OpenGL OpenGL Lighting and Materials 2

Question 1

Which OpenGL fixed-function call is used to set material properties used in lighting calculations?

Accepted Answer

glMaterialfv()

Answer

glMaterialfv() sets a float vector material parameter such as GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR, or GL_EMISSION for a specified face.

Question 2

Which GL_MATERIAL parameter controls the color of light a surface appears to emit on its own?

Accepted Answer

GL_EMISSION

Answer

GL_EMISSION adds a constant color to the fragment independently of any light source, simulating self-illumination or glowing surfaces.

Question 3

What does enabling GL_COLOR_MATERIAL allow in OpenGL?

Accepted Answer

Tracking the current glColor value to automatically set material properties

Answer

GL_COLOR_MATERIAL enables color tracking, where calls to glColor() automatically update the specified material parameter (e.g., GL_DIFFUSE) to match.

Question 4

Phong shading interpolates normals per-fragment and produces smoother highlights than which shading alternative?

Accepted Answer

Gouraud shading

Answer

Gouraud shading computes lighting at vertices and interpolates colors, while Phong shading interpolates normals and evaluates the lighting equation per fragment for smoother specular highlights.

Question 5

What is the primary purpose of surface normal vectors in OpenGL lighting calculations?

Accepted Answer

They determine how light reflects off the surface

Answer

Normal vectors describe the orientation of a surface at each point, which is used to compute the angle of incidence for diffuse lighting and the reflection direction for specular lighting.

OpenGL Practice Test

OpenGL Practice Test

OpenGL OpenGL Lighting and Materials 2