OpenGL OpenGL Lighting and Materials

Question 1

In OpenGL's Phong lighting model, which component represents light scattered equally in all directions regardless of viewing angle?

Accepted Answer

Ambient

Answer

Ambient light is a constant, non-directional approximation of indirect light that illuminates all surfaces equally regardless of orientation or viewer position.

Question 2

Which OpenGL fixed-function call correctly sets the position of a light source?

Accepted Answer

glLightfv(GL_LIGHT0, GL_POSITION, pos)

Answer

glLightfv() is the correct function for setting float vector parameters of a light source, using GL_POSITION as the parameter name.

Question 3

In the Phong reflection model, the specular component is determined by which pair of vectors?

Accepted Answer

View direction and reflection vector

Answer

The specular term is computed from the dot product of the view (eye) direction and the reflection vector, raised to the shininess exponent.

Question 4

What does the GL_SHININESS material parameter control in OpenGL's legacy lighting model?

Accepted Answer

The size and sharpness of specular highlights

Answer

GL_SHININESS is the specular exponent; higher values produce smaller, sharper highlights while lower values create broader, softer ones.

Question 5

What is the maximum number of light sources supported by OpenGL's fixed-function pipeline (GL_MAX_LIGHTS)?

Accepted Answer

8

Answer

The OpenGL specification guarantees at least 8 light sources (GL_LIGHT0 through GL_LIGHT7) in the fixed-function pipeline.

OpenGL Practice Test

OpenGL Practice Test

OpenGL OpenGL Lighting and Materials