Merge pull request #4750 from PhilipRosedale/master

Add limit to grab range to reduce max energy added by grabbing

examples/grab.js

@@ -1,3 +1,16 @@
+
+//  grab.js
+//  examples
+//
+//  Created by Eric Levin on May 1, 2015
+//  Copyright 2015 High Fidelity, Inc.
+//
+//  Grab's physically moveable entities with the mouse, by applying a spring force. 
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
 var isGrabbing = false;
 var grabbedEntity = null;
 var prevMouse = {};
@@ -8,7 +21,7 @@ var entityProps;
 var targetPosition;
 var moveUpDown = false;
 
-var currentPosition, currentVelocity; 
+var currentPosition, currentVelocity, cameraEntityDistance; 
 
 var grabSound = SoundCache.getSound("https://hifi-public.s3.amazonaws.com/eric/sounds/CloseClamp.wav");
 var releaseSound = SoundCache.getSound("https://hifi-public.s3.amazonaws.com/eric/sounds/ReleaseClamp.wav");
@@ -23,16 +36,6 @@ var DROP_WIDTH = 2;
 
 
 var dropLine = Overlays.addOverlay("line3d", {
-  start: {
-    x: 0,
-    y: 0,
-    z: 0
-  },
-  end: {
-    x: 0,
-    y: 0,
-    z: 0
-  },
   color: DROP_COLOR,
   alpha: 1,
   visible: false,
@@ -64,12 +67,8 @@ function mousePressEvent(event) {
 function updateDropLine(position) { 
       Overlays.editOverlay(dropLine, {
       visible: true,
-      start: position,
+      start: { x: position.x, y: position.y + DROP_DISTANCE, z: position.z },
-      end: Vec3.sum(position, {
+      end: { x: position.x, y: position.y - DROP_DISTANCE, z: position.z }
-        x: 0,
-        y: -DROP_DISTANCE,
-        z: 0
-      })
     })
 }
 
@@ -103,11 +102,11 @@ function mouseMoveEvent(event) {
     var camYaw = Quat.safeEulerAngles(Camera.getOrientation()).y;
     var dPosition = Vec3.multiplyQbyV(Quat.fromPitchYawRollDegrees(0, camYaw, 0), deltaMouse);
     //  Adjust target position for the object by the mouse move 
-    var avatarEntityDistance = Vec3.distance(Camera.getPosition(), currentPosition);
+    cameraEntityDistance = Vec3.distance(Camera.getPosition(), currentPosition);
       //  Scale distance we want to move by the distance from the camera to the grabbed object 
       //  TODO:  Correct SCREEN_TO_METERS to be correct for the actual FOV, resolution
     var SCREEN_TO_METERS = 0.001;
-    targetPosition = Vec3.sum(targetPosition, Vec3.multiply(dPosition, avatarEntityDistance * SCREEN_TO_METERS));
+    targetPosition = Vec3.sum(targetPosition, Vec3.multiply(dPosition, cameraEntityDistance * SCREEN_TO_METERS));
   }
   prevMouse.x = event.x;
   prevMouse.y = event.y;
@@ -136,15 +135,21 @@ function update(deltaTime) {
 
     var dPosition = Vec3.subtract(targetPosition, currentPosition);
     var CLOSE_ENOUGH = 0.001;
-    if (Vec3.length(dPosition) > CLOSE_ENOUGH) {
+    var FULL_STRENGTH = 0.025;
+    var distanceToTarget = Vec3.length(dPosition);
+    if (distanceToTarget / cameraEntityDistance > CLOSE_ENOUGH) {
       //  compute current velocity in the direction we want to move 
       var velocityTowardTarget = Vec3.dot(currentVelocity, Vec3.normalize(dPosition));
       //  compute the speed we would like to be going toward the target position 
-      var SPRING_RATE = 0.35;
+      var SPRING_RATE = 1.5;
-      var DAMPING_RATE = 0.55;
+      var DAMPING_RATE = 0.80;
       var desiredVelocity = Vec3.multiply(dPosition, (1.0 / deltaTime) * SPRING_RATE);
       //  compute how much we want to add to the existing velocity
       var addedVelocity = Vec3.subtract(desiredVelocity, velocityTowardTarget);
+      //  If target is too far, roll off the force as inverse square of distance
+      if (distanceToTarget / cameraEntityDistance > FULL_STRENGTH) {
+        addedVelocity = Vec3.multiply(addedVelocity, Math.pow(FULL_STRENGTH / distanceToTarget, 2.0));
+      }
       var newVelocity = Vec3.sum(currentVelocity, addedVelocity); 
       //  Add Damping 
       newVelocity = Vec3.subtract(newVelocity, Vec3.multiply(newVelocity, DAMPING_RATE));
@@ -153,7 +158,7 @@ function update(deltaTime) {
       velocity: newVelocity
       })
     } 
-    updateDropLine(currentPosition);
+    updateDropLine(targetPosition);
   }
 }