Help Please - 2D Game Perspective Camera

Question

Hi

I've change the camera to Perspective to give it a '3D' look, but in doing so, my mouse clicks are all over the place.

Can anyone help?

      if (Input.GetMouseButtonDown(0)) {
         Vector2 point = controlCamera.ScreenPointToRay(Input.mousePosition).origin;
         hit = Physics2D.Raycast(point, Vector2.zero);
         if (!hit.transform) return;
         pressedChip = hit.transform.GetComponent<Chip>();
         pressPoint = Input.mousePosition; 
     }
     if (Input.GetMouseButton(0) && pressedChip != null) {
         Vector2 move = Input.mousePosition;
         move -= pressPoint;
         if (move.magnitude > Screen.height * 0.05f) {
             foreach (Side side in Utils.straightSides)
                 if (Vector2.Angle(move, Utils.SideOffsetX(side) * Vector2.right + Utils.SideOffsetY(side) * Vector2.up) <= 45)
                     pressedChip.Swap(side);
             pressedChip = null;
         }
     }

Answer 1

Best Answer

Answer by wibble82 · Dec 07, 2015 at 11:20 AM

Your issue comes fromt the fact that with an orthographic camera, the x and y of the ray direction returned by ScreenPointToRay are 0 (assuming the camera is facing directly forwards). This is because an orthographic camera is 'flat', so regardless of where you click, your ray is correctly represented by an 'origin' on the front camera plane, and a ray that points directly forwards.

In your case you disregard the z of the camera origin, and use the x and z to construct a 2d ray that goes from where the user clicked to [0,0]. Assuming the camera is at [0,0,something], this is a ray pointing from where the user cicked to the centre of the screen.

Once you switch to a perspective camera, your assumption is no longer true - the direction of the ray changes depending on where you click. This link might help:

http://blender.stackexchange.com/questions/648/what-are-the-differences-between-orthographic-and-perspective-views

As a result you need to do a few extra steps:

First, get the ray from the perspective camera that corresponds to where the user clicked
Now project forwards along this ray, to calculate the world space position that the user clicked on that corresponds to the world space z position of your level (probably 0?)
From there, you have a position you can run your existing logic with

This would look something like the below:

 //first we get the ray represented by the mouse click. because its a perspective camera, 
 //the direction will change depending on where you click
 Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
 
 //the ray origin is the position in world space on the 'front' plane of the camera. however
 //for your game we need to go forwards to the plane of your objects. I am going to assume
 //that is z==0 for now, so...
 float z_plane_of_2d_game = 0;
 Vector3 pos_at_z_0 = ray.origin + ray.direction * (z_plane_of_2d_game - ray.origin.z) / ray.direction.z;
 
 //now we have a 3D point on the correct plane, we can continue with your code
 Vector2 point = new Vector2(pos_at_z_0.x,pos_at_z_0.y);
 hit = Physics2D.Raycast(point, Vector2.zero);

Hope that helps

-Chris

Add comment · Show 5 · Share

solideuk · Dec 07, 2015 at 12:13 PM 0

Share

Thanks for such an amazing answer.

I'll begin to implement this at once, how about the segment of code below as it is Vector2 do I need to convert the Vector3 readings to Vector2?

You see I want the 2D game mechanics to work as normal and just change the way the mouse clicks are recognised.

 if (move.magnitude > Screen.height * 0.05f) {
              foreach (Side side in Utils.straightSides)
                  if (Vector2.Angle(move, Utils.SideOffsetX(side) * Vector2.right + Utils.SideOffsetY(side) * Vector2.up) <= 45)
                      pressedChip.Swap(side);
              pressedChip = null;
          }

wibble82 solideuk · Dec 07, 2015 at 12:25 PM 0

Share

No prob :)

The general rule is that whenever you're doing stuff that depends on conversion from screen positions (i.e. mouse clicks) to world space positions, you'll want to make sure you're working in the correct plane using the approach I showed (crucially the getting of a ray, then calculating a position on the correct plane).

I'm not sure exactly whether your code below will need changing as I can't see precisely what it does. If you're dependent on 'move' being in world space, you'll need to do some extra work. If all you're interested in is how much the user moved the cursor, then you needn't worry!

wibble82 · Dec 07, 2015 at 12:26 PM 0

Share

BTW - if you're happy with the answer, mark it as 'correct' - then others with similar questions will find it more easily! :)

solideuk · Dec 07, 2015 at 09:09 PM 0

Share

I honestly can't thank you enough, it worked perfectly!

Thanks again!!

Tato-Marinelli · Aug 30, 2021 at 11:34 PM 0

Share

Me funcionó a la primera, que ganas de chuparte la pija hermano.

Answer 2

Answer by Yword · Dec 07, 2015 at 10:56 AM

Maybe you should try Physics2D.GetRayIntersection.

             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
 
             RaycastHit2D hit = Physics2D.GetRayIntersection(ray);

Add comment · Share

Help Please - 2D Game Perspective Camera

2 Replies

Your answer

Follow this Question

Related Questions