Realtime raytraced shadows: mission impossible?

have u managed multi lights?

i have managed it a bit, but the spheres arent shadowed very much,...why??

Include "Raytracer.bb"

Graphics 640, 480, 32, 2
SetBuffer BackBuffer()
SeedRnd MilliSecs()

;Raytracer
InitRaytracer()
SetCameraPosition(0, -25, -130)
SetAmbientLight(255)
CreateScene()

;Loadscreen
SetFont LoadFont("Arial", GraphicsHeight() / 5, True, False, False)
Text GraphicsWidth() / 2, GraphicsHeight() / 2, "Please wait...", True, True
Flip

;Render
Raytrace()
Flip
WaitKey()
End

Function CreateScene()
AddEntity("Light", 50, 1000, 800)                 ;Light1
AddEntity("Light", -200, 200, 400)                ;Light2
AddEntity("Plane", 1, 100, $857830)               ;Floor
AddEntity("Sphere", 100, 10, 200, 100, $FF0000)   ;Red ball
AddEntity("Sphere", -100, -80, 385, 100, $00FF00) ;Green ball
AddEntity("Sphere", 0, -50, 510, 100, $0000FF)    ;Blue ball
End Function

Type Light
	Field x#, y#, z#
End Type
Type Plane
	Field nx#, ny#, nz#
	Field dis#
	Field argb
End Type
Type Sphere
	Field x#, y#, z#
	Field rad#
	Field argb
End Type
Dim normalx#(-1, -1)
Dim normaly#(-1, -1)
Dim normalz#(-1, -1)
Global camerax#, cameray#, cameraz#
Global ambientcol

Function InitRaytracer()
w = GraphicsWidth()
h = GraphicsHeight()
Dim normalx#(w, h)
Dim normaly#(w, h)
Dim normalz#(w, h)
SetupNormals()
End Function

Function Raytrace()
Cls
LockBuffer()
width = GraphicsWidth()
height = GraphicsHeight()
For y = 0 To height - 1
	For x = 0 To width - 1
		rgb = SendRay(camerax#, cameray#, cameraz#, normalx#(x, y), normaly#(x, y), normalz#(x, y), ambientcol)
		If rgb <> $000000 Then WritePixelFast x, y, rgb, BackBuffer()
	Next
Next
UnlockBuffer()
End Function

