Develop Reference

How do I match the rotation of a cube to a quad so it stays flat on it as I move it?

To keep it simple, I'm just trying to draw an arrow prefab along a quad that is at an angle. I need it to be flat against it (slightly raised) whatever position it's in.
What I'm doing right now is I've got a cube for the body of the arrow and a "triangle" prefab for the head. I click on the screen to get the "start position" (using a raycast hit point to make sure I'm over the my rotated quad below), then as I drag the mouse around it updates the "end position" vector 3. I simply calculate the distance between both points to see what "localScale.y" to expand it by, which works perfectly for the arrow length. For the head, I just attach it to the "end point", so it just follows the mouse.
The problem I have is that it isn't staying "flat" against the quad, which is rotated at X by 70 (in the inspector). And because of this, it rotates around length axis as I move and rotate the mouse in a circle.
Here my code:
if (Physics.Raycast(mouseRay, out hit))
{
arrowEndPoint = hit.point;
// Get rotation of Quad
quadRotation = rotatedQuad.transform.rotation.eulerAngles.x;
var arrowBodyRotation = simpleArrowBody.transform.rotation.eulerAngles;
var arrowHeadRotation = simpleArrowHead.transform.rotation.eulerAngles;
arrowBodyRotation.x = quadRotation; // Doesn't seem to be affecting it
arrowHeadRotation.x = quadRotation;
// Follow arrow head to mouse
simpleArrowHead.transform.position = arrowEndPoint;
// Get distance between Start and End point
arrowLength = Vector3.Distance(arrowStartPoint, arrowEndPoint);
// Direction based on the start and end points
var direction = (arrowEndPoint - arrowStartPoint).normalized;
// Adjust scale and rotation of Body
simpleArrowBody.transform.localScale = new Vector3(simpleArrowBody.transform.localScale.x, arrowLength, simpleArrowBody.transform.localScale.z);
simpleArrowBody.transform.up = direction;
// Adjust rotation of Head
simpleArrowHead.transform.up = direction;
simpleArrowHead.transform.up = -rotatedQuad.transform.forward; // Didn't work
}

quadRotation = rotatedQuad.transform.rotation.eulerAngles.x;
var arrowBodyRotation = simpleArrowBody.transform.rotation.eulerAngles;
var arrowHeadRotation = simpleArrowHead.transform.rotation.eulerAngles;
arrowBodyRotation.x = quadRotation; // Doesn't seem to be affecting it
arrowHeadRotation.x = quadRotation;
of course this has no effect at all!
You are only assigning this to a local variable Vector3 (which is a struct and thereby a copied value).
If you wanted to actually apply this back you would e.g. use
quadRotation = rotatedQuad.transform.rotation.eulerAngles.x;
var arrowBodyRotation = simpleArrowBody.transform.rotation.eulerAngles;
var arrowHeadRotation = simpleArrowHead.transform.rotation.eulerAngles;
arrowBodyRotation.x = quadRotation;
arrowHeadRotation.x = quadRotation;
simpleArrowBody.transform.rotation.eulerAngles = arrowBodyRotation;
simpleArrowHead.transform.rotation.eulerAngles = arrowHeadRotation;
BUT note that eulerAngles are pretty unreliable for his!
Working with rotation directly is often quite tricky. So I usually prefer to wok with vectors simply because I understand them better ;)
What I would do is
Rather design your arrow in a way that it is "normally" oriented. Meaning that it points into local Z (forward) direction and the one facing towards you is its local up direction.. Unity provides helper methods in this case.
And then you can simply use Quaternion.LookRotation with your direction and as the up vector pass in the -rotatedQuad.transform.forward
Something like e.g.
public class Example : MonoBehaviour
{
public Transform rotatedQuad;
public Transform simpleArrowHead;
public Transform simpleArrowBody;
private Vector3? arrowStartPoint;
private void Update()
{
var mouseRay = Camera.main.ScreenPointToRay(Input.mousePosition);
if (Input.GetMouseButtonDown(0) && Physics.Raycast(mouseRay, out var hit))
{
arrowStartPoint = hit.point;
}
else if (arrowStartPoint.HasValue && Input.GetMouseButton(0) && Physics.Raycast(mouseRay, out hit))
{
var arrowEndPoint = hit.point;
// Get distance between Start and End point
var delta = arrowEndPoint - arrowStartPoint.Value;
var arrowLength = delta.magnitude;
// Direction based on the start and end points
var direction = delta.normalized;
// Adjust position, scale and rotation of Body
var scale = simpleArrowBody.localScale;
scale.z = arrowLength;
simpleArrowBody.localScale = scale;
// make the forward point into the direction while maintaining the
// up vector aligned with the quad surface
simpleArrowBody.rotation = Quaternion.LookRotation(direction, -rotatedQuad.forward);
// place at center between start and end
simpleArrowBody.position = arrowStartPoint.Value + delta / 2f;
// Follow arrow head to mouse and adjust rotation of Head
simpleArrowHead.position = arrowEndPoint;
// make the forward point into the direction while maintaining the
// up vector aligned with the quad surface
simpleArrowHead.rotation = Quaternion.LookRotation(direction, -rotatedQuad.forward);
}
}
}

