Vertical Counter / Clockwise

Question

I read several books about OpenGL, and in two of them they always define vertices counterclockwise. From what I read, this is very important because it determines where the front and back are.

But I also read the tutorial at http://www.arcsynthesis.org/gltut/ And it identifies them clockwise.

const float vertexPositions[] = { 0.75f, 0.75f, 0.0f, 1.0f, 0.75f, -0.75f, 0.0f, 1.0f, -0.75f, -0.75f, 0.0f, 1.0f, }; 

Should I always use counterclockwise notation because this is the default value in opengl?

Also why is the type a float ? Shouldn't it be GLfloat ?

Answer 1

Shouldn't you always use counterclockwise notation, because it's the default in opengl?

This is your choice. You can use CCW or CW notation. You can always override this behavior with glFrontFace() . For the hardware, it makes no difference which way it works, but I think using CW may cause some unexpected problems when trying to use a third-party library that prefers CCW or something like that.

Also why is the type float? Won't it be GLfloat?

It should be GLfloat . On the other hand, on most platforms, float and GLfloat exactly the same, and there can be no difference. Using GLfloat is best practice in terms of portability. Another consideration: it emphasizes that the variable is used to render graphics, so that’s good.