diff --git a/src/components/GameObjectView.tsx b/src/components/GameObjectView.tsx
new file mode 100644
index 0000000..42df29b
--- /dev/null
+++ b/src/components/GameObjectView.tsx
@@ -0,0 +1,17 @@
+import { observer } from "mobx-react-lite";
+import type { ObjectInstance, Runtime } from "../types";
+import { state } from "../state";
+import { ObjectViewInternal } from "./ObjectViewInternal";
+
+export type GameObjectViewProps = {
+    object: Runtime<ObjectInstance>;
+}
+
+export const GameObjectView = observer(function (props: GameObjectViewProps) {
+
+    const objectType = state.world.getObjectTypeById(props.object.typeId);
+    if (!objectType)
+        return null;
+
+    return <ObjectViewInternal {...props} objectType={objectType} />
+});
diff --git a/src/components/ObjectEditorView.tsx b/src/components/ObjectEditorView.tsx
new file mode 100644
index 0000000..af8dae3
--- /dev/null
+++ b/src/components/ObjectEditorView.tsx
@@ -0,0 +1,62 @@
+import { observer } from "mobx-react-lite";
+import type { ObjectInstance, R3, Runtime } from "../types";
+import { useRef, type RefObject } from "react";
+import type { Group } from "three";
+import { TransformControls, useHelper } from "@react-three/drei";
+import { BoxHelper } from "three";
+import type { ThreeEvent } from "@react-three/fiber";
+import { state } from "../state";
+import { nextSelectionEditMode } from "../state/worldEditorState";
+import { ObjectViewInternal } from "./ObjectViewInternal";
+
+type ObjectEditorViewProps = {
+    object: Runtime<ObjectInstance>;
+}
+
+export const ObjectEditorView = observer(function ({ object }: ObjectEditorViewProps) {
+    const groupRef = useRef<Group>(null);
+
+    const objectType = state.world.getObjectTypeById(object.typeId);
+
+    const isSelected = state.worldEditor.isEnabled &&
+        state.worldEditor.selectedObjectId === object.id;
+    const selectionMode = isSelected ? state.worldEditor.selectedObjectMode : undefined;
+
+    useHelper(isSelected ? groupRef : { current: null } as any, BoxHelper, 'white');
+
+    if (!objectType)
+        return null;
+
+    function handleClick(e: ThreeEvent<MouseEvent>) {
+        if (e.delta > 5) return;
+        e.stopPropagation();
+        state.worldEditor.setSelectedObject(object.id, nextSelectionEditMode(selectionMode));
+    }
+
+    function handleTransformEnd() {
+        const group = groupRef.current;
+        if (group)
+            state.worldEditor.setObjectTransform(
+                object.id,
+                group.position.toArray(),
+                group.rotation.toArray().slice(0, 3) as R3,
+                group.scale.toArray(),
+            );
+    }
+
+    return (<>
+        {(isSelected && selectionMode !== undefined && groupRef.current) &&
+            <TransformControls
+                object={groupRef as RefObject<Group>}
+                mode={selectionMode}
+                onMouseUp={handleTransformEnd}
+            />
+        }
+        <ObjectViewInternal
+            ref={groupRef}
+            object={object}
+            objectType={objectType}
+            onClick={handleClick}
+        />
+    </>);
+});
diff --git a/src/components/ObjectView.tsx b/src/components/ObjectView.tsx
deleted file mode 100644
index cd042a0..0000000
--- a/src/components/ObjectView.tsx
+++ /dev/null
@@ -1,153 +0,0 @@
-import { observer } from "mobx-react-lite";
-import type { ObjectType, ObjectInstance } from "../types";
-import { useRef, useMemo, type RefObject } from "react";
-import type { Group } from "three";
-import { Instance, Instances, TransformControls, useHelper } from "@react-three/drei";
-import { BoxHelper } from "three";
-import type { ThreeEvent } from "@react-three/fiber";
-import { state } from "../state";
-import { nextSelectionEditMode } from "../state/worldEditorState";
-import type { R3 } from "../types/3d";
-import { TrimeshCollider } from "@react-three/rapier";
-import { SyncRigidBody } from "./SyncRigidBody";
-import { runInAction } from "mobx";
-import { getObjectVoxelGroups } from "../utils/graphics/voxelGroup";
-
-type ObjectViewProps = {
-    object: ObjectInstance;
-}
-
-function buildTrimesh(objectType: ObjectType, voxelTypes: typeof state.world.data.voxelTypes): [Float32Array, Uint32Array] | null {
-    const collidable = objectType.voxels.filter(
-        v => voxelTypes[v.typeId]?.collidable !== false
-    );
-    if (!collidable.length) return null;
-
-    const n = collidable.length;
-    const verts = new Float32Array(n * 8 * 3);
-    const idxs = new Uint32Array(n * 36);
-
-    for (let i = 0; i < n; i++) {
-        const p = collidable[i].position;
-        const vb = i * 8;
-
-        // 8 corners of unit box at position p (no +0.5 — group transform handles offset)
-        verts.set([
-            p[0], p[1], p[2],
-            p[0] + 1, p[1], p[2],
-            p[0], p[1] + 1, p[2],
-            p[0] + 1, p[1] + 1, p[2],
-            p[0], p[1], p[2] + 1,
-            p[0] + 1, p[1], p[2] + 1,
-            p[0], p[1] + 1, p[2] + 1,
-            p[0] + 1, p[1] + 1, p[2] + 1,
-        ], vb * 3);
-
-        // 12 triangles (CCW outward normals)
-        idxs.set([
-            vb, vb + 2, vb + 3, vb, vb + 3, vb + 1,  // -Z
-            vb + 4, vb + 5, vb + 7, vb + 4, vb + 7, vb + 6,  // +Z
-            vb, vb + 1, vb + 5, vb, vb + 5, vb + 4,  // -Y
-            vb + 2, vb + 6, vb + 7, vb + 2, vb + 7, vb + 3,  // +Y
-            vb, vb + 4, vb + 6, vb, vb + 6, vb + 2,  // -X
-            vb + 1, vb + 3, vb + 7, vb + 1, vb + 7, vb + 5,  // +X
-        ], i * 36);
-    }
-
-    return [verts, idxs];
-}
-
-export const ObjectView = observer(function ({ object }: ObjectViewProps) {
-
-    const objectType = state.world.getObjectTypeById(object.typeId);
-
-    const groupRef = useRef<Group>(null);
-
-    const isSelected = state.worldEditor.isEnabled &&
-        state.worldEditor.selectedObjectId === object.id;
-
-    useHelper(isSelected ? groupRef : { current: null } as any, BoxHelper, 'white');
-
-    // Must be before early return to satisfy hooks rules
-    const trimeshArgs = useMemo(
-        () => objectType
-            ? buildTrimesh(objectType, state.world.data.voxelTypes)
-            : null,
-        // eslint-disable-next-line react-hooks/exhaustive-deps
-        [objectType?.id]
-    );
-
-    if (!objectType)
-        return null;
-
-    const selectionMode = isSelected
