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Ballistic Path Line Render

BallisticPathLineRender visualizes a projectile’s trajectory (including optional bounces) by drawing a line in world space. Designers can configure launch parameters, gravity behavior, collision layers, resolution, and bounce settings directly in the Inspector. Calling Simulate() (or enabling runOnStart/continuousRun) computes the full flight path via the corresponding BallisticsData.Predict(...) method and updates a LineRenderer to show the arc.

Public Fields & Properties

Start

  • public Vector3 start

    • World-space origin point where the projectile is launched.

    • Designers can set this to a turret’s muzzle, character’s hand, or any desired source.

Projectile

  • public BallisticsData projectile

    • Reference to a BallisticsData asset or component that holds: initial speed, radius, drag, etc.

    • Used internally to call projectile.Predict(...) and retrieve a BallisticPath.

Run On Start

  • public bool runOnStart (default: true)

    • If checked, the component immediately calls Simulate() in Start(), rendering the path once when the scene begins.

Continous Run

  • public bool continuousRun (default: false)

    • If enabled, Simulate() is called every LateUpdate(), allowing the line to update in real time as launch parameters change (e.g., moving start or adjusting gravity).

Collision Layers

  • public LayerMask collisionLayers (default: 0)

    • Specifies which layers to test for collisions when predicting the path.

    • Designers must assign relevant layers (e.g., “Environment”, “Obstacles”) so that the trajectory stops or bounces correctly.

Trigger Interaction

  • public QueryTriggerInteraction triggerInteraction (default: UseGlobal)

    • Controls whether triggers are included in collision checks (e.g., UseGlobal, Ignore, Collide).

    • Adjust if you want the trajectory to stop or bounce off trigger colliders.

Resolution

  • [Min(0.001f)] public float resolution (default: 0.1f)

    • The distance increment at which the path is sampled.

      • Lower values (e.g., 0.05f) yield a smoother, more accurate curve but cost more CPU.

      • Higher values (e.g., 0.2f–0.5f) produce fewer points and can miss short‐range collisions.

Max Length

  • public float maxLength (default: 10f)

    • Maximum distance the simulation traces before stopping if no impact occurs.

    • Designers can increase for long‐range arcs or decrease to limit preview length.

Max Bounces

  • public int maxBounces (default: 0)

    • Number of times the trajectory should bounce (up to) after its first impact.

    • Each bounce uses a reflected velocity scaled by (1 – bounceDamping).

Bounce Damping

  • [Range(0f, 1f)] public float bounceDamping (default: 0.2f)

    • Fraction of velocity lost on each bounce (e.g., 0.2f means the new speed is 80% of pre‐impact speed).

    • Only used if maxBounces > 0. Value must be in [0, 1].

Gravity Mode

  • public GravityMode gravityMode (enum: None, Physics, Custom; default: Physics)

    • Selects how gravity is applied during simulation:

      1. None – No gravity. The path is a straight line.

      2. Physics – Uses Physics.gravity (typically (0, –9.81f, 0)).

      3. Custom – Uses the vector set in customGravity.

Custom Gravity

  • public Vector3 customGravity (default: Vector3.zero)

    • Only used if gravityMode == GravityMode.Custom. Defines a custom gravity vector (e.g., (0, –15f, 0) for heavier gravity).

Public Methods

Simulate

  • public void Simulate()

    • Computes a full, sampled trajectory and updates the attached LineRenderer.

    • Designer-Visible Behavior:

      1. Check “Speed”

        • If projectile.Speed ≤ 0f, Simulate() returns immediately (nothing to draw).

      2. Select Gravity

        • Uses gravityMode to pick Vector3 gravity = Physics.gravity or customGravity, or Vector3.zero.

      3. Clear Previous Data

        • Empties internal List<Vector3> trajectory and List<RaycastHit> impacts to avoid stale points.

      4. Initial Prediction

        csharpCopyEditvar result = projectile.Predict(
    start,              // launch origin
    null,               // no ignore-collider on first segment
    resolution,         // sampling resolution
    maxLength,          // maximum trace length
    collisionLayers,    // layers to hit
    triggerInteraction, // include/exclude triggers
    gravity             // chosen gravity vector
);

        • Appends every step.position from result.steps into trajectory.

        • If result.impact.HasValue, also stores the RaycastHit in impacts.

      5. Handle Bounces (if maxBounces > 0 and there was an impact)

        • Computes remainingLength = maxLength – result.flightDistance.

        • Copies projectile locally (so original asset remains unchanged).

        • Reflects last‐sample velocity about the impact normal (using Vector3.Reflect) and multiplies by (1 – bounceDamping).

