cleaned up ecs interface

src/ecs/entities.zig

@@ -42,6 +42,50 @@ pub const Pool = struct {
         return pool;
     }
 
+    pub fn getQuery(self: *@This(), comptime T: type) []T {
+        const set = switch (T) {
+            components.Speed => &self.speed,
+            components.Position => &self.position,
+            else => unreachable,
+        };
+
+        return set.components.items;
+    }
+
+    pub fn getEntity(self: *@This(), component: usize, comptime T: type) usize {
+        const set = switch (T) {
+            components.Speed => &self.speed,
+            components.Position => &self.position,
+            else => unreachable,
+        };
+
+        return set.dense.items[component];
+    }
+
+    pub fn getComponent(self: *@This(), entity: usize, comptime T: type) ?T {
+        const set = switch (T) {
+            components.Speed => &self.speed,
+            components.Position => &self.position,
+            else => unreachable,
+        };
+
+        if (self.hasComponent(entity, T)) {
+            return set.components.items[set.sparse.items[entity]];
+        } else {
+            return null;
+        }
+    }
+
+    pub fn hasComponent(self: *@This(), entity: usize, component: type) bool {
+        const set = switch (component) {
+            components.Speed => &self.speed,
+            components.Position => &self.position,
+            else => unreachable,
+        };
+
+        return set.dense.items[set.sparse.items[entity]] == entity;
+    }
+
     pub fn addSystemGroup(self: *@This(), group: SystemGroup) !void {
         try self.system_groups.append(group);
     }

src/main.zig

@@ -12,24 +12,14 @@ const components = @import("ecs/components.zig");
 const entities = @import("ecs/entities.zig");
 
 fn testSystem2(pool: *entities.Pool) void {
-    var i = @as(usize, 0);
-    //std.debug.print("test: {d}\n", .{pool.position.components.items.len});
-    for (pool.position.components.items) |position| {
-        const entity = pool.position.dense.items[i];
-        if (pool.speed.dense.items[pool.speed.sparse.items[entity]] == entity) {
-            const speed = pool.speed.components.items[pool.speed.sparse.items[entity]];
+    for (pool.getQuery(components.Position), 0..) |position, i| {
+        const entity = pool.getEntity(i, components.Position);
+        if (pool.getComponent(entity, components.Speed)) |speed| {
             std.debug.print("entity{d}: {any},{any},{any} {any}\n", .{ i, position.x, position.y, position.z, speed.speed });
         }
-
-        i += 1;
     }
 }
 
-fn testSystem(pool: *entities.Pool) void {
-    _ = pool;
-    std.debug.print("test\n", .{});
-}
-
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     const allocator = gpa.allocator();
@@ -58,9 +48,11 @@ pub fn main() !void {
             testSystem2,
         });
 
+        for (0..1000) |_| {
             const entity = try pool.createEntity();
             try pool.addComponent(entity, components.Position{ .x = 1.0, .y = 0.5, .z = 3.0 });
             try pool.addComponent(entity, components.Speed{ .speed = 5.0 });
+        }
 
         // TODO(luccie-cmd): Renderer.create shouldn't return an error
         var r = try Renderer.create(allocator, w);