iB::Topic::some math help please?

	Damn Small Linux :: Damn Small Linux Board The DSL Forums

» Welcome Guest
[ Log In :: Register ]

Damn Small Linux Board » Non-DSL Topics » Programming and Scripting » some math help please?

		Mini-ITX Boards Sale, Fanless BareBones Mini-ITX, Bootable 1G DSL USBs, 533MHz Fanless PC <-- SALE $200 each!
		Get The Official Damn Small Linux Book. DSL Market , Great VPS hosting provided by Tektonic

Pages: (3) </ 1 [2] 3 >/

[ Track this topic :: Email this topic :: Print this topic ]

Topic: some math help please?

< Next Oldest | Next Newest >

mikshaw

Group: Members
Posts: 4856
Joined: July 2004

Posted: Jan. 23 2008,20:03

Quote

since you're taking the squares of the distance, you don't need to take the absolute values of each component

I didn't know that. Thanks.
EDIT: seems like it is needed after a quick test

Quote

Also, it seems that there is always a gravity point at the top left corner (0,0)?

I'd seen that in other tests as well. Since I don't know real math, I just ignored that. I think I've got that fixed, though, as well as the problem with all objects always moving at 45 degree angles.

I messed around with the numbers for a while and came up with something else I like. So far I see one problem with it, that the objects gravitate toward a single x,y intersection over time if you don't move the mouse.

Code Sample

balls=1500
bsize=2
min_grav=0
max_grav=6

function grav_loop()
local my_x,bx=Fl:event_x(),0
local my_y,by=Fl:event_y(),0
local c=math.random(1,255) -- random color
for i=1,balls do
local xdistance=math.abs(my_x-ball[i]:x())
local ydistance=math.abs(my_y-ball[i]:y())
local distance=math.sqrt(xdistance*xdistance+ydistance*ydistance)
local xspeed=(min_grav+max_grav)/distance*xdistance
local yspeed=(min_grav+max_grav)/distance*ydistance
if distance <= 25 then -- warp it offscreen
ball[i]:color(c)
xspeed=xspeed*max_x/distance*math.random(2,3)
yspeed=yspeed*max_y/distance*math.random(2,3)
end
if my_x > ball[i]:x() then bx=ball[i]:x()+xspeed else bx=ball[i]:x()-xspeed end
if my_y > ball[i]:y() then by=ball[i]:y()+yspeed else by=ball[i]:y()-yspeed end
ball[i]:position(bx,by)
end
w:redraw()
grav_timer:doWait(.05)
end

w=fltk:Fl_Double_Window(Fl:w(),Fl:h(),"gravity test")
w:color(0)

math.randomseed(os.time())
max_x=w:w()-bsize
max_y=w:h()-bsize
ball={}
for i=1,balls do
ball[i]=fltk:Fl_Box(math.random(1,max_x),math.random(1,max_y),bsize,bsize)
ball[i]:box(fltk.FL_FLAT_BOX)
end

grav_timer = murgaLua.createFltkTimer()
grav_timer:callback(grav_loop)
grav_timer:do_callback()

w:fullscreen()
w:show()
Fl:run()

EDIT: fixed a typo

--------------
http://www.tldp.org/LDP/intro-linux/html/index.html

curaga

Group: Members
Posts: 2163
Joined: Feb. 2007

Posted: Jan. 23 2008,20:20

Quote

I messed around with the numbers for a while and came up with something else I like. So far I see one problem with it, that the objects gravitate toward a single x,y intersection over time if you don't move the mouse.

If you could decide that point, it could be desired behavior. I suggest setting it to the center of the display.

--------------
There's no such thing as life. Those mean little jocks invented it ;)
-
Windows is not a virus. A virus does something!

mikshaw

Group: Members
Posts: 4856
Joined: July 2004

Posted: Jan. 23 2008,20:25

That wouldn't be very useful, though, If this turns into something I might want to use as a screensaver. When I say an intersection, I mean all objects gravitate to travelling along either a single x coordinate or a single y coordinate, so what you have on screen is essentially just two lines that intersect at the location of the cursor.

--------------
http://www.tldp.org/LDP/intro-linux/html/index.html

^thehatsrule^ Offline

Group: Members
Posts: 3275
Joined: July 2006

Posted: Jan. 23 2008,20:37

Quote (mikshaw @ Jan. 23 2008,15:03)

Quote

since you're taking the squares of the distance, you don't need to take the absolute values of each component

I didn't know that. Thanks.
EDIT: seems like it is needed after a quick test

That was just for your first one where you only used the direct distance.

Your 2nd one is looking better too - but seeing the same problems that you have described.

Took at look at your 2nd one... not sure if you already have something like this:

Code Sample

-- snip
local yspeed=(min_grav+max_grav)/distance*ydistance
-- cut out if statement
if my_x > ball[i]:x() then bx=ball[i]:x()+xspeed else bx=ball[i]:x()-xspeed end
if my_y > ball[i]:y() then by=ball[i]:y()+yspeed else by=ball[i]:y()-yspeed end
-- add back warp
if distance <= 25 then -- warp it
ball[i]:color(b)
bx = math.random(1,max_x)
by = math.random(1,max_y)
end
-- /snip

This doesn't make the new dots offscreen though... did you want to specifically do that?

mikshaw

Group: Members
Posts: 4856
Joined: July 2004

Posted: Jan. 23 2008,20:59

Quote

This doesn't make the new dots offscreen though... did you want to specifically do that?

Yeah, It pretty much just shoots them forward a ways, but I don't really understand how much. It looks like somewher between halfway across the screen to waaay outside the screen. I'm working on a different method now that should place them just offscreen and also hopefully cut down on the processing a little.

--------------
http://www.tldp.org/LDP/intro-linux/html/index.html

13 replies since Jan. 23 2008,00:42

< Next Oldest | Next Newest >

[ Track this topic :: Email this topic :: Print this topic ]

Pages: (3) </ 1 [2] 3 >/

Damn Small Linux Board » Non-DSL Topics » Programming and Scripting » some math help please?