how to get the actual width and height of the near clipping plane

Unity Engine
1

Hi,
I want to draw a rectangular mesh in front of my camera. For this i want to control its size and position in pixels.
This is what i have so far…
The position of this mesh is at the near clipping plane position + 0.0001f (so its not clipped by the camera).
The orientation is towards the camera.

Now i need the actual width and height of the near clipping plane so i can calculate the dimensions of my mesh.

Does anyone have a idea?

2

Use “ScreenToWorldPoint (Vector3 (0, 0, camera.nearClipPlane+.0001) )” and “ScreenToWorldPoint (Vector3 (Screen.width-1, Screen.height-1, camera.nearClipPlane+.0001) )”.

–Eric

3

I dont get it… Can you tell me what it does?

thanx in advance

4

It gives you the positions of two of the four vertices. You can create the other two using info from those, or use ScreenToWorldPoint again.

–Eric

5

Heej Eric… Thanx for you’re answer. But i’ve found another solution since i didn’t get your’s properly working…
I sat behind my screen scribbling on some paper and suddenly i saw it… Here is it…

Rect NearPlaneDimensions(Camera cam)
    {
        Rect r = new Rect();
        float a = cam.nearClipPlane;//get length
        float A = cam.fieldOfView * 0.5f;//get angle
        A = A * Mathf.Deg2Rad;//convert tor radians
        float h = (Mathf.Tan(A) * a);//calc height
        float w = (h / cam.pixelHeight) * cam.pixelWidth;//deduct width

        r.xMin = -w;
        r.xMax = w;
        r.yMin = -h;
        r.yMax = h;
        return r;
    }

but if you have a better solution or faster/simpler then i realy lik to know…

thanx again

1 Like