-        ? state.worldEditor.selectedObjectMode
-        : undefined;
-
-    function handleClick(e: ThreeEvent<MouseEvent>) {
-        if (!state.worldEditor.isEnabled)
-            return;
-        if (e.delta > 5)
-            return;
-        e.stopPropagation();
-        state.worldEditor.setSelectedObject(object.id, nextSelectionEditMode(selectionMode));
-    };
-
-    function handleTransformEnd() {
-        const group = groupRef.current;
-        if (group)
-            state.worldEditor.setObjectTransform(
-                object.id,
-                group.position.toArray(),
-                group.rotation.toArray().slice(0, 3) as R3,
-                group.scale.toArray(),
-            );
-    };
-
-    return (<>
-        {
-            (isSelected && (selectionMode !== undefined) && groupRef.current) &&
-            <TransformControls
-                object={groupRef as RefObject<Group>}
-                mode={selectionMode}
-                onMouseUp={handleTransformEnd}
-            />
-        }
-        <SyncRigidBody
-            colliders={false}
-            // gravityScale={object.gravityScale}
-            // type={object.physics ? 'dynamic' : 'fixed'}
-            gravityScale={object.physics ? 1 : 0.1}
-            onSync={(data) => {
-                // console.log(`changed object ${object.id} ${JSON.stringify(data)}`);
-                runInAction(() => {
-                    const obj = state.game?.scene.objects[object.id];
-                    if (obj) {
-                        obj.position = data.position;
-                        obj.rotation = data.rotation;
-                        obj.linearVelocity = data.linearVelocity;
-                        obj.radialVelocity = data.radialVelocity;
-                    }
-                });
-            }}
-        >
-            <group
-                ref={groupRef}
-                name={`${object.id} (${object.typeId} instance)`}
-                position={object.position}
-                rotation={object.rotation}
-                scale={object.scale}
-                onClick={handleClick}
-            >
-                {getObjectVoxelGroups(objectType, state.world.data.voxelTypes).map((vg) =>
-                    <Instances key={vg.id} limit={vg.positions.length}>
-                        <boxGeometry args={[1, 1, 1]} />
-                        <meshStandardMaterial color={vg.color} opacity={vg.opacity} transparent={vg.opacity < 1} />
-                        {vg.positions.map((pos, i) => <Instance key={i} position={pos} />)}
-                    </Instances>
-                )}
-                {trimeshArgs && <TrimeshCollider args={trimeshArgs} />}
-            </group>
-        </SyncRigidBody>
-    </>);
-});
diff --git a/src/components/ObjectViewInternal.tsx b/src/components/ObjectViewInternal.tsx
new file mode 100644
index 0000000..1b44d8c
--- /dev/null
+++ b/src/components/ObjectViewInternal.tsx
@@ -0,0 +1,65 @@
+import { observer } from "mobx-react-lite";
+import type { ObjectType, RuntimeObjectInstance } from "../types";
+import { forwardRef, useMemo } from "react";
+import type { Group } from "three";
+import { Instance, Instances } from "@react-three/drei";
+import type { ThreeEvent } from "@react-three/fiber";
+import { state } from "../state";
+import { TrimeshCollider } from "@react-three/rapier";
+import { SyncRigidBody } from "./SyncRigidBody";
+import { runInAction } from "mobx";
+import { buildObjectTrimesh } from "../utils/graphics/mesh";
+
+type ObjectViewInternalProps = {
+    object: Omit<RuntimeObjectInstance, 'typeId'>;
+    objectType: ObjectType;
+    onClick?: (e: ThreeEvent<MouseEvent>) => void;
+}
+
+export const ObjectViewInternal = observer(forwardRef<Group, ObjectViewInternalProps>(
+    function ({ object, objectType, onClick }, ref) {
+        const trimeshArgs = useMemo(
+            () => buildObjectTrimesh(objectType, state.world.data.voxelTypes),
+            // eslint-disable-next-line react-hooks/exhaustive-deps
+            [objectType.id]
+        );
+
+        return (
+            <SyncRigidBody
+                colliders={false}
+                gravityScale={object.physics ? 1 : 0.1}
+                onSync={(data) => {
+                    runInAction(() => {
+                        const obj = state.game?.scene.objects[object.id];
+                        if (obj) {
+                            obj.position = data.position;
+                            obj.rotation = data.rotation;
+                            obj.linearVelocity = data.linearVelocity;
+                            obj.radialVelocity = data.radialVelocity;
+                        }
+                    });
+                }}
+            >
+                <group
+                    ref={ref}
+                    name={`${object.id} (${objectType.id} instance)`}
+                    position={object.position}
+                    rotation={object.rotation}
+                    scale={object.scale}
+                    onClick={onClick}
+                >
+                    {
+                        object.cache.voxelGroups.map((vg) =>
+                            <Instances key={vg.id} limit={vg.positions.length}>
+                                <boxGeometry args={[1, 1, 1]} />
+                                <meshStandardMaterial color={vg.color} opacity={vg.opacity} transparent={vg.opacity < 1} />
+                                {vg.positions.map((pos, i) => <Instance key={i} position={pos} />)}
+                            </Instances>
+                        )
+                    }
+                    {trimeshArgs && <TrimeshCollider args={trimeshArgs} />}
+                </group>
+            </SyncRigidBody>
+        );
+    }
+));
diff --git a/src/components/SceneView.tsx b/src/components/SceneView.tsx
index 9b696f7..8ad814a 100644
--- a/src/components/SceneView.tsx
+++ b/src/components/SceneView.tsx
@@ -1,13 +1,13 @@
 import { observer } from "mobx-react-lite";
-import type { Scene } from "../types";
+import type { RuntimeScene } from "../types";
 import { CharacterView } from "./CharacterView";
-import { ObjectView } from "./ObjectView";
+import { GameObjectView } from "./GameObjectView";
 import { useFrame } from "@react-three/fiber";
 import { useRapier } from "@react-three/rapier";
-import { state } from "../state";
+import { ObjectEditorView } from "./ObjectEditorView";
 
