[Code Snippet] Rotation à partir d'une origine

set display mode desktop width(),desktop height(),32,0
sync on

Type Tsquare
x1 as float
y1 as float
x2 as float
y2 as float
x3 as float
y3 as float
x4 as float
y4 as float
EndType

square as Tsquare
square.x1=screen width()/2-50
square.y1=screen height()/2-50
square.x2=screen width()/2+50
square.y2=screen height()/2-50
square.x3=screen width()/2+50
square.y3=screen height()/2+50
square.x4=screen width()/2-50
square.y4=screen height()/2+50

Global newx as float : Global newy as float : angle as integer

ox as integer
oy as integer

do

   cls

   rem l'origine de la rotation est le curseur de la souris
   ox=mousex()
   oy=mousey()

   rem control de la rotation avec les clic de souris
   angle=0
   if mouseclick()=1 : angle=1 : endif
   if mouseclick()=2 : angle=-1 : endif

   rem on récupere la nouvelle position modifiée par l'angle(angle) et l'origine(ox,oy) 
   rem pour chaque sommets du carré
   rotation_par_origine(ox,oy,square.x1,square.y1,angle) : square.x1=newx : square.y1=newy
   rotation_par_origine(ox,oy,square.x2,square.y2,angle) : square.x2=newx : square.y2=newy
   rotation_par_origine(ox,oy,square.x3,square.y3,angle) : square.x3=newx : square.y3=newy
   rotation_par_origine(ox,oy,square.x4,square.y4,angle) : square.x4=newx : square.y4=newy

   rem affichage du carré
   line square.x1,square.y1,square.x2,square.y2
   line square.x2,square.y2,square.x3,square.y3
   line square.x3,square.y3,square.x4,square.y4
   line square.x4,square.y4,square.x1,square.y1

   sync

loop

rem rotation à partir d'une origine
function rotation_par_origine(ox as float,oy as float,x as float,y as float,angle as integer)
x=x-ox : y=y-oy
newx=ox+x*cos(angle)-y*sin(angle)
newy=oy+x*sin(angle)+y*cos(angle)
endfunction