Transform.translate in tiny

Hi there,

There are multiple ways to accomplish this. I'll attach an example here that uses a version of Rodriques' formula. In my opinion the pros of this method are ease of writing and avoiding unnecessary operations.

Code (JavaScript):

1. namespace game {
2.     export class SelfMoveSystem extends ut.ComponentSystem {
3.         OnUpdate():void {
4.             this.world.forEach(
5.                 [ut.Entity, ut.Core2D.TransformLocalPosition, ut.Core2D.TransformLocalRotation, game.SelfMove],
6.                 (entity, localPos, localRot, selfMove) => {
7.                 // movement speed
8.                 const speed = this.scheduler.deltaTime();
9.                 // object rotation
10.                 const q = localRot.rotation;
11.                 // required translation in self-space
12.                 const v = new Vector3(0, speed, 0);
13.  
14.                 // rotate v according to Rodrigues' formula
15.                 const axis = new Vector3(q.x, q.y, q.z);
16.                 const temp = new Vector3(2 * axis.x, 2 * axis.y, 2 * axis.z);
17.                 axis.cross(v);
18.                 axis.add(new Vector3(q.w * v.x, q.w * v.y, q.w * v.z));
19.                 temp.cross(axis);
20.                 const move = new Vector3(v.x + temp.x, v.y + temp.y, v.z + temp.z);
21.  
22.                 // set new position
23.                 const pos = localPos.position;
24.                 localPos.position = new Vector3(pos.x + move.x, pos.y + move.y, pos.z + move.z);
25.             });
26.         }
27.     }
28. }

To use the system, create an empty component named 'SelfMove' and add it to a sprite for example. The sprite should then move along its local y-axis.

Cheers!

 

In the example, you can remove the calls to cross() and add() by writing the operations manually:

Code (JavaScript):

1. const ax = q.y * v.z - q.z * v.y + q.w * v.x;
2. const ay = q.z * v.x - q.x * v.z + q.w * v.y;
3. const az = q.x * v.y - q.y * v.x + q.w * v.z;
4. const tx = q.x + q.x;
5. const ty = q.y + q.y;
6. const tz = q.z + q.z;
7. const move = new Vector3(
8.         ty * az - tz * ay + v.x,
9.         tz * ax - tx * az + v.y,
10.         tx * ay - ty * ax + v.z);

If you prefer this way, just replace the part under "rotate v according to Rodriques' formula" with the above.

Cheers!