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"Fade with Transparency", by super maaka

A couple of routines to perform fade operation on images. Also includes the option to create images with a varying degree of transparency (like looking through glass) by sampling a referenced image and overlaying it onto an existing image. Simple yet effective.

Both fade and transparency can be applied at varying degress.

Code

; ============================================================================
;     PROJECT:          SPECIAL EFFECTS
;          Description:
;               The routine can be called from a calling routine in 1 of 3 
;               modes.  These modes are as follows:
;                    1).     Fade an image
;                    2).     Paste a faded image onto the front/back buffer
;                    3).     Paste an image onto front/back buffer with transparency.
;
;          Routine:     fnImg_Sfx:
;                         is the main routine to call.
;
;          Routine:     fnImg_Sfx_ScrnBuffer:
;                         is used by the fnImg_Sfx when you request to work with 
;                          the screen buffer.
;     --------------------------------------------------------------------------
;          Version:     1.2
;          Date:          6th Mar 2005
;          Author:          Alan Simmons
;          Comments:     This sample has been developed to provide a reliable 
;                         method of applying special effects on images.
;
;          Note(s):     
;               Speed     When compiled to an executable the routines take hardly 
;                         any time at all to execute.  Although this sample program compiles 
;                         to a super fast executable, running with debug enabled will 
;                         result in the user experiencing a little degrade in the 
;                         performance.
;
; ============================================================================

Graphics 640, 480, 24, 2

Local Caption$
Local fade%
Local fxImage%
Local fxImageBackGround%
Local fxImageCopy%
Local ImgFile$
Local ImgHeight%
Local ImgWidth%
Local opt%                    ; Options

Caption = "Special effects"
     
     ImgFile = "graphics\disc.bmp"
     fxImage = LoadImage( ImgFile )
     fxImageCopy = CopyImage( fxImage )
     
     ImgFile = "graphics\forest.bmp"
     fxImageBackGround = LoadImage( ImgFile )
     
     ImgWidth = ImageWidth( fxImage )
     ImgHeight = ImageHeight( fxImage )
     
     ;     Set special effects options.
     opt = g_fnimage_opt_frontbuffer + g_fnimage_opt_transparency
     
     For fade = 0 To 255 Step 2
          Delay 1
          
          DrawBlock fxImageBackGround, 0, 0
          DrawBlock fxImageBackGround, 0, ImageHeight( fxImageBackGround )
          
          ;     Paste the copy of the original image to the working copy image.
          CopyRect 0, 0, ImgWidth, ImgHeight, 0, 0, ImageBuffer( fxImage ), ImageBuffer( fxImageCopy )
          
          ;     Apply special effect.
          fnImage_Sfx( fxImageCopy, 90, ImgWidth, fade, opt )
     Next
     
     AppTitle Caption + " Press any key to quit"
     
     FlushKeys
     WaitKey()

Const g_fnImg_opt_fade% = 1
Const g_fnImg_opt_transparency% = 2
Const g_fnImg_opt_backbuffer% = 256
Const g_fnImg_opt_frontbuffer% = 512
Const g_fnImg_opt_defaultbuffer% = 1024
Const g_fnImg_opt_preservecanvas% = 2048

; ========================================================================
; DESCRIPTION:
;     This routine has been designed to accept an image and apply a 
;     special effect to/from it.
;
;     The default Special Effect operation is a fade of various intensities.
;
; ------------------------------------------------------------------------
;
; VERSION:          1.01
;     Date:          25-Jan-2005     17:50
;     Author:          Alan Simmons
;     Comment:     .
;
;
; NOTE(S):
;     Buffers               If the calling routine does NOT specify buffer 
;                         information in its options, the routine assumes that 
;                         the operation should be applied to the image 
;                         (ie. change the image with a fade effect).
;
;
; PARAMETER(S):
;     par_fxImage          Integer
;          Image handle.
;
;     par_effect          Integer.
;          The value fade that should be applied.  From 0 - 255.
;
;     par_x               String,  Default ="".
;          Co-ordinates.
;
;     par_y               String,  Default ="".
;          Co-ordinates.
;
;     par_options          String,  Default ="".
;          Run options (for example, write to front buffer).
;
;
; RETURN:          Boolean/Integer.
;     TRUE          Success.
;     FALSE          Failure.
;
;
; DEPENDENCIES:
;     Var(s):          .
;     Type(s):     .
;     File(s):     .
;
; ========================================================================
Function fnImg_Sfx%( par_fxImage%, par_effect%, par_x$ ="", par_y$ ="", par_options$ ="" )

