Motion Blur Glitch: PdN v3.22

[Mike Ryan]

Please note that this glitch was found in PdN v3.22!

Anyways, to recreate this glitch create a new image (I used 500x500)

Fill it black

Create a new layer and make a white square near the bottom

Duplicate layer and merge the two white square layers

Use Motion blur at a 90 degree angle, make sure it is centered.

Notice the glitch to the left

Here is a screenshot:

[Rick Brewster]

I was just looking at this in the debugger. Looks like a precision problem, where the angle you set is 90 degrees but actually ends up being computed to be just slightly more than 90 degrees. Like 90.0000000000000001 or something. In any case, an 'x' variables ends up computing to -0.0000000000000018369095307335659 instead of straight 0, which is then treated as "out of bounds" and so it doesn't contribute to some of the sampling that's being done.

Probably just have to live with it ... or try rotating 90 degrees (Image->Rotate), do your motion blur at a -90 offset, then rotate by -90 degrees. As a workaround anyway.