• Advertisement
Sign in to follow this  

MDX 2D to 3D Points

This topic is 4247 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I have been trying to convert from a 2D mouse coordinate to a 3D coordinate using the Vector3.Unproject method. I plan to eventually use this to do picking in the scene but I decided that before I tried picking, I wanted to make sure that the rays I was casting started and ended at the correct position. The program is designed so that when I click the mouse button, a ray is supposed to appear where I clicked the mouse in the 3D scene. The rays are defniately affected by a change in the mouse position and they appear relative to each other in the correct direction (if I click the mouse to the left, the rays appear more to the left). However, they only seem to work the best when the camera is at 0, 0, for X and Y (Z doesn't have any effect) and even then, they don't seem perfectly along with the mouse. As I move the camera left, the X coordinates of the rays move to the right and if I move the camera right, the X coordinates of the rays move to the left. The code I use to get the start and end points of the rays is:
Vector3 start, end;
Matrix viewMat = Matrix.LookAtLH(Center, Center + Direction, new Vector3(0, 1, 0));
Matrix projectionMat = Matrix.PerspectiveFovLH((float)Math.PI / 4, device.Viewport.Width / device.Viewport.Height, 0f, 100f);

start = Vector3.Unproject(new Vector3(x, y, 0), device.Viewport, projectionMat, viewMat, Matrix.Identity);
end = Vector3.Unproject(new Vector3(x, y, 1), device.Viewport, projectionMat, viewMat, Matrix.Identity);
Where 'Center' is a Vector3 indicating the position of the camera, 'Direction' is a C# property I wrote that returns a Vector3 going in the direction of the camera, 'device' is the Direct3D device, and 'x' and 'y' are variables containing the x and y position of the mouse when it was clicked. 'start' and 'end' are used to construct rays that appear on the screen so I can check to see if my function is working properly. I would greatly appreciate any help on this problem.

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Advertisement