keep hokey paddle in playing field

examples/example/games/grabHockey.js

@@ -1,4 +1,3 @@
-
 //  grab.js
 //  examples
 //
@@ -11,12 +10,38 @@
 //  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
 //
 
+// these are hand-measured bounds of the AirHockey table
+var fieldMaxOffset = {
+  x: 0.475,
+  y: 0.315,
+  z: 0.830
+};
+var fieldMinOffset = {
+  x: -0.475,
+  y: 0.315,
+  z: -0.830
+};
+
+// parameters for storing the table playing field
+var fieldMax = {
+  x: 0,
+  y: 0,
+  z: 0
+};
+var fieldMin = {
+  x: 0,
+  y: 0,
+  z: 0
+};
+
 var isGrabbing = false;
 var grabbedEntity = null;
 var prevMouse = {};
 var deltaMouse = {
   z: 0
 }
+
+var TABLE_SEARCH_RANGE = 10;
 var entityProps;
 var moveUpDown = false;
 var CLOSE_ENOUGH = 0.001;
@@ -26,8 +51,13 @@ var DAMPING_RATE = 0.80;
 var ANGULAR_DAMPING_RATE = 0.40;
 var SCREEN_TO_METERS = 0.001;
 var currentPosition, currentVelocity, cameraEntityDistance, currentRotation;
+var grabHeight;
 var velocityTowardTarget, desiredVelocity, addedVelocity, newVelocity, dPosition, camYaw, distanceToTarget, targetPosition;
-var originalGravity = {x: 0, y: 0, z: 0};
+var originalGravity = {
+  x: 0,
+  y: 0,
+  z: 0
+};
 var shouldRotate = false;
 var dQ, theta, axisAngle, dT;
 var angularVelocity = {
@@ -75,9 +105,15 @@ function mousePressEvent(event) {
   if (!event.isLeftButton) {
     return;
   }
+  prevMouse.x = event.x;
+  prevMouse.y = event.y;
+
   var pickRay = Camera.computePickRay(event.x, event.y);
   var intersection = Entities.findRayIntersection(pickRay, true); // accurate picking
-  if (intersection.intersects && intersection.properties.collisionsWillMove) {
+  if (!intersection.intersects) {
+    return;
+  }
+  if (intersection.properties.collisionsWillMove) {
     grabbedEntity = intersection.entityID;
     var props = Entities.getEntityProperties(grabbedEntity)
     isGrabbing = true;
@@ -87,14 +123,34 @@ function mousePressEvent(event) {
     currentVelocity = props.velocity;
     updateDropLine(targetPosition);
 
+    // remember the height of the object when first grabbed
+    // we'll try to maintain this height during the rest of this grab
+    grabHeight = currentPosition.y;
+
     Entities.editEntity(grabbedEntity, {
-      gravity: {x: 0, y: 0, z: 0}
+      gravity: {
+        x: 0,
+        y: 0,
+        z: 0
+      }
     });
 
     Audio.playSound(grabSound, {
       position: props.position,
       volume: VOLUME
     });
+
+    //We want to detect table once user grabs something that may be on a table...
+    var potentialTables = Entities.findEntities(MyAvatar.position, TABLE_SEARCH_RANGE);
+    potentialTables.forEach(function(table) {
+      var props = Entities.getEntityProperties(table);
+      if (props.name === "table") {
+        var tablePosition = props.position;
+        // when we know the table's position we can compute the X-Z bounds of its field
+        fieldMax = Vec3.sum(tablePosition, fieldMaxOffset);
+        fieldMin = Vec3.sum(tablePosition, fieldMinOffset);
+      }
+    });
   } 
 }
 
@@ -144,6 +200,7 @@ function mouseReleaseEvent() {
   }
 }
 
+// new mouseMoveEvent
 function mouseMoveEvent(event) {
   if (isGrabbing) {
     // see if something added/restored gravity
@@ -152,6 +209,7 @@ function mouseMoveEvent(event) {
       originalGravity = props.gravity;
     }
 
