Another per pixel lighting system :)

BlitzMax Forums/BlitzMax Programming/Another per pixel lighting system :)

fredborg (Posted 2005) [#1]

Hi, As mentioned in the other thread: http://www.blitzbasic.com/Community/posts.php?topic=49403 You can use the accumulation buffer for lighting as well. It should be a lot faster on newish graphics cards, but maybe not on older ones? Anyway, it's OpenGL only. If someone can do it in DX then show us! Here's some simple code: Strict SetGraphicsDriver(GLMax2DDriver(),GRAPHICS_BACKBUFFER|GRAPHICS_ACCUMBUFFER) Graphics 640,480,0,0 SeedRnd MilliSecs() ' ' Box type...just for testing ' Type Box Global BoxList:TList Field x,y,w,h Field r,g,b Method New() If BoxList= Null BoxList= New TList EndIf BoxList.AddLast Self EndMethod Method Delete() BoxList.Remove Self EndMethod Function Create:Box(x=0,y=0,w=10,h=10,r=255,g=255,b=255) Local o:Box = New Box o.x = x o.y = y o.w = w o.h = h o.r = r o.g = g o.b = b Return o End Function Function Render() SetRotation 0 SetScale 1,1 SetOrigin 0,0 SetBlend ALPHABLEND For Local o:Box = EachIn BoxList SetColor o.r,o.g,o.b DrawRect o.x,o.y,o.w,o.h Next EndFunction End Type ' ' Light type ' Type Light Global LightList:TList Field x:Float,y:Float Field rad:Float,size:Float Field a:Float,spd:Float Field r:Float,g:Float,b:Float Field img:TImage Method New() If LightList = Null LightList = New TList EndIf LightList.AddLast Self EndMethod Method Delete() LightList.Remove Self EndMethod Method Free() LightList.Remove Self EndMethod Function Create:Light(image:TImage,x:Float=0,y:Float=0,size:Float,a:Float=0,spd:Float=0,rad:Float=0.0,r:Float=255,g:Float=255,b:Float=255) Local l:Light = New Light l.img = image l.x = x l.y = y l.size = size l.a = a l.spd = spd l.rad = rad l.r = r l.g = g l.b = b Return l End Function Function Render(ambience:Float,intensity:Float) ' ' Clear Accum buffer ' glClear(GL_ACCUM_BUFFER_BIT) ' ' Grab backbuffer and place it in accumbuffer ' (note subtraction "ambience-1.0") ' glAccum(GL_ACCUM,1.0) glAccum(GL_ADD,ambience-1.0) ' ' Draw Lights ' Cls SetRotation 0 SetScale 1,1 SetOrigin 0,0 SetBlend LIGHTBLEND For Local l:Light = EachIn LightList l.a :+ l.spd SetScale l.size,l.size SetColor l.r,l.g,l.b DrawImage l.img,l.x+Sin(l.a)*l.rad,l.y+Cos(l.a)*l.rad Next ' ' Mix lights with accumbuffer (note multiply by intensity) ' glAccum(GL_ACCUM,intensity) ' ' Draw accumulated result to backbuffer ' glAccum(GL_RETURN,1.0) EndFunction EndType Global lightimg:TImage = CreateLightImage(256,256) ' ' Create a few lights ' For Local i = 0 To 5 Light.Create(lightimg,Rnd(640),Rnd(480),Rnd(1,2),Rnd(360),Rnd(-2,2),Rnd(5,50),Rnd(128,255),Rnd(128,255),Rnd(128,255)) Next ' ' Create some ugly backdrop For Local i = 0 To 100 Box.Create(Rnd(640),Rnd(480),Rnd(50,250),Rnd(50,250),Rnd(128,255),Rnd(128,255),Rnd(128,255)) Next ' ' Main loop ' Global lighton:Int = True Global lightpow:Float = 1.5 Global ambpow:Float = 0.0 Repeat If KeyHit(KEY_SPACE) lighton = Not lighton EndIf If KeyDown(KEY_UP) lightpow :+ 0.01 If lightpow>3 Then lightpow = 3 EndIf If KeyDown(KEY_DOWN) lightpow :- 0.01 If lightpow<0 Then lightpow = 0 EndIf If KeyDown(KEY_RIGHT) ambpow :+ 0.01 If ambpow>1 Then ambpow = 1 EndIf If KeyDown(KEY_LEFT) ambpow :- 0.01 If ambpow<0 Then ambpow = 0 EndIf Cls Box.Render() If lighton Then Light.Render(ambpow,lightpow) SetScale 1,1 SetColor 255,255,255 Local t:String = "Space - Lights On/Off | Up/Down - Intensity | Left/Right - Ambient" DrawText t,(GraphicsWidth()-TextWidth(t))*0.5,0 If lighton Local t2:String = "Intensity - "+lightpow+"| Ambient - "+ambpow DrawText t2,(GraphicsWidth()-TextWidth(t2))*0.5,GraphicsHeight()-15 EndIf Flip Until KeyHit(KEY_ESCAPE) End Function CreateLightImage:TImage(width,height,kapow:Float = 2.0) SetScale 1,1 SetRotation 0 SetOrigin 0,0 Local xrad:Float = width*0.5 Local yrad:Float = height*0.5 For Local x = 0 To width-1 For Local y = 0 To height-1 Local dx:Float = (x-xrad)/xrad Local dy:Float = (y-yrad)/yrad Local c:Float = 1.0-Sqr(dx*dx + dy*dy) If c<0.0 Then c = 0.0 c = (c^kapow)*255 SetColor c,c,c Plot x,y Next Next Local img:TImage = CreateImage(width,height,1,FILTEREDIMAGE|MIPMAPPEDIMAGE) GrabImage(img,0,0,0) SetImageHandle img,xrad,yrad Return img End Function [edit]Screenie of how it should look with an image, instead of the boxes...

