OpenGL Computer Graphics 5

Question 1

What is the purpose of a Transform Feedback object in OpenGL?

Accepted Answer

Capturing vertex shader output into buffer objects for later use

Answer

Sending user input events back to shaders

Answer

Reducing shader compilation overhead

Answer

Feeding fragment shader results into vertex buffers

Question 2

What is the difference between GL_LINEAR and GL_NEAREST texture filtering?

Accepted Answer

GL_LINEAR blends adjacent texels (smoother), GL_NEAREST selects the closest texel (pixelated)

Answer

GL_NEAREST blends four texels; GL_LINEAR takes one exact sample

Answer

GL_LINEAR applies mipmapping; GL_NEAREST disables it

Answer

There is no visual difference at native texture resolution

Question 3

Which stage of the OpenGL pipeline converts primitives into fragments?

Accepted Answer

Rasterization

Answer

Vertex processing

Answer

Fragment shading

Answer

Geometry shading

Question 4

What does the OpenGL function glUniform1i() do?

Accepted Answer

Sets an integer uniform variable in the currently active shader program

Answer

Activates a specific texture unit

Answer

Uploads a single integer into a VBO

Answer

Queries the location of a named uniform block

Question 5

What is a Renderbuffer Object (RBO) in OpenGL and how does it differ from a texture attachment?

Accepted Answer

An RBO is an off-screen image optimized for rendering but not directly sampleable in shaders

Answer

An RBO stores color data and a texture stores depth data

Answer

An RBO supports mipmaps while textures do not when used as FBO attachments

Answer

An RBO is always multi-sampled; textures are single-sampled

Question 6

In OpenGL, what is the correct order of matrix multiplication to transform a vertex from object space to clip space?

Accepted Answer

clip = Projection × View × Model × vertex

Answer

clip = Model × View × Projection × vertex

Answer

clip = View × Model × Projection × vertex

Answer

clip = Projection × Model × View × vertex

Question 7

Which OpenGL feature allows rendering to multiple color attachments in a single draw call?

Accepted Answer

Multiple Render Targets (MRT) via glDrawBuffers()

Answer

Layered rendering with geometry shaders

Answer

Multisampled FBOs with glRenderbufferStorageMultisample()

Answer

Instanced rendering with gl_InstanceID