I want to know how to render 3D objects at the same position on the screen with projection matrix.

I suppose I must use View matrix which has view direction strictly along Z axis, but what else?

I am asking because I want to draw GUI in 2D coordinates like usual UI 0,0 - is the upper left corner.

I know that OrthoOffCenterLH matrix can project 3d 0.0.0 to 2d 0.0 with left upper corner, but with ortho matrix there is no visible depth.

Thats why I want to use projection matrix.

I suppose that in this case I must manually calculate position of each element to move it from center in 3D to upper left corner in 2D.

Am I right?

I know that OrthoOffCenterLH matrix can project 3d 0.0.0 to 2d 0.0 with left upper corner, but with ortho matrix there is no visible depth.

Thats why I want to use projection matrix.

What do you mean by "visible depth"? Do you want to have z-ordering (with a zbuffer), or do you want an actually 2.5D UI where you can have elements further behind appear smaller than in front? Also do you want to actually render real 3D objects, or where you referring to 2D textured sprites?

If you do not want an UI that uses such "real 3D" behaviour and just use sprites, you actually don't need any matrix at all, you can just perform the projection manually (eigther in shader or on the CPU):

        float2 projectPoint(float2 vPoint)
        {
            float2 vProjected;
            vProjected.x = vPoint.x * (1.0f / (vResolution.x * 0.5f)) - 1.0f;
            vProjected.y = vPoint.y * (1.0f / (vResolution.y * 0.5f)) + 1.0f;
            return vProjected;
        }

vPoint is a point in range of upper left (0.0/0.0) to lower right(vResolution.x/vResolution.y), so you basically multiply by the reciproc half screen/viewport size and add some offset to bring it in the screen coordinate range.

In any other case, you'd need someone else to answer your question.

By visible depth I mean z-ordering with z-buffer. I want a real 3D UI behaviour.

How I need to render it in that case taking into account that I want to convert 3D Zero(0,0,0) in the middle of coordinates to the 2D Zero (0,0) at the left top corner?

I mean that I want to draw controls using true depth feeling, which could be made only with projection matrix. With ortho I need to scale objects manually if I want make them smaller when they are far from the camera.

Thanks to all for your answers.

What do you think about using PerspectiveOffCenterLH matrix for this?

Seems it project DirectX units directly to pixels and position correspondingly. Using this matrix 0.0 will be at the top left corner of the window without any additional manipulations.