Gyroscope with compass help needed

I need to have a game object point north AND I want to combine this with gyro.attitude input. I have tried, unsuccessfully, to do this in one step. That is, I couldn't make any gyro script, which I found on the net, work with the additional requirement of always pointing north. Trust me, I have tried every script I could find on the subject. I deduced that it's impossible and probably was stupid to think it could be done; at least not this way (i.e. all-in-one). I guess you could say I surmised that you can't do two things at once. Then I thought possibly I could get the same effect by breaking-up the duties. That is, a game object that always points north via the Y axis. Great, got that done like this:
_parentDummyRotationObject.transform.rotation = Quaternion.Slerp(_parentDummyRotationObject.transform.rotation, Quaternion.Euler(0, 360 - Input.compass.trueHeading, 0), Time.deltaTime * 5f);
And with the game object pointing north on the Y, I wanted to add the second game-object, a camera in this case, with rotation using gyro input on the X and Z axis. The reason I have to eliminate the Y axes on the camera is because I get double rotation. With two things rotating at once (i.e. camera and game-object), a 180 degree rotation yielded 360 in the scene. Remember I need the game object to always point north (IRL) based on the device compass. If my device is pointing towards the East, then my game-object would be rotated 90 degrees in the unity scene as it points (rotation) towards the north.
I have read a lot about gyro camera controllers and one thing I see mentioned a lot is you shouldn't try to do this (limit it) on just 1 or 2 axis, when using Quaternions it's impossible when you don't know what you're doing, which I clearly do not.
I have tried all 3 solutions from this solved question: Unity - Gyroscope - Rotation Around One Axis Only and each has failed to rotate my camera on 1 axis to satisfy my rotational needs. Figured I'd try getting 1 axis working before muddying the waters with the 2nd axis. BTW, my requirements are simply that the camera should only rotate on 1 axis (in any orientation) based on the X axis of my device. If I could solve for X, then I thought it'd be great to get Z gyro input to control the camera as well. So far I cannot get the camera controlled on just 1 axis (X). Anyway, here are my findings...
The first solution, which used Input.gyro.rotationRateUnbiased, was totally inaccurate. That is, if I rotated my device around a few times and then put my phone/device down on my desk, the camera would be in a different rotation/location each time. There was no consistency. Here's my code for the first attempt/solution:
<code>
private void Update()
{
Vector3 previousEulerAngles = transform.eulerAngles;
Vector3 gyroInput = Input.gyro.rotationRateUnbiased;
Vector3 targetEulerAngles = previousEulerAngles + gyroInput * Time.deltaTime * Mathf.Rad2Deg;
targetEulerAngles.y = 0.0f;
targetEulerAngles.z = 0.0f;
transform.eulerAngles = targetEulerAngles;
}
</code>
The second solution was very consistent in that I could rotate my device around and then put it down on the desk and the unity camera always ended up in the same location/rotation/state so-to-speak. The problem I had was the camera would rotate on the one axis (X in this case), but it did so when I rotated my device on either the y or x axis. Either type of rotation/movement of my phone caused the unity camera to move on the X. I don't understand why the y rotation of my phone caused the camera to rotate on X. Here is my code for solution #2:
private void Start()
{
Input.gyro.enabled = true;
startEulerAngles = transform.eulerAngles;
startGyroAttitudeToEuler = Input.gyro.attitude.eulerAngles;
}
private void Update()
{
Vector3 deltaEulerAngles = Input.gyro.attitude.eulerAngles - startGyroAttitudeToEuler;
deltaEulerAngles.y = 0.0f;
deltaEulerAngles.z = 0.0f;
transform.eulerAngles = startEulerAngles - deltaEulerAngles;
}
The 3rd solution: I wasn't sure how to complete this last solution, so it never really worked. With the 2 axis zeroed-out, the camera just flipped from facing left to right and back, or top to bottom and back; depending on which axis were commented out. If none of the axis were commented-out (like the original solution) the camera would gyro around on all axis. Here's my code for attempt #3:
private void Start()
{
_upVec = Vector3.zero;
Input.gyro.enabled = true;
startEulerAngles = transform.eulerAngles;
}
private void Update()
{
Vector3 gyroEuler = Input.gyro.attitude.eulerAngles;
phoneDummy.transform.eulerAngles = new Vector3(-1.0f * gyroEuler.x, -1.0f * gyroEuler.y, gyroEuler.z);
_upVec = phoneDummy.transform.InverseTransformDirection(-1f * Vector3.forward);
_upVec.z = 0;
// _upVec.x = 0;
_upVec.y = 0;
transform.LookAt(_upVec);
// transform.eulerAngles = _upVec;
}
Originally I thought it was my skills, but after spending a month on this I'm beginning to think that this is impossible to do. But that just can't be. I know it's a lot to absorb, but it's such a simple concept.
Any ideas?
EDIT: Thought I'd add my hierarchy:
CameraRotator (parent with script) -> MainCamera (child)
CompassRotator (parent) -> Compass (child with script which rotates parent)

