[bb] 2D fade by jhocking [ 1+ years ago ]

[BlitzBot]

Title : 2D fade
Author : jhocking
Posted : 1+ years ago

Description : This code will fade an image to and from black.  Unlike doing fades with Gamma this works in both fullscreen and windowed mode.  Unlike the 3D graphics trick of varying alpha on a black sprite this works in 2D graphics mode.

This code is based on a function darklordz posted in the "2D Graphics" forum (but I/we have no idea who first wrote it.)  The posted function only worked in fullscreen; I modified it to work windowed too.

Code :

Code: BlitzBasic

1. Graphics 800,600,32,2
2. SetBuffer BackBuffer()
3.  
4. logo = LoadImage("facing.jpg")
5.  
6. Blend_Black(logo,0,0,0,1000)
7. time=MilliSecs()+1000
8. While MilliSecs()<time
9.         DrawBlock logo,0,0
10.         Flip
11. Wend
12. Blend_Black(logo,0,0,1,1000)
13.  
14. While Not KeyHit(1)
15. Wend
16. End
17.  
18. ;------------------------------------------------------------------
19. ; Blends an Image with a Black Background (In & Out)
20. ; -----------------------------------------------------------------
21. ; Image = The Image to Blend
22. ; x     = X Coordinate in the Screen
23. ; y     = Y Coordinate in the Screen
24. ;         50000 for both to center image
25. ; Mode  = 0 Blend In
26. ;       = 1 Blend Out
27. ; Time  = Time in Milliseconds
28. ;------------------------------------------------------------------
29.  
30. Function Blend_Black(image,x,y,mode,time)
31.         source = ImageBuffer(image)
32.         dest   = BackBuffer()
33.         maxx   = ImageWidth(image)-1
34.         maxy   = ImageHeight(image)-1
35.         start  = MilliSecs()
36.        
37.         LockBuffer source
38.        
39.         If X = 50000 And y = 50000
40.                 x = (GraphicsWidth()/2)-(ImageWidth(image)/2)
41.                 y = (GraphicsHeight()/2)-(ImageHeight(image)/2)
42.         EndIf
43.        
44.         While MilliSecs()-start<time
45. Cls
46.                 LockBuffer dest
47.                 count=(count+1) Mod 4
48.                 If count=0 Then minx=0: miny=0
49.                 If count=1 Then minx=1: miny=1
50.                 If count=2 Then minx=1: miny=0
51.                 If count=3 Then minx=0: miny=1
52.                 If mode=0 Then value=MilliSecs()-start
53.                 If mode=1 Then value=time-MilliSecs()+start
54.                 For ii=miny To maxy Step 2
55.                         For i=minx To maxx Step 2
56.                                 rgb=ReadPixelFast(i,ii,source)
57.                                 r=(rgb And $FF0000)/$10000
58.                                 g=(rgb And $FF00)/$100
59.                                 b=rgb And $FF
60.                                 rgb=r*value/time*65536+g*value/time*256+b*value/time
61.                                 WritePixelFast x+i,y+ii,rgb,dest
62.                         Next
63.                 Next
64.                 UnlockBuffer dest
65.                 Flip
66.         Wend
67.         UnlockBuffer source
68.         If mode=0 Then DrawBlock image,x,y
69.         If mode=1 Then Color 0,0,0: Rect x,y,maxx+1,maxy+1
70.         Flip
71. End Function

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