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COM3503 3D Computer Graphics

 COM3503 3D Computer Graphics: Assignment (50%)

Dr Steve Maddock
1. Introduction
The assignment will involve using modern OpenGL to render a scene. Scene graphs are required in the modelling 
process and animation controls are required for hierarchical models.
2. The task
Figure 1 shows a room scene containing a table and a window looking out onto a view. There is a noticeboard on one 
wall. On the table is an unusual angle-poise lamp, a mini helicopter-like object, a piece of paper and a drawing pen. 
The whole scene can be modelled using planes, cubes and spheres.
Figure 1. The scene
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2
3. Requirements
You must satisfy all the following requirements:
• Only two walls and a floor for the room should be 
modelled. The walls and floor should be texture 
mapped to look like a room in a house. For example, 
the floor could be made of wood. The walls may have 
wallpaper on them or a paint pattern. • The table can be modelled as one scaled flat cube on 
top of four legs made out of cubes. The table should be 
texture-mapped, for example, to look like wood or 
some other material. • The hierarchical model of the basic angle-poise lamp
(see Figure 2) should be made up of five parts: a base, 
a lower arm, an upper arm, and a head, which contains 
a protruding lightbulb (a nose) in the shape of a cube 
(the details of the lighting technology used are not 
important). There are also some additional pieces.
o The base is fixed at one position on the table. 
Three other parts can articulate as illustrated in 
Figures 1 and 2. The lower arm can rotate about 
the connection point with the base in two 
directions (around the vertical y axis and around 
the x axis), the upper arm can rotate about the 
lower arm (like an elbow joint, the x axis) and the 
head can rotate about the upper arm (in one axis, 
the x axis). (The x axis could be substituted by the 
z axis if you prefer.) The lightbulb shines in the 
same direction that the head is pointing in, as 
indicated by the dotted lines in Figures 1 and 2. o A company is using this lamp in an advertising 
campaign in which they hope to sell more 
interesting angle-poise lamps. Thus, you need to 
add some decorative pieces that make the lamp
look unusual or like an animal (see Figure 2). Do 
not just copy the decorative pieces used in Figure 
2; invent your own pieces. For example, you might 
add a hat or make the ears more interesting, or 
add some hair, or horns, or a larger nose, or a 
different tail or a different base.
o Use simple objects for the individual parts, i.e. 
scaled spheres or cubes. For example, in Figure 2, 
the head is made from a combination of a cube for 
the lamp head and a cube for the bulb, with some 
other cubes and spheres for the decorations. 
Cubes and spheres are the only pieces needed to 
model the lamp. The hierarchy and associated 
transformations are more important than the 
quality of the pieces in the hierarchy. I want you to 
demonstrate that you understand transformations 
and a scene graph hierarchy. o The pieces of the lamp must be texture-mapped. 
For example, you might decide to make the pieces 
spotty to look like a particular animal. o The head of the lamp must include an object (e.g. 
a nose bulb), modelled as a cube or sphere, which 
mimics the effects of a spotlight. The object gives 
the position of the spotlight and the orientation of 
the head gives the direction the spotlight is 
pointing in. The spotlight will thus illuminate the 
scene in the direction the lamp head is pointing in. 
There must be an option in the interface to turn 
the spotlight (and associated object) on and off. 
(You are responsible for working out how to 
implement a spotlight effect – read the relevant 
section in Joey’s online tutorial.)
• The mini helicopter-like object can be made of a 
combination of spheres and/or cubes. The propellors 
must spin as the cube lifts off the desk, rises up and 
then descends back down to the tabletop. It should do 
this under menu control, e.g. a button to start and a 
button to stop. The body of the mini helicopter-like 
object should have separate matt and shiny parts. 
(Hint: diffuse and specular maps.)
• There should be a piece of paper and a pen (a scaled 
sphere will suffice) on the tabletop and a notice board 
on the wall above the desk. Exact sizes are not 
important.
• An outside scene can be seen through the window –
this might be a garden scene or a city scene. You could 
use a picture out of a window in your own 
accommodation or you could invent a picture. 
Consider how you might do the scene outside. Should 
it be a texture map pasted onto the wall to look like a 
window and a scene? Or should it be a texture map 
pasted onto another surface that is a certain distance 
outside the window? Figure 1 illustrates both (with the 
outside scene a bit too close to the wall due to the 
limitations of space for the illustration). How does each 
look when the camera moves position? Also, should 
the scene outside the window be the same at different 
Figure 2. A model of an angle-poise lamp
that looks like a strange alien animal
3
times in the day? Should the scene change for night 
and day? Another option might be a skybox outside the 
window. Note: If there is a hole in the wall, this will 
mean making the wall from a set of pieces with a hole 
where the window is. The quality of what you produce 
for this part of the scene will be part of the marking.
• The scene should be illuminated with at least two 
general world lights which can be positioned anywhere
in the world (perhaps with one in the general direction 
of the sun). It should be possible to turn each of the 
lights on and off (or dim, i.e. reduce the intensity) from 
the interface. These general world lights will illuminate 
all parts of the scene and help visualise the scene 
during development and testing. When you switch off 
the general light(s), the effects of the lamp spotlight 
will be much clearer on the table and the rest of the 
room. • A user-controlled camera should be positioned in the 
scene. Use the camera that was given in one of the 
exercise sheets – the mouse can be used to change the 
direction the camera is pointing in and the keys can be 
used to move about. Do not change the key mappings 
from the one on the exercise sheet. If you change the 
key mappings it will make it difficult for me to mark. It 
doesn’t matter that the camera can see outside the 
room.
