gl matrix mode question

[nobond]

if I want to use glFrustrum() correctly, is it necessary for to set the glMatrixMode(GL_PROJECTION) first or it will be done automatically by OGL?

Same thing, is glMatrixMode(GL_MODELVIEW) must happen before glTranslate?

[Rodéric]

You can find that by reading the "OpenGL Reference Manual" also known as the blue book.
Some versions a freely available online. (such as : http://www.opengl.org/sdk/docs/man/xhtml/glFrustum.xml)

The short answer is : you need to call glMatrixMode yourself.