Scratch

...imo, it's not clear enough.
especially...
" the script would make it point in a 45 degree angle, and point accordingly to other values the x and y velocities may give."

Ohhhhh.

IDK atm, I'll try and think about it...

HOLD UP LOL
SLOPE



Do you know slope?

You know, you could have this long complicated formula with trig or a long complicated formula with if-then and slope.
Take a pick.

1. We can easily discover the 45, 135, 225 (-135), and 315 (-45) degree.

[if <x pos - y pos = 0>]
[if x > 0 and y > 0]
[set direction to 135]
[/if]
[if x > 0 and <not y > 0>>]
[set direction to 45] 
[/if]
[if <not <x > 0 and y > 0>>]
[set direction to -135]
[/if]
[if <not <x > 0>> and <y > 0>]
[set direction to -45]
[/if]
[/if]

That's for now.
I'ma do the rest soon.

Last edited by bbbeb (2011-10-03 19:47:58)

^^ Precisely. Give me a minute to get pen and paper and I'll give you the answer 

ok, i'm not sure, but using arctan(hspeed/vspeed) should help. try add 90/180/270 degrees if its not working, or switch hspeed with vspeed. i don't have scratch at the moment so i can't check it

i think this should be in all about scratch.

zxz1661 wrote:

ok thanks for all the help guya! didn't know you could get this much math help in the scratch forums    ill test it out

EDIT: i noticed, as you said, it gets very messed up in the 'lower hemishpere'...which i cant find a workaround for...

I've found a way:

if <(y position) > [0]>
 point in direction ([atan v] of (([0] - (x position)) / ([0] - (y position))))
else
 point in direction ([0] - ([atan v] of (([0] - (x position)) / ([0] - (y position)))))

Last edited by Splodgey (2012-03-10 05:53:19)

aw man. I love trig. I wish saw this earlier!

Trigo for curves...

It like you want what is commonly known as the atan2 function. It's like atan(y/x) but it accepts x and y individually. Normal atan wouldn't work because the it gets messed up in the lower hemisphere. You could use the standard definition, which would be complicated to program, or you could use:

and define a special case for when x=0. (Remember to swap x and y, as rotation in Scratch is different than in math) This is my preferred method, as it's relatively smaller. It's probably a bit slower, but Scratch is slow anyway, so there's not much difference there.

Last edited by floppy_gunk (2011-12-12 03:09:30)

MoreGamesNow wrote:

Err... I hate to sound ignorant, but isn't it just this:

Code:

if( Yvelocity > 0 )
{
     point in direction ( atain (Yvelocity / Xvelocity) )
}
else
{
     if()
     {
          point in direction ( atan (Yvelocity / Xvelocity) + 180 )
     }
     else
     {
          point in direction ( abs of (Xvelocity / Xvelocity) * 90)
     }
}

Um.. I thought it was

if <(y position) > [0]>
 point in direction ([atan v] of (([0] - (x position)) / ([0] - (y position))))
else
 point in direction ([0] - ([atan v] of (([0] - (x position)) / ([0] - (y position)))))