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View Full Version : Converting vertexes to pixels



Phynix
05-15-2009, 03:47 PM
Hello, I'm wondering how to convert a world coordinate, with x, y and z values, to x and y pixel values. I've seen the gluProject/gluUnproject methods, but ive heard they're slow. Please help!

yooyo
05-15-2009, 04:28 PM
Depends on what do you want as result... image or numbers?

Phynix
05-15-2009, 04:43 PM
Well first of all, what do you mean by an image result? I just want the mouse location that is projected to the screen (in pixels) by a specific point in 3d space

Brolingstanz
05-16-2009, 02:56 AM
Multiply by the whole enchilada that takes you into screen space - wrong if you're following the spec to the letter as GL applies the perspective division before the viewport transform whereas DX performs it last. Mathematically they're equivalent but numerically they're likely to be different (as Yooyo points out).

I tend to do it the wrong way... *hangs head in shame*

V-man
05-17-2009, 09:01 PM
Here's the source code
http://www.opengl.org/wiki/GluProject_and_gluUnProject_code

Why would it be slow if you just want to transform just 1 position?