Added final part of 08 interaction with balls

Author: Habrador

Assets/_10 Minute Physics/08 User Interaction/Grabber.cs

@@ -7,7 +7,6 @@ public class Grabber
     //Data needed 
     private Camera mainCamera;
 
-
     //Ball grabbing data
     private float distanceToBall;
 
@@ -25,68 +24,77 @@ public Grabber(Camera mainCamera)
 
 
 
-    public void MyUpdate()
+    public void StartGrab(InteractiveBall ball)
     {
-        //Move the ball to the position of the ray if it has been grabbed
         if (grabbedBall != null)
         {
-            //A ray from the mouse into the scene
-            Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
+            return;
+        }
+        
+        //A ray from the mouse into the scene
+        Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
+
+        //Find if the ray hit a sphere
+        CustomPhysicsRaycast(ray, out CustomHit hit, ball);
+
+        if (hit != null)
+        {
+            //Debug.Log("Ray hit");
 
-            Vector3 ballPos = ray.origin + ray.direction * distanceToBall;
+            grabbedBall = hit.ball;
 
-            lastBallPos = grabbedBall.pos;
+            //Move the ball to the ray because the ray may not have hit at the center of the ball
+            Vector3 ballPosOnRay = UsefulMethods.GetClosestPointOnRay(grabbedBall.pos, ray);
 
-            grabbedBall.MoveGrabbed(ballPos);
+            grabbedBall.StartGrab(ballPosOnRay);
+
+            lastBallPos = ballPosOnRay;
+
+            distanceToBall = (ray.origin - grabbedBall.pos).magnitude;
+        }
+        else
+        {
+            //Debug.Log("Ray missed");
         }
     }
 
 
-    public void MyLateUpdate(InteractiveBall ball)
+
+
+    public void MoveGrab()
     {
-        //If we press left mouse button and the ball is not grabbed, then try to grab it 
-        if (Input.GetMouseButtonDown(0) && grabbedBall == null)
+        if (grabbedBall == null)
         {
-            //Debug.Log("Ray fired");
-
-            //A ray from the mouse into the scene
-            Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
+            return;
+        }
 
-            //Find if the ray hit a sphere
-            CustomPhysicsRaycast(ray, out CustomHit hit, ball);
+        //A ray from the mouse into the scene
+        Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
 
-            if (hit != null)
-            {
-                //Debug.Log("Ray hit");
+        Vector3 ballPos = ray.origin + ray.direction * distanceToBall;
 
-                grabbedBall = hit.ball;
+        lastBallPos = grabbedBall.pos;
 
-                //Move the ball to the ray because the ray may not have hit at the center of the ball
-                Vector3 ballPosOnRay = UsefulMethods.GetClosestPointOnRay(grabbedBall.pos, ray);
+        grabbedBall.MoveGrabbed(ballPos);
+    }
 
-                grabbedBall.StartGrab(ballPosOnRay);
 
-                distanceToBall = (ray.origin - grabbedBall.pos).magnitude;
-            }
-            else
-            {
-                //Debug.Log("Ray missed");
-            }
 
+    public void EndGrab()
+    {
+        if (grabbedBall == null)
+        {
+            return;
         }
 
-        //If we release left mouse, then ungrab the ball
-        if (Input.GetMouseButtonUp(0) && grabbedBall != null)
-        {
-            //Add a velocity to the ball
-            float vel = (grabbedBall.pos - lastBallPos).magnitude / Time.deltaTime;
+        //Add a velocity to the ball
+        float vel = (grabbedBall.pos - lastBallPos).magnitude / Time.deltaTime;
 
-            Vector3 dir = (grabbedBall.pos - lastBallPos).normalized;
+        Vector3 dir = (grabbedBall.pos - lastBallPos).normalized;
 
-            grabbedBall.EndGrab(grabbedBall.pos, dir * vel);
+        grabbedBall.EndGrab(grabbedBall.pos, dir * vel);
 
-            grabbedBall = null;
-        }
+        grabbedBall = null;
     }
 
 
@@ -97,6 +105,6 @@ private void CustomPhysicsRaycast(Ray ray, out CustomHit hit, InteractiveBall ba
         //hit = null;
 
         //Assumer we have just spheres, then we need to do ray-sphere collision detection
-        ball.IsRayHitting(ray, out hit);
+        ball.IsRayHittingThisBall(ray, out hit);
     }
 }

Assets/_10 Minute Physics/08 User Interaction/InteractiveBall.cs

@@ -45,62 +45,13 @@ public void EndGrab(Vector3 pos, Vector3 vel)
     }
 
 
-    //Ray-sphere collision detection
-    //https://www.lighthouse3d.com/tutorials/maths/ray-sphere-intersection/
-    public void IsRayHitting(Ray ray, out CustomHit hit)
+    public void IsRayHittingThisBall(Ray ray, out CustomHit hit)
     {
         hit = null;
 
