3D Graphics & Audio 1x - Institute of Technology Carlow

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No:187a



Institute of Technology, Carlow

School of Science

Department of Computing & Networking

Autumn 2009 EXAMINATIONS





Course Code:

KCCGDB (CW208)





Course Title:

BSc (Hons) in Computer Games Development




Course Year:

2





Subject:

3D
Graphics & Audio 1







Date:

27/08 PM




Duration:

3 hours





Examiners:

Mr K Power



Mr S Howell



Dr B Nolan


Special Requirements:



Instructions to Candidate:




1.


Write your Name, Course, Course Year and Class Group on your answer book.

2.


Answer any FOUR questions.

3.

The maximum marks allowed for each part of a question is given in brackets on the right.
All questions carry equal marks.

Note carefully the
allocation of marks within each
question
.

Be particularly careful not to leave any part of your answers in rough work
.

4. Start each question on a new page.



Question 1.


a).

Draw a labelled diagram representing the rendering pipeline. Write a short

description of the
role of each stage of the pipeline

(7 Marks)

b).

Derive a matrix for perspective projection. (assume the eye is on the n
-
axis). Draw a diagram
to illustrate your approach.

(12 marks)

c).

Given a
n

eye position of (
-
5,0), and a polygon containing

the point (3,1) and a normal to the
polygon of (
-
1,1). Is this polygon a backface? Show your calculations fully.
(6 marks)


Question 2.



a).

Describe an efficient method to remove hidden surfaces while rendering.
(10 Marks)

b).

What sequence of OpenGL commands would you us
e to render a 2D animation of two
moons orbiting a planet? Assume you have a function
DrawDisk()

which draws a disk at the
origin.
The details of the syntax does not matter, I am concerned with the ORDER in
which transformations happen.

(6 Marks)

c).

What is t
he ModelView matrix in OpenGL? What 3 functions are typically used to modify
the ModelView matrix?

(
6

Marks)

d).

In an “
Explicit Mesh Representation”

each polygon is stored as a list of vertex coordinates.
What problems might this representation cause?

(3
Marks)



Question 3.


a).

Compare and contrast the Phong Specular reflection and Blinn
-
Phong Specular reflection
models.

(8 Marks)

b).

OpenGL supports only Gouraud

shading which generally renders specular reflection poorly.
Describe a technique to render specular reflection more accurately under OpenGL.

(3
Marks)

c).

Outline the steps needed to render an illuminated object in OpenGL.

(6 marks)

d).

Why is a vertex array used

in OpenGL programs?

(3 Marks)

e).

Describe
specifically how each of

these OpenGL primitives

are used
.

(5 Marks)

i).

GL_LINES

ii).

GL_LINE_STRIP

iii).

GL_TRIANGLES

iv).

GL_TRIANGLE_FAN

v).

GL_POLYGON





a).

Describe possible aliasing problems associated with texture mapping. Outline thr
ee
techniques to reduce aliasing in texture mapping.

(9 Marks)


b).


The above diagram shows a planar square composed of two triangles. The square is textured
with a regular checker pattern and the square is presented to the viewer at an angle (left
-
hand
side

is nearest to the viewer). The pattern shows some distortion, especially along the diagonal.
Explain, with the aid of a diagram what has caused the distortion. Also explain how to render the
texture to remove the distortion.

(9 Marks)

c).

Describe a data stru
cture suitable for representing objects and their spatial relationship in a
game.

(4 Marks)

d).

Why are surface normals important in lighting calculations?

(
3

Marks)





a).

Identify the
sources of error in digitizing

audio and suggest how the errors can be reduced.

(6 Marks)

b).

A 12 second audio sample is encoded using stereo PCM, at 16 bits per sample and 44,100
Hertz. How many
Bytes

of storage will it require?

(3 Marks)

c).

How does OpenGL use the depth buffer for HSR?

(8
Marks)

d).

What are the 3 primary subtractive colors?

(2 Marks)

e).

Which of these color media are additive: CRT display, printed paper, negative film?

(2
Marks)

f).

The
FMod

Audio API handles two type of audio source;
samples

&
streams.

What is the
difference betwe
en these sources? What are the limitations of the two sources?
(
4

marks)