rainerpl Posted October 12, 2016 Share Posted October 12, 2016 Hi, Is there a built in way to "lookAt" a point in 3D space, using only 2 coordinates( x and y ). I found a lookAt function from this forum, but that used 3 coordinates which screws up the camera and player orientation. Id like to keep my player's z rotation always at 0. JackFalcon 1 Quote Link to comment Share on other sites More sharing options...
aWeirdo Posted October 12, 2016 Share Posted October 12, 2016 Hi @rainerpl We can accomplish this by making a function, we'll simply borrow the 2d rotation parts of the lookAt function, mainly var dv = targetPoint.subtract(this.position); var yaw = -Math.atan2(dv.z, dv.x) - Math.PI / 2; now we insert it in a function.. function lookAt(tM, lAt) { /* * tM = mesh to rotate. * lAt = vector3(xyz) of target position to look at */ lAt = lAt.subtract(tM.position); tM.rotation.y = -Math.atan2(lAt.z, lAt.x) - Math.PI/2; } and finally we use it like this; //mesh = Mesh we want to rotate //target = Target point to make the mesh look at. lookAt(mesh, target); PG; //Click on the ground to rotate the box http://www.babylonjs-playground.com/#Q4LKP#2 rainerpl and JackFalcon 2 Quote Link to comment Share on other sites More sharing options...
iiceman Posted October 12, 2016 Share Posted October 12, 2016 Hi rainerpl and welcome to the forum! @getzel made this playground yesterday, maybe that helps: http://www.babylonjs-playground.com/#1JPHAD#1 rainerpl 1 Quote Link to comment Share on other sites More sharing options...
HenryPeng Posted November 7, 2016 Share Posted November 7, 2016 On 2016/10/12 at 5:57 PM, iiceman said: Hi rainerpl and welcome to the forum! @getzel made this playground yesterday, maybe that helps: http://www.babylonjs-playground.com/#1JPHAD#1 I have a question. How to change its rotation in 3D space, not only change rotation.y. @iiceman Quote Link to comment Share on other sites More sharing options...
iiceman Posted November 7, 2016 Share Posted November 7, 2016 @HenryPeng I am afraid I don't have a good answer. I remember I tried to achieve the same when I played with this here: http://p215008.mittwaldserver.info/space/ if you click at an asteroid the ship is supposed to smoothly align with the target and then shoot. But if I remember right it doesn't always work, so I guess there is a flaw in my way of doing it. I also remember I have tried a lot of things but it was never perfect. Maybe somebody else has a good idea how to achieve the in a way that's more...bulletproof. :-/ I think those where the important functions: /** * @param rotatingObject * @param pointToRotateTo * @returns {boolean} */ function facePoint(rotatingObject, pointToRotateTo) { // a directional vector from one object to the other one var direction = pointToRotateTo.subtract(rotatingObject.position); var distanceToTargetPoint = direction.length(); if(distanceToTargetPoint > 0.5) { var axisVectorY = new BABYLON.Vector3(0, 0, 1); var directionAxisForY = 'x'; var deltaY = calculateRotationDeltaForAxis(rotatingObject, 'y', axisVectorY, direction, directionAxisForY); var axisVectorZ = new BABYLON.Vector3(0, 1, 0); var directionAxisForZ = 'z'; var deltaZ = calculateRotationDeltaForAxis(rotatingObject, 'z', axisVectorZ, direction, directionAxisForZ); var turnAroundYAxisDone = applyRotationForAxis(rotatingObject, 'y', deltaY); var turnAroundZAxisDone = applyRotationForAxis(rotatingObject, 'z', deltaZ); return (turnAroundYAxisDone && turnAroundZAxisDone) ? true : false; } } function faceTarget(rotatingObject, target){ return facePoint(rotatingObject, target.position); } function calculateRotationDeltaForAxis(rotatingObject, axis, axisVector, direction, directionAxis){ var axisVectorNormalized = axisVector.normalize(); var directionVectorNormalized = direction.normalize(); // calculate the angel for the new direction var angle = Math.acos(BABYLON.Vector3.Dot(axisVectorNormalized, directionVectorNormalized)); if (directionAxis == 'x') { // decide it the angle has to be positive or negative if (direction[directionAxis] < 0) angle *= -1; // compensate initial rotation of imported spaceship mesh angle += Math.PI / 2; } else { angle -= Math.PI / 2; } // calculate both angles in degrees var playerRotationOnAxis = rotatingObject.rotation[axis]; // calculate and return the delta return playerRotationOnAxis - angle; } function applyRotationForAxis(rotatingObject, axis, delta){ var pi = Math.PI; // check what direction to turn to take the shortest turn if (delta > pi) { delta -= pi*2; } else if (delta < -pi) { delta += pi*2; } var absDelta = Math.abs(delta); // rotate until the difference between the object angle and the target angle is no more than 3 degrees if (absDelta > pi/360) { var rotationSpeed = Math.max(0.2, Math.min(absDelta*absDelta, 1)); if (delta > 0) { rotatingObject.rotation[axis] -= rotationSpeed * 0.1; if (rotatingObject.rotation[axis] < -pi) { rotatingObject.rotation[axis] = pi; } } if (delta < 0) { rotatingObject.rotation[axis] += rotationSpeed * 0.1; if (rotatingObject.rotation[axis] > pi) { rotatingObject.rotation[axis] = -pi; } } // turn not done yet return false; } else { // turn done return true; } } Quote Link to comment Share on other sites More sharing options...
HenryPeng Posted November 7, 2016 Share Posted November 7, 2016 17 minutes ago, iiceman said: /** * direction vector x,y,z, * @param x * @param y * @param z * @param defaultVec default direction(just you set) */ function getFaceRotation(x, y, z, defaultVec) { defaultVec = defaultVec || new BABYLON.Vector3(0,0,1); //forward var v1 = new BABYLON.Vector3(x,y,z); v1.normalize(); var v2 = defaultVec; var axis = BABYLON.Vector3.Cross(v2, v1); axis.normalize(); var angle = Math.acos(BABYLON.Vector3.Dot(v1, v2)); var rotation = BABYLON.Quaternion.RotationAxis(axis, angle).toEulerAngles(); return rotation } @iiceman I think it mybe a way Quote Link to comment Share on other sites More sharing options...
iiceman Posted November 7, 2016 Share Posted November 7, 2016 Well, here is a playground with my version... http://www.babylonjs-playground.com/#1SP0QL#0 ... it demonstrates that mine is no good... some hit pretty good, some almost..and some are pretty far off. I am nor exactly sure how to use yours, maybe you can make a playground, too? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.