Import mojo

Extern
	Function realTime()="(new Date()).getTime"
Public

Function DrawArrow(x1#,y1#,x2#,y2#,l#=5)
	Local an#=ATan2(y2-y1,x2-x1)
	DrawLine x1,y1,x2,y2
	Local mx#=(x1+x2)/2, my#=(y1+y2)/2
	DrawLine mx,my,mx+Cos(an+150)*l,my+Sin(an+150)*l
	DrawLine mx,my,mx+Cos(an-150)*l,my+Sin(an-150)*l
End

'returns True if p1 and p2 are on the same side of the line a->b
Function sameside:Bool(p1x#,p1y#,p2x#,p2y#,ax#,ay#,bx#,by#)
	Return ((bx-ax)*(p1y-ay)-(p1x-ax)*(by-ay))*((bx-ax)*(p2y-ay)-(p2x-ax)*(by-ay)) >= 0
End Function	


Class World
	Field width#,height#
	Field flipTop:Bool=True, flipSide:Bool=True
	Field things:List<Thing>
	
	Method New(_width#,_height#)
		width=_width
		height=_height
		things = New List<Thing>
	End
	
	Method Update()
		Local t:Thing
		
		For t=Eachin things
			t.Update
		Next
		
		For t=Eachin things
			While t.x<-width/2
				t.x+=width
				If flipSide
					t.y=-t.y
					t.vy=-t.vy
					t.an=-t.an
					t.van=-t.van
					t.flip=-t.flip
				Endif
			Wend
			While t.x>width/2
				t.x-=width
				If flipSide
					t.y=-t.y
					t.vy=-t.vy
					t.an=-t.an
					t.van=-t.van
					t.flip=-t.flip
				Endif
			Wend
			While t.y<-height/2
				t.y+=height
				If flipTop
					t.x=-t.x
					t.vx=-t.vx
					t.an=180-t.an
					t.van=-t.van
					t.flip=-t.flip
				Endif
			Wend
			While t.y>height/2
				t.y-=height
				If flipTop
					t.x=-t.x
					t.vx=-t.vx
					t.an=180-t.an
					t.van=-t.van
					t.flip=-t.flip
				Endif
			Wend
		Next
	End
	
	Method geodesic#[](t1:Thing,t2:Thing)
		Return geodesic(t1.x,t1.y,t2.x,t2.y)
	End
	
	Method geodesic#[](x1#,y1#,x2#,y2#)
		Local x3#,y3#,x4#,y4#
		Local mx#,my#,mdx#,mdy#
		
		'top or bottom
		If flipTop Then x3 = -x2 Else x3=x2
		y3 = y2-Sgn(y2)*height
		
		'left or right
		x4 = x2-Sgn(x2)*width
		If flipSide Then y4 = -y2 Else y4=y2

		mx=(x3+x2)/2
		my=(y3+y2)/2
		mdx=Sgn(y2)
		mdy=-Sgn(y2)*(x3-x2)/(y3-y2)
		
		'decide between real and top/bottom
		If sameside(x1,y1,x2,y2,mx,my,mx+mdx,my+mdy)
			'real point
			'so decide between real and left/right
			mx=(x4+x2)/2
			my=(y4+y2)/2
			mdx = -Sgn(x2)*(y4-y2)/(x4-x2)
			mdy = Sgn(x2)
			
			If sameside(x1,y1,x2,y2,mx,my,mx+mdx,my+mdy)
				'real point
				Return [x2-x1,y2-y1]
			Else
				'left/right point
				Return [x4-x1,y4-y1]
			Endif
		Else
			'top/bottom point
			'so decide between top/bottom and left/right
			mx = (x4+x3)/2
			my = (y4+y3)/2
			mdx = -(y4-y3)/(x4-x3)
			mdy = 1
			
			If sameside(x1,y1,x3,y3,mx,my,mx+mdx,my+mdy)
				'top/bottom point
				Return [x3-x1,y3-y1]
			Else
				'left/right point
				Return [x4-x1,y4-y1]
			Endif
		Endif
		
	End
	
	Method Draw()
		Local fx,fy
		If flipTop fx=-1 Else fx=1
		If flipSide fy=-1 Else fy=1
		
		'normal view in centre
		PushMatrix
			DrawAll
		PopMatrix
		
		'flipped vertically on sides
		PushMatrix
			Scale 1,fy
			Translate -width,0
			DrawAll
			Translate 2*width,0
			DrawAll
		PopMatrix
		
		'flipped horizontally on top and bottom
		PushMatrix
			Scale fx,1
			Translate 0,-height
			DrawAll
			Translate 0,2*height
			DrawAll
		PopMatrix
		
		'flipped both ways on corners
		PushMatrix
			Scale fx,fy
			Translate width,height
			DrawAll
			Translate -2*width,0
			DrawAll
			Translate 0,-2*height
			DrawAll
			Translate 2*width,0
			DrawAll
		PopMatrix
	End
	
