btw, don't worry about clipping the distorted vertices to the screen bbox, the
renderer only worries about clipping to the near-Z plane. The only time you
need to worry about the screen edges is if you're wrapping around like the
spherical projection does.
On Jun 27, 2011, at 11:15 AM, Ivan Busquets wrote:
> Wow, thanks for the info, Jonathan. I looked at CameraOp::LensNFunc, but
> didn't know what to make of it, or where to start, really. So that's exactly
> the kind of info I was hoping for.
>
> At DD there was a custom 'HypeCamera' that supported the 'Hype' distortion
> file format so you could load a Hype file directly into the camera and it
> applied the forward distortion via this method. There was also a
> 'HypeDistort' geometry modifier that warped a card with the reverse
> distortion so you could do a undistort/redistort in a single render/filter
> pass.
>
> And that's exactly the kind of application I wanted it for. :)
>
> Thanks,
> Ivan
>
>
> On Mon, Jun 27, 2011 at 11:03 AM, Jonathan Egstad <jegs...@earthlink.net>
> wrote:
> So the current scanline renderer does handle general camera distortions -
> with poly subdivision memory limitations.
>
> The CameraOp class supports several built-in linear projection and non-linear
> distortions using its LensFunc/LensNFunc methods that are passed back to the
> renderer via the CameraOp::lens_function()/lensNfunction() virtual methods,
> then on to the Primitives in the Scene structure for use during tessellation.
>
> You can implement your own LensFunc routines and return them via the virtual
> method. The idea is that a primitive can subdivide itself using the output
> of a LensFunc by passing in vertex info which gets modified. The 'void *'
> parameter at the end is a way to get add'l info from the Primitive into the
> lens function.
>
>
> /*! Simple perspective projection lens function. */
> static void perspLensFunc(Scene* scene, CameraOp* cam, MatrixArray*
> transforms,
> const VArray& in, Vector4& out,
> void* data) {
> out = transforms->matrix(LOCAL_TO_SCREEN).transform(in.PL(), 1.0f);
> }
>
> /*! Simple UV projection lens function. */
> static void perspLensFunc(Scene* scene, CameraOp* cam, MatrixArray*
> transforms,
> const VArray& in, Vector4& out,
> void* data) {
> out = transforms->matrix(CLIP_TO_SCREEN).transform(in.UV()*2.0f -
> Vector4(1,1,1,1));
> }
>
> The LensNFunc method does the same thing, but operates on arrays of vert info.
>
> At DD there was a custom 'HypeCamera' that supported the 'Hype' distortion
> file format so you could load a Hype file directly into the camera and it
> applied the forward distortion via this method. There was also a
> 'HypeDistort' geometry modifier that warped a card with the reverse
> distortion so you could do a undistort/redistort in a single render/filter
> pass.
>
>
> Have fun,
>
> -jonathan
>
>
> On Jun 26, 2011, at 2:12 PM, Ivan Busquets wrote:
>
> > Hi,
> >
> > I've been looking at the lens_distortion parameters in CameraOp, and was
> > wondering if there's any way to implement a different lens
> > distortion/correction model within a CameraOp, or if one would need to
> > write a specific renderer to handle that.
> >
> > Specifically, I'm looking for a way to handle off-center and asymmetric
> > distortions. Assuming I can get a function that maps destination to source
> > vectors(uvs), would this be possible within a CameraOp?
> >
> > Many thanks,
> > Ivan
> >
> >
> >
> >
> >
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>
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