OpenGL Functions 3

Question 1

What is the function signature purpose of glVertexAttribPointer()?

Accepted Answer

Defines the layout of vertex attribute data in a buffer

Answer

glVertexAttribPointer() tells OpenGL how to interpret the bytes in a bound VBO for a specific vertex attribute index.

Question 2

Which function checks whether a specific OpenGL extension is available?

Accepted Answer

glGetString(GL_EXTENSIONS)

Answer

glGetString(GL_EXTENSIONS) returns a space-separated string of all supported extension names (in legacy contexts).

Question 3

What does glReadPixels() do?

Accepted Answer

Reads a rectangle of pixels from the framebuffer into client memory

Answer

glReadPixels() reads a rectangular block of pixel data from the current read framebuffer into a client-side array.

Question 4

Which function must be called after glLinkProgram() to actually use a shader program for rendering?

Accepted Answer

glUseProgram()

Answer

glUseProgram() installs the specified program object as part of the current rendering state.

Question 5

What is the role of glScissor()?

Accepted Answer

Defines a rectangular region outside which fragments are discarded

Answer

glScissor() defines a scissor rectangle; any fragments outside this rectangle are automatically discarded before reaching the framebuffer.

OpenGL Practice Test