I'd do this in the following way:
Camara with default 0, 0, 0 rotation
Screenshot
Object placed at the center of the default position of the camera.
Script for the Camera:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class NewBehaviourScript : MonoBehaviour
{
Camera m_MainCamera;
// Start is called before the first frame update
void Start()
{
// Disable the sleep timeout during gameplay.
// You can re-enable the timeout when menu screens are displayed as necessary.
Screen.sleepTimeout = SleepTimeout.NeverSleep;
// Enable the gyroscope.
if (SystemInfo.supportsGyroscope)
{
Input.gyro.enabled = true;
}
m_MainCamera = Camera.main;
m_MainCamera.enabled = true;
}
// Update is called once per frame
void Update()
{
if (m_MainCamera.enabled)
{
// First - Grab the Gyro's orientation.
Quaternion tAttitude = Input.gyro.attitude;
// The Device uses a 'left-hand' orientation, we need to transform it to 'right-hand'
Quaternion tGyro = new Quaternion(tAttitude.x, tAttitude.y, -tAttitude.z, -tAttitude.w);
// the gyro attitude is tilted towards the floor and upside-down reletive to what we want in unity.
// First Rotate the orientation up 90deg on the X Axis, then 180Deg on the Z to flip it right-side up.
Quaternion tRotation = Quaternion.Euler(-90f, 0, 0) * tGyro;
tRotation = Quaternion.Euler(0, 0, 180f) * tRotation;
// You can now apply this rotation to any unity camera!
m_MainCamera.transform.localRotation = tRotation;
}
}
}
With this script my Object always face SOUTH no matter what.
If you want the object to face NORTH you just have to turn the view 180º on the Y axis as a last rotation:
Quaternion tRotation = Quaternion.Euler(-90f, 0, 0) * tGyro;
tRotation = Quaternion.Euler(0, 0, 180f) * tRotation;
//Face NORTH:
tRotation = Quaternion.Euler(0,180f, 0) * tRotation;
Hope this might help ;)