• The interface should have a button (labelled ‘Random 
Pose’) to make the lamp parts adopt random angles to 
each other to make a pose. The angles between the 
parts of the lamp should be within certain ranges so 
that the result is plausible, i.e. just as you elbow cannot 
bend ‘backwards’, the lower and upper arm of the 
lamp should not be able to bend backwards with 
respect to each other. Also, the main lamp parts 
shouldn’t intersect each other or the table – don’t 
worry about the decorative parts of the lamp. Some of 
the decorative pieces might move in response to the 
pose adopted by the lamp. The lamp should animate 
between the poses rather than immediately assume 
the new pose. A reset button can be used to reposition 
the lamp to some neutral pose. Also, you should 
consider the speed of the animation. It is perfectly 
acceptable to animate the Euler angles to achieve 
movement of the hierarchy. Do not consider using 
quaternions, as this is beyond the requirements for 
this assignment.
• You do NOT have to do shadows. Do not worry about 
shadow effects.
4. Deliverables
• You should submit a zip file containing a copy of your 
program code (and any other necessary resources, e.g. 
image files for the textures and a readme.txt file that 
describes everything) via Blackboard – this can be done 
via the link to the assignment handout. You should 
submit whatever you have done, even if you have not 
completed all the requirements – for example, you 
might have produced a model but not done the 
animation. If you submit nothing, you cannot receive 
any marks. The program MUST compile and run from 
the command window on a Windows PC or the 
terminal window on a Mac. You should assume that 
the jogl environment (and paths) has already been set 
up, so you do not have to include this as part of what 
you hand in. I won’t install ‘YetAnotherIDE’ to make 
your program work; I want to run the program (and, if 
necessary, check the compilation) from a command or 
terminal window. • You must include appropriate comments in your 
program to identify that you wrote the code, e.g.
/* I declare that this code is my own work */
/* Author
address here> */
• You can make use of all the code that I have given you 
on exercise sheets. However, state that you have used 
it as part of your comments and briefly summarise
which bits you used. • The body of the Blackboard submission message 
should state that the work you have handed in is your 
own. 
• The name of the main class in your program should be 
Anilamp. That way it is easy for me to run the 
program. (Last year, I wasted time for some handins 
trying to work out which was the main class to run.) It 
would be useful to include a batch/script file to 
automatically compile and/or run the program.
• Optional: You might like to make a short video of your 
animation. If you do so, DO NOT include this in the 
handin as it will be too big for Blackboard to handle –
we tried using Blackboard for this in the past and it 
crashed the system!! Instead, put the animation on 
youtube or your personal website and give the URL of 
the animation in a readme.txt file. Indeed, if you are 
thinking of a career in the graphics industry, then you 
should be adding such animation pieces to your 
personal website (your digital portfolio) to show off 
what you are capable of.
5. Marking
I will check that the program meets the requirements 
listed above. To make sure you get some marks, the 
program must compile and do some part of the work 
requested even if it is not complete. Your program code 
will be run and exercised thoroughly.
Marks will be available for:
• The quality of the programming (20%)
• Satisfying the requirements (80%)
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In assessing the quality of your program code, four 
aspects will be considered:
• (5 marks) General style: layout; neat, organised code; 
comments; use of constants and variables; methods 
not over long;
• (5 marks) Program and data structures for the models: 
use of separate methods and classes, e.g. separate 
classes for things like the lamp; (The online tutorial 
does not make use of classes for the more complex 
examples, partly on purpose. You must consider the 
use of classes for the assignment – this demonstrates 
your programming ability and ability to work with 
scene graphs.)
• (5 marks) Neat and tidy coding for dealing with 
transformations in the scene; How will you organise 
the construction and use of the scene graphs?
• (5 marks) Animation/posing control: how tidy and 
flexible is the coding?
In considering the requirements, four aspects will be 
considered:
• (25 marks) Modelling the lamp and other parts of the 
scene: the lamp must be a hierarchical model. 
(Consider drawing scene graphs for the lamp model, 
the helicopter and the full scene before starting to 
program.)
• (20 marks) Texturing: lamp, room (walls and floor), 
poster board, table, objects on table and window. The 
quality of the texturing will be considered, e.g. use of 
diffuse and specular textures, seams between textures 
and any extra texturing effects such as the changing 
window view texture.
• (15 marks) Lighting and interface controls: lights
should behave correctly such that their effect is seen 
on the scene. Necessary interface controls, as 
described in the above specification, should also be 
included. • (20 marks) Lamp pose control and animation and mini
helicopter animation. Is the animation smooth? Does 
it look plausible? The quality of the animation will be 
considered. Are the random poses for the lamp
plausible?
6. Unfair means
• The Department’s student handbooks (UG and PGT) 
give detailed information on the topic of unfair means 
and what happens if unfair means is used.
7. Late handin
• Standard Department rules will be applied if the work 
is handed in late: UG and PGT.
Links to handbooks
UG: 
https://sites.google.com/sheffield.ac.uk/comughandboo
k/general-information/assessment
PGT: 
https://sites.google.com/sheffield.ac.uk/compgtstudent
handbook/menu/assessment
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