OpenGL OpenGL Shaders

Question 1

Which language is used to write shaders in OpenGL?

Accepted Answer

GLSL

Answer

OpenGL uses GLSL (OpenGL Shading Language) to write vertex, fragment, and other shader programs.

Question 2

Which built-in GLSL variable holds the final position of a vertex in clip space?

Accepted Answer

gl_Position

Answer

The vertex shader must write the clip-space position to gl_Position for the rasterizer to use.

Question 3

What OpenGL function is used to compile a shader object?

Accepted Answer

glCompileShader

Answer

glCompileShader(shader) compiles the GLSL source code that was previously loaded with glShaderSource.

Question 4

What qualifier is used in GLSL to declare a variable that passes data from the vertex shader to the fragment shader?

Accepted Answer

out/in

Answer

The 'out' qualifier in the vertex shader and matching 'in' qualifier in the fragment shader define interpolated varyings.

Question 5

What is a 'uniform' variable in GLSL?

Accepted Answer

A constant set by the CPU that is the same across all shader invocations

Answer

Uniform variables are set once by the application and remain constant for all vertices or fragments in a draw call.

OpenGL Practice Test