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Re: Simple renderer in .net with direct3d
avatarNovember 25, 2013 11:45PM
I can't directly answer your question, since I don't know Direct3D. However, I can give an overview of what LDView does.

IIRC, LDView first calculates the bounding box for the whole model. Next, using the center of that box, it calculates the bounding sphere for the whole model. It then moves the camera to the center of the sphere, then backs it up by an amount calculated based on the FOV and the sphere radius. I believe that the distance to move back is:

radius / sin(fov/2)

Note that I believe fov in the above is either the horizontal FOV (if the window is taller than it is wide) or the vertical FOV (if the window is wider than it is tall). OpenGL expects you to always give it the vertical FOV, so LDView calculates that based on the horizontal FOV when the window is taller than it is wide. I suspect that Direct3D also wants the vertical FOV. If you always use the same FOV value, no matter what the window shape, I believe you'll get a cropped image if you use that in the above calculation when the window is taller than it is wide.

If have have the horizontal FOV, the vertical FOV can be calculated like so:

VFOV = 2*atan(tan(hfov/2)/(width/height))

Note also that LDView's default zoom level (calculated as per above) is set up so that no matter how you rotate the model, it will always be fully visible (which is why it uses the bounding sphere).

LDView's "zoom to fit" functionality uses an algorithm I got from Lars C. Hassing that solves numerous equations for numerous unknowns to move the view pyramid around until at least two points on the model are exactly at the edge of the view. (Those two points are either at the top and bottom of the view, or at the left and right.) The pyramid is moved in such a way that the view direction remains constant, but the camera position moves in all three dimensions, so the look-at point also moves.
SubjectAuthorViewsPosted
Simple renderer in .net with SharpGL (openGL) Michael Heidemann405November 23, 2013 04:48AM
Re: Simple renderer in .net with direct3d Roland Melkert154November 23, 2013 09:47AM
Re: Simple renderer in .net with direct3d Michael Heidemann130November 23, 2013 10:16AM
Re: Simple renderer in .net with direct3d Roland Melkert139November 23, 2013 10:36AM
Re: Simple renderer in .net with direct3d Michael Heidemann113November 23, 2013 10:39AM
Re: Simple renderer in .net with direct3d Michael Heidemann190November 23, 2013 10:48AM
Re: Simple renderer in .net with direct3d Roland Melkert90November 23, 2013 11:15AM
Re: Simple renderer in .net with direct3d Michael Heidemann108November 23, 2013 11:19AM
Re: Simple renderer in .net with direct3d Roland Melkert107November 23, 2013 11:22AM
Re: Simple renderer in .net with direct3d Michael Heidemann102November 23, 2013 11:32AM
Re: Simple renderer in .net with direct3d Roland Melkert98November 23, 2013 11:40AM
Re: Simple renderer in .net with direct3d Michael Heidemann95November 23, 2013 11:54AM
Re: Simple renderer in .net with direct3d Michael Heidemann107November 23, 2013 11:59AM
Re: Simple renderer in .net with direct3d Roland Melkert99November 23, 2013 12:27PM
Re: Simple renderer in .net with direct3d Michael Heidemann98November 23, 2013 12:16PM
Re: Simple renderer in .net with direct3d Roland Melkert102November 23, 2013 12:25PM
Re: Simple renderer in .net with direct3d Michael Heidemann114November 23, 2013 12:30PM
Re: Simple renderer in .net with direct3d Roland Melkert101November 23, 2013 12:50PM
Re: Simple renderer in .net with direct3d Michael Heidemann108November 23, 2013 12:58PM
Re: Simple renderer in .net with direct3d Roland Melkert93November 23, 2013 01:06PM
Re: Simple renderer in .net with direct3d Michael Heidemann124November 23, 2013 01:13PM
Re: Simple renderer in .net with direct3d Travis Cobbs205November 25, 2013 11:45PM
Re: Simple renderer in .net with direct3d Michael Heidemann160November 26, 2013 09:36AM
Re: Simple renderer in .net with direct3d Michael Heidemann138November 29, 2013 03:18AM
Re: Simple renderer in .net with direct3d Roland Melkert132November 29, 2013 10:22AM
Re: Simple renderer in .net with direct3d Michael Heidemann109November 30, 2013 02:55AM
Re: Simple renderer in .net with direct3d Michael Heidemann92November 30, 2013 07:08AM
Re: Simple renderer in .net with openTK (openGL) Michael Heidemann148November 30, 2013 07:48AM
Re: Simple renderer in .net with openTK (openGL) Roland Melkert136November 30, 2013 10:40AM
Re: Simple renderer in .net with openTK (openGL) Michael Heidemann113November 30, 2013 11:44AM
Re: Simple renderer in .net with openTK (openGL) Roland Melkert234November 30, 2013 12:04PM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann174December 01, 2013 04:33AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann145December 01, 2013 08:34AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann137December 01, 2013 08:58AM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert140December 01, 2013 09:51AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann242December 01, 2013 09:54AM
Re: Simple renderer in .net with SharpGL (openGL) Travis Cobbs152December 01, 2013 09:08PM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann146December 02, 2013 09:58AM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert151December 02, 2013 10:05AM
Re: Simple renderer in .net with SharpGL (openGL) Steffen136December 02, 2013 11:58PM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann153December 03, 2013 08:53AM
Re: Simple renderer in .net with SharpGL (openGL) Steffen235December 07, 2013 01:57AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann118December 07, 2013 03:10AM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert177December 02, 2013 09:59AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann191December 06, 2013 09:30AM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert131December 06, 2013 10:20AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann114December 06, 2013 11:30AM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert133December 06, 2013 12:27PM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann113December 06, 2013 01:22PM
Re: Simple renderer in .net with SharpGL (openGL) Travis Cobbs137December 06, 2013 03:25PM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann177December 06, 2013 11:06PM
Re: Simple renderer in .net with SharpGL (openGL) Roland Melkert130December 07, 2013 10:11AM
Re: Simple renderer in .net with SharpGL (openGL) Michael Heidemann209December 08, 2013 02:46AM



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