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Newcomers DBPro Corner / Are normal normals normal norman?

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Scraggle
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Posted: 22nd Oct 2003 19:14
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Sorry - couldn't resist the silly subject

My question really is: What are normals?

I hear them mentioned a lot but have no idea what they are.
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Hamish McHaggis
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Posted: 22nd Oct 2003 19:16
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They are lines that are perpendicular to a plane, so the line is at 90 degrees to every part of the plane.

Brains are for idiots.

Athelon XP 1400 Plus - Nvidia Geforce MX400 - 256mb RAM
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Scraggle
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Posted: 22nd Oct 2003 19:28
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eh?
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HardBoot
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Posted: 22nd Oct 2003 22:12
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take a pencil.
Stand it straight up on your desk.
The pencil is now a normal of the desk
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ReD_eYe
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Posted: 22nd Oct 2003 22:18 Edited at: 22nd Oct 2003 22:19
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have you done reflection/refraction etc in physics at school? the normal is the line at 90degrees to the surface of the prism in all the stupid diagrams you have to do.





Go on, click on my signature image, you know you want to
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Black Hydra
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Posted: 22nd Oct 2003 23:17
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Think perpendicular... perpendicular...
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IanM
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Posted: 23rd Oct 2003 01:24
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Depending on the graphics engine, they can be used for a few things

- Lighting. When adjusted according to the camera direction, they can determine the strength of the light reflected from the surface (and so the brightness of the colour of the polygons)

- Culling (not in DBPro). Polygons that are pointing away from the camera (according to the direction of the normal) can be considered hidden, so they don't need to be drawn.
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Scraggle
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Posted: 23rd Oct 2003 01:42
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Quote: "have you done reflection/refraction etc in physics at school"


Maybe. But I left school 18 years ago, so I don't remember.


Quote: "- Lighting. When adjusted according to the camera direction"


Is this something that can be done in DBP because I can't think of any commands that do this kind of thing? Or are normals used more in the 3D modelling world?
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ESC_
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Posted: 23rd Oct 2003 01:49
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Scraggle: You can adjust them via memblocks, and there is also a command to adjust them on matrices

"That's not a bug, it's a feature!"
"Variables won't, constants aren't."
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zircher
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Posted: 23rd Oct 2003 03:27
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"Set normalization on" can make a MAJOR difference in how your scenes are rendered and light is used. My models looked like crap until I found out this command.
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Scraggle
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Posted: 23rd Oct 2003 10:55
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Thanks zircher.

I tried SET NORMALIZATION ON and it cured the problem with lighting I was having. The one that you helped me with in the thread called 'Problem with the SCALE OBJECT command.'.

OK, I can see the end result of what SET NORMALIZATION ON has done and now I know that a 'normal' is perpendicular to a plain, but what happened on a low level when this command was executed.
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zircher
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Posted: 23rd Oct 2003 16:20 Edited at: 23rd Oct 2003 16:26
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Light comes in at a vector to the face. The normal is used to determine the angle of the face. The amount of light reflected back to the camera (based on the specularity of the face) is calculated from this and thus how much lighting/shading is used.
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TAZ
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Scraggle
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Posted: 23rd Oct 2003 20:21
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Thanks again zircher.

I seem to spend most of my time on this forum thanking you.

So here it is again - thanks.
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zircher
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Posted: 24th Oct 2003 03:00
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I've had my share of thanking other people in the past. I'm just passing on the torch so to speak.
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