 type SceneViewProps = {
-    scene: Scene,
+    scene: RuntimeScene,
     editMode?: boolean;
 }
 
@@ -28,8 +28,13 @@ export const SceneView = observer(function (props: SceneViewProps) {
     return (<>
         <ambientLight intensity={0.5} />
         <directionalLight position={[5, 5, 5]} intensity={1} />
-        {Object.values(props.scene.objects).map((obj) =>
-            <ObjectView key={obj.id} object={obj} />)}
+        {
+            Object.values(props.scene.objects).map((obj) => (
+                props.editMode
+                    ? <ObjectEditorView key={obj.id} object={obj} />
+                    : <GameObjectView key={obj.id} object={obj} />
+            ))
+        }
         {/* {props.editMode && <CharacterView character={props.scene.character} />} */}
         {<CharacterView character={props.scene.character} />}
     </>);
diff --git a/src/components/SyncRigidBody.tsx b/src/components/SyncRigidBody.tsx
index ade0e54..0d5c48f 100644
--- a/src/components/SyncRigidBody.tsx
+++ b/src/components/SyncRigidBody.tsx
@@ -2,7 +2,7 @@ import { RigidBody, type RigidBodyProps, type RapierRigidBody } from "@react-thr
 import { useFrame } from "@react-three/fiber";
 import { useRef } from "react";
 import { Euler, Quaternion } from "three";
-import type { R3, V3 } from "../types/3d";
+import type { R3, V3 } from "../types";
 
