OpenGL Normal Maps (Y = Up)

I tried generating diffuse, specular, and normal maps and putting them in a game, but after scratching my head for a while trying to figure out why it looked so weird, I realized the normal maps were backwards. At first I was going to file this as a bug report, but then somebody informed me that DirectX normal maps are backwards, which I assume is what you're generating these normal maps for. In OpenGL, Y is up. In DirectX, Y is down (what were they thinking?). I inverted the bump map and thought that fixed it, but X ended up being backwards (which wasn't quite as obvious).

I personally think Y should be up by default. It just makes more sense, and I think is more widely used. OpenGL is available on almost every platform: Windows, Linux, MacOS, Unix, and even some consoles. It's also used in a number of professional 3d rendering applications, such as Maya. When Y is up, you can also just look at the normal map and it visually "looks right", since lighting usually comes from the top and you'll have green/cyan highlights there. When the green is on the bottom, it just looks inverted.

Anyway, enough with my opinions -- this definitely needs to be an option (or did I just overlook it?).

Much appreciated.

True, but I'd rather have that than have to manually adjust the channels every time I render a texture, or worse yet, be stuck wondering why it looks so bad in-game because I wasn't aware the normals were backwards to begin with.

I'd second jitspoe's sentiment. Having an option that sets FF to default to either DirectX or OpenGL normal conventions would be preferable, IMHO. That way both DirectX and OpenGL application users can live happily everafter.

The balloon popup sounds like a very good idea for alerting users to this general issue (and the current default), but it shouldn't be an excuse for leaving them out there in the cold with having to fix this manually.

The preview window looks like it only shows the complete render (is there a setting for that somewhere?), so the only visual mismatch would be with the website. I don't think anybody is going to be sitting there looking at the website saying, "Hey, this doesn't match," especially if you have a bubble help explaining the issue and the user had to manually change the setting.

Ahh, I see. You can save a preset with the normal map. That's simple enough to resolve -- just re-render the thumbnail. It seems to re-render thumbnails rather frequently anyway.

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jitspoe wrote: just re-render the thumbnail. It seems to re-render thumbnails rather frequently anyway.

If I remember correctly, thumbnails for library filters are downloaded from the server, pre-rendered of course, and since the user can't change these factory presets, they are never re-rendered. So, that mismatch will remain...

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Vladimir Golovin wrote: I think a balloon and a set of options would be the best solution here.

I concur.

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Vladimir Golovin wrote: However, 3DS Max uses the following set of options for the normal map: [...]

Well, I'll take your word for it, then.

Sorry to dredge up an old thread, but I ran into this issue today.

The shaders in our real-time 3D software expect the red normals to point left, and green to point down. But FF only allows me to control the green channel, not the red.

Not a huge problem, I can easily invert my red in Photoshop. I'd just like to second the request to have toggles for the normalmap directions in the FF options.

Thanks!

The option only inverts Y, but I also need to invert X. FF assumes X is pointing to the right, but our shaders assume the opposite.