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Quad directly infront of the camera gives artifacts
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Description

rendering a quad thats directly in front of the camera can give artifacts. (diagonal black area)
I have had this trouble more then once on 32/64 bit systems.

Attached a file with the artifact packed into an image.

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Nobody (None) closed this task as Archived.Dec 6 2008, 2:56 AM

It only shows that artifact when set to 50% render. Regardless of size settings (for certain resolution it might be more prominent), all presets gave the same kind of error along the diagonal, some a couple of pixel wide only but still there, again, only at 50%, not at 100%, not at 75% nor at 25%.

The black line has Z=max, so smells like a z buf error.

It's not a clipping problem (changing those had no effect).

Rotating all objects at once does remove the artifact, but only for rotations over 5degree or so.

closed duplicate report
[#18282] Rendering bug depending on very specific values

Though the files from the report may be useful.

I have a similar file in my own "bugs" directory. On exceptional cases, indeed when values perfectly align, the zbuffer and clipping code have a numerical precision error. Intersections for clipping then go precisely through a vertex... this is like booleans you know!

The code for clipping is like a 100 years old, and quite nicely finetuned so it nearly always works. Fixing this I'd love to do once, but is on a very long todo... dont want to break stuff here.