 export type SyncRigidBodyData = {
     position: V3;
diff --git a/src/components/tools/CameraSync.tsx b/src/components/tools/CameraSync.tsx
index 34781cd..70df28a 100644
--- a/src/components/tools/CameraSync.tsx
+++ b/src/components/tools/CameraSync.tsx
@@ -1,5 +1,5 @@
 import { useThree } from "@react-three/fiber";
-import type { Pos3 } from "../../types/3d";
+import type { Pos3 } from "../../types";
 import { useLayoutEffect } from "react";
 import { observer } from "mobx-react-lite";
 
diff --git a/src/model/defaultVoxelTypes.ts b/src/model/defaultVoxelTypes.ts
index bde74cd..5f9f7e1 100644
--- a/src/model/defaultVoxelTypes.ts
+++ b/src/model/defaultVoxelTypes.ts
@@ -1,4 +1,4 @@
-import type { VoxelType } from "../types/voxel";
+import type { VoxelType } from "../types";
 
 const stone: VoxelType = {
     id: 'stone',
diff --git a/src/model/gameFactory.ts b/src/model/gameFactory.ts
index 53b30bb..1fd92f2 100644
--- a/src/model/gameFactory.ts
+++ b/src/model/gameFactory.ts
@@ -1,13 +1,16 @@
-import type { Game, RuntimeScene, World } from "../types";
+import type { Game, RuntimeGameScene, RuntimeScene, World } from "../types";
 import { clone } from "../utils";
+import { populateRuntimeScene } from "../utils/runtime";
 
 export class GameFactory {
 
     public static create(world: World): Game {
+        const scene = populateRuntimeScene(clone(world.initialScene), world);
+
         return {
             paused: false,
             time: 0,
-            scene: clone(world.initialScene) as RuntimeScene,
+            scene: GameFactory.initGameScene(scene),
         }
     }
 
@@ -21,4 +24,8 @@ export class GameFactory {
     public static save(game: Game): void {
         localStorage.setItem("game", JSON.stringify(game));
     }
+
+    private static initGameScene(scene: RuntimeScene): RuntimeGameScene {
+        return scene as RuntimeGameScene;
+    }
 }
diff --git a/src/model/objectPrefabs/terrain.ts b/src/model/objectPrefabs/terrain.ts
index c550fdc..5223364 100644
--- a/src/model/objectPrefabs/terrain.ts
+++ b/src/model/objectPrefabs/terrain.ts
@@ -1,4 +1,4 @@
-import type { Voxel } from "../../types/voxel";
+import type { Voxel } from "../../types";
 
 export function terrainXZ(width: number, length: number): Voxel[] {
 
diff --git a/src/model/objectPrefabs/wolf.ts b/src/model/objectPrefabs/wolf.ts
index 65a5fa9..7ffffc3 100644
--- a/src/model/objectPrefabs/wolf.ts
+++ b/src/model/objectPrefabs/wolf.ts
@@ -1,4 +1,4 @@
-import type { Voxel } from "../../types/voxel";
+import type { Voxel } from "../../types";
 
 const G = '#808080'; // gray fur
 const L = '#d0c8b8'; // light beige-gray (snout / face)
diff --git a/src/model/worldFactory.ts b/src/model/worldFactory.ts
index 5f54e83..a6f7413 100644
--- a/src/model/worldFactory.ts
+++ b/src/model/worldFactory.ts
@@ -1,10 +1,11 @@
-import type { World } from "../types";
+import { type RuntimeWorld, type World } from "../types";
+import { depopulateRuntimeWorld, populateRuntimeWorld } from "../utils/runtime";
 import { DEFAULT_VOXEL_TYPES } from "./defaultVoxelTypes";
 
 export class WorldFactory {
 
-    public static create(): World {
-        return {
+    public static create(): RuntimeWorld {
+        return populateRuntimeWorld({
             objectTypes: {},
             voxelTypes: DEFAULT_VOXEL_TYPES,
             initialScene: {
@@ -23,17 +24,17 @@ export class WorldFactory {
                 position: [0, 5, 10],
                 look: [0, 0, 0],
             },
-        }
+        });
     }
 
