calculating normals
Author
Hello!
Somebody, please tell me how to calculate normals for a square.
I have a square consisting of 4 points. (a.x, a.y, a.z, b.x, ...)
But how do I give that square a normal?
I would like to see some code, not some replies like: search the net...
thanx.
---
marius
http://fr.ee/linux
It is very easy, if you make the assumption that your rectangle is flat.
just do it like this:
a-----b
|ooooo|
|ooooo|
c-----d
no you just need to do the cross product between two of the vectors going from one of the point to the two points next to it.
example:
normal = (c - a ) x ( b - a )
Simple!
there are problems though..
you shading wont be nice though if you just use one normal for each surface..
and the method i have shown will give you the same normal for each corner, so that wouldnt help either..
Edited by - ZubZorro on January 13, 2001 4:00:23 AM
just do it like this:
a-----b
|ooooo|
|ooooo|
c-----d
no you just need to do the cross product between two of the vectors going from one of the point to the two points next to it.
example:
normal = (c - a ) x ( b - a )
Simple!
there are problems though..
you shading wont be nice though if you just use one normal for each surface..
and the method i have shown will give you the same normal for each corner, so that wouldnt help either..
Edited by - ZubZorro on January 13, 2001 4:00:23 AM
The normal of any point on a polygon (triangle, quad, octagon, etc...)
v1 = lastpoint - currentpoint;
v2 = nextpoint - currentpoint;
normalize v1 and v2
calculate the cross product of v1 & v2
The result is the normal for the current point.
I also have a page about this at
http://tannara.2y.net/Graphics/Theory/finding_the_normal_of_a_surface.htm
l8r,
Rob
http://tannara.2y.net/
v1 = lastpoint - currentpoint;
v2 = nextpoint - currentpoint;
normalize v1 and v2
calculate the cross product of v1 & v2
The result is the normal for the current point.
I also have a page about this at
http://tannara.2y.net/Graphics/Theory/finding_the_normal_of_a_surface.htm
l8r,
Rob
http://tannara.2y.net/
Once you find the normal of the surface, would you then set the normal of each of those vertexes to the calculated surface normal?
ok VERY basic question.. by lastpoint-currentpoint do you mean the distance between them? i.e sqrt(x^2+y^2+z^2). or is it
vector1.x = lastpointx - currentpointx
vector1.y = lastpointy - currentpointy
vector1.z = lastpointz - currentpointz
vector1.x = lastpointx - currentpointx
vector1.y = lastpointy - currentpointy
vector1.z = lastpointz - currentpointz
The second. When I wrote v1 = lastpoint - currentpoint I meant it as vector math so...
v1.X = LastPoint.X - CurrentPoint.X;
v1.Y = LastPoint.Y - CurrentPoint.Y;
v1.Z = LastPoint.Z - CurrentPoint.Z;
I''ve also updated my page with calculating normals with some sample code.
http://tannara.2y.net/Graphics/Theory/finding_the_normal_of_a_surface.htm
l8r,
Rob
http://tannara.2y.net/
v1.X = LastPoint.X - CurrentPoint.X;
v1.Y = LastPoint.Y - CurrentPoint.Y;
v1.Z = LastPoint.Z - CurrentPoint.Z;
I''ve also updated my page with calculating normals with some sample code.
http://tannara.2y.net/Graphics/Theory/finding_the_normal_of_a_surface.htm
l8r,
Rob
http://tannara.2y.net/
Author
Thanx, everybody. Got them working.
i needed them on a terrain engine that I was creating. But now the entire terrain is all blocky. Check the url below for the topic.
http://www.gamedev.net/community/forums/topic.asp?topic_id=37246
---
marius
http://fr.ee/linux
i needed them on a terrain engine that I was creating. But now the entire terrain is all blocky. Check the url below for the topic.
http://www.gamedev.net/community/forums/topic.asp?topic_id=37246
---
marius
http://fr.ee/linux
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