Unity3D Position and Rotation matching on Waypoints

I have a simple waypoint system. It uses a transform of arrays that act as the bucket what holds the waypoint values.
I use this waypoint system to move a camera throughout a scene by moving towards one point to another. The scene is not big - so everything is close to each other.
The camera moves from one position to another by button click/press. This works fine.
void Start()
{
//Sets the Camera to the first point
Camera = GameObject.Find("Main Camera");
Camera.transform.position = patrolPoints[0].position
currentPoint = 0;
}
//Fixed Update seems to work better for LookAt
void FixedUpdate()
{
//Looks at initial Target
Camera.transform.LookAt(TargetPoints[0]);
if (click == true)
{
Camera.transform.position = Vector3.MoveTowards(Camera.transform.position, patrolPoints[currentPoint].position, moveSpeed * Time.deltaTime);
//Camera.transform.rotation = Quaternion.Slerp(Camera.transform.rotation, patrolPoints[currentPoint].transform.rotation, Time.deltaTime);
Camera.transform.LookAt(TargetPoints[currentPoint]);
}
}
public void onNextClick()
{
if (currentPoint >= patrolPoints.Length)
{
currentPoint = 0;
}
if (Camera.transform.position == patrolPoints[currentPoint].position)
{
currentPoint++;
click = true;
}
}
I am having difficulty with one aspect of the transform that I haven't talked about yet. That is the rotation.
I have used lookAt for setting up the target of the first look at point and that works. However when it runs to the next target in the look at array - the change is sudden.
I have tried an Slerp in the shot as well - and this works when the waypoint has been placed in the appropriate rotation value - and the value Slerps from one position to the next. However, the timing isn't quite aligning up yet. Some position transitions get there quicker - meaning the rotation is trying to get caught up / while others are lagging behind.
I have tried getting the distance between the current waypoint and the next waypoint and treating that as an overall percentage in the update relative to the current position of the camera - I believe this could help work out how far the rotation should be orientated given the position update.
However, I am somewhat lost on it. Many examples suggest looking at iTween - and I wouldn't imagine this would work - however, I want to get into the math a bit.
Can anyone put me in the right direction?

Looks like the Lerp for Position and a Slerp for Rotation done the trick.
MoveTowards wasn't playing ball with a Slerp on rotation - so I believe the timings weren't aligning.
if (click == true)
{
Camera.transform.position = Vector3.MoveTowards(Camera.transform.position, patrolPoints[currentPoint].position, moveSpeed * Time.deltaTime);
Camera.transform.rotation = Quaternion.Lerp(Camera.transform.rotation, patrolPoints[currentPoint].rotation, moveSpeed * Time.deltaTime);
I've been led to believe the lerp values work like a percentage of such - so the same input value works for it.
Finally I used a range on the distance between current position and update on the click - this helped speed up the button click.
if (Vector3.Distance(Camera.transform.position, patrolPoints[currentPoint].position) < PositionThreshold)
{
currentPoint++;
click = true;
}
Thank you for your time.

Rotation of a Sprite Around Its Pivot

I have a class below that I attach to a object in order to make it rotate around its pivot. I sent the pivot of the sprite via the inspector.
This works exactly how I want it too, BUT the issue I am having is that whenever I touch and drag it, and then touch and drag it again, it snaps to a new position.
What I would like for it to do is, when it is rotated and then rotated again, the sprite stays in its same rotation and not snap to a new position and I would like the angle of the sprite to be reset to 0. The next then is that I want the angle to continually rotate. So if I rotate it in the positive direction, the angle should keep increasing in the positive direction and not change..Such as 0---> 360 ----> 720 -----> etc, etc. And then when the mouse is released, the sprite stays in the same position but the angle is now set back to 0. And then when clicked again to rotate, it rotates from that exact position.
Here is my code thus far which works well for rotating, but I would like to modify it to achieve the above scenario. Any help with this?
public class Steering : MonoBehaviour {
float prevAngle,wheelAngle,wheelNewAngle = 0;
public SpriteRenderer sprite;
void Start () {
}
void Update () {
}
public float GetAngle(){
return wheelAngle;
}
void OnMouseDrag(){
Vector3 mouse_pos = Input.mousePosition;
Vector3 player_pos = Camera.main.WorldToScreenPoint(this.transform.position);
mouse_pos.x = mouse_pos.x - player_pos.x;
mouse_pos.y = mouse_pos.y - player_pos.y;
wheelNewAngle = Mathf.Atan2 (mouse_pos.y, mouse_pos.x) * Mathf.Rad2Deg;
if (Input.mousePosition.x > sprite.bounds.center.x) {
wheelAngle += wheelNewAngle - prevAngle;
} else {
wheelAngle -= wheelNewAngle - prevAngle;
}
this.transform.rotation = Quaternion.Euler (new Vector3(0, 0, wheelAngle));
Debug.Log (wheelAngle);
prevAngle = wheelNewAngle;
}
void OnMouseUp(){
prevAngle = wheelNewAngle;
wheelAngle = 0;
}
}

