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View Full Version : Lighting on wrong side? which part of Manual?



Johnny
02-02-2004, 09:03 AM
Can anyone point me to that part of the manual which explains lighting in layout with respect to having a light on one side of an object, but layout showing the Opposite side of that object illuminated?

When I hit F9, the object is shown lit from the side where I have my light.

is this an OPen GL thing?

J

eblu
02-02-2004, 09:16 AM
johnny are your normals flipped?
look up "surface normals" in the manual.
if thats not it, then you have to describe it more accurately for me to understand your plight, sorry.

Johnny
02-02-2004, 09:25 AM
the normals are pointing out..is that what you're asking, as opposed to normals pointing inward?

some times I notice the correct side of an object is lit, but when I move or rotate a lite, say, to the right, the left side gets brighter, IOW the opposite side of that receiving light actually shows the light.

seems like something is reversed...

J

themaxx
02-02-2004, 09:38 AM
Are you looking at the object from the other side? (ie, camera positioned to look at the front, viewport looking at the back?)

Johnny
02-02-2004, 09:51 AM
it would be in perspective view..the one that lets you dolly all around the scene..

camera and light will be on one side, for example, but the OGL preview of the item is lighted opposite where the light is pointing.

J

themaxx
02-02-2004, 09:55 AM
can you post a screengrab?

Johnny
02-02-2004, 10:51 AM
I can't re-create it..should have taken a screencap yesterday when I saw it first...

but, literally, the light was shining on one side, but it was the opposite side of this element which appeared to be illuminated.

Is this related to the fact that when you work on surfaces, the little sphere preview appears in darkness, tho you know you have lights pointed on it?

J

BeeVee
02-02-2004, 10:57 AM
Were you using a distant light? Had you changed its rotation? Distant lights only have direction and not proximity, so it wouldn't matter if you had a distant light pointing right on the right side of an object. The left side would still be lit.

B

PS. Edited with an example. There is only one light in this scene.

themaxx
02-02-2004, 10:59 AM
Originally posted by BeeVee
Were you using a distant light? Had you changed its rotation? Distant lights only have direction and not proximity, so it wouldn't matter if you had a distant light pointing right on the right side of an object. The left side would still be lit.

that occurred to me too, but wouldn't the open gl view display that properly?

BeeVee
02-02-2004, 11:00 AM
That IS displayed properly. Here's the pic

B

Johnny
02-02-2004, 11:06 AM
Originally posted by BeeVee
That IS displayed properly. Here's the pic

B

OK..BeeVee, that is what I saw except that my light was pointing right AT the cube.

I had loaded the wood.lwo to test something else, and had a WTF moment when I saw the light direction didn't correspond to the illumination of the cube...moving the light had a reverse effect on which side was lit.

wierd...

J