Local col_blue%
Local col_green%
Local col_red%
Local fade_red%
Local fade_green%
Local fade_blue%
Local ImgHeight%
Local ImgWidth%
Local opt_backbuffer%
Local opt_frontbuffer%
Local opt_defaultbuffer%
Local opt_imagebuffer%
Local RetVal%                    ; Return value to calling routine.
Local rgb%
Local run_options%
Local x%
Local y%
     
     If Not par_options = "" Then run_options = par_options
     If par_effect > 255 Then par_effect = 255
     
     opt_backbuffer = False
     opt_frontbuffer = False
     opt_imagebuffer = False
     
     If run_options And g_fnImg_opt_backbuffer Then
          opt_backbuffer = True
     ElseIf run_options And g_fnImg_opt_frontbuffer Then
          opt_frontbuffer = True
     ElseIf run_options And g_fnImg_opt_defaultbuffer Then 
          opt_defaultbuffer = True
     Else
          opt_imagebuffer = True
     End If
     
     If opt_backbuffer Then
          SetBuffer BackBuffer()
          RetVal = fnImg_Sfx_ScrnBuffer( par_fxImage, par_effect, par_x, par_y, par_options )
          Goto fnImg_Sfx_Exit
     ElseIf opt_frontbuffer Then
          SetBuffer FrontBuffer()
          RetVal = fnImg_Sfx_ScrnBuffer( par_fxImage, par_effect, par_x, par_y, par_options )
          Goto fnImg_Sfx_Exit
     ElseIf opt_defaultbuffer Then
          ;     use the default buffer.
          RetVal = fnImg_Sfx_ScrnBuffer( par_fxImage, par_effect, par_x, par_y, par_options )
          Goto fnImg_Sfx_Exit
     End If
     
     ;     ----------------------------------------------------------------
     ;     In the event of the calling routine NOT specifying a buffer to 
     ;     use as a target for modified version of image, presume that 
     ;     the calling routine requires the image to be faded.
     ;     ----------------------------------------------------------------
     
     fade_blue = par_effect
     fade_green = par_effect * 256
     fade_red = (par_effect * 256 ) * 256
     
     ImgWidth = ImageWidth( par_fxImage )
     ImgHeight = ImageHeight( par_fxImage )
     
     LockBuffer ImageBuffer( par_fxImage )
     
     For y = 0 To ImgHeight -1
          For x = 0 To ImgWidth -1
               rgb = ReadPixelFast( x, y, ImageBuffer( par_fxImage )) And $FFFFFF
               If Not rgb = 0 Then
                    col_blue = rgb And 255
                    col_green = ( rgb And 65280 )
                    col_red = ( rgb And 16711680 )
                    
                    If col_red > fade_red Then 
                         col_red = col_red -fade_red
                    ElseIf col_red > 0 Then
                         ; set the colour to its darkest shade.
                         col_red = 1 Shl 16
                    End If
                    
                    If col_green > fade_green Then
                         col_green = col_green -fade_green
                    ElseIf col_green > 0 Then
                         ; set the colour to its darkest shade.
                         col_green = 1 Shl 8
                    End If
                    
                    If col_blue > fade_blue Then
                         col_blue = col_blue -fade_blue 
                    ElseIf col_blue > 0 Then
                         ; set the colour to its darkest shade.
                         col_blue =1
                    End If
                    WritePixelFast x, y, col_red +col_green +col_blue, ImageBuffer( par_fxImage )
               End If
          Next
     Next
     
     UnlockBuffer ImageBuffer( par_fxImage )
     
     RetVal = True
     
.fnImg_Sfx_Exit
     Return RetVal
     
End Function ;          fnImg_Sfx%( 
 )

