get xy coordinate from xyz
anyone know of a simple way to calculate the actual pixel coordinate (based on window dimensions) of a "3D" opengl coordinate. . .?
Thanks!
Project a vertex with the modelview matrix, and then with the perspective matrix and you'll have the pixel coordinate. To get the matrices use glGetMatrix and for the use of matrices check out this article.
EDIT: i am not really sure the perspective matrix also handles the pixel coordinates, does anyone know? Thanks
[edited by - Tree Penguin on March 24, 2004 6:41:39 AM]
EDIT: i am not really sure the perspective matrix also handles the pixel coordinates, does anyone know? Thanks
[edited by - Tree Penguin on March 24, 2004 6:41:39 AM]
The projection matrix only transforms from eye to clip space. To get pixel coordinates, you also need to perform the perspective division to normalized device coordinates, and finally the viewport transform.
Check the Red Book or the OpenGL specification for information about these steps.
Check the Red Book or the OpenGL specification for information about these steps.
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