ArrayList(Etyp.Signature).initCapacity(std.heap.page_allocator, Etyp.MAXEntitys);
}
pub fn CreateEntity() !Etyp.Entity{
    return try CreateEntitysub();
}

pub fn DestroyEntity(Entity: Etyp.entity) void{
    DestroyEntitysub(Entity);
    EntityDestroyed(Entity);
}

pub fn RegisterComponent(comptime in: anytype) !void{
    try RegisterComponentsub(in);
}

pub fn AddComponent(Entity: Etyp.Entity, comptime in: anytype) void{
    AddComponentsub(Entity, in);
    var sig = GetSignature(Entity);
    sig.setValue(GetComponentTypesub(in), true);
    SetSignature(Entity, sig);
}

pub fn RemoveComponent(Entity: Etyp.Entity, comptime in: anytype) void{
    RemoveComponentsub(Entity, in);
    var sig = GetSignature(Entity);
    sig.setValue(GetComponentTypesub(in), false);
    SetSignature(Entity, sig);
}

pub fn GetComponent(Entity: Etyp.Entity, comptime in: anytype) @TypeOf(in){
    return GetComponentsub(Entity, in);
}

pub fn GetComponentType(comptime in: anytype) Etyp.Component{
    return GetComponentTypesub(in);
}
pub fn GetEntitys(Signature: Etyp.Signature) []Etyp.Entity{
    var sel = std.ArrayList(Etyp.Entity).init(std.heap.page_allocator);
    for(Signatures.items, 0..)|val, i|{
        if(val.intersectWith(Signature) == Signature){
            try sel.append(i);
        }
    }
    return sel.items;
}