+    if (shouldRotate) {
       deltaMouse.x = event.x - prevMouse.x;
       if (!moveUpDown) {
         deltaMouse.z = event.y - prevMouse.y;
@@ -160,16 +218,6 @@ function mouseMoveEvent(event) {
         deltaMouse.y = (event.y - prevMouse.y) * -1;
         deltaMouse.z = 0;
       }
-    //  Update the target position by the amount the mouse moved
-    camYaw = Quat.safeEulerAngles(Camera.getOrientation()).y;
-    dPosition = Vec3.multiplyQbyV(Quat.fromPitchYawRollDegrees(0, camYaw, 0), deltaMouse);
-    if (!shouldRotate) {
-      //  Adjust target position for the object by the mouse move 
-      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
-      targetPosition = Vec3.sum(targetPosition, Vec3.multiply(dPosition, cameraEntityDistance * SCREEN_TO_METERS));
-    } else if (shouldRotate) {
       var transformedDeltaMouse = {
         x: deltaMouse.z,
         y: deltaMouse.x,
@@ -180,15 +228,37 @@ function mouseMoveEvent(event) {
       theta = 2 * Math.acos(dQ.w);
       axisAngle = Quat.axis(dQ);
       angularVelocity = Vec3.multiply((theta / dT), axisAngle);
-    }
+    } else {
+      var relativePosition = Vec3.subtract(currentPosition, Camera.getPosition());
+      if (relativePosition.y < 0) {
+        // grabee is below camera, so movement is valid
+        // compute intersectionPoint where mouse ray hits grabee's current x-z plane
+        var pickRay = Camera.computePickRay(event.x, event.y);
+        var mousePosition = pickRay.direction;
+        var length = relativePosition.y / mousePosition.y;
+        mousePosition = Vec3.multiply(mousePosition, length);
+        mousePosition = Vec3.sum(Camera.getPosition(), mousePosition);
 
+        // clamp mousePosition to table field
+        if (mousePosition.x < fieldMin.x) {
+          mousePosition.x = fieldMin.x;
+        } else if (mousePosition.x > fieldMax.x) {
+          mousePosition.x = fieldMax.x;
+        }
+        if (mousePosition.z < fieldMin.z) {
+          mousePosition.z = fieldMin.z;
+        } else if (mousePosition.z > fieldMax.z) {
+          mousePosition.z = fieldMax.z;
+        }
+        mousePosition.y = grabHeight;
+        targetPosition = mousePosition;
+      }
+    }
   }
   prevMouse.x = event.x;
   prevMouse.y = event.y;
-
 }
 
-
 function keyReleaseEvent(event) {
   if (event.text === "SHIFT") {
     moveUpDown = false;
@@ -237,7 +307,11 @@ function update(deltaTime) {
       newVelocity = Vec3.subtract(newVelocity, Vec3.multiply(newVelocity, DAMPING_RATE));
       //  Update entity
     } else {
-      newVelocity = {x: 0, y: 0, z: 0};
+      newVelocity = {
+        x: 0,
+        y: 0,
+        z: 0
+      };
     }
     if (shouldRotate) {
       angularVelocity = Vec3.subtract(angularVelocity, Vec3.multiply(angularVelocity, ANGULAR_DAMPING_RATE));
@@ -245,6 +319,12 @@ function update(deltaTime) {
       angularVelocity = entityProps.angularVelocity;
     }
 
+    // enforce that grabee's rotation is only about y-axis while being grabbed
+    currentRotation.x = 0;
+    currentRotation.z = 0;
+    currentRotation.y = Math.sqrt(1.0 - currentRotation.w * currentRotation.w);
+    // Hrm... slamming the currentRotation doesn't seem to work
+
     Entities.editEntity(grabbedEntity, {
       position: currentPosition,
       rotation: currentRotation,