Computes a point for a gun to aim at in order to hit a target using linear prediction.

ComputeGunLead.cs

/// <summary>
/// Computes a point for a gun to aim at in order to hit a target using linear prediction.
/// Assumes a bullet with no gravity or drag. I.e. A bullet that maintains a constant
/// velocity after it's been fired.
/// </summary>
public static Vector3 ComputeGunLead(Vector3 targetPos, Vector3 targetVel, Vector3 ownPos, Vector3 ownVel, float muzzleVelocity)
{
    // Extremely low muzzle velocities are unlikely to ever hit. This also prevents a
    // possible division by zero if the muzzle velocity is zero for whatever reason.
    if (muzzleVelocity < 1f)
        return targetPos;

    // Figure out ETA for bullets to reach target.
    Vector3 predictedTargetPos = targetPos + targetVel;
    Vector3 predictedOwnPos = ownPos + ownVel;

    float range = Vector3.Distance(predictedOwnPos, predictedTargetPos);
    float timeToHit = range / muzzleVelocity;

    // Project velocity of target using the TimeToHit.
    Vector3 leadMarker = (targetVel - ownVel) * timeToHit + targetPos;

    return leadMarker;
}