Dreamora (Posted 2005) [#2]

Works great ... *somehow beeing a little shocked that it can be done "that simple" ...*

Space_guy (Posted 2005) [#3]

How is it supposed to look? I imadgine it doesnt look like it should on my computer here at work. awfully slow and colors that doesnt seem to be correct. ascreenshot of a working one pls :)

Beaker (Posted 2005) [#4]

Looks a bit of a mess here as well (on my old machine at least - GF4 MX 440).

boomboommax (Posted 2005) [#5]

ditto slow mess, ermmmmmm o_O

fredborg (Posted 2005) [#6]

It's probably dog slow on GeForce 4 and older. It will need a hardware accumulation buffer to work properly, otherwise it will chug along and probably not work correctly.

Tom (Posted 2005) [#7]

Nice effect from the king of lightmapping! :) Runs very fast here, I'm on what's probably an average card these days FX5600.

altitudems (Posted 2005) [#8]

Great job fredborg! Very fast! WinXP SP1, AMD-XP 2400+, 512 MB, GF-FX5200

tonyg (Posted 2005) [#9]

Hi Fredborg, very nice but how can you stop the lights 'blobbing' together? If I have two lights and shine them on the same wall the result is a light equal to the brightest of the two not the sum of them (if you know what I mean). I'm guessing this is what the accum buffer does.

fredborg (Posted 2005) [#10]

Um, I would think decreasing the brightness of the individual lights, while pumping up the overall light intensity would do the trick. It happens because the values the accum buffer can store are limited (from -1 to 1)...

Bot Builder (Posted 2005) [#11]

I think you'll find two lights together equals their sum, tonyg.

tonyg (Posted 2005) [#12]

Surely not! Shine a very bright light on a wall and then a dim torch. The result is the same very bright light and not a bright light with a brighter section where the torch is shining. e.g. A 'force 5' torch shining with a 'force 6' torch makes a force 6 light not a force 11 light.... surely?

Dreamora (Posted 2005) [#13]

perhaps using alphablend with Alpha instead of LightBlend works? *haven't tried as I am trying to kick my windows system ;-)*

fredborg (Posted 2005) [#14]

