Given the view angle, distance from camera, 2D point (where 0,0 is the top left and xres,yres is the bottom right) and the desired 3D Z location, how do I calculate the final 3D x,y position where 0,0 is the center of the screen and the abs of the distance from the 0 to the edge of the screen is unknown in both the X and Y directions? I can figure it out pretty quickly using fake math and by matching mouse movement with the pixel movement but I'd like to have a generic function that will calculate that distance for any Z value. Ben IcarusIndie.com [ The Rabbit Hole | The Labyrinth | DevZone | Gang Wars | The Wall | Hosting | Tiberian Merchandise!!!! | GameShot ] [edited by - KalvinB on October 13, 2002 5:14:09 PM]

For z=-3.63 all those values work out perfectly.

How do I get 4.0f and 1.00f in the first place based on the z value? It just happens that at -3.63, 1 unit equals 256 pixels.

So I guess the equation I need is how many pixels per unit given the aspect ratio, distance from screen and z value. And how do I use that value to calculate the 4.0f and 1.00f?

Ben


IcarusIndie.com [ The Rabbit Hole | The Labyrinth | DevZone | Gang Wars | The Wall | Hosting | Tiberian Merchandise!!!! | GameShot ]

[edited by - KalvinB on October 13, 2002 5:50:37 PM]

You''ll want to use gluUnProject. It takes in the view/camera matrices, the screen (x,y,z), and gives you back the world-space (x,y,z).

Pretty much it just inverses the two matrices and puts the screen coordinates through them, so if you need to do a lot of these, you''ll probably be better off inversing the matrices yourself and caching them...

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Actually I was hoping for something more generic and not a prewritten function. I don't want an othogonal view. I just want to reference Unit values using pixel values.




From that you can do




Where X and Y are the pixel coordinates.

But what I need to know is the significance of the value calculated by xRatio/zValue = -1.10193.

By using that ratio I can then pass any zValue and adjust the xRatio accordingly.

I assume that ratio is based off of the aspect ratio (4/3), the field of view(45 degrees) and distance to screen (100.0f) but I'm not sure what the function for that is.

Ben


IcarusIndie.com [ The Rabbit Hole | The Labyrinth | DevZone | Gang Wars | The Wall | Hosting | Tiberian Merchandise!!!! | GameShot ]

[edited by - KalvinB on October 14, 2002 9:05:11 PM]