Objectives

To practice function implementation, stack usage, and memory operations

Description

Create a program that draws a stick figure using the Bresenham line and circle algorithms. The pseudo$-$code for the algorithms is provided below. These drawing functions are interesting in the fact that they only use integer operations and do not require any fractional math.

In your main program, execute the following commands to draw a stick figure:

Circle$(30,100,20)$ #head

Line$(30,80,30,30)$ #body

Line$(20,1,30,30)$ #left leg

Line$(40,1,30,30)$ #right leg

Line$(15,60,30,50)$ #left arm

Line$(30,50,45,60)$ #right arm

Circle$(24,105,3)$ #left eye

Circle$(36,105,3)$ #right eye

Line$(25,90,35,90)$ #mouth center

Line$(25,90,20,95)$ #mouth left

Line$(35,90,40,95)$ #mouth right

Requirements

Enable the bitmap display under $$Tools$->$Bitmap Display$$

Click $$Connect to Program$$

Set the display width and height to $256$x$256$

Starting in the upper left, the display layout is row$-$by$-$row:

Address $0$x$10010000$ is row $0,$ column $0$

Address $0$x$10010004$ is row $0,$ column $1$

Address $0$x$10010008$ is row $0,$ column $2....$and so on

Each word holds a $3-$byte RGB value and you can make a pixel white with the value $0$xFFFFFF

All pixel values should be $0$xFFFFFF

Your code should have the following functions

plot

abs $-$ absolute value

circle

line

swap$()$ does not have to be a function

Your main should have calls to circle and line to draw the figure as listed above

If you need more space to hold local variables, you can store them on the stack

Static data should only be used for the graphics display

You do not need to handle invalid arguments to any of the functions

You may have additional files, but your main program should be contain in stick$\_$figure.asm.

For full credit, your stick figure must appear upright and not upside down.

The pseudocode for the line algorithm is:

def Line $($x$0,$ y$0,$ x$1,$ y$1)\{$

if abs$($y$1-$ y$0)>$ abs$($x$1-$ x$0)\{$

st $=1$

$\}$ else $\{$

st $=0$

$\}$

if st $==1\{$

swap$($x$0,$ y$0)$

swap$($x$1,$ y$1)$

$\}$

if x$0>$ x$1\{$

swap$($x$0,$ x$1)$

swap$($y$0,$ y$1)$

$\}$

deltax $=$ x$1-$ x$0$

deltay $=$ abs$($y$1-$ y$0)$

error $=0$

y $=$ y$0$

if y$0<$ y$1\{$

ystep $=1$

$\}$ else $\{$

ystep $=-1$

$\}$

for x from x$0$ to x$1\{//$include x$0$ and x$1$

if st $==1\{$

plot$($y$,$x$)$

$\}$ else $\{$

plot$($x$,$y$)$

$\}$

error $=$ error $+$ deltay

if $2*$error $>=$ deltax $\{$

y $=$ y $+$ ystep

error $=$ error $-$ deltax

$\}//$end if

$\}//$end for loop

$\}//$end function

The pseudocode for the circle algorithm is:

def Circle$($xc$,$ yc$,$ r$)\{//$xc $=$ center x coordinate, yc $=$ center y coordinate, r $=$ radius

x $=0$

y $=$ r

g $=3-2*$r

diagonalInc $=10-4*$r

rightInc $=6$

while x $<=$ y $\{$

plot $($xc$+$x$,$ yc$+$y$)//$plot the circle points

plot $($xc$+$x$,$ yc$-$y$)$

plot $($xc$-$x$,$ yc$+$y$)$

plot $($xc$-$x$,$ yc$-$y$)$

plot $($xc$+$y$,$ yc$+$x$)$

plot $($xc$+$y$,$ yc$-$x$)$

plot $($xc$-$y$,$ yc$+$x$)$

plot $($xc$-$y$,$ yc$-$x$)$

if g $>=0\{$

g $+=$ diagonalInc

diagonalInc $+=8$

y $-=1$

$\}$ else $\{$

g $+=$ rightInc

diagonalInc $+=4$

$\}$

rightInc $+=4$

x $+=1$

$\}//$end while loop

$\}//$end function