	Method DrawAll()
		SetColor 100,100,100
		If flipTop
			DrawArrow width/2,-height/2,-width/2,-height/2,15
		Else
			DrawArrow -width/2,-height/2,width/2,-height/2,15
		Endif
		If flipSide
			DrawArrow -width/2,height/2,-width/2,-height/2,15
		Else
			DrawArrow -width/2,-height/2,-width/2,height/2,15
		Endif
		DrawArrow width/2,-height/2,width/2,height/2,15
		DrawArrow -width/2,height/2,width/2,height/2,15
		
		For Local t:=Eachin things
			PushMatrix
				Translate t.x,t.y
				Rotate -t.an
				Scale 1,t.flip
				t.Draw
			PopMatrix
		Next
	End
End

Class Thing
	Field world:World
	Field an#,van#
	Field vx#,vy#
	Field x#,y#
	Field flip=1
	
	Method New(_world:World)
		world=_world
		world.things.AddLast Self
	End
	
	Method Update()
	End
	
	Method Draw() Abstract
End

Class Target Extends Thing
	Method New(_world:World)
		Super.New(_world)
	End

	Method Draw()
		SetColor 255,0,0
		DrawLine -3,-3,3,3
		DrawLine 3,-3,-3,3
	End
End

Class Ship Extends Thing
	Field target:Thing

	Method New(_world:World)
		Super.New(_world)
	End
	
	Method Update()
		x+=vx
		y+=vy
		vx*=.99
		vy*=.99
		
		Local diff#[] = world.geodesic(Self,target)
		Local dx#,dy#,d#
		dx=diff[0]
		dy=diff[1]
		d=Sqrt(dx*dx+dy*dy)
		Local wan# = (ATan2(dy,dx)-an) Mod 360
		If wan<-180 wan+=360
		If wan>180 wan-=360
		If Abs(wan)>3
			wan=3*Sgn(wan)
		Endif
		
		'If TouchDown(0)
			an+=wan

			vx += Cos(an)*.1
			vy += Sin(an)*.1
		'Endif
	End

	Method Draw()
		SetColor 255,255,255
		SetAlpha .1
		DrawCircle 0,0,20
		SetAlpha 1
		DrawPoly([6.0,0.0,-3.0,3.0,0.0,0.0,-3.0,-3.0])
	End
End

Class Asteroid Extends Thing
	Field poly#[]
	Method New(_world:World)
		Super.New(_world)

		x=Rnd(-.5,.5)*world.width
		y=Rnd(-.5,.5)*world.height
		vx=Rnd(-1,1)
		vy=Rnd(-1,1)
		van=Rnd(-3,3)

		
		Local n=Rnd(6,10)
		Local r#[n]
		For Local i=0 To n-1
			r[i]=Rnd(10,20)
		Next
		poly=New Float[n*2]
		For Local i=0 To n-1
			poly[i*2]=Cos(i*360/n)*r[i]
			poly[i*2+1]=Sin(i*360/n)*r[i]
		Next
	End Method
	
	Method Update()
		x+=vx
		y+=vy
		an=(an+van) Mod 360
	End
	
	Method Draw()
		SetColor 255,0,0
		DrawPoly poly
		SetColor 0,0,0
		Scale .95,.95
		DrawPoly poly
	End
End

Class AsteroidApp Extends App
	Field screenMatrix#[]
	Field mx#,my#
	
	Field world:World
	Field dude:Ship,target:Target
	
	Field scale#=.9
	Field x1#,y1#

	Method OnCreate()
		Seed = realTime()
		SetUpdateRate 60
		
		world = New World(DeviceWidth,DeviceHeight)
		target=New Target(world)
		dude = New Ship(world)
		dude.target = target
	End
	
	Method OnUpdate()
		PushMatrix
			Translate DeviceWidth/2,DeviceHeight/2
			Local s#
			If DeviceWidth/world.width>DeviceHeight/world.height
				s=scale*DeviceHeight/world.height
			Else
				s=scale*DeviceWidth/world.width
			Endif
			Scale s,s
			screenMatrix = GetMatrix()
			Local mouse#[]=InvTransform([MouseX(),MouseY()])
			mx=mouse[0]
			my=mouse[1]
		
		PopMatrix
		
		target.x=mx
		target.y=my
		
		scale += (KeyDown(KEY_UP)-KeyDown(KEY_DOWN))*.05
		
		If KeyHit(KEY_T)
			world.flipTop = Not world.flipTop
		Endif
		If KeyHit(KEY_L)
			world.flipSide = Not world.flipSide
		Endif
		
		If TouchHit(0)
			New Asteroid(world)
		Endif
		
		world.Update
	End
	
	Method OnRender()
		Cls

		SetColor 255,255,255
		
		PushMatrix
			SetMatrix screenMatrix
		
			world.Draw
		PopMatrix
		
		DrawText MouseX(),0,60
		DrawText MouseY(),0,75
		
		SetColor 255,255,255
		DrawText "Press T to change top/bottom flip.",0,0
		DrawText "Press L to change left/right side flip",0,15
		DrawText "Press up or down to zoom",0,30
		
	End
End

Function Main()
	New AsteroidApp
End