-        Vector3 p = ray.origin;
-        Vector3 dir = ray.direction;
-
-        Vector3 c = pos;
-        float r = radius;
-
-        //This is the vector from p to c
-        Vector3 vpc = c - p;  
-
-        //Assume the ray starts outside of the sphere
-
-        //The closest point on the ray from the sphere center
-        Vector3 pc = UsefulMethods.GetClosestPointOnRay(c, ray);
-
-        //Debug.DrawRay(pc, Vector3.up * 5f, Color.white, 20f);
-
-        //There is no intersection if the distance between the center of the sphere and the closest point on the ray is larger than the radius of the sphere  
-        if ((pc - c).sqrMagnitude > r * r)
+        if (UsefulMethods.IsRayHittingSphere(ray, pos, radius, out float hitDistance))
         {
-            //Debug.Log("No intersection from within algorithm");
-        
-            return;
-        }
-        else
-        {
-            //Distance from pc to i1 (itersection point 1) by using the triangle pc - c - i1
-            float dist_i1_pc = Mathf.Sqrt(Mathf.Pow(radius, 2f) - Mathf.Pow((pc - c).magnitude, 2f));
-
-            //The distance to the first intersection point (there are two because the ray is also exiting the sphere) from the start of the ray
-            //But we don't care about exiting the sphere becase that intersection point is further away 
-            float dist_i1 = 0f;
-
-            //Ray start is outside sphere	
-            if (vpc.sqrMagnitude > r * r) 
-            {
-                dist_i1 = (pc - p).magnitude - dist_i1_pc;
-            }
-            //Ray start is inside sphere
-            else
-            {
-                dist_i1 = (pc - p).magnitude + dist_i1_pc;
-            }
-
-            //Vector3 intersection = p + dir * dist_i1;
-
-            //Debug.DrawRay(intersection, Vector3.up * 5f, Color.white, 20f);
-
-            //float distance = (ray.origin - intersection).magnitude;
-
-            hit = new CustomHit(dist_i1, this);
+            hit = new CustomHit(hitDistance, this);
         }
     }
 

Assets/_10 Minute Physics/08 User Interaction/UserInteractionController.cs

@@ -38,15 +38,23 @@ private void Update()
         //Update the visual position of the ball
         ball.UpdateVisualPosition();
 
-        grabber.MyUpdate();
+        grabber.MoveGrab();
     }
 
 
 
     //User interactions should be in LateUpdate
     private void LateUpdate()
     {
-        grabber.MyLateUpdate(ball);
+        if (Input.GetMouseButtonDown(0))
+        {
+            grabber.StartGrab(ball);
+        }
+
+        if (Input.GetMouseButtonUp(0))
+        {
+            grabber.EndGrab();
+        }
     }
 
 

Assets/_10 Minute Physics/UsefulMethods.cs

@@ -63,4 +63,63 @@ public static Vector3 GetClosestPointOnLineSegment(Vector3 p, Vector3 a, Vector3
 
 
 
+    //Ray-sphere collision detection
+    //https://www.lighthouse3d.com/tutorials/maths/ray-sphere-intersection/
+    public static bool IsRayHittingSphere(Ray ray, Vector3 sphereCenter, float radius, out float hitDistance)
+    {
+        Vector3 p = ray.origin;
+        Vector3 dir = ray.direction;
+
+        Vector3 c = sphereCenter;
+        float r = radius;
+
+        //This is the vector from p to c
+        Vector3 vpc = c - p;
+
+        //Assume the ray starts outside of the sphere
+
+        //The closest point on the ray from the sphere center
+        Vector3 pc = UsefulMethods.GetClosestPointOnRay(c, ray);
+
+        //Debug.DrawRay(pc, Vector3.up * 5f, Color.white, 20f);
+
+        //There is no intersection if the distance between the center of the sphere and the closest point on the ray is larger than the radius of the sphere  
+        if ((pc - c).sqrMagnitude > r * r)
+        {
+            //Debug.Log("No intersection from within algorithm");
+            hitDistance = 0f;
+
+            return false;
+        }
+        else
+        {
+            //Distance from pc to i1 (itersection point 1) by using the triangle pc - c - i1
+            float dist_i1_pc = Mathf.Sqrt(Mathf.Pow(radius, 2f) - Mathf.Pow((pc - c).magnitude, 2f));
+
+            //The distance to the first intersection point (there are two because the ray is also exiting the sphere) from the start of the ray
+            //But we don't care about exiting the sphere becase that intersection point is further away 
+            float dist_i1 = 0f;
+
+            //Ray start is outside sphere	
+            if (vpc.sqrMagnitude > r * r)
+            {
+                dist_i1 = (pc - p).magnitude - dist_i1_pc;
+            }
+            //Ray start is inside sphere
+            else
+            {
+                dist_i1 = (pc - p).magnitude + dist_i1_pc;
+            }
+
+            //Vector3 intersection = p + dir * dist_i1;
+
+            //Debug.DrawRay(intersection, Vector3.up * 5f, Color.white, 20f);
+
+            //float distance = (ray.origin - intersection).magnitude;
+
+            hitDistance = dist_i1;
+
+            return true;
+        }
+    }
 }

README.md

@@ -41,4 +41,4 @@ Simulate the chaotic behavior of a triple pendulum with different mass
 
 Catch and throw a ball with your mouse
 
-TODO
+<img src="/_media/08-user-interaction.png" width="400">