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Games => Spelunky Support => Topic started by: NalaNosivad on August 16, 2013, 03:54:15 PM



Title: Very slight, almost unnoticeable lighting/sprite/scrolling bug with spikes
Post by: NalaNosivad on August 16, 2013, 03:54:15 PM
Edit: Just getting the technical stuff out of the way first: It occurs on either the GOG.com or Steam versions, and all of my drivers are up to date for my GTX 580. Forced AA/AF/transparency AA are disabled by default in my graphics control panel, no special profile in place for Spelunky.exe.

I realise that title is fairly obtuse, but I hope the video I'll link to at the end of this thread explains it better than I can here.

The problem is that when the screen vertically, the top edge of the spike sprite seems to get a very slight, but noticeable shadow on the top of it. Now, I've had a look through the textures in alltex.wad, and can't see anything amiss in the textures themselves, but looking at the normal maps in alltilesN.jpg, I think I might have figured out what's doing it.

First of all, it's a jpeg. Quite why a normal map is being stored in a format that creates compression artifacts, I don't know, but if you look at this small snippet here with the contrast turned right up on the normalmap layer, which is underneath the transparent tilemap layer:
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/normalmapunderlaycontrast.png)

You'll see that the compression creates a LOT of artifacts that somewhere along the game reading in the normal map, it might be applying something to the top edge of the spike sprite, causing just such the bug mentioned. I can't say for sure, of course, since I don't exactly have access to the source! :P

Here are a few more images of the same area of the tilemap:
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/onwhite.png)
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/onblack.png)
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/onrainbow.png)
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/normalmapunderlay.png)
(http://alandavison.co.uk/images/spelunky_hd/spike_bug/normalmapunderlaycontrast.png)

The video demonstrating it is here (http://www.youtube.com/watch?v=n3Z3tqpZexo).