Create 3D axis to move object (in Unity)

Question

Hello !

I want to make a level editor for a project and for this I need 3D axis to move an object. I have the axes but I want the user to be able to move them by dragging one axis: click on the X axis (red), drag the axis and it moves (like unity, blender or UE does it).

My problem is that I don't know how to get the mouse input to move on the correct axis. Actually, we can move it but when you move the X axis, the mouse doesn't have to follow the X axis in the world but on the screen, so you just have to move your mouse left to right.

Blublub.

score 0 · Accepted Answer · answered Aug 08 '21 at 17:49

Here's one way to do it:

Raycast against XZ plane
Find the direction vector that starts from the arrows' center and ends at the hit point
Since that direction vector can be looking at any direction in XZ plane, project it onto the X axis to constraint it to that axis
Move arrows by the resulting vector

Vector3 xAxis = Vector3.right;
Vector3 yAxis = Vector3.up;
Vector3 arrowsCenterPosition = ...;
Plane plane = new Plane( yAxis, arrowsCenterPosition ); // Create a virtual plane on XZ directions
Ray ray = Camera.main.ScreenPointToRay( Input.mousePosition );
if( plane.Raycast( ray, out float enter ) ) // Raycast against that plane
{
    Vector3 hitPoint = ray.GetPoint( enter ); // The point that hit the virtual plane
    Vector3 directionToHitPoint = hitPoint - arrowsCenterPosition;

    // We want to move in X axis but our directionToHitPoint can be in any direction in XZ plane,
    // so we need to project it onto X axis
    Vector3 xAxisMovement = Vector3.Project( directionToHitPoint, xAxis );

    // You can move the arrows by xAxisMovement amount
    arrowsCenterPosition += xAxisMovement;
}

Create 3D axis to move object (in Unity)

1 Answers1