Problem with triangle strips for 3d mesh and normals

OpenGL Development
#1

Hello!
I’m new to opengl programing. I’m currently making animation of cave shaft formation. I have a set of coordinats for profiles of the shaft along the z-axis. My plan is to make a 3d mesh from this data
and to do that I’ve decieded to use TRIANGLE_STRIPS. The way I did this was that I’ve created multiple strips like this:

11----12 5------6
| / | | / |
| / | | / |
9-----10 3------4
| / | | / |
| / | | / |
7-----8 1------2

My questions are:

  1. Is this the right way to do it? Because now I have problems with normals. I would like to use GL_SMOOTH shading and for that as I understand I need to calculate normals of vertices? But in my cas vertex 10 and 3 are the same
    so there would be two normals??? Is that a problem? And is there any other way to create multiple strips?
#2

Hi

Sorry to reply only now, I had missed that one. You can use gl.glEnable(GL_AUTO_NORMAL) if you don’t want to compute normals but you’d better to compute a normal per vertex.

#3

Nope, read the docs. GL_AUTO_NORMAL will renormalise existing normals (handy if you’ve scaled your model or something) but it won’t generate them for you.

#4

No you’re wrong, you’re speaking about GL_NORMALIZE which renormalizes existing normals :wink: I advise you to read the docs :point:

[quote]GL_NORMALIZE

If enabled, normal vectors are scaled to unit length after transformation. See glNormal and glNormalPointer.

[/quote]
Source: http://www.khronos.org/opengles/documentation/opengles1_0/html/glEnable.html

However, GL_AUTO_NORMAL does not work with OpenGL-ES and seems to work only with Bezier curves and NURBS. Some professional graphics cards have a different implementation but we should not rely on such a behaviour, sorry.