Normal Vectors?

What the hell is a vector''s origin?

The "ray" of the vector should start at the vertex''s location, not 0,0,0.

-~-The Cow of Darkness-~-

excuse zealouselixir, i guess thats just his way of saying that vectors dont have origins, its why there vectors. anyways you always want your normal vector to be perpendicular (orthogonal) to the vertex its attached to; thats what makes it a normal, since its normal (perpendicular) to the vertex and the plain the vertecies define.
now thats just a whorable description, so check these links out:
http://www.flipcode.com/tutorials/tut_vnormals.shtml

and for a basic linear algebra primer check:
http://chortle.ccsu.ctstateu.edu/VectorLessons/vectorIndex.html

hope those help better than my discription does

Yeah, maybe that was rude. However, it served its purpose in causing one to consider the question.

And I don''t know what cowsarenotevil is talking about. Normal vectors, in order to be useful, have to be normalized (have a length of 1). Therefore, since the only defining characteristic remaining of a vector is its direction, it has no "start" or "origin", however you say it. It''s simply a direction, a vector which points perpendicular to the surface.

If you shone a flashlight on a polygon and moved it aside, keeping it''s orientation, it would not continue to be illuminated. If vectors had no starting point, however, they would always face the flashlight, thus keeping them light. So wouldn''t they almost need an origin? (please correct me... I know I probably sound completely dumb, but bear with me, I''m very young.)

-~-The Cow of Darkness-~-

quote:

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Original post by cowsarenotevil
If you shone a flashlight on a polygon and moved it aside, keeping it''s orientation, it would not continue to be illuminated. If vectors had no starting point, however, they would always face the flashlight, thus keeping them light. So wouldn''t they almost need an origin? (please correct me... I know I probably sound completely dumb, but bear with me, I''m very young.)

-~-The Cow of Darkness-~-

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A flashlight isn''t a vector. A model of a flashlight would require storing a direction (that''s a vector), a position (of the flashlight), color, ...etc

Cheers,
Muhammad Haggag

Technically, a vertex normal is only a direction so it doesn''t have an "origin". Why are you asking?

quote:

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Original post by Coder
[quote]Original post by cowsarenotevil
If you shone a flashlight on a polygon and moved it aside, keeping it''s orientation, it would not continue to be illuminated. If vectors had no starting point, however, they would always face the flashlight, thus keeping them light. So wouldn''t they almost need an origin? (please correct me... I know I probably sound completely dumb, but bear with me, I''m very young.)

-~-The Cow of Darkness-~-

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A flashlight isn''t a vector. A model of a flashlight would require storing a direction (that''s a vector), a position (of the flashlight), color, ...etc

Cheers,
Muhammad Haggag

No, I ment the normal vector of the polygon, and to move the polygon.



-~-The Cow of Darkness-~-