By angle of the sprite, do you mean the rotation? I'm not sure how the position is changing if there's nothing in your code doing that. Does it always move to the same position? I'm having a little trouble visualizing how your system is supposed to look but I hope this helps.
It looks like you might want to store the previous mouse position so you can get the relative amount to rotate each frame.
At the top:
Vector3 prevMousePos = Vector3.zero;
This method will help get the position when the player pressed:
void OnMouseDown(){
prevMousePos = Input.mousePosition;
}
Then in OnMouseDrag() get the difference between the two mouse positions to get the relative position (if you moved the mouse left, right, up, or down since pressing):
Vector3 mouseDiff = Input.mousePosition - prevMousePos;
With this it will use the relative mouse position after pressing instead of the current one, which should smooth things out.

Accurate Pinch Zoom

I'm trying to figure out how to create an accurate pinch zoom for my camera in Unity3D/C#. It must be based on the physical points on the terrain. The image below illustrates the effect I want to achieve.
The Camera is a child of a null which scales (between 0,1 and 1) to "zoom" as not to mess with the perspective of the camera.
So what I've come up with so far is that each finger must use a raycast to get the A & B points as well as the current scale of the camera parent.
EG: A (10,0,2), B (14,0,4), S (0.8,0.8,0.8) >> A (10,0,2), B (14,0,4), S (0.3,0.3,0.3)
The positions of the fingers will change but the hit.point values should remain the same by changing the scale.
BONUS: As a bonus, it would be great to have the camera zoom into a point between the fingers, not just the center.
Thanks so much for any help or reference.
EDIT:
I've come up with this below so far but it's not accurate the way I want. It incorporates some of the ideas I had above and I think that the problem is that it shouldn't be /1000 but an equation including the current scale somehow.
if (Input.touchCount == 2) {
if (!CamZoom) {
CamZoom = true;
var rayA = Camera.main.ScreenPointToRay (Input.GetTouch (0).position);
var rayB = Camera.main.ScreenPointToRay (Input.GetTouch (1).position);
int layerMask = (1 << 8);
if (Physics.Raycast (rayA, out hit, 1500, layerMask)) {
PrevA = new Vector3 (hit.point.x, 0, hit.point.z);
Debug.Log ("PrevA: " + PrevA);
}
if (Physics.Raycast (rayB, out hit, 1500, layerMask)) {
PrevB = new Vector3 (hit.point.x, 0, hit.point.z);
Debug.Log ("PrevB: " + PrevB);
}
PrevDis = Vector3.Distance (PrevB, PrevA);
Debug.Log ("PrevDis: " + PrevDis);
PrevScaleV = new Vector3 (PrevScale, PrevScale, PrevScale);
PrevScale = this.transform.localScale.x;
Debug.Log ("PrevScale: " + PrevScale);
}
if (CamZoom) {
var rayA = Camera.main.ScreenPointToRay (Input.GetTouch (0).position);
var rayB = Camera.main.ScreenPointToRay (Input.GetTouch (1).position);
int layerMask = (1 << 8);
if (Physics.Raycast (rayA, out hit, 1500, layerMask)) {
NewA = new Vector3 (hit.point.x, 0, hit.point.z);
}
if (Physics.Raycast (rayB, out hit, 1500, layerMask)) {
NewB = new Vector3 (hit.point.x, 0, hit.point.z);
}
DeltaDis = PrevDis - (Vector3.Distance (NewB, NewA));
Debug.Log ("Delta: " + DeltaDis);
NewScale = PrevScale + (DeltaDis / 1000);
Debug.Log ("NewScale: " + NewScale);
NewScaleV = new Vector3 (NewScale, NewScale, NewScale);
this.transform.localScale = Vector3.Lerp(PrevScaleV,NewScaleV,Time.deltaTime);
PrevScaleV = NewScaleV;
CamAngle();
}
}

