fix boids escaping edge wrappinig using Centering Velocity to force return to Rectangle, move velocity limiting logic into Util, abs vector function

2025-12-07 18:06:23 -06:00 · 2020-05-17 13:05:24 -05:00
parent 44fb0f3bfe
commit b6812cc9a8
5 changed files with 388 additions and 29 deletions
--- a/Assets/Boid.cs
+++ b/Assets/Boid.cs
@@ -14,10 +14,12 @@ public class Boid : MonoBehaviour {
    [NonSerialized] private bool _isWrappingX = false;
    [NonSerialized] private bool _isWrappingY = false;
    [NonSerialized] private Renderer[] _renderers;
+    [NonSerialized] private Vector2 _centeringVelocity;
    private BoidController _parent;

    void Start() {
-        _parent = transform.parent.GetComponent<BoidController>(); // Parent used to perform physics math without caching
+        _parent = transform.parent
+            .GetComponent<BoidController>(); // Parent used to perform physics math without caching
        _renderers = transform.GetComponents<Renderer>(); // Acquire Renderer(s) to check for Boid visibility
        _velocity = GetRandomVelocity(_parent.boidStartVelocity); // Acquire a Velocity Vector with a magnitude
        _position = transform.position; // Track 2D position separately
@@ -25,38 +27,41 @@ public class Boid : MonoBehaviour {
    }

    void OnDrawGizmos() {
-        Handles.color = _isWrappingX || _isWrappingY ? Color.red : Color.white;
-        Vector3 viewportPosition = _parent.cam.WorldToViewportPoint(transform.position);
-        Handles.Label(transform.position, $"{(Vector2) viewportPosition} {(_isWrappingX ? "Y" : "N")} {(_isWrappingY ? "Y" : "N")}");
+        // Handles.color = _isWrappingX || _isWrappingY ? Color.red : Color.white;
+        // Vector3 viewportPosition = _parent.cam.WorldToViewportPoint(transform.position);
+        // Handles.Label(transform.position,
+            // $"{(Vector2) viewportPosition} {(_isWrappingX ? "Y" : "N")} {(_isWrappingY ? "Y" : "N")}");
+            var transform_ = transform;
+            Handles.Label(transform_.position, $"{transform_.name}");
    }

-     void Update() {
+    void Update() {
        // Updates the rotation of the object based on the Velocity
        transform.rotation = Quaternion.Euler(0, 0, Mathf.Rad2Deg * -Mathf.Atan2(_velocity.x, _velocity.y));

        // Skip Flock Calculations if wrapping in progress
        if (_isWrappingX || _isWrappingY) {
-            _position += _velocity;
+            UpdateCenteringVelocity();
+            _position += _centeringVelocity;
            transform.position = _position;
        }
+        else {
+            List<Boid> flock = _parent.localFlocks ? GetFlock(_parent.boids, _parent.boidGroupRange) : _parent.boids;

-        List<Boid> flock = _parent.localFlocks ? GetFlock(_parent.boids, _parent.boidGroupRange) : _parent.boids;
-        
-        if (flock.Count > 0) {
            // Calculate all offsets and multiple by magnitudes given
-            Vector2 r1 = Rule1(flock) * _parent.cohesionBias;
-            Vector2 r2 = Rule2(flock) * _parent.separationBias;
-            Vector2 r3 = Rule3(flock) * _parent.alignmentBias;
-            _velocity += r1 + r2 + r3;
-        }
+            if (flock.Count > 0) {
+                Vector2 r1 = Rule1(flock) * _parent.cohesionBias;
+                Vector2 r2 = Rule2(flock) * _parent.separationBias;
+                Vector2 r3 = Rule3(flock) * _parent.alignmentBias;
+                _velocity += r1 + r2 + r3;
+            }

-        // Limit the Velocity Vector to a certain Magnitude
-        if (_velocity.magnitude > _parent.boidVelocityLimit) {
-            _velocity = (_velocity / _velocity.magnitude) * _parent.boidVelocityLimit;
-        }
+            // Limit the Velocity Vector to a certain Magnitude
+            _velocity = Util.LimitVelocity(_velocity, _parent.boidVelocityLimit);

