CSUDH Computer Science Department

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14 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

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CSUDH Computer Science Department


CSC
461 Computer Graphics I

(
Fall

200
5
)


Final Examination

(1
0
:
0
0
a
m


12:00
pm
,
December

12
, 200
5
)


1.


(
2
0 points,
4

points each)
Briefly e
xplain

1)

Additive color model and subtractive color model


2)

P
rojection normalization

an
d projection pipeline


3)

Opacity and RGBA color


4)

Local rendering and global rendering


5)

Advantages and disadvantages of orthogonal projection


2.


(20 points)
Assume that
a unit cube

is rotated
with 5

degree
s each step

around a given
line x+
z
=
2 and y
=1 at the lo
cation (
1
,
1
, 1)

and alternately shrinks and grows with 50%.

Outline how to implement this rotating and scaling cube in OpenGL

by
(specifying the
parameters of transformation functions used, if any)

1)

(4 points) Outlining the

main function


2)

(6

points) Outli
ning the display callback


3)

(6

points) Outlining the idle callback


4)

(4 points) Outlining the reshape callback


3.


(
20

points)
The OpenGL function
gl
Frustum

requires
that
six parameters
be

used to
determine the projection matrix and the viewing volume. Assu
me the projection plane
is the default plane z = 0). Consider the function call
gl
Frustrum
(
1
,

5
,
3, 9
,
2
,

6
)
.

1)

(
2

points)

Explain the difference of
glFrustrum

from the function
glPerspective
.



2)

(6 points)
Explain the six parameters of the
glFrustrum

functi
on

by illustrating the
view volume


3)


(6 points)
Describe the t
hree

steps to
find
the projection

matrix


4)

(6

points)
Find the final projection matrix


4.


(20

points) The Phong reflection model

uses the four vectors and supports the three
types of material
-
ligh
t interactions.

CSC461

Final Examinat
ion

(
Fall

200
5
)

1

1)

(3 points) One of the four vectors is the reflection vector. What are the other three
vectors?


2)

(3 points) What are the three types of material
-
light interactions?


3)

(4 points) What are the assumptions in the Phong reflection model with whic
h the
reflection vector can be computed with the given other vectors?


4)

(4 points) Describe the
four
steps of shading in OpenGL.


5)

(6 points) Show how the reflection vector is computed in terms of other vectors.