Intro
I had to solve this same problem recently and started off with the same approach as you, which is to think of it as though the user is interacting with the scene and we need to figure out where in the scene their fingers are and how they're moving and then invert those actions to reflect them in our camera.
However, what we're really trying to achieve is much simpler. We simply want the to user feel like the area of the screen that they are pinching changes size with the same ratio as their pinch changes.
Aim
First let's summarise our goal and constraints:
Goal: When a user pinches, the pinched area should appear to scale to match the pinch.
Constraint: We do not want to change the scale of any objects.
Constraint: Our camera is a perspective camera.
Constraint: We do not want to change the field of view on the camera.
Constraint: Our solution should be resolution/device independent.
With all that in mind, and given that we know that with a perspective camera objects appear larger when they're closer and smaller when they're further, it seems that the only solution for scaling what the user sees is to move the camera in/out from the scene.
Solution
In order to make the scene look larger at our focal point, we need to position the camera so that a cross-section of the camera's frustum at the focal point is equivalently smaller.
Here's a diagram to better explain:
The top half of the image is the "illusion" we want to achieve of making the area the user expands twice as big on screen. The bottom half of the image is how we need to move the camera to position the frustum in a way that gives that impression.
The question then becomes how far do I move the camera to achieve the desired cross-section?
For this we can take advantage of the relationship between the frustum's height h at a distance d from the camera when the camera's field of view angle in degrees is θ.
Since our field of view angle θ is constant per our agreed constraints, we can see that h and d are linearly proportional.
This is useful to know because it means that any multiplication/division of h is equally reflected in d. Meaning we can just apply our multipliers directly to the distance, no extra calculation to convert height to distance required!
Implementation
So we finally get to the code.
First, we take the user's desired size change as a multiple of the previous distance between their fingers:
Touch touch0 = Input.GetTouch(0);
Touch touch1 = Input.GetTouch(1);
Vector2 prevTouchPosition0 = touch0.position - touch0.deltaPosition;
Vector2 prevTouchPosition1 = touch1.position - touch1.deltaPosition;
float touchDistance = (touch1.position - touch0.position).magnitude;
float prevTouchDistance = (prevTouchPosition1 - prevTouchPosition1).magnitude;
float touchChangeMultiplier = touchDistance / prevTouchDistance;
Now we know by how much the user wants to scale the area they're pinching, we can scale the camera's distance from its focal point by the opposite amount.
The focal point is the intersection of the camera's forward ray and the thing you're zooming in on. For the sake of a simple example, I'll just be using the origin as my focal point.
Vector3 focalPoint = Vector3.zero;
Vector3 direction = camera.transform.position - focalPoint;
float newDistance = direction.magnitude / touchChangeMultiplier;
camera.transform.position = newDistance * direction.normalized;
camera.transform.LookAt(focalPoint);
That's all there is to it.
Bonus
This answer is already very long. So to briefly answer your question about making the camera focus on where you're pinching:
When you first detect a 2 finger touch, store the screen position and related world position.
When zooming, move the camera to put the world position back at the same screen position.

This is a small example:
if (_Touches.Length == 2)
{
Vector2 _CameraViewsize = new Vector2(_Camera.pixelWidth, _Camera.pixelHeight);
Touch _TouchOne = _Touches[0];
Touch _TouchTwo = _Touches[1];
Vector2 _TouchOnePrevPos = _TouchOne.position - _TouchOne.deltaPosition;
Vector2 _TouchTwoPrevPos = _TouchTwo.position - _TouchTwo.deltaPosition;
float _PrevTouchDeltaMag = (_TouchOnePrevPos - _TouchTwoPrevPos).magnitude;
float _TouchDeltaMag = (_TouchOne.position - _TouchTwo.position).magnitude;
float _DeltaMagDiff = _PrevTouchDeltaMag - _TouchDeltaMag;
_Camera.transform.position += _Camera.transform.TransformDirection((_TouchOnePrevPos + _TouchTwoPrevPos - _CameraViewsize) * _Camera.orthographicSize / _CameraViewsize.y);
_Camera.orthographicSize += _DeltaMagDiff * _OrthoZoomSpeed;
_Camera.orthographicSize = Mathf.Clamp(_Camera.orthographicSize, _MinZoom, _MaxZoom) - 0.001f;
_Camera.transform.position -= _Camera.transform.TransformDirection((_TouchOne.position + _TouchTwo.position - _CameraViewsize) * _Camera.orthographicSize / _CameraViewsize.y);
}
In the second video of this tutorial explains it