-    public static load(): World | undefined {
+    public static load(): RuntimeWorld | undefined {
         const json = localStorage.getItem("world");
         if (json) {
-            return JSON.parse(json) as World;
+            return populateRuntimeWorld(JSON.parse(json) as World);
         }
     }
 
-    public static save(world: World): void {
-        localStorage.setItem("world", JSON.stringify(world));
+    public static save(world: RuntimeWorld): void {
+        localStorage.setItem("world", JSON.stringify(depopulateRuntimeWorld(world)));
     }
 }
diff --git a/src/state/gameState.ts b/src/state/gameState.ts
index 5893126..03b522c 100644
--- a/src/state/gameState.ts
+++ b/src/state/gameState.ts
@@ -1,7 +1,6 @@
 import { makeAutoObservable, reaction, toJS } from "mobx";
 import type { WorldState } from "./worldState";
-import type { Game, RuntimeScene } from "../types";
-import type { Pos3, V3, R3 } from "../types/3d";
+import type { Game, Pos3, V3, R3, RuntimeGameScene } from "../types";
 import type { CameraProps } from "@react-three/fiber";
 import { GameFactory } from "../model/gameFactory";
 
@@ -34,7 +33,7 @@ export class GameState {
         return this.data.paused;
     }
 
-    public get scene(): RuntimeScene {
+    public get scene(): RuntimeGameScene {
         return this.data.scene;
     }
 
diff --git a/src/state/worldEditorState.ts b/src/state/worldEditorState.ts
index e4b480c..ef8e0aa 100644
--- a/src/state/worldEditorState.ts
+++ b/src/state/worldEditorState.ts
@@ -1,10 +1,10 @@
 import { makeAutoObservable, runInAction } from "mobx";
 import type { WorldState } from "./worldState";
-import type { ObjectInstance, Scene } from "../types";
+import { type ObjectInstance, type Pos3, type R3, type V3, type RuntimeScene } from "../types";
 import { createObjectInstance } from "../utils/object";
 import { randomId } from "../utils";
-import type { Pos3, R3, V3 } from "../types/3d";
 import { state } from "./rootState";
+import { populateRuntimeObject } from "../utils/runtime";
 
 export const SelectionEditModeEnum = [
     'translate',
@@ -51,7 +51,7 @@ export class WorldEditorState {
         this.selectedObjectMode = undefined;
     }
 
-    public get scene(): Scene {
+    public get scene(): RuntimeScene {
         return this.world.data.initialScene;
     }
 
@@ -82,7 +82,7 @@ export class WorldEditorState {
         typeId: string,
         pos: { x: number; y: number; z: number; },
     ): ObjectInstance {
-        const obj = createObjectInstance(randomId(), typeId);
+        const obj = populateRuntimeObject(createObjectInstance(randomId(), typeId), this.world.data);
         obj.position = [pos.x, pos.y, pos.z];
         obj.rotation = [0, 0, 0];
 
diff --git a/src/state/worldState.ts b/src/state/worldState.ts
index 1fbaa1d..004ac45 100644
--- a/src/state/worldState.ts
+++ b/src/state/worldState.ts
@@ -1,14 +1,14 @@
 import { makeAutoObservable, reaction, toJS } from "mobx";
 import { WorldFactory } from "../model/worldFactory";
-import type { ObjectInstance, ObjectType, World } from "../types";
-import type { VoxelType } from "../types/voxel";
+import { type ObjectInstance, type ObjectType, type World, type VoxelType, type RuntimeWorld } from "../types";
 import { state } from "./rootState";
 import { DEFAULT_VOXEL_TYPES } from "../model/defaultVoxelTypes";
 import { wolf } from "../model/objectPrefabs/wolf";
 import { terrainXZ } from "../model/objectPrefabs/terrain";
+import { populateRuntimeWorld } from "../utils/runtime";
 
 export class WorldState {
-    public data: World = WorldFactory.create();
+    public data: RuntimeWorld = WorldFactory.create();
 
     private startAutoSave() {
         return reaction(() => toJS(this.data), (data) => this.saveData(data), { delay: 500 });
@@ -39,7 +39,7 @@ export class WorldState {
     public loadMock() {
         console.log('Mocking world...');
 
-        const objects = Array(0).fill(0)
+        const objects = Array(3).fill(0)
             .map((_, idx) => ({
                 id: `obj${idx}`,
                 typeId: 'wolf',
@@ -52,7 +52,7 @@ export class WorldState {
             objects.map((obj) => [obj.id, obj]),
         ) as Record<string, ObjectInstance>
 