If you scale your light colors so that the sum of them will not exceed 255,255,255 and then increase the Intensity, you shouldn't have any problems. Example: Strict SetGraphicsDriver(GLMax2DDriver(),GRAPHICS_BACKBUFFER|GRAPHICS_ACCUMBUFFER) Graphics 640,480,0,0 SeedRnd MilliSecs() ' ' Box type...just for testing ' Type Box Global BoxList:TList Field x,y,w,h Field r,g,b Method New() If BoxList= Null BoxList= New TList EndIf BoxList.AddLast Self EndMethod Method Delete() BoxList.Remove Self EndMethod Function Create:Box(x=0,y=0,w=10,h=10,r=255,g=255,b=255) Local o:Box = New Box o.x = x o.y = y o.w = w o.h = h o.r = r o.g = g o.b = b Return o End Function Function Render() SetRotation 0 SetScale 1,1 SetOrigin 0,0 SetBlend ALPHABLEND For Local o:Box = EachIn BoxList SetColor o.r,o.g,o.b DrawRect o.x,o.y,o.w,o.h Next EndFunction End Type ' ' Light type ' Type Light Global LightList:TList Field x:Float,y:Float Field rad:Float,size:Float Field a:Float,spd:Float Field r:Float,g:Float,b:Float Field img:TImage Method New() If LightList = Null LightList = New TList EndIf LightList.AddLast Self EndMethod Method Delete() LightList.Remove Self EndMethod Method Free() LightList.Remove Self EndMethod Function Create:Light(image:TImage,x:Float=0,y:Float=0,size:Float,a:Float=0,spd:Float=0,rad:Float=0.0,r:Float=255,g:Float=255,b:Float=255) Local l:Light = New Light l.img = image l.x = x l.y = y l.size = size l.a = a l.spd = spd l.rad = rad l.r = r l.g = g l.b = b Return l End Function Function Render(ambience:Float,intensity:Float) ' ' Clear Accum buffer ' glClear(GL_ACCUM_BUFFER_BIT) ' ' Grab backbuffer and place it in accumbuffer ' (note subtraction "ambience-1.0") ' glAccum(GL_ACCUM,1.0) glAccum(GL_ADD,ambience-1.0) ' ' Draw Lights ' (note multiply by intensity) ' Local intenslight:Float = 1' intensity If intenslight>1.0 Then intenslight = 1.0 Cls SetRotation 0 SetScale 1,1 SetOrigin 0,0 SetBlend LIGHTBLEND For Local l:Light = EachIn LightList l.a :+ l.spd SetScale l.size,l.size SetColor l.r*intenslight,l.g*intenslight,l.b*intenslight DrawImage l.img,l.x+Sin(l.a)*l.rad,l.y+Cos(l.a)*l.rad Next ' ' Mix lights with accumbuffer ' 'If intensity<1.0 Then intensity = 1.0 glAccum(GL_ACCUM,intensity) ' ' Draw accumulated result to backbuffer ' glAccum(GL_RETURN,1.0) EndFunction Function ScaleColors(maxbright:Float) ' ' Scale colors so they cannot exceed maxbright ' when drawn on top of each other ' Local red:Float = 0 Local green:Float = 0 Local blue:Float = 0 For Local l:Light = EachIn LightList red :+ l.r green :+ l.g blue :+ l.b Next Local cmax:Float = Max(red,green) cmax = Max(cmax,blue) For Local l:Light = EachIn LightList l.r = (l.r*maxbright) / cmax l.g = (l.g*maxbright) / cmax l.b = (l.b*maxbright) / cmax Next EndFunction EndType Global lightimg:TImage = CreateLightImage(256,256) ' ' Create a few lights ' Local lcount:Float = 5 For Local i = 0 To lcount-1 Local hue:Float = (i/lcount)*180.0 Local r:Float = 40+Sin(hue)*255 Local g:Float = 40+Sin(hue+45)*255 Local b:Float = 40+Sin(hue+90)*255 If r<0 Then r = 0 If g<0 Then g = 0 If b<0 Then b = 0 Light.Create(lightimg,Rnd(640),Rnd(480),Rnd(1.5,2),Rnd(360),Rnd(-2,2),Rnd(25,50),r,g,b) Next ' ' Scale colors ' Light.ScaleColors(255) ' ' Create some ugly backdrop For Local i = 0 To 100 Box.Create(Rnd(640),Rnd(480),Rnd(50,250),Rnd(50,250),Rnd(128,255),Rnd(128,255),Rnd(128,255)) Next ' ' Main loop ' Global lighton:Int = True Global lightpow:Float = 1.5 Global ambpow:Float = 0.0 Repeat If KeyHit(KEY_SPACE) lighton = Not lighton EndIf If KeyDown(KEY_UP) lightpow :+ 0.01 If lightpow>10 Then lightpow = 10 EndIf If KeyDown(KEY_DOWN) lightpow :- 0.01 If lightpow<0 Then lightpow = 0 EndIf If KeyDown(KEY_RIGHT) ambpow :+ 0.01 If ambpow>1 Then ambpow = 1 EndIf If KeyDown(KEY_LEFT) ambpow :- 0.01 If ambpow<0 Then ambpow = 0 EndIf Cls Box.Render() If lighton Then Light.Render(ambpow,lightpow) SetScale 1,1 SetColor 255,255,255 Local t:String = "Space - Lights On/Off | Up/Down - Intensity | Left/Right - Ambient" DrawText t,(GraphicsWidth()-TextWidth(t))*0.5,0 If lighton Local t2:String = "Intensity - "+lightpow+"| Ambient - "+ambpow DrawText t2,(GraphicsWidth()-TextWidth(t2))*0.5,GraphicsHeight()-15 EndIf Flip Until KeyHit(KEY_ESCAPE) End Function CreateLightImage:TImage(width,height,kapow:Float = 2.0) SetScale 1,1 SetRotation 0 SetOrigin 0,0 Local xrad:Float = width*0.5 Local yrad:Float = height*0.5 For Local x = 0 To width-1 For Local y = 0 To height-1 Local dx:Float = (x-xrad)/xrad Local dy:Float = (y-yrad)/yrad Local c:Float = 1.0-Sqr(dx*dx + dy*dy) If c<0.0 Then c = 0.0 c = (c^kapow)*255 SetColor c,c,c Plot x,y Next Next Local img:TImage = CreateImage(width,height,1,FILTEREDIMAGE|MIPMAPPEDIMAGE) GrabImage(img,0,0,0) SetImageHandle img,xrad,yrad Return img End Function As you can see this results in some artifacts, but if you tweak it, it'll look fine.

SillyPutty (Posted 2005) [#15]

wow, great work fredborg !

Proger (Posted 2005) [#16]

Wow! Its cool! ...how use it in DX 7? ;) Please...

Proger (Posted 2005) [#17]

Accumulation Buffer Techniques with DirectX® 7 http://www.ati.com/developer/sdk/RadeonSDK/Html/Samples/Samples.html