Function SendRay(ex#, ey#, ez#, evx#, evy#, evz#, c = 255, recursive_times = 4)
If recursive_times < 0 Then Return
z# = 10000
l.Light = First Light
For p.Plane = Each Plane
	nx# = p\nx#
	ny# = p\ny#
	nz# = p\nz#
	dis# = nx# * evx# + ny# * evy# + nz# * evz#
	If dis# < 0 Then
		dis2# = -(p\dis# + nx# * ex# + ny# * ey# + nz# * ez#) / dis#
		ix# = ex# + evx# * dis2#
		iy# = ey# + evy# * dis2#
		iz# = ez# + evz# * dis2#
		lvx# = l\x# - ix#
		lvy# = l\y# - iy#
		lvz# = l\z# - iz#
		dis# = Sqr(lvx# * lvx# + lvy# * lvy# + lvz# * lvz#)
		lvx# = lvx# / dis#
		lvy# = lvy# / dis#
		lvz# = lvz# / dis#
		dis# = (nx# * evx# + ny# * evy# + nz# * evz#) * 2
		rnx# = evx# - nx# * dis#
		rny# = evy# - ny# * dis#
		rnz# = evz# - nz# * dis#
		c1 = (nx# * lvx# + ny# * lvy# + nz# * lvz#) * 256
		argb = p\argb
		z# = dis2#
	EndIf
Next
For s.Sphere = Each Sphere
	svx# = s\x# - ex#
	svy# = s\y# - ey#
	svz# = s\z# - ez#
	dis2# = svx# * evx# + svy# * evy# + svz# * evz#
	dis# = svx# * svx# + svy# * svy# + svz# * svz# - dis2# * dis2#
	If dis# <= s\rad# * s\rad# Then
		dis2# = dis2# - Sqr(s\rad# * s\rad# - dis#)
		If dis2# > 0 And dis2# < z# Then
			ix# = ex# + evx# * dis2#
			iy# = ey# + evy# * dis2#
			iz# = ez# + evz# * dis2#
			nx# = Float(ix# - s\x#) / s\rad#
			ny# = Float(iy# - s\y#) / s\rad#
			nz# = Float(iz# - s\z#) / s\rad#
			For l.Light = Each Light
				lvx# = l\x# - ix#
				lvy# = l\y# - iy#
				lvz# = l\z# - iz#
				dis# = Sqr(lvx# * lvx# + lvy# * lvy# + lvz# * lvz#)
				lvx# = lvx# / dis#
				lvy# = lvy# / dis#
				lvz# = lvz# / dis#
				dis# = (nx# * evx# + ny# * evy# + nz# * evz#) * 2
				rnx# = evx# - nx# * dis#
				rny# = evy# - ny# * dis#
				rnz# = evz# - nz# * dis#
				xx = Shadowed(ix#, iy#, iz#)
				If xx < 255 Then xx = 1 Else xx = 2
				c1 = (nx# * lvx# + ny# * lvy# + nz# * lvz#) * 256 * xx
				c2 = c2 + (rnx# * lvx# + rny# * lvy# + rnz# * lvz#) ^ 10 * 256
			Next
			argb = s\argb
			z# = dis2#
		EndIf
	EndIf
Next
sh = Shadowed(ix#, iy#, iz#)
If sh < 255 Then
	c1 = (255 - 10000.0 / Float(sh)) * .4
	If c1 < 0 Then c1 = 0
	If c1 > 255 Then c1 = 255
	c2 = cs * 255.0 / Float(sh)
Else
	If c1 < 30 Then c1 = 30
	If c2 < 0 Then c2 = 0
EndIf
c3 = c1 * c Shr 8
r = (argb And $FF0000) * c3 Shr 8 + c2 Shl 16
g = (argb And $00FF00) * c3 Shr 8 + c2 Shl 8
b = (argb And $0000FF) * c3 Shr 8 + c2
;If argb <> 0 Then argb = SendRay(ix#, iy#, iz#, rnx#, rny#, rnz#, c - 32, recursive_times - 1)
r = r + (argb And $FF0000)
g = g + (argb And $00FF00)
b = b + (argb And $0000FF)
If r > $FF0000 Then r = $FF0000 Else r = r And $FF0000
If g > $00FF00 Then g = $00FF00 Else g = g And $00FF00
If b > $0000FF Then b = $0000FF Else b = b And $0000FF
Return r Or g Or b
End Function

Function Shadowed(x#, y#, z#)
col = 255
For l.Light = Each Light
	evx# = l\x# - x#
	evy# = l\y# - y#
	evz# = l\z# - z#
	dis# = Sqr(evx# * evx# + evy# * evy# + evz# * evz#)
	evx# = evx# / dis#
	evy# = evy# / dis#
	evz# = evz# / dis#
	ar = False
	For s.Sphere = Each Sphere
		svx# = s\x# - x#
		svy# = s\y# - y#
		svz# = s\z# - z#
		dis2# = svx# * evx# + svy# * evy# + svz# * evz#
		dis# = svx# * svx# + svy# * svy# + svz# * svz# - dis2# * dis2#
		If dis2# > 0 And dis# < s\rad# * s\rad# And ar = False Then
			col = col / 5
			ar = True
		EndIf
	Next
Next
Return col
End Function

Function SetCameraPosition(x#, y#, z#)
camerax# = x#
cameray# = y#
cameraz# = z#
End Function

Function SetAmbientLight(col)
ambientcol = col
End Function

Function AddEntity(typ$, p1$ = "", p2$ = "", p3$ = "", p4$ = "", p5$ = "")
Select Lower(typ$)
	Case "sphere"
		s.Sphere = New Sphere
		s\x# = p1$
		s\y# = p2$
		s\z# = p3$
		s\rad# = p4$
		s\argb = p5$
	Case "plane"
		p.Plane = New Plane
		p\ny# = p1$
		p\dis# = p2$
		p\argb = p3$
	Case "light"
		l.Light = New Light
		l\x# = p1$
		l\y# = p2$
		l\z# = p3$
	Default
		RuntimeError "Entity type not found."
End Select
End Function

Function SetupNormals()
width = GraphicsWidth()
height = GraphicsHeight()
nz# = 200
For y = 0 To height - 1
	ny# = Float(height Shr 1 - y) * 240.0 / Float(width)
	For x = 0 To width - 1
		nx# = Float(width Shr 1 - x) * 240.0 / Float(width)
		dis# = Sqr(nx# * nx# + ny# * ny# + nz# * nz#)
		normalx#(x, y) = -nx# / dis#
		normaly#(x, y) = ny# / dis#
		normalz#(x, y) = nz# / dis#
	Next
Next
End Function