# System

The `FloraSystem` is the global runtime API for Flora instances.

## What It Is

`FloraSystem` stores runtime instance data and provides methods to create, modify, query, and destroy instances.

## When To Use It

Use `FloraSystem` when you need runtime control (spawning, simulation updates, queries, bulk enable/disable).

## Access Pattern

Use `FloraSystem.GetOrCreate()` to guarantee an active system.

```csharp
var flora = FloraSystem.GetOrCreate();
```

***

## Core Tasks

### Create or destroy a single instance

```csharp
FloraInstanceHandle handle = FloraSystem.GetOrCreate()
    .CreateInstance(prefab, parent, pos, rot, scale);

FloraSystem.Instance?.DestroyInstance(handle);
```

### Create or destroy a batch of instances

```csharp
FloraSystem.GetOrCreate().CreateInstances(prefab, parentObj, handlesArray, transformsArray);
FloraSystem.Instance?.DestroyInstances(handlesArray);
```

### Control instance visibility

```csharp
FloraSystem.Instance?.SetInstanceEnabled(instanceHandle, false);
FloraSystem.Instance?.SetInstancesEnabled(instanceHandleArray, false);
```

### Query instances by sphere or bounds

```csharp
var inSphere = FloraSystem.Instance?.FindInstancesIntersectingSphereMatching(filter, sphere, Allocator.Temp);
var inBounds = FloraSystem.Instance?.FindInstancesIntersectingBoundsMatching(filter, bounds, Allocator.Temp);
```

***

## Example

```csharp
var flora = FloraSystem.GetOrCreate();

var handles = new NativeArray<FloraInstanceHandle>(100, Allocator.Temp);
var transforms = new NativeArray<FloraInstanceTransform>(100, Allocator.Temp);

for (int i = 0; i < 100; i++)
    transforms[i] = FloraInstanceTransform.FromPositionRotationScale(RandomPosition(), quaternion.identity, 1f);

flora.CreateInstances(grassPrefab, owner, handles, transforms);

var sphere = new BoundingSphere(playerPos, 10f);
var filter = FloraInstanceFilter.ByIdentitySource(grassPrefab);
using var nearby = flora.FindInstancesIntersectingSphereMatching(filter, sphere, Allocator.Temp);

flora.SetInstancesEnabled(nearby.AsArray(), false);

handles.Dispose();
transforms.Dispose();
```

## How To Verify

* Created instances are visible and have valid handles.
* Query returns expected subset.
* Destroy/disable calls remove visibility and invalidate stale handles.

## Migration Note

Older names like `FindInstancesInSphereMatching` and `FindInstancesInBoundsMatching` were replaced by `FindInstancesIntersectingSphereMatching` and `FindInstancesIntersectingBoundsMatching`.