-        this.data = {
+        this.data = populateRuntimeWorld({
             objectTypes: {
                 wolf: {
                     id: 'wolf',
@@ -93,7 +93,8 @@ export class WorldState {
             gameRules: {
                 gravity: true,
             },
-        };
+        });
+
         console.log(objects);
         state.worldEditor.resetSelectedObject();
     }
diff --git a/src/types/character.ts b/src/types/character.ts
deleted file mode 100644
index ab9c92d..0000000
--- a/src/types/character.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-import type { Pos3 } from "./3d";
-import type { RuntimeObjectData } from "./object";
-
-export type Character = {
-    transform: Pos3,
-}
-
-export type RuntimeCharacter = Character & RuntimeObjectData;
diff --git a/src/types/game.ts b/src/types/game.ts
deleted file mode 100644
index e48f5d1..0000000
--- a/src/types/game.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-import type { RuntimeScene } from "./scene";
-
-export type Game = {
-    paused: boolean;
-    time: number;
-    scene: RuntimeScene;
-}
diff --git a/src/types/index.ts b/src/types/index.ts
index 098f42a..eafa3a5 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -1,9 +1,3 @@
-export * from './object';
-export * from './scene';
-export * from './world';
-export * from './gameRules';
-export * from './game';
-export * from './character';
-
-
-
+export * from './3d';
+export * from './model';
+export * from './runtime';
diff --git a/src/types/model/character.ts b/src/types/model/character.ts
new file mode 100644
index 0000000..820861f
--- /dev/null
+++ b/src/types/model/character.ts
@@ -0,0 +1,8 @@
+import type { Pos3 } from "../3d";
+import type { GameObjectData } from "./object";
+
+export type Character = {
+    transform: Pos3,
+}
+
+export type GameCharacter = Character & GameObjectData;
diff --git a/src/types/model/game.ts b/src/types/model/game.ts
new file mode 100644
index 0000000..dd9f5d3
--- /dev/null
+++ b/src/types/model/game.ts
@@ -0,0 +1,7 @@
+import type { RuntimeGameScene } from "./scene";
+
+export type Game = {
+    paused: boolean;
+    time: number;
+    scene: RuntimeGameScene;
+}
diff --git a/src/types/gameRules.ts b/src/types/model/gameRules.ts
similarity index 100%
rename from src/types/gameRules.ts
rename to src/types/model/gameRules.ts
diff --git a/src/types/model/index.ts b/src/types/model/index.ts
new file mode 100644
index 0000000..a0f4417
--- /dev/null
+++ b/src/types/model/index.ts
@@ -0,0 +1,8 @@
+export * from './object';
+export * from './scene';
+export * from './world';
+export * from './gameRules';
+export * from './game';
+export * from './character';
+export * from './voxel';
+export * from './runtime';
diff --git a/src/types/object.ts b/src/types/model/object.ts
similarity index 52%
rename from src/types/object.ts
rename to src/types/model/object.ts
index cf8fb52..4d5b313 100644
--- a/src/types/object.ts
+++ b/src/types/model/object.ts
@@ -1,4 +1,5 @@
-import type { R3, V3 } from "./3d";
+import type { R3, V3 } from "../3d";
+import type { Runtime } from "./runtime";
 import type { Voxel } from "./voxel";
 
 export type ObjectType = {
@@ -17,9 +18,12 @@ export type ObjectInstance = {
     scale: V3;
 }
 
-export type RuntimeObjectData = {
+export type GameObjectData = {
     linearVelocity: V3;
     radialVelocity: R3;
 }
 
-export type RuntimeObjectInstance = ObjectInstance & RuntimeObjectData;
+export type GameObjectInstance = ObjectInstance & GameObjectData;
+
+export type RuntimeObjectInstance = Runtime<ObjectInstance>;
+export type RuntimeGameObjectInstance = Runtime<GameObjectInstance>;
diff --git a/src/types/model/runtime.ts b/src/types/model/runtime.ts
new file mode 100644
index 0000000..c37461c
--- /dev/null
+++ b/src/types/model/runtime.ts
@@ -0,0 +1,10 @@
+import type { VoxelGroup } from "../runtime";
+import type { ObjectInstance } from "./object";
+
+export type ObjectInstanceRuntimeData = {
+    cache: {
+        voxelGroups: VoxelGroup[];
+    };
+}
+
+export type Runtime<T extends ObjectInstance> = T & ObjectInstanceRuntimeData;
diff --git a/src/types/model/scene.ts b/src/types/model/scene.ts
new file mode 100644
index 0000000..98ae942
--- /dev/null
+++ b/src/types/model/scene.ts
@@ -0,0 +1,22 @@
+import type { Character, GameCharacter } from "./character";
+import type { GameObjectInstance, ObjectInstance, RuntimeGameObjectInstance, RuntimeObjectInstance } from "./object";
+
+export type Scene = {
+    character: Character;
+    objects: Record<string, ObjectInstance>;
+}
+
+export type RuntimeScene = {
+    character: Character;
+    objects: Record<string, RuntimeObjectInstance>;
+}
+
+export type GameScene = {
+    character: GameCharacter;
+    objects: Record<string, GameObjectInstance>;
+}
+
+export type RuntimeGameScene = {
+    character: GameCharacter;
+    objects: Record<string, RuntimeGameObjectInstance>;
+}
diff --git a/src/types/voxel.ts b/src/types/model/voxel.ts
similarity index 87%
rename from src/types/voxel.ts
rename to src/types/model/voxel.ts
index fc22092..9d40a05 100644
--- a/src/types/voxel.ts
+++ b/src/types/model/voxel.ts
@@ -1,4 +1,4 @@
-import type { V3 } from "./3d";
+import type { V3 } from "../3d";
 
