Create dynamic GameObjects and transform their positions together from JSON data - unity3d

Question

Consider this dataset:
[
{
PartId: 0,
Positions: [
{ x: 0, y: 0, z: 0, timeCode: 0.0000 },
{ x: 0, y: 0, z: 1, timeCode: 0.0025 },
{ x: 0, y: 0, z: 2, timeCode: 0.0050 },
{ x: 0, y: 0, z: 3, timeCode: 0.0075 },
{ x: 0, y: 0, z: 4, timeCode: 0.0100 },
{ x: 0, y: 0, z: 5, timeCode: 0.0125 },
{ x: 0, y: 0, z: 6, timeCode: 0.0150 },
{ x: 0, y: 0, z: 7, timeCode: 0.0175 },
{ x: 0, y: 0, z: 8, timeCode: 0.0200 },
]
},
{
PartId: 1,
Positions: [
{ x: 0, y: 0, z: 0, timeCode: 0.0000 },
{ x: 0, y: 0, z: 2, timeCode: 0.0025 },
{ x: 0, y: 0, z: 4, timeCode: 0.0050 },
{ x: 0, y: 0, z: 6, timeCode: 0.0075 },
{ x: 0, y: 0, z: 8, timeCode: 0.0100 },
{ x: 0, y: 0, z: 10, timeCode: 0.0125 },
{ x: 0, y: 0, z: 12, timeCode: 0.0150 },
{ x: 0, y: 0, z: 14, timeCode: 0.0175 },
{ x: 0, y: 0, z: 16, timeCode: 0.0200 },
]
}
]
I am able to load and parse the JSON data and I can create a new GameObject for each PartId. I am trying to figure out the best way to transform each "Part" according to the Position collection all at the same time.
I have an empty GameObject in the scene with an attached class. Inside the Start method I get the JSON data and then in a loop I create the GameObject class, set its initial position and then start a coroutine defined in the same class.
Main class:
void Start() {
// do json stuff...
// ........
// then
// for each part...
foreach(PartGroup pg in Parts) {
// create a new GameObject from the Part class
Part part = gameObject.AddComponent(typeof(Part)) as Part;
// send this part data to the new GameObject
part.PartGroup = pg;
// set the initial position for the part
part.Init();
// start a IEnumerator Coroutine in the part class
StartCoroutine(part.PlayFrom());
}
}
Part class:
public void Init() {
Joint = GameObject.CreatePrimitive(PrimitiveType.Sphere);
Joint.transform.localScale = new Vector3(jointSize, jointSize, jointSize);
Joint.transform.position = new Vector3(PartGroup.Positions[0].X, PartGroup.Positions[0].Z, PartGroup.Positions[0].Y);
}
public IEnumerator PlayFrom(float time = 0f) {
while (PlayBack(time)) {
yield return null;
time += Time.fixedDeltaTime;
}
}
bool PlayBack(float time) {
float sample = time / (Time.fixedDeltaTime / speed);
int previousIndex = (int)(sample);
int last = PartGroup.Positions.Count - 1;
if (previousIndex < last) {
int nextIndex = previousIndex + 1;
float interpolation = sample - previousIndex;
Joint.transform.position = Vector3.Lerp(
new Vector3(PartGroup.Positions[previousIndex].X, PartGroup.Positions[previousIndex].Z, PartGroup.Positions[previousIndex].Y),
new Vector3(PartGroup.Positions[nextIndex].X, PartGroup.Positions[nextIndex].Z, PartGroup.Positions[nextIndex].Y),
interpolation);
return true;
}
Joint.transform.position = new Vector3(PartGroup.Positions[last].X, PartGroup.Positions[last].Z, PartGroup.Positions[last].Y);
return false;
}
This is how I currently have it set up. It does work, but it is not smooth motion and sometimes it seems to lag or jump frames. Is this the best way to accomplish this, or is there a better way (like FixedUpdate)? I have set the fixed time property in my project settings to match the data timeCode.
Any help with best practices for stuff like this is greatly appreciated!

Answer 1

You have to use Time.deltaTime in
time += Time.deltaTime;
and
float sample = time / (Time.deltaTime / speed);
Coroutines are executed together with all Update calls so using fixedDeltaTime breaks the frame independency.
or probably use WaitForFixedUpdate to execute it like FixedUpdate
while (PlayBack(time)) {
yield return new WaitForFixedUpdate();
time += Time.fixedDeltaTime;
}
Also in
foreach(PartGroup pg in Parts)
{
// create a new GameObject from the Part class
Part part = gameObject.AddComponent(typeof(Part)) as Part;
// send this part data to the new GameObject
part.PartGroup = pg;
// set the initial position for the part
part.Init();
// start a IEnumerator Coroutine in the part class
StartCoroutine(part.PlayFrom());
}
it looks like you are adding a component for each element in the list all to one and the same GameObject .. I don't know if that's what you planned to do. AddComponent does not create a new GameObject with that component but attaches that component to the same gameObject that script is attached to.
You probably ment to use new GameObject
Part part = new GameObject("new GameObject").AddComponent<Part>();
// make it a child of this gameObject?
part.SetParent(gameObject, false);
also the calculations
float sample = time / (Time.fixedDeltaTime / speed);
int previousIndex = (int)(sample);
...
float interpolation = sample - previousIndex;
seems a bit odd .. are you sure it always returns a value between 0 and 1?