-        _position += _velocity;
-        transform.position = new Vector3(_position.x, _position.y, 0);
+            _position += _velocity;
+            transform.position = new Vector3(_position.x, _position.y, 0);
+        }

        Wrapping();
    }
@@ -70,11 +75,13 @@ public class Boid : MonoBehaviour {
            if (!_isWrappingX && (viewportPosition.x > 1 || viewportPosition.x < 0)) {
                newPosition.x = -newPosition.x;
                _isWrappingX = true;
+                UpdateCenteringVelocity();
            }

            if (!_isWrappingY && (viewportPosition.y > 1 || viewportPosition.y < 0)) {
                newPosition.y = -newPosition.y;
                _isWrappingY = true;
+                UpdateCenteringVelocity();
            }

            transform.position = newPosition;
@@ -87,6 +94,13 @@ public class Boid : MonoBehaviour {
        }
    }

+    // When Wrapping, this Velocity directs the Boid to the center of the Rectangle
+    void UpdateCenteringVelocity() {
+        _centeringVelocity = Util.RotateBy(new Vector2(_parent.boidVelocityLimit, _parent.boidVelocityLimit),
+            Vector2.Angle(_position, _parent.Space.center));
+        _centeringVelocity = Util.LimitVelocity(_parent.Space.center - _position, _parent.boidVelocityLimit / 2.0f);
+    }
+    
    Vector2 GetRandomVelocity(float magnitude) {
        Vector2 vector = new Vector2(magnitude, magnitude);
        return Util.RotateBy(vector, Random.Range(0, 180));
@@ -106,7 +120,7 @@ public class Boid : MonoBehaviour {
        Vector2 c = Vector2.zero;
        foreach (Boid boid in flock) {
            Vector2 diff = boid._position - this._position;
-            if (diff.magnitude < _parent.separationRange)
+            if (diff.sqrMagnitude < _parent.separationRange)
                c -= diff;
        }

--- a/Assets/BoidController.preset
+++ b/Assets/BoidController.preset
@@ -0,0 +1,324 @@
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--- a/Assets/BoidController.preset.meta
+++ b/Assets/BoidController.preset.meta
@@ -0,0 +1,8 @@
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--- a/Assets/Scenes/SampleScene.unity
+++ b/Assets/Scenes/SampleScene.unity
@@ -173,7 +173,7 @@ Camera:
  far clip plane: 1000
  field of view: 60
  orthographic: 1
-  orthographic size: 22.68
+  orthographic size: 25
  m_Depth: -1
  m_CullingMask:
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@@ -232,17 +232,18 @@ MonoBehaviour:
  m_Script: {fileID: 11500000, guid: 7d72224fef7a4fb4a998b0980fe0eb77, type: 3}
  m_Name: 
  m_EditorClassIdentifier: 
-  boidCount: 208
-  boidGroupRange: 5
+  boidCount: 100
+  boidGroupRange: 3.6
  boidStartVelocity: 0.05
-  boidVelocityLimit: 0.8
-  separationRange: 2.3
+  boidVelocityLimit: 0.3
+  separationRange: 2.8
  separationBias: 0.01
-  alignmentBias: 0.01
-  cohesionBias: 0.01
+  alignmentBias: 0.05
+  cohesionBias: 0.05
+  localFlocks: 1
  boidObject: {fileID: 1737515784064720040, guid: 23e1eaaf69d4ef342ac3ef9590f6c642,
    type: 3}
-  boids: []
+  cam: {fileID: 519420031}
 --- !u!4 &1321165554
 Transform:
  m_ObjectHideFlags: 0
--- a/Assets/Util.cs
+++ b/Assets/Util.cs
@@ -10,6 +10,18 @@ public class Util {
        return new Vector2((float) rx, (float) (v.x * sa + v.y * ca));
    }

+    public static Vector2 LimitVelocity(Vector2 v, float max) {
+        if (v.magnitude > max) {
+            v = (v / v.magnitude) * max;
+        }
+
+        return v;
+    }
+
+    public static Vector2 AbsVector(Vector2 vector) {
+        return new Vector2(vector.x, vector.y);
+    }
+    
    public class ReadOnlyAttribute : PropertyAttribute {
    }