 export type VoxelType = {
     id: string;
diff --git a/src/types/world.ts b/src/types/model/world.ts
similarity index 66%
rename from src/types/world.ts
rename to src/types/model/world.ts
index c3736a9..4e187ac 100644
--- a/src/types/world.ts
+++ b/src/types/model/world.ts
@@ -1,7 +1,7 @@
 import type { GameRules } from "./gameRules";
 import type { ObjectType } from "./object";
-import type { Scene } from "./scene";
-import type { Pos3 } from "./3d";
+import type { RuntimeScene, Scene } from "./scene";
+import type { Pos3 } from "../3d";
 import type { VoxelType } from "./voxel";
 
 export type World = {
@@ -11,3 +11,7 @@ export type World = {
     initialScene: Scene;
     gameRules: GameRules;
 }
+
+export type RuntimeWorld = World & {
+    initialScene: RuntimeScene;
+}
diff --git a/src/types/runtime/index.ts b/src/types/runtime/index.ts
new file mode 100644
index 0000000..2aaaab3
--- /dev/null
+++ b/src/types/runtime/index.ts
@@ -0,0 +1 @@
+export * from './voxelGroup';
diff --git a/src/types/runtime/voxelGroup.ts b/src/types/runtime/voxelGroup.ts
new file mode 100644
index 0000000..cabbc36
--- /dev/null
+++ b/src/types/runtime/voxelGroup.ts
@@ -0,0 +1,9 @@
+import type { V3 } from "../3d";
+
+export type VoxelGroup = {
+    id: string;
+    color: string;
+    opacity: number;
+    positions: V3[];
+};
+
diff --git a/src/types/scene.ts b/src/types/scene.ts
deleted file mode 100644
index 9e74291..0000000
--- a/src/types/scene.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-import type { Character, RuntimeCharacter } from "./character";
-import type { ObjectInstance, RuntimeObjectInstance } from "./object";
-
-export type Scene = {
-    character: Character;
-    objects: Record<string, ObjectInstance>;
-}
-
-export type RuntimeScene = {
-    character: RuntimeCharacter;
-    objects: Record<string, RuntimeObjectInstance>;
-}
diff --git a/src/utils/graphics/mesh.ts b/src/utils/graphics/mesh.ts
new file mode 100644
index 0000000..f868343
--- /dev/null
+++ b/src/utils/graphics/mesh.ts
@@ -0,0 +1,41 @@
+import type { ObjectType, VoxelType } from "../../types";
+
+export function buildObjectTrimesh(objectType: ObjectType, voxelTypes: Record<string, VoxelType>): [Float32Array, Uint32Array] | null {
+    const collidable = objectType.voxels.filter((v) => voxelTypes[v.typeId]?.collidable !== false);
+
+    if (!collidable.length)
+        return null;
+
+    const n = collidable.length;
+    const verts = new Float32Array(n * 8 * 3);
+    const idxs = new Uint32Array(n * 36);
+
+    for (let i = 0; i < n; i++) {
+        const p = collidable[i].position;
+        const vb = i * 8;
+
+        // 8 corners of unit box at position p (no +0.5 — group transform handles offset)
+        verts.set([
+            p[0], p[1], p[2],
+            p[0] + 1, p[1], p[2],
+            p[0], p[1] + 1, p[2],
+            p[0] + 1, p[1] + 1, p[2],
+            p[0], p[1], p[2] + 1,
+            p[0] + 1, p[1], p[2] + 1,
+            p[0], p[1] + 1, p[2] + 1,
+            p[0] + 1, p[1] + 1, p[2] + 1,
+        ], vb * 3);
+
+        // 12 triangles (CCW outward normals)
+        idxs.set([
+            vb, vb + 2, vb + 3, vb, vb + 3, vb + 1,  // -Z
+            vb + 4, vb + 5, vb + 7, vb + 4, vb + 7, vb + 6,  // +Z
+            vb, vb + 1, vb + 5, vb, vb + 5, vb + 4,  // -Y
+            vb + 2, vb + 6, vb + 7, vb + 2, vb + 7, vb + 3,  // +Y
+            vb, vb + 4, vb + 6, vb, vb + 6, vb + 2,  // -X
+            vb + 1, vb + 3, vb + 7, vb + 1, vb + 7, vb + 5,  // +X
+        ], i * 36);
+    }
+
+    return [verts, idxs];
+}
\ No newline at end of file
diff --git a/src/utils/graphics/voxelGroup.ts b/src/utils/graphics/voxelGroup.ts
index 6f04d33..7736567 100644
--- a/src/utils/graphics/voxelGroup.ts
+++ b/src/utils/graphics/voxelGroup.ts
@@ -1,12 +1,4 @@
-import type { ObjectType } from "../../types";
-import type { VoxelType } from "../../types/voxel";
-
-export type VoxelGroup = {
-    id: string;
-    color: string;
-    opacity: number;
-    positions: [number, number, number][];
-};
+import type { ObjectType, VoxelGroup, VoxelType } from "../../types";
 
