CODEWITHSUNDEEP
opengl-es
GLaddict
GLaddict

Reputation:

What's the purpose of glNormal3f in OpenGL ES?

What's the purpose of glNormal3f in OpenGL ES? If there is no immediate mode available in OpenGL ES, for what would I use glNormal3f? Example code would be nice.

Upvotes: 8

Views: 6042

Answers (5)

meca soft
meca soft

Reputation: 111

In OpenGL|ES glNormal3f() is not a deprecated function,
because it is useful for rendering flat 2D shapes in the {X,Y} plane:

instead of using:

glEnableClientState( GL_NORMAL_ARRAY );
glNormalPointer( GL_FLOAT, 0, vbuf + normal_offset );

it is simpler and it requires less VBO memory to call:

glNormal3f( 0, 0, 1 );

Upvotes: 0

ralphtheninja
ralphtheninja

Reputation: 133118

You are not supposed to use these functions anymore. Stick to the glXXXXArray(). I suspect that they are just left overs hanging in there to make OpenGL to OpenGL ES transfer easier.

Upvotes: 0

glAddict
glAddict

Reputation:

OpenGL ES 1.1 does mention it but yes that's an error there in the iPhone programming tutorial.

Upvotes: 0

unwind
unwind

Reputation: 399959

The only reason I can think of is that it is there to support efficiently expressing surfaces where many vertices share the same normal. With the arrays-based approach, you'd have to create an array with the same value repeated for each vertex, which wastes memory.

I find it curious that the manual page (OpenGL ES 1.1, there) doesn't even mention it. I found one iPhone programming tutorial (PDF) that even claimed glNormal() was not there anymore.

Upvotes: 0

Maurice Gilden
Maurice Gilden

Reputation: 1954

I think it's for the same reason that there is a glColor function. If the normal of your whole geometry is the same for all vertices you could specify it with glNormal before calling glDrawArrays/glDrawElements.

Upvotes: 6

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