Mesidin · October 15, 2016 04:54 · Jul 10, 2016
diff --git a/TrajectoryCalculation.cs b/TrajectoryCalculation.cs
@@ -0,0 +1,86 @@
+using UnityEngine;
+using System.Collections;
+
+public class TrajectoryCalculation : MonoBehaviour 
+{
+	public Rigidbody projectile;
+	public Transform target;
+	[Header("CalculateBestThrowSpeed")]
+	public float timeToTarget = 1f;
+	[Header("CalculateTrajectory")]
+	public float speed = 10;
+	[Range(0, 1)] public float arc = 0;
+
+
+	void Update()
+	{
+		if (Input.GetKeyDown("a"))
+		{
+			GameObject p = Instantiate(projectile, transform.position, transform.rotation) as GameObject;
+			p.GetComponent<Rigidbody>().AddForce(CalculateBestThrowSpeed(transform.position, target.position, timeToTarget), ForceMode.VelocityChange);
+			Destroy(p, 10);
+		}
+
+		if (Input.GetKeyDown("b"))
+		{
+			Vector3 velocity;
+			if (CalculateTrajectory(transform.position, target.position, speed, out velocity, arc))
+			{
+				GameObject p = Instantiate(projectile, transform.position, transform.rotation) as GameObject;
+				p.GetComponent<Rigidbody>().AddForce(velocity, ForceMode.VelocityChange);
+				Destroy(p, 10);
+			}
+			else
+			{
+				Debug.Log("Target cannot be reached. Increase speed or reduce distance.");
+			}
+		}
+	}
+
+
+	// from http://answers.unity3d.com/answers/456066/view.html
+	static Vector3 CalculateBestThrowSpeed(Vector3 origin, Vector3 target, float timeToTarget)
+	{
+		Vector3 toTarget = target - origin;
+		Vector3 toTargetXZ = toTarget;
+		toTargetXZ.y = 0;
+		float y = toTarget.y;
+		float xz = toTargetXZ.magnitude;
+		float v0y = y / timeToTarget + 0.5f * Physics.gravity.magnitude * timeToTarget;
+		float v0xz = xz / timeToTarget;
+		Vector3 result = toTargetXZ.normalized;
+		result *= v0xz;
+		result.y = v0y;
+		return result;
+	}
+
+
+	// based on http://gamedev.stackexchange.com/questions/114522/how-can-i-launch-a-gameobject-at-a-target-if-i-am-given-everything-except-for-it/114547
+	static bool CalculateTrajectory(Vector3 origin, Vector3 target, float speed, out Vector3 velocity, float arc = 0f)
+	{
+		Vector3 toTarget = target - origin;
+		Vector3 toTargetXZ = toTarget;
+		toTargetXZ.y = 0;
+		float y = toTarget.y;
+		float xz = toTargetXZ.magnitude;
+		float gravity = Physics.gravity.magnitude;
+		float b = speed*speed - y * gravity;
+		float discriminant = b * b - gravity * gravity * (xz * xz + y * y);
+		if (discriminant < 0) // out of range, need higher shot speed
+		{
+			velocity = Vector3.zero;
+			return false;
+		}
+		float discRoot = Mathf.Sqrt(discriminant);
+		float minTime = Mathf.Sqrt((b - discRoot) * 2) / Mathf.Abs(gravity); // impact time for the most direct shot that hits
+		float maxTime = Mathf.Sqrt((b + discRoot) * 2) / Mathf.Abs(gravity); // impact time for the highest shot that hits
+		float time = (maxTime - minTime) * arc + minTime;
+		float v0xz = xz / time;
+		float v0y = y / time + time * gravity / 2;
+		velocity = toTargetXZ.normalized;
+		velocity *= v0xz;
+		velocity.y = v0y;
+		return true;
+	}
+
+}