OpenGL Functions 4

Question 1

What does glCompileShader() do?

Accepted Answer

Compiles the GLSL source code attached to a shader object

Answer

glCompileShader() compiles the GLSL source strings previously provided to the shader object via glShaderSource().

Question 2

Which function is used to perform instanced rendering?

Accepted Answer

glDrawArraysInstanced()

Answer

glDrawArraysInstanced() renders multiple instances of a primitive set in a single draw call, with each instance able to access gl_InstanceID in the shader.

Question 3

What is returned by glGetError()?

Accepted Answer

The most recent error flag, which is then cleared

Answer

glGetError() returns the value of the error flag and resets it to GL_NO_ERROR, so multiple errors require multiple calls.

Question 4

Which function enables a vertex attribute array so it can be used in vertex shaders?

Accepted Answer

glEnableVertexAttribArray()

Answer

glEnableVertexAttribArray() activates the vertex attribute at the given index so the shader can receive per-vertex data from the buffer.

Question 5

What does glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE) do?

Accepted Answer

Clamps UV coordinates to the edge texel color on the S axis

Answer

GL_CLAMP_TO_EDGE ensures UV coordinates outside [0,1] on the S axis sample the nearest edge texel rather than repeating or wrapping.

OpenGL Practice Test

OpenGL Practice Test

OpenGL Functions 4