Free OpenGL Computer Graphics Questions and Answers

Question 1

What are a 3D transformation matrix's dimensions?

Accepted Answer

3x3

Answer

A 3x3 matrix is the standard size for representing 3D linear transformations like rotation and scaling, since each of the three output coordinates (x, y, z) is a combination of the three input coordinates. A 2x2 matrix only handles 2D, while 4x4 is used when translation is added via homogeneous coordinates and 3x4 is non-square and can't be composed cleanly for these operations.

Question 2

In OpenGL, is it possible to specify the location of a light source?

Accepted Answer

Yes

Answer

Explanation:
In OpenGL you can specify the location of a light source using various functions provided by the OpenGL API.

Question 3

How can one revolve about a location other than the origin?

Accepted Answer

Translate to origin, rotate about origin, then translate back to original position

Answer

Rotation matrices inherently spin objects around the origin, so to rotate around any other point you translate the object so that point lands on the origin, perform the rotation, then translate back to its original location. The claim that rotations can only happen around the origin is false, and simply specifying a point in glRotate does not change that — glRotate always rotates about the origin along the given axis.

Question 4

What stands for GLUT?

Accepted Answer

Opengl utility toolkit

Answer

Explanation:
GLUT is a library of utility functions for OpenGL programming that simplifies the process of creating windows and handling input events. It provides a set of functions that allow programmers to create windows, menus, and user interfaces for their OpenGL applications, without having to worry about the low-level details of window management and event handling.

Question 5

What is glMaterialf(...) used for?

Accepted Answer

Defines the material properties of a drawn object for visual effects

Answer

Explanation:
The glMaterialf function in OpenGL is used to set a single floating-point value for a specific material property of a drawn object. The material properties defined using this function affect the way that an object interacts with light, and can be used to achieve various visual effects.

OpenGL Practice Test

OpenGL Practice Test

Free OpenGL Computer Graphics Questions and Answers