Hello!
As you can probably understand from the title, asking this here is my last resort. (Ok maybe not my absolutely last resort Razz )
What I need to do is rotate a point P around another point O. What i've used this far is the standard formula of:
x' = cos(θ) * (xP - xO) - sin(θ) * (yP - yO) + xO

y' = sin(θ) * (xP - xO) + cos(θ) * (yP - yO) + yO

But this obviously doesn't work because Ice doesn't support negative numbers. I've been banging my head against my table for the past 2 days trying to figure out a fix but haven't been able to come up with a formula that works.

Also sorry if there are any formatting errors in this post as this is my first post on this forum!
Thank you in advance! Smile
I had this problem too, here is how I did it:
note: Ice only crashes by dividing negative numbers; the cos numbers has a radius of 255 (because only integer) and it has only 256 instead of 360
L is the length
n is the NEW number
A is the Angle

cos(A) * L / 255 (rule of three)
= (255 + cos(A)) * L / 255 - L
now cos is between 0 and 510 (not between -255 and 255)


for your therm this means:
(255+cos(A))→C
(255+sin(A))→S

C * (Xp - Xo) / 255 - (Xp - Xo)
//now it would work if Xp -Xo ≥ 0, so you have to write it a bit different
C * Xp / 255 - C * Xo / 255 - (Xp - Xo)


in fact:
(255+cos(A))→C
(255+sin(A))→S
(
C * Xp / 255 - C * Xo / 255 -Xp + Xo) - (S * Yp / 255 - S * Yo / 255 -Yp + Yo) + Xo→Xn
(S * Xp / 255 - S * Xo / 255 -Xp + Xo) + (C * Yp / 255 - C * Yo / 255 -Yp + Yo) + Yo→Yn





Thats a bit long, so You could write:
9000→Q (Q is only a huge number and higher than Xp-Xo and Yp-Yo)
(C * (Q + Xp - Xo) / 255 - (Q + Xp - Xo) ) ....


The 2nd variant:
9000→Q (Xp + Xo + Q must be greater than 0)
(255+cos(A))→C
(255+sin(A))→S
Q + Xp - Xo→dX (d instead of delta)
Q + Yp - Yo→dY

C * Q / 255 -Q→CQ (later you subtract CQ (cosQ) because you added it to dX)
S * Q / 255 -Q→SQ


(C * dX / 255 - dX - CQ) - (S * dY / 255 -dY - SQ) +Xo→Xn
(S * dX / 255 - dX - SQ) + (C * dY / 255 -dY - CQ) +Yo→Yn



I hope this can help you Cool
on my Calculator it worekd.
  
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