COM4503/6503: 3D Computer
Graphics: Assignment (27%)
Dr. Steve Maddock
Deadline: 3pm, Wednesday 5 December
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 a hierarchical model.
2. The task
Figure 1 shows a model of a large, human-sized, angle-
poise lamp, which is decorated to look like an animal. This
is made up of 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). The lower arm can rotate about
the base, the upper arm can rotate about the lower arm
and the head can rotate about the upper arm. The
lightbulb shines in the same direction that the head is
pointing in, as indicated by the dotted lines in Figure 1.
Imagine the lamp is standing on a tabletop in a room
looking out of a window. The lamp can also jump around
the tabletop. A company is using this lamp in an
advertising campaign in which they hope to sell more
interesting angle-poise lamps. Your challenge is to create
this scenario.
You must satisfy all the following requirements:
Produce a hierarchical model of an angle-poise lamp,
made up of the four basic parts (and the lightbulb)
listed above and some decorative pieces that make it
look unusual. Do not just copy the decorative pieces
used in Figure 1; 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. Use simple objects for
the individual parts, i.e. scaled spheres or cubes. For
example, in Figure 1, 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.
The pieces of the lamp must be texture-mapped. For
example, you might decide to make the pieces of the
lamp look like they are made of wood or brick or
whatever, perhaps with shiny reflective markings.
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 lamp should be placed on a tabletop, with the
table under a window in a wall (Figure 2).
Only one wall and a floor for the room should be
modelled. The wall and floor should be texture
mapped to look like a room in a house. For example,
the floor could be made of wood. The wall may have
wallpaper on it.
The table can be modelled as one scaled flat cube on
top of 4 legs made out of cubes. The table should be
texture-mapped, for example, to look like wood.
There should be three objects on the table top (not
including the lamp) that should each be textured.
Example objects might include: a mobile phone (cube
with relevant textures), a picture frame. (cube with
relevant textures), a paperweight (sphere with
relevant textures), a desk tidy (cube with relevant
textures and pens sticking out of the top), a cactus
plant (spheres with relevant textures), etc. The objects
should be made out of simple pieces, with textures
used to make them more interesting. There will be
some reward for inventiveness.
At least one of the objects on the tabletop should
demonstrate a combination of specular and diffuse
texture maps.
An outside scene can be seen through the window –
this might be a garden scene or a city scene. Consider
Figure 1. A model of an angle-poise lamp that
looks like a strange alien animal
2
how you might do the scene outside. Should it be a
texture map pasted onto the window, or should it be a
texture map pasted onto another surface that is a
certain distance outside the window? How does each
look when the camera moves position? You need to
use the right OpenGL settings to make sure the
textures display well. For extra marks, consider
switching between different window textures at
certain points in time to model a change outside the
room, e.g. daytime versus night-time or adding a
moving texture to the window view.
(Note: You will have to work out how to model the wall
with a hole in it for the window, and decide how big
the hole for the window should be.)
The scene should be illuminated with at least two
general world lights which can be positioned anywhere
in the world. It should be possible to turn 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 spotlight will be
much clearer on the table and the nearby wall.
A user-controlled camera should be positioned in the
room. 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.
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. Thus the
lower arm might rotate about the base and the upper
arm might rotate about the lower arm and the head
might rotate about the upper arm. Also, the tail might
rotate about the attachment point between the lower
and upper arms. 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.
The interface should have a button (labelled ‘Jump’) to
make the lamp jump from its current position to a new
random position nearby to its current position – the
lamp must remain on the table top. The lamp must
jump in a plausible way, e.g. be smooth and
bend/compress more for bigger jumps. How should
the decorations behave when the lamp jumps? You are
not being asked to physically model a jump, but to
provide a simple procedure with parameters that can
be used to give a variety of jumps. For example, a curve
could be used to control the height of the base of the
lamp off the tabletop and the angles between the parts
of the lamp could be animated using sine waves to
control the size of the angle to make it look like the
lamp is compressing and preparing before a jump.
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. Also, do not worry about the
decoration parts of the lamp intersecting with the wall,
table or with other parts of the lamp.
Each time the jump button is pressed, the lamp will
jump from its current position to a new position. The
new position will then become the current position.
Over time the lamp will move around the table top.
You do NOT have to do shadows. Do not worry about
shadow effects.
3. 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 MOLE – this can be done via
the link to the assignment handout. You should submit
whatever you have done, even if you have not
Figure 2: The lamp positioned on the tabletop – the table
could be much bigger to give the lamp room to jump
3
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 line on a standard Windows PC (such as
the ones in the Diamond). 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 the command
line on my Windows PC.
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 */
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 identify which bits
you used.
The body of the MOLE 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 an Anilamp.bat 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 MOLE to handle – we
tried using MOLE 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.
4. 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.
1 https://sites.google.com/sheffield.ac.uk/comughandbook-
201819/general-information/assessment/unfair-means
2
https://sites.google.com/sheffield.ac.uk/pgtstudenthandbook20
18-19/menu/assessment/unfair-means
Marks will be available for:
The quality of the programming (20%)
Satisfying the requirements (80%)
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 the room, table and l
(5 marks) Neat and tidy coding for dealing with
transformations in the scene;
(5 marks) Animation/posing control: how tidy and
flexible is the coding?
In considering the requirements, five aspects will be
considered:
(25 marks) Modelling the lamp and other parts of the
scene: the lamp must be a hierarchical model.
(Consider drawing a scene graph for the lamp model
and another for the full scene before starting to
program.)
(20 marks) Texturing: lamp, room (wall and floor),
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
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) Jumping lamp animation and pose control.
Is the animation smooth? Does it look plausible? The
quality of the animation will be considered. Are the
random poses plausible?
5. Unfair means
The Department’s student handbooks (UG1 and PGT2)
give detailed information on the topic of unfair means
and what happens if unfair means is used.
6. Late handin