Hi!

I wonder if there is a possibility to calculate the 3d coordinates of 2d point on my screen. I know that there is a infinite number of solutions when transforming a 2d point to 3d-space, so i’d like to do it on a plane with y=0.

Any suggestions?

obj.project();
obj.unproject();

Could you be a little more specific? I found these two methods but aren’t really sure how to use them.

Example: I have a camera, a Plane and a Sphere. The plane is used as a floor, where i want to position the sphere on it. But: i want the sphere to be on the left side of the 2d-screen (x=0) depending on a varying z-position in the scene. I thought about transforming the 3d z-position to a 2d y-position and then transforming this 2d Point (0,y) into 3d space with (x,0,z).

also i’d like to find the “right edge” of my screen, with x=1920 (2d space) what must be the x position of my sphere in 3d-space with a given z and y=0?

Thank you in advance, i hope my description is not too much confusing you

I’m sorry,English is not my mother tongue.. it confuse me too much:-S:-S
would you make it easy?

Ok, i’ll try – it’s not my mothertounge either..

I’ve attached an image to describe the problem better.

i am looking into a 3d-scene.
From a plane i take a certain z-value.

On my Screen i imagine a Point P, this Point is in 2d-space. Now, in the 3D-space, i would like to position a Object at the exact Position of Point P, but in 3D-Space. I already know the z Value (it’s z1 like in the image) and i know the y-value (its 0, because it is on a flat plane). what i need is the x-value.

So to say it short: i want to transform a 2d-x-value into the 3d-space.

Do you have any further ideas or explanations how to achieve this with project/unproject? Or anything else? like the FOV of the camera?

Thank you!

Homogeneous Coordinates are what your looking for. I’ll need to study up on them tonight and then I’ll post an answer later.