GUI elements and lighting

l0calh05t · Post by **l0calh05t** » Sat Jun 19, 2004 8:23 am

Dunno, maybe it's supposed to be this way but GUI elements are affected by lighting (same thing with 2D images drawn directly as for example a mouse cursor)

If it helps, I use OpenGL and I don't know if this happens with DirectX, as i can't use it. Oh, and it doesn't happen with software rendering.

by doing

driver->setMaterial(nolight);
before drawing the gui elements etc., i can prevent this, but it does seem wierd

l0calh05t · Post by **l0calh05t** » Tue Jun 29, 2004 10:46 am

did no one else experience this or is this already known?

bal · Post by **bal** » Tue Jun 29, 2004 11:11 am

Quite normal I think. They are drawn by the same engine like any other 3d-object. Or is there another explanation

?

l0calh05t · Post by **l0calh05t** » Tue Jun 29, 2004 2:11 pm

bal wrote:Quite normal I think. They are drawn by the same engine like any other 3d-object. Or is there another explanation ?

Yeah, but shouldn't lighting be automatically deactivated for the gui?

Tyn · Post by **Tyn** » Tue Jun 29, 2004 5:39 pm

Never effected me. Are you sure you haven't got a slight transparancy on the elements? If it is doing that then it definatly isn't normal and is a bug, I'm not sure how the GUI is represented in a 3D engine but even if it is just a billboard attached to the camera at the right point so it looks like a 2D image blitted over the screen then it would have the lighting flag disabled so the lighting wouldn't effect it.

l0calh05t · Post by **l0calh05t** » Tue Jun 29, 2004 7:20 pm

nope, no transparency is set, I had 50% transparency at the beginning as I noticed it so I turned transparency off to see if it is the transparency causing the problem, but it wasn't.

Tyn · Post by **Tyn** » Tue Jun 29, 2004 9:34 pm

Can you post a screenshot? I might have seen it myself if I see the effect in a picture. As they say, a picture is worth a 1000 words.

l0calh05t · Post by **l0calh05t** » Wed Jun 30, 2004 8:12 am

Compare the first two screen shots (both OpenGL):

http://www.8ung.at/splugs/screen1.jpg
http://www.8ung.at/splugs/screen2.jpg

Another screenshot (DirectX8):

http://www.8ung.at/splugs/screen3.jpg

Apparently the bug only occurs in OpenGL, and seems to be located in the draw2dimage function, as this is also used by the GUI elements.

Tyn · Post by **Tyn** » Wed Jun 30, 2004 7:24 pm

You're right there, definatly not transparency. It seems a fairly isolated problem, I wondered if it were a specific device. The tech demo loads lighting from the BSP file, does it show the same problems? I couldn't see any on my computer, I wonder if it's a problem with a certain make of video cards?

l0calh05t · Post by **l0calh05t** » Wed Jun 30, 2004 8:44 pm

Tyn wrote:You're right there, definatly not transparency. It seems a fairly isolated problem, I wondered if it were a specific device. The tech demo loads lighting from the BSP file, does it show the same problems? I couldn't see any on my computer, I wonder if it's a problem with a certain make of video cards?

Perhaps. I own an ATI Radeon 9700 Pro. Possibly the error lies in my graphic card's opengl implementation.

Robomaniac · Post by **Robomaniac** » Wed Jun 30, 2004 8:59 pm

I had this problem on my GeForce4 GO! and my GeForce2

l0calh05t · Post by **l0calh05t** » Thu Jul 01, 2004 6:25 am

Robomaniac wrote:I had this problem on my GeForce4 GO! and my GeForce2

in that case it possibly is not an error but rather something that isn't clearly defined in the OpenGL specs (if or if not camera-space 2d images should be rendered with or without light)

niko · Post by **niko** » Sat Jul 03, 2004 5:52 am

Hm strange. I'm nearly sure that the lighting is turned off everywhere for 2d stuff. Maybe it is a problem with the driver you are using.

l0calh05t · Post by **l0calh05t** » Sat Jul 03, 2004 12:44 pm

niko wrote:Hm strange. I'm nearly sure that the lighting is turned off everywhere for 2d stuff. Maybe it is a problem with the driver you are using.

Yeah, I just checked, it draw2dimage (which in this case seems to be the buggy function) calls setRenderStates2dMode which disables lighting using glDisable(GL_LIGHTING) unless ERM_2D is already set, but if it were it would cause the images to be diplayed using the wrong projection and transformation matrices, which is not the case. Very wierd...

EDIT: It gets even wierder: if you set a material with lighting turned off the OpenGL driver also calls glDisable(GL_LIGHTING); ...

EDIT2: The error also occurs when using a Geforce 4 MX