OpenGL OpenGL MCQ 5

Question 1

What is the difference between glDrawArrays() and glDrawElements()?

Accepted Answer

glDrawElements uses an index buffer to reuse vertices; glDrawArrays reads vertices sequentially

Answer

glDrawElements reads vertex indices from an Element Buffer Object (EBO) allowing vertex reuse, while glDrawArrays reads vertices in order without reuse.

Question 2

Which OpenGL mechanism allows the CPU to read back rendered pixels from the framebuffer?

Accepted Answer

glReadPixels()

Answer

glReadPixels() copies pixel data from the framebuffer to CPU memory, though it causes a GPU-CPU sync stall and should be avoided in performance-critical paths.

Question 3

In OpenGL, what does the LOD (Level of Detail) bias affect?

Accepted Answer

Which mipmap level is selected during texture sampling

Answer

LOD bias shifts the computed LOD value up or down, causing OpenGL to select a sharper or blurrier mipmap level than it would automatically choose.

Question 4

What is transform feedback in OpenGL used for?

Accepted Answer

Capturing vertex shader or geometry shader outputs into buffer objects

Answer

Transform feedback captures the output of the vertex or geometry shader into VBOs, enabling GPU-side particle systems and physics simulations.

Question 5

Which OpenGL extension introduced bindless textures to reduce CPU driver overhead?

Accepted Answer

GL_ARB_bindless_texture

Answer

GL_ARB_bindless_texture lets shaders access textures via GPU handles instead of texture units, eliminating bind/unbind overhead for scenes with many textures.

OpenGL Practice Test

OpenGL Practice Test

OpenGL OpenGL MCQ 5