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Category: Basic 2D

Version: 1.0

Information

Uploaded: 9th Oct 2003 01:56

Modified: 1st Jan 1970 01:00

Author: Easily Confused

Summary

A function for drawing an ellipse at any angle

Full Description

This is my first posting in the CodeBase so forgive me if this is not a mind blowing piece of code :)<br /> <br /> So, for anyone who needs it, here is the ability to draw angled ellipses. The function parameters should be self explanatory. Although written in DBPro this might work in DBClassic with little or no alteration.

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

` ########################################################################

` ###  RotateEllipse by I.M.L. Oct 2003  (aka Easily Confused)         ###

` ###  ...and no, I'm not telling you what I.M.L means :)              ###

` ########################################################################

` This is a demonstration of the function below, This is about as fast I

` can make it go. On my humble AMD 650, GForce 2MX I can draw an ellipse

` with 360 sides in about 1/50th of a second.

sync on : sync rate 50

xr = 50

yr = 100

sd = 360

cls

mx = mousex() : my = mousey()

xd = mx - 320 : yd = my - 240

mouseangle# = 180.0 - atanfull(xd,yd)

if mouseclick() = 1 then xr = sqrt((xd*xd)+(yd*yd))

if mouseclick() = 2 then yr = sqrt((xd*xd)+(yd*yd))

if upkey() or downkey()

if upkey() and (sd < 360) then sd = sd + 5

if downkey() and (sd > 5) then sd = sd - 5

` 1/10th of a sec delay

t = timer() + 100

repeat : until timer() >= t

endif

tim = timer()

RotateEllipse(320,240,xr,yr,mouseangle#,sd)

tim = timer()-tim

text 0,0, "X radius (left button) : " + str$(xr)

text 0,16,"Y radius (right button): " + str$(yr)

text 0,32,"Rotation (move mouse)  : " + str$(mouseangle#)

text 0,48,"Sides (up & down keys) : " + str$(sd)

text 0,64,"Draw Time: " + str$(tim) + "/1000th sec"

sync

loop

` ------------------------------------------------------------------------

function RotateEllipse(centerx#,centery#,xradius#,yradius#,rotation#,sides)

st# = 360.0 / abs(sides)

a# = 0.0

for s = 0 to sides

` first calculate point without rotation

px# = xradius# * sin(a#)

py# = yradius# * cos(a#)

` now rotate the point

ang# = (180.0 - atanfull(px#,py#)) - rotation#

ra# = sqrt((px#*px#) + (py#*py#))

px# = ra# * sin(ang#) + centerx#

py# = ra# * cos(ang#) + centery#

` draw

if s > 0 then line lastpx#,lastpy#,px#,py#

lastpx# = px# : lastpy# = py#

a# = a# + st#

endfunction

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CodeBase - RotateEllipse