On 12/06/2016 02:30 PM, Orchid Win7 v1 wrote:
> In full:
>
> void TracePixel::JitterCameraRay(Ray& ray, DBL x, DBL y, size_t ray_number)
> {
> DBL xjit, yjit, xlen, ylen, r;
> Vector3d temp_xperp, temp_yperp, deflection;
>
> r = camera.Aperture * 0.5;
>
> Jitter2d(x, y, xjit, yjit);
> xjit *= focalBlurData->Max_Jitter * 2.0;
> yjit *= focalBlurData->Max_Jitter * 2.0;
>
> xlen = r * (focalBlurData->Sample_Grid[ray_number].x() + xjit);
> ylen = r * (focalBlurData->Sample_Grid[ray_number].y() + yjit);
>
> // Deflect the position of the eye by the size of the aperture, and in
> // a direction perpendicular to the current direction of view.
>
> temp_xperp = focalBlurData->XPerp * xlen;
> temp_yperp = focalBlurData->YPerp * ylen;
>
> deflection = temp_xperp - temp_yperp;
>
> ray.Origin += deflection;
>
> // Deflect the direction of the ray in the opposite direction we deflected
> // the eye position. This makes sure that we are looking at the same place
> // when the distance from the eye is equal to "Focal_Distance".
>
> ray.Direction *= focalBlurData->Focal_Distance;
> ray.Direction -= deflection;
>
> ray.Direction.normalize();
> }
>
> Good luck *ever* figuring out what the hell any of it means, of course...

I'm not entirely sure why that method is so complicated, but it 
*appears* the key part of the algorithm is this:

ray.Origin += deflection;
ray.Direction *= focus_distance;
ray.Direction -= deflection;
ray.Direction.normalize();

The aperture determines the maximum size of deflection, and the focus 
distance is mentioned above. Plugging these two into my shader, I seem 
to be able to get it to produce blurry images focused at a specific 
distance.

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