preliminary work on ecs

1 files changed, 96 insertions, 0 deletions

diff --git a/src/ecs/entities.zig b/src/ecs/entities.zig
new file mode 100644
index 0000000..6d091e2
--- /dev/null
+++ b/src/ecs/entities.zig
@@ -0,0 +1,96 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const components = @import("components.zig");
+const sparse = @import("sparse.zig");
+
+const System = *const fn (Pool) void;
+const SystemGroup = std.ArrayList(System);
+
+pub const Pool = struct {
+    // Components
+    position: sparse.SparseSet(components.Position),
+    speed: sparse.SparseSet(components.Speed),
+
+    system_groups: std.ArrayList(SystemGroup),
+    thread_pool: std.Thread.Pool,
+    wait_group: std.Thread.WaitGroup,
+    mutex: std.Thread.Mutex,
+    last_entity: usize,
+    free_ids: std.ArrayList(usize),
+
+    component_flags: std.AutoHashMap(usize, usize),
+
+    pub fn init(allocator: Allocator) !@This() {
+        var thread_pool: std.Thread.Pool = undefined;
+        try thread_pool.init(.{
+            .allocator = allocator,
+            .n_jobs = 4,
+        });
+
+        return @This(){
+            .position = sparse.SparseSet(components.Position).init(allocator),
+            .speed = sparse.SparseSet(components.Speed).init(allocator),
+
+            .system_groups = std.ArrayList(SystemGroup).init(allocator),
+            .thread_pool = thread_pool,
+            .wait_group = .{},
+            .mutex = .{},
+            .last_entity = 0,
+            .free_ids = std.ArrayList(usize).init(allocator),
+            .component_flags = std.AutoHashMap(usize, usize).init(allocator),
+        };
+    }
+
+    pub fn tick(self: *@This()) void {
+        for (self.system_groups) |group| {
+            self.thread_pool.spawnWg(&self.wait_group, struct {
+                fn run(pool: *Pool) void {
+                    for (group) |system| {
+                        system(pool);
+                    }
+                }
+            }.run, .{self});
+        }
+        self.wait_group.wait();
+    }
+
+    pub fn createEntity(self: *@This()) !usize {
+        const id = self.free_ids.pop() orelse self.last_entity;
+        self.last_entity += 1;
+        try self.component_flags.put(2, 0x2);
+
+        return id;
+    }
+
+    pub fn destroyEntity(self: *@This(), entity: usize) void {
+        self.free_ids.append(entity);
+
+        const flags = self.component_flags.get(entity);
+        for (0..components.COMPONENT_NUMBER) |i| {
+            if (((flags >> i) & 0x1) != 0x0) {
+                self.removeComponent(entity, i);
+            }
+        }
+    }
+
+    pub fn addComponent(self: *@This(), entity: usize, component: anytype) !void {
+        var set = switch (@TypeOf(component)) {
+            components.Speed => self.speed,
+            components.Position => self.position,
+            else => unreachable,
+        };
+
+        try self.component_flags.put(entity, self.component_flags.get(entity).? | (0x1 << @TypeOf(component).id));
+        try set.addEntity(entity, component);
+    }
+
+    pub fn removeComponent(self: *@This(), entity: usize, component_id: usize) void {
+        const set = switch (component_id) {
+            components.Speed.id => self.speed,
+            components.Position.id => self.position,
+        };
+
+        self.component_flags.put(entity, self.component_flags.get(entity) & ~(0x1 << component_id));
+        set.removeEntity(entity);
+    }
+};