Young Wu's Homepage

# QS11: Week 11 Survey Questions

📗 Enter your ID (the wisc email ID without @wisc.edu) here: and click (or hit the "Enter" key)

📗 Your answers are not saved when you refresh or close the browser. You could print the page: , solve the problems, then enter all your answers at the end.

📗 For all questions except for the last one, you can select one or more choices. You get the point for the question only if you selected all the correct choices.

📗 Question 0

📗 Question 1

Question 2

📗 Question 3

Question 4

📗 Question 5

Question 6

📗 Question 7

Question 8

📗 Question 9

# Grade

* * * * *

* * * * *

📗 Please do not modify the content in the above text field: use the "Grade" button to update.

📗 Please wait for the message "Successful submission." to appear after the "Submit" button. If there is an error message or no message appears after 10 seconds, please email the instructor or make a Piazza post about it. You could submit multiple times (but please do not submit too often): only the latest submission will be counted.

📗 If there are problems with grading, please try Ctrl+F5 or Shift+F5 or Shift+Command+R or Incognito mode or Private Browsing to refresh the cached JavaScript.

📗 [1 points] Which of the following variable types (or variables) are used in the vertex shader?

uniform
attribute
varying
gl_Position
gl_FragColor
None of the above.

📗 [1 points] Which of the following variable types (or variables) are used in the fragment shader?

uniform
gl_FragColor
varying
gl_Position
attribute
None of the above.

📗 [1 points] What is viewMatrix * vec4(cameraPosition, 1.0) in the vertex shader?

vec4(0.0, 0.0, 0.0, 1.0)
vec4(1.0, 1.0, 1.0, 1.0)
vec4(position, 1.0)
vec4(cameraPosition - position, 1.0)
vec4(position - cameraPosition, 1.0)
None of the above.

📗 [1 points] Which ones of the following evaluates to 0.0 in the shader? step(t, x) means x < t ? 0.0 : 1.0.

step(0.75, 0.5)
step(1.0, 0.5)
step(0.5, 0.5)
step(0.25, 0.5)
step(0.0, 0.5)
None of the above.

📗 [1 points] Given mesh = new THREE.Mesh(geometry, material) with material = new THREE.ShaderMaterial({uniforms ...}), where does the vertex shader get values for attribute vec3 color?

geometry.getAttribute("color")
material.color
mesh.getAttribute("color")
mesh.color
material.uniforms.color
None of the above.

📗 [1 points] Which of the following compute the cosine of the angle between a = vec3(1.0, 0.0, 0.0) and b = normalize(vec3(1.0, 1.0, 0.0))?

dot(a, b)
dot(b, a)
-dot(b, a)
cos(atan(b / a))
cos(atan(a \ b))
None of the above.

📗 [1 points] If the cosine of the angle between the camera position and the reflected light direction is cos(theta) = -1 and the Phong coefficient or shininess is p = 3. What is the intensity of the specular light? Note: the intensity is calculated by pow(clamp(cos(theta), 0.0, 1.0), p).

0.0
1.0
-1.0
3
-3
None of the above.

📗 [1 points] Which of the following lines transform the position of the light lp = vec3(1.0, 1.0, 1.0) in the scene coordinates to the camera coordinates in the vertex shaders (so that the light does not move with the camera)?

vec3(viewMatrix * vec4(lp, 1.0))
viewMatrix * lp
normalMatrix * lp
vec3(projectionMatrix * viewMatrix * vec4(lp, 1.0))
projectionMatrix * viewMatrix * lp
None of the above.

📗 [1 points] Please provide additional comments, questions, or feedback:

📗 [1 points] Have you completed the in-class quiz on TopHat?

Note: if you selected the second or third choice, you will get the same grade from this survey for the in-class quiz; if you selected the forth choice, you only have to complete the last question.

# QS11: Week 11 Survey Questions

# Grade

# Submission