Graphics 600,600,0
Global bullets:TList=New TList
Type bullet
Field x#,y#
Field vx#,vy#
Field path#[]
Function Create:bullet(x#,y#,vx#,vy#)
b:bullet=New bullet
bullets.addlast b
b.x=x
b.y=y
b.vx=vx
b.vy=vy
Return b
End Function
Method update()
path:+[x,y]
x:+vx
y:+vy
vy:+g
DrawRect x-5,y-5,10,10
For i=0 To Len(path)-1 Step 2
DrawRect path[i],path[i+1],1,1
Next
If x>600 Or y>600
bullets.remove Self
EndIf
End Method
End Type
'the setup is that you've got a cannon at (0,300), trying to fire at the mouse cursor.
'gravity is directed down the screen and the velocity of the projectiles is fixed at 20 px per frame.
'there will be some inaccuracy in the projectiles drawn on the screen because I'm using a discrete timestep model, due to I'm lazy.
Const g#=1,v#=20
While Not (KeyHit(KEY_ESCAPE) Or AppTerminate())
sx#=MouseX()
sy#=MouseY()-300
a#=g*sx*sx/(2*v*v) 'coefficients of the quadratic equation
b#=sx
c#=a-sy
If b*b>4*a*c 'if solution exists
t#=(-b+Sqr(b*b-4*a*c))/(2*a) 'this is tan(phi)
an#=ATan(t)
DrawLine 0,300,sx,sy+300
If MouseHit(1)
bullet.Create 0,300,v*Cos(an),v*Sin(an)
EndIf
Else
DrawText "no solution!",0,0
EndIf
For bu:bullet=EachIn bullets
bu.update
Next
Flip
Cls
Wend |
