LoadAlphaChannel

This code has been declared by its author to be Public Domain code.

LoadAlphaChannel by jfk EO-11110 (Posted 22 years ago)
Huge Textures in 32 Bit TGA or PNG with Alpha Channel usually have big filesizes. To shrink the Release Size it is sometimes better to use a JPG for the RGB Channels and a 8-Bit PNG for the Alpha Channel.
; example , texture flags have to be used individually, but ; of course the Flag 2 (alpha) must be set. ; Both textures need to have the same size. ; loading the RGB channels from a lossy compressed JPG: hudtex=LoadTexture("data\hud.jpg",256 Or 16 Or 32 Or 2) ; Assigning the Alpha Channel form a 8- Bit PNG: LoadAlphaChannel(hudtex,"data\hud_mask.png") Function LoadAlphaChannel(id,file$) tex4=LoadTexture(file$,2) If tex4<>0 If TextureWidth(id)=TextureWidth(tex4) If TextureHeight(id)=TextureHeight(tex4) SetBuffer TextureBuffer(id) LockBuffer(TextureBuffer(tex4)) LockBuffer(TextureBuffer(id)) For j=0 To TextureHeight(tex4)-1 For i=0 To TextureWidth(tex4)-1 argb=ReadPixelFast(i,j,TextureBuffer(tex4)) And $ffffff r=(argb Shr 16)And $FF g=(argb Shr 8)And $FF b=argb And $FF grey= ((r+g+b)/3) If grey > 255 Then grey=255 rgb=(ReadPixelFast(i,j,TextureBuffer(id))) And $FFFFFF WritePixelFast i,j,rgb Or (grey Shl 24),TextureBuffer(id) Next Next UnlockBuffer(TextureBuffer(tex4)) UnlockBuffer(TextureBuffer(id)) SetBuffer BackBuffer() EndIf EndIf FreeTexture tex4 EndIf End Function

LoadAlphaChannel by jfk EO-11110

(Posted 22 years ago)

Huge Textures in 32 Bit TGA or PNG with Alpha Channel usually have big filesizes. To shrink the Release Size it is sometimes better to use a JPG for the RGB Channels and a 8-Bit PNG for the Alpha Channel.

; example , texture flags have to be used individually, but
; of course the Flag 2 (alpha) must be set.
; Both textures need to have the same size.

; loading the RGB channels from a lossy compressed JPG:
hudtex=LoadTexture("data\hud.jpg",256 Or 16 Or 32 Or 2)
; Assigning the Alpha Channel form a 8- Bit PNG:
LoadAlphaChannel(hudtex,"data\hud_mask.png")


Function LoadAlphaChannel(id,file$)
 tex4=LoadTexture(file$,2)
 If tex4<>0
  If TextureWidth(id)=TextureWidth(tex4)
   If TextureHeight(id)=TextureHeight(tex4)
    SetBuffer TextureBuffer(id)
    LockBuffer(TextureBuffer(tex4))
    LockBuffer(TextureBuffer(id))
    For j=0 To TextureHeight(tex4)-1
     For i=0 To TextureWidth(tex4)-1
      argb=ReadPixelFast(i,j,TextureBuffer(tex4)) And $ffffff
      r=(argb Shr 16)And $FF
      g=(argb Shr 8)And $FF
      b=argb And $FF
      grey= ((r+g+b)/3)
      If grey > 255 Then grey=255
      rgb=(ReadPixelFast(i,j,TextureBuffer(id))) And $FFFFFF
      WritePixelFast i,j,rgb Or (grey Shl 24),TextureBuffer(id)
     Next
    Next
    UnlockBuffer(TextureBuffer(tex4))
    UnlockBuffer(TextureBuffer(id))
    SetBuffer BackBuffer()
   EndIf
  EndIf
  FreeTexture tex4
 EndIf
End Function