Print X, Y on Mouse Click

[Cytruss]

Hi Guys,

I have a 2D display:

        self.grid = self.grid.create()
        self.grid.reparentTo(render)
        self.grid.setAlphaScale(0.1)
        self.grid.setScale(1.00, 1.00, 1.00)
        self.grid.setPos(0, 0, 0)

        self.lens = OrthographicLens()
        ratio = base.getAspectRatio()
        self.lens.setFilmSize(10000.0, 10000.0/ratio)
        #self.lens.setNearFar(-1000, 1000)
        base.cam.node().setLens(self.lens)

        base.cam.setPos(0, -90, 0)
        base.cam.lookAt(0,0,0)

base.mouseWatcherNode.getMouse()

• Seems to get a percentage of where I’m at, but I need the spacial co-ordinates.

Thanks.

[Stein]

On a more post related note:

Do you want the x and y coordinates on the mouse on the screen?
Then indeed base.mouseWatcherNode.getMouse() returns the fraction of the screen at which the mouse is (0.5,0.5 as the center).

mouse_x = base.mouseWatcherNode.getMouseX()*base.win.getXSize()
mouse_y = base.mouseWatcherNode.getMouseY()*base.win.getYSize()

Or do you want the x and y coordinates of the position inside the game world where the mouse is pointing?
Then this might help:
panda3d.org/manual/index.php … 3D_Objects

[Cytruss]

Yep, I’m looking for the coordinates in the game world. Slowly trying to figure this example out. Thanks. I can’t seem so far to figure where I read the coordinates in the world though.

[Thaumaturge]

Do you mean that, considering the camera’s view-plane to be a plane located in the world, you want the coordinates of a point on that plane based on a given mouse coordinate? If so, surely that would be a 3D point, not a 2D point?

If that is what you want, and there’s nothing in the API that provides it, I think that it should largely be a matter of trigonometry. I think that the following should be more or less correct:

• Let the input mouse coordinates be “mouseX” and “mouseY”, specified both in the range [-1, 1].

• Find the camera’s position, which we’ll call “posCam”, the world-space depth of the near-plane, “nearDepth”, and the world-space width-and-height size of the camera’s film, “filmSize”. I’m not sure that the results of the Lens class’s “getNear” and “getFilmSize” will get quite the values desired here; if not, I think that you should be able to use the “extrude” method, passing in a 2D point of (1, 1) to specify a corner of the near-plane, and then examine the result returned in the “near_point” parameter.

• Let the output 3D vector be “result”.

• Find the camera’s right-, up- and forward- vectors (using something along the lines of “camera.getQuat().getForward()” and the similar “getRight()” and “getUp()” methods); we’ll here call them “camForward” and “camRight”.

• result = camForwardnearDepth + mouseXfilmSize.xcamRight + mouseYfilmSize.y*camUp

If you just want the coordinates relative to the plane, that would seem to just be a multiple of the mouse coordinates that you already have.

[wezu]

If that’s a plane in the 3d scene you want the mouse pointer to collide with then there’s this great snippet by rdb, that I use all the time:

Super-fast mouse ray collisions with ground plane

I was shocked to learn that many users do not know about the existence of many useful mathematical classes and functions that Panda provides. Thus, many users use Panda’s collision system if they want to detect where a mouse ray hit a ground plane (for point-n-click movement in a 2d world) etc etc. Thus, I quickly threw this snippet together that shows how to use the Plane class to calculate the intersection point with a mouse line. Super-fast. (Note that there are many more uses to this.) fro…

[Cytruss]

Thanks everyone,

I should have mentioned, I have a 2D space:

        
self.lens = OrthographicLens()
ratio = base.getAspectRatio()
self.lens.setFilmSize(10000.0, 10000.0/ratio)
base.cam.node().setLens(self.lens)

base.cam.setPos(0, -90, 0)
base.cam.lookAt(0,0,0)

[Thaumaturge]

In that case, is the point not just:

worldX = (mouseX*0.5 + 0.5)*filmSize.x

worldZ = (mouseY*0.5 + 0.5)*filmSize.y

(I’ve used worldZ above because you’ve used your world-space y-axis as the depth axis.)

Regarding the mutiplication and addition of 0.5 above, I checked, and in my version of Panda at least (1.8.0, I think) mouse coordinates range from (-1, -1) at the bottom-left of the screen to (1, 1) at the top-right, if I recall correctly. Hence, in order for the mouse to map from (0, 0) at the bottom-left to (filmSize.x, filmSize.y) at the top-right we halve the range of the mouse coordinates (so that they cover a range of 1 instead of 2) and then shift them so that (0, 0) is at the bottom-left rather than the centre.