Does anyone know of a method to calculate the extents for all 3D objects in a scene?
So I want x_min,x_max........z_max calculated by comparing each solid after any transformations.
But he does seem to want AABBs, and I ask because this topic was started because of the extents3d computation, which is simple in both OBB and AABB case. OBB is simpler/faster if only thing needed is extents.
Posted Wednesday, 1 July, 2009 - 07:54 by Soundbomber
I only want to calculate the physical extents of my objects so I can fit my scene into the OpenGL control correctly.
(No collision detection needed)
So really I just need to know the minimum and maximum x,y and z values. (After transforms)
Comments
Re: 3D extents
@Soundbomber
Why do you want AABBs?
Re: 3D extents
I'm not Soundbomber, but one advantage of AABBs is dead-simple collision detection.
Re: 3D extents
.. I know :)
But he does seem to want AABBs, and I ask because this topic was started because of the extents3d computation, which is simple in both OBB and AABB case. OBB is simpler/faster if only thing needed is extents.
For collision detecion AABBs are simpler/faster.
Re: 3D extents
I only want to calculate the physical extents of my objects so I can fit my scene into the OpenGL control correctly.
(No collision detection needed)
So really I just need to know the minimum and maximum x,y and z values. (After transforms)
Re: 3D extents
The aforementioned gamasutra articale describes how to calculate the correct AABBs (go to second page).
Re: 3D extents
As I am applying my transforms to each object as it is rendered, presumably I would have to carry out this calculation at render time also?
Re: 3D extents
Yes, you have to recalculate AABBs at render time, but only if you rotate an object. Fortunately this is fairly fast.
Re: 3D extents
Cool. Does OpenTK have a function to multiply a vector by a matrix?
Re: 3D extents
Yes, Vector3.Transform(). It is a static method.
Use the overload tat takes 3 parameters by reference, as it is much faster.
Re: 3D extents
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