Question

How to convert a 3D coordinate to 2D screen coordinate

Asked by: WiteFalcon

Hi everyone,

The question I have might sound out of normal because people tend to do the opposite. i.e. convert mouse coordinates to 3D space cordinates. But for apparent reasons I need the reverse to be done. This is to convert a 3D cursor position to 2D cursor position (just above where the 3D cursor is). This should also take into consideration the view matrix (camera matrix) and projection matrix. Thanks in advance.

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Asked On
2008-01-23 at 13:18:43ID23105890
Tags

C++

,

3D coordinates to mouse coordinates

Topics

Graphics & Game Programming

,

DirectX Graphics & Game Programming

,

OpenGL Graphics & Game Programming

Participating Experts
1
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Comments
3

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Answers

 

by: ozoPosted on 2008-01-23 at 13:29:59ID: 20728053

 

by: WiteFalconPosted on 2008-01-23 at 14:47:01ID: 20728756

The code wikipedia explaination considers both the 3D point and 2D point to be inside the same projection. This is not the solution I'm looking for I'm afraid. When converting a 3D point to 2D screen point it's necessary to consider the projection matrix of the 3D point (as far as i know) and combined with the camera matrix we'll be able to get the 2D SCREEN coordinates. Thanks for the effort anyway.

 

by: WiteFalconPosted on 2008-01-23 at 14:51:00ID: 20728780

I found the solution to it...

This is done by multiplying the point with the WorldViewProjection matrix... i.e.

WorldViewProjection Matrix = World Matrix * View Matrix * Projection Matrix

2D Point = 3D Point * WorldViewProjectionMatrix

I got the answer from here...
http://irrlicht.sourceforge.net/phpBB2/viewtopic.php?p=131156&sid=f001f842064ca09595aea258f0410e03

20120131-EE-VQP-002

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