        • Repeats Predict(...) from the impact point, ignoring the now‐hit collider, up to maxBounces times or until no further impact.

        • Each subsequent segment’s positions are appended to trajectory, and each new impact is added to impacts.

        • Deducts each segment’s flightDistance from remainingLength to cap total drawn length.

      6. Feed Data to LineRenderer

        • Ensures an internal buffer (positionBuffer) is at least trajectory.Count in length; resizes if needed.

        • Copies trajectory into positionBuffer.

        • Sets lineRenderer.positionCount = trajectory.Count and lineRenderer.SetPositions(positionBuffer).

    • Designer Tips:

      • Call Simulate() explicitly after changing start, projectile, or any parameters at runtime (unless continuousRun is true).

      • Make sure projectile.Speed is set properly in your BallisticsData asset before calling Simulate().

      • If you want the line to auto-update whenever the camera or launch origin moves (e.g., an aiming reticle), enable continuousRun = true and adjust parameters in real time.

Inspector Setup & Typical Usage

  1. Attach to a GameObject

    • Create an empty GameObject (e.g., “TrajectoryPreview”) in your scene.

    • Add a LineRenderer component and configure its material (e.g., a simple unlit color) and width.

    • Add the BallisticPathLineRender component to the same GameObject.

  2. Assign Launch & Projectile Data

    • start: Drag a Transform (e.g., a turret’s muzzle or player’s hand) from your scene into this field or set a static coordinate.

    • projectile: Select the BallisticsData asset (ScriptableObject) or component that contains the projectile’s initial speed, radius, drag, etc.

  3. Configure Collision & Bounce

    • collisionLayers: Tick the layers you want to hit (e.g., “Environment” or “Obstacles”).

    • triggerInteraction: Choose whether triggers count as hits.

    • maxLength: Set the maximum trace length in world units (e.g., 50f).

    • maxBounces: If you want to preview up to N bounces, set this (e.g., 1 for one bounce).

    • bounceDamping: Adjust how much speed is lost each bounce (e.g., 0.3f → 70% retention).

    • resolution: Lower for finer curves (e.g., 0.05f), higher for performance (e.g., 0.2f).

    • gravityMode:

      • Physics if you want standard Unity gravity.

      • Custom if you’re simulating in a non‐Earth environment (e.g., customGravity = (0, –20f, 0)).

      • None for a straight-line preview (e.g., lasers or bullets without drop).

  4. Choose Run Behavior

    • runOnStart = true → Preview appears immediately when you enter Play Mode.

    • continuousRun = true → Preview updates every frame (useful for runtime adjusting aim).

    • Otherwise, call Simulate() from your script when you want to refresh the trajectory.

  5. Scripting Examples

    • Manual Recalculation (e.g., when player aims):

      public class TrajectoryController : MonoBehaviour
{
    [SerializeField] private BallisticPathLineRender pathPreview;
    [SerializeField] private Transform muzzle;
    [SerializeField] private BallisticsData projectileData;

    void Update()
    {
        // Example: continuously update the start point and re-simulate
        pathPreview.start = muzzle.position;
        pathPreview.projectile = projectileData;
        pathPreview.Simulate();
    }
}

    • One-Off Preview (e.g., on button press):

      public class PreviewOnDemand : MonoBehaviour
{
    [SerializeField] private BallisticPathLineRender pathPreview;
    [SerializeField] private Transform muzzle;
    [SerializeField] private BallisticsData projectileData;

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.T))
        {
            pathPreview.start = muzzle.position;
            pathPreview.projectile = projectileData;
            pathPreview.Simulate();
        }
    }
}

Designer Tips & Gotchas

  • LineRenderer Configuration

    • Adjust the material and width curve so the path is clearly visible (e.g., a bright color or dashed texture).

  • Performance Considerations

    • High resolution (small steps) + many bounces can generate hundreds of sample points. If updating every frame (continuousRun), consider a coarser resolution (e.g., 0.2f–0.5f).

    • If you only need a quick preview in the Editor and not at runtime, disable continuousRun and run Simulate() via a custom Editor script or button.

  • Max Length vs. Bounces

    • maxLength is total distance for each segment. Each bounce reduces remainingLength by the previous segment’s flightDistance. If you want a guaranteed total limit across all bounces, subtract each segment from a master length before calling Predict(...).

  • Trigger Colliders

    • If you have invisible triggers (e.g., detection zones) in your scene, set triggerInteraction = Ignore if you don’t want the path to stop on them.

  • Ensuring Up-to-Date Data

    • If you change BallisticsData (speed/radius) in Play Mode, call Simulate() again to reflect those changes. Otherwise, the path will still show the old values.

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