 export function getObjectVoxelGroups(
     object: ObjectType,
diff --git a/src/utils/object.ts b/src/utils/object.ts
index b6c7482..2bc3dfb 100644
--- a/src/utils/object.ts
+++ b/src/utils/object.ts
@@ -4,7 +4,10 @@ export function createObjectInstance(id: string, typeId: string): ObjectInstance
     return {
         id,
         typeId: typeId,
+        physics: false,
+        gravityScale: 1,
         position: [0, 0, 0],
         rotation: [0, 0, 0],
+        scale: [1, 1, 1],
     };
 }
diff --git a/src/utils/runtime/index.ts b/src/utils/runtime/index.ts
new file mode 100644
index 0000000..53f97dd
--- /dev/null
+++ b/src/utils/runtime/index.ts
@@ -0,0 +1,3 @@
+export * from './world';
+export * from './scene';
+export * from './object';
diff --git a/src/utils/runtime/object.ts b/src/utils/runtime/object.ts
new file mode 100644
index 0000000..8f48946
--- /dev/null
+++ b/src/utils/runtime/object.ts
@@ -0,0 +1,19 @@
+import { getObjectVoxelGroups } from "../graphics/voxelGroup";
+import type { ObjectInstance, RuntimeObjectInstance, World } from "../../types";
+
+export function populateRuntimeObject(object: ObjectInstance, world: World): RuntimeObjectInstance {
+    const objectType = world.objectTypes[object.typeId];
+
+    return {
+        ...object,
+        cache: {
+            voxelGroups: getObjectVoxelGroups(objectType, world.voxelTypes),
+        },
+    };
+
+}
+
+export function depopulateRuntimeObject(object: RuntimeObjectInstance, _world: World): ObjectInstance {
+    const { cache, ...result } = object;
+    return result;
+}
diff --git a/src/utils/runtime/scene.ts b/src/utils/runtime/scene.ts
new file mode 100644
index 0000000..11f59a1
--- /dev/null
+++ b/src/utils/runtime/scene.ts
@@ -0,0 +1,16 @@
+import type { RuntimeScene, Scene, World } from "../../types";
+import { depopulateRuntimeObject, populateRuntimeObject } from "./object";
+
+export function populateRuntimeScene(scene: Scene, world: World): RuntimeScene {
+    return {
+        ...scene,
+        objects: Object.fromEntries(Object.entries(scene.objects).map(([id, obj]) => [id, populateRuntimeObject(obj, world)])),
+    }
+}
+
+export function depopulateRuntimeScene(scene: RuntimeScene, world: World): Scene {
+    return {
+        ...scene,
+        objects: Object.fromEntries(Object.entries(scene.objects).map(([id, obj]) => [id, depopulateRuntimeObject(obj, world)])),
+    }
+}
diff --git a/src/utils/runtime/world.ts b/src/utils/runtime/world.ts
new file mode 100644
index 0000000..f509a99
--- /dev/null
+++ b/src/utils/runtime/world.ts
@@ -0,0 +1,16 @@
+import type { RuntimeWorld, World } from "../../types";
+import { depopulateRuntimeScene, populateRuntimeScene } from "./scene";
+
+export function populateRuntimeWorld(world: World): RuntimeWorld {
+    return {
+        ...world,
+        initialScene: populateRuntimeScene(world.initialScene, world),
+    };
+}
+
+export function depopulateRuntimeWorld(world: RuntimeWorld): World {
+    return {
+        ...world,
+        initialScene: depopulateRuntimeScene(world.initialScene, world),
+    };
+}