[bb] 2d Alpha for b3d by Nate the Great [ 1+ years ago ]

[BlitzBot]

Title : 2d Alpha for b3d
Author : Nate the Great
Posted : 1+ years ago

Description : This program allows alpha blending on images.  It comes with two types of blending, addative and something that I am still figuring out a name for.  I would have found this very useful when I used to program 2d games.

Code :

Code (blitzbasic) Select Expand

Graphics 640,480,0,2

Dim aray(60,60,3)


img = CreateImage(50,50)
img1 = CreateImage(50,50)
SetBuffer ImageBuffer(img)
ClsColor 255,0,0
Cls
Color 0,255,0
Rect 20,20,15,10
SetBuffer ImageBuffer(img1)
ClsColor 0,0,255
Cls

SetBuffer BackBuffer()
ClsColor 0,0,0

While Not KeyDown(1)
Cls

DrawImage img1,MouseX(),MouseY()

DrawImage1(img,320,240,0,.5,1)

Flip
Wend
End

Function DrawImage1(name,x,y,frm = 0,alpha# = 1,alphabmode = 0,red = 255,green = 255,blue = 255)

If alphabmode > 0 Then



SetBuffer ImageBuffer(name,frm)

LockBuffer ImageBuffer(name,frm)

For x1 = 1 To ImageWidth(name)-1
For y1 = 1 To ImageHeight(name)-1
rgb = ReadPixelFast(x1,y1)
aray(x1,y1,0) = getred(rgb)
aray(x1,y1,1) = getgreen(rgb)
aray(x1,y1,2) = getblue(rgb)
Next
Next

UnlockBuffer ImageBuffer(name,frm)

SetBuffer BackBuffer()

LockBuffer BackBuffer()

For x1 = 1 To ImageWidth(name)-1
For y1 = 1 To ImageHeight(name)-1
If alphabmode = 1 Then
If x1 + x > 0 And x1+x < GraphicsWidth()-1 And y1 + y > 0 And y1 + y < GraphicsHeight()-1 Then
rgb = ReadPixelFast(x1+x,y1+y)
WritePixelFast(x1+x,y1+y,getrgb(getred(rgb)+aray(x1,y1,0)*alpha#*(red/255),getgreen(rgb)+aray(x1,y1,1)*alpha#*(green/255),getblue(rgb)+aray(x1,y1,2)*alpha#*(blue/255)))
EndIf
ElseIf alphabmode = 2 Then
If x1 + x > 0 And x1+x < GraphicsWidth()-1 And y1 + y > 0 And y1 + y < GraphicsHeight()-1 Then
rgb = ReadPixelFast(x1+x,y1+y)
brt = getred(rgb)+getgreen(rgb)+getblue(rgb)
WritePixelFast(x1+x,y1+y,getrgb(getred(rgb)+aray(x1,y1,0)*alpha#*(red/255)*brt/765,getgreen(rgb)*aray(x1,y1,1)*alpha#*(green/255)*brt/765,getblue(rgb)*aray(x1,y1,2)*alpha#*(blue/255)*brt/765))
EndIf
EndIf
Next
Next
Else
DrawImage name,x,y,frm
EndIf

UnlockBuffer BackBuffer()
End Function

Function GetRed(rgb)
Return rgb Shr 16 And %11111111
End Function
Function GetGreen(rgb)
Return rgb Shr 8 And %11111111
End Function
Function GetBlue(rgb)
Return rgb And %11111111
End Function






Function GetRGB(red,green,blue)
Return blue Or (green Shl 8) Or (red Shl 16)
End Function

Comments :


Nate the Great(Posted 1+ years ago)

 Sorry. I think there was a flaw in it earlier.  I fixed it now though.


Nate the Great(Posted 1+ years ago)

 Hmmm...Now it should workcould someone try this and tell me if it works


LamptonWorm(Posted 1+ years ago)

 Hi, works for me... good stuff.


Ryudin(Posted 1+ years ago)

 Thanks. This'll work perfectly for my semi-transparent cursor.By the way, what to the red, green, and blue values do? When I use them, my image disappears completely.


Nate the Great(Posted 1+ years ago)

 <a href="codearcs2fe9.html?code=2348#comments" target="_blank">http://www.blitzbasic.com/codearcs/codearcs.php?code=2348#comments</a>Ryudin... if you are using blitz3d then try this instead it is much faster and more flexible