Computer Graphics with Matlab - Lecture`s of computer graphics

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COMPUTER GRAPHICS WITH
MATLAB
COMPUTER GRAPHICS
MATLAB
MATrix LABoratory
•Designed for matrix manipulations and operations
•Numerical computing environment
•Plotting of functions and data
•Algorithm implementation
•User interfaces
•Rapid prototyping, with toolboxes
WHY MATLAB?
•Ease of use
•Platform independence
•Predefined functions
•Device-independent plotting
•Graphical user interface
•MATLAB compiler
MATLAB BASICS
Fundamental unit of data in MATLAB is array
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Array–collection of data values organized into rows and columns
MATLAB environment
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Command window
Command history window
Edit/Debug window
Figure window
Workspace browser/Variable editor
Help browser
Current directory browser
Work directory
MATLAB PLOTTING
• MATLAB has extensive device-independent plotting
capabilities
• Very simple and easy to plot data
x=0:1:10;
y=x.^2-10.*x+15;
plot(x,y);
GETTING ACCUSTOMED TO MATLAB
Open matlab and see following features on matlab desktop
Current folder : access your files
Command window: Enter commands at the command line
indicated by prompt (>>)
WorkSpace: explore data that you create or export files from
Command History: view or rerun commands
GETTING STARTED WITH MATLAB
Type clc in command window, now matlab is ready to be used
Create variables;
a=1
b= 2
c= a+b
d= sin(b)
e= a*b;
GETTING STARTED WITH MATLAB
Semicolon (;) suppress the display of output in command
window
Do not use same variable symbol twice in the same matlab
session!
Use clear command to clear workspace variables
GETTING STARTED WITH MATLAB
Array Creation:
f=[1 2 3 4]
Use space or comma (,) to separate elements of an array
• to create a matrix having multiple rows and columns use
semicolon (;)
g=[1 2 3; 4 5 6; 7 8 9]
Create a matrix having 5 rows and 6 columns?
GETTING STARTED WITH MATLAB
Try these commands
h= g+10
 g*5
Sin(g)
To transpose a matrix use single quote (‘)
e.g.
g’
GETTING STARTED WITH MATLAB
Complex numbers in matlab
Complex numbers have both real and imaginary part
 sqrt(-1)
ans=
0.0000 + 1.0000i
To represent imaginary part of the complex number, use either I
or j
m= [3+4i 1+2j; -5i 7+8j]
GETTING STARTED WITH MATLAB
Use whos to check workspace variables
w h o s
GETTING STARTED WITH MATLAB
Character strings
mytext= ‘Hello World’
To c o n v e r t n u m e r i c v a l u e s t o s t r i n g s u s e n u m 2 s t r
or int2str
u=71;
v= (n-32)/1.8;
t e m p t e x t = [ ‘ Te m p e r a t u r e i s ’ n u m 2 s t r ( v ) , ‘ v ’ ]
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
Hint* Assign
variables
and compute
these terms
GETTING STARTED WITH MATLAB
2D and 3D plots:
Line Function:
To create two dimensional graph use plot function.
Use label and title
GETTING STARTED WITH MATLAB
LEGENDS
xlabel(‘x’)
ylabel(‘sin(y)’)
title(‘graph of sine function’)
LINE STYLE, MARKER STYLE, COLOR
Using a third input argument, plot function with red dash line type.
plot(x,y, ’r - -’)
The ‘ r- -’ string is a line specification. Each specification can
include characters for the line color, and marker style. A marker
style that appears at each plotted data point such as a +, o, *
For example, ‘g:* ’ requests a dotted plot with * markers
GETTING STARTED WITH MATLAB
ADD PLOTS ON AN EXISTING GRAPH
Use hold on command
To plot legends on the same
Graph.
GETTING STARTED WITH MATLAB
PLOTTING - MULTIPLE PLOTS
PLOTTING - MULTIPLE PLOTS
The first two inputs to the subplot indicates the number of
rows and columns and the third input specifies which plot
is active
GETTING STARTED WITH MATLAB
3D plots:
Three dimensional plots typically display a surface defined by
a function in two variables,
Z= f(x,y)
To evaluate z, first creat a set of (x,y) points over the domain
of the function using meshgrid
GETTING STARTED WITH MATLAB
[x,y] = meshgrid(-2: .2: 2);
Z= x.*exp(-x.^2 – y.^2);
Surf(x,y,z)
GETTING STARTED WITH MATLAB
[x,y] = cylinder(-2: .2: 2);
Z= x.*exp(-x.^2 – y.^2);
Surf(x,y,z)
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB
GETTING STARTED WITH MATLAB

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