I am messing around with some augmented reality library, which I have working. Now, I don't actually plan to use it for augmented reality, but rather to help me track markers.
Now, the output of the library algorithm is a transformation matrix. What I really need, is screen coordinates.
Now, my question is this:
Given my transformation (World) matrix, my View matrix, my Projection matrix and the Vector3 that is the position of my model, can I get the screen coordinates?
I tried:
Vector3.Transform(Positon, World*Projection*View), but that leaves me with another Vector3.
I'm a but lost here, so any advice you can give is appreciated.
On a second note, should I be using a different library for this? (as in: not an augmented reality library)
I want to create a board game where a projector projects the board and a webcam tracks the pieces. So basically, I just want a plane in 3D space. (I cannot be certain that the webcam and the projector are perfectly aligned*)
*some would even argue that it is a physical impossibility.
World, View and Projection
You don't mention what API you're using. For C#, you can use Project(viewport,projection,view,world). In DX (C++), D3DXVec3Project(...).
The vector returned has x & y values as screen coordinates (floats which can be converted to integers). The z value is a normalized depth (and can be ignored if you don't need it).
The vector returned has x & y values as screen coordinates (floats which can be converted to integers). The z value is a normalized depth (and can be ignored if you don't need it).
Quote:Original post by chucaraThat is the correct approach, though I expect that you need to change the order in which you multiply the matrices.
I tried:
Vector3.Transform(Positon, World*Projection*View), but that leaves me with another Vector3.
The x and y coordinates of the result will be screen-space x and y, while the z coordinate will be the depth into the scene. You can safely ignore the z component, and just use x, y as a point in screen coordinates.
Author
Indeed.. In XNA, GraphicsDevice.Viewport.Project(...) does the trick.
Thanks for your help!
Thanks for your help!
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