; ========================================================================
; DESCRIPTION:
;     This routine has been designed to accept an image and fade the image 
;     by the requested amount.
;
;     This routine reads an image (as the source) and write the image to 
;     the screen buffer (front buffer).
;
; ------------------------------------------------------------------------
;
; VERSION:          1.01
;     Date:          25-Jan-2005     17:50
;     Author:          Alan Simmons
;     Comment:     .
;
;
; NOTE(S):          
;     Default Buffer:     This routine has been designed to be a sub routine 
;                         for the routine 'fnImage_Sfx'.  The routine presumes 
;                         that the write operations should be applied to the 
;                         current deafult buffer.
;
;
; PARAMETER(S):
;     par_fxImage          Integer
;          Image handle.
;
;     par_effect          Integer.
;          The value fade that should be applied.  From 0 - 255.
;
;     par_x               String,  Default ="".
;          Co-ordinates.
;
;     par_y               String,  Default ="".
;          Co-ordinates.
;
;     par_options          String,  Default ="".
;          Run options.
;
; RETURN:          Boolean/Integer.
;     TRUE          Success.
;     FALSE          Failure.
;
;
; DEPENDENCIES:
;     Var(s):          .
;     Type(s):     .
;     File(s):     .
;
; ========================================================================
Function fnImg_Sfx_ScrnBuffer%( par_fxImage%, par_effect%, par_x$ ="", par_y$ ="", par_options$ ="" )

Local col_src_blue%
Local col_src_green%
Local col_src_red%
Local col_des_blue%
Local col_des_green%
Local col_des_red%
Local dest_x%
Local dest_y%
Local fade_red%
Local fade_green%
Local fade_blue%
Local ImgHeight%
Local ImgWidth%
Local opt_fade%
Local opt_transparency%
Local rgb_src%
Local rgb_des%
Local run_options%
Local val%
Local x%
Local y%

opt_fade = False
     opt_transparency = False
     
     If Not par_options = "" Then run_options = par_options
     
     If par_x = "" Then
          dest_x = 0
     Else
          dest_x = par_x
     End If
     
     If par_y = "" Then
          dest_y = 0
     Else
          dest_y = par_y
     End If
     
     ImgWidth = ImageWidth( par_fxImage )
     ImgHeight = ImageHeight( par_fxImage )
     
     fade_blue = par_effect
     fade_green = par_effect
     fade_red = par_effect
     
     If run_options And g_fnImg_opt_transparency Then opt_transparency = True
     If run_options And g_fnImg_opt_fade Then opt_fade = True
     
     LockBuffer ImageBuffer( par_fxImage )
     LockBuffer GraphicsBuffer()
     
     If opt_transparency Then
          If opt_fade Then
               ;     >>     Copy source image (faded) to default buffer <<
               ;          with transparency
               For y = 0 To ImgHeight -1
                    For x = 0 To ImgWidth -1
                         rgb_src = ReadPixelFast( x, y, ImageBuffer(par_fxImage)) And $FFFFFF
                         If Not rgb_src = 0 Then
                              col_src_blue = rgb_src And 255
                              col_src_green = ( rgb_src And 65280 )
                              col_src_red = ( rgb_src And 16711680 )
                              
                              rgb_des = ReadPixelFast( dest_x +x, dest_y + y ) And $FFFFFF
                              col_des_blue = rgb_des And 255
                              col_des_green = ( rgb_des And 65280 )
                              col_des_red = ( rgb_des And 16711680 )
                              
                              ; use shr to prepare it for comaprison.
                              col_src_green =col_src_green Shr 8
                              col_src_red =col_src_red Shr 16
                              col_des_green =col_des_green Shr 8
                              col_des_red =col_des_red Shr 16
                              
                              ; fade rgb.
                              If col_des_blue >fade_blue Then 
                                   col_des_blue = col_des_blue -fade_blue 
                              ElseIf col_des_blue >0 Then
                                   col_des_blue = 1
                              End If
                              
                              If col_des_green >fade_green Then 
                                   col_des_green = col_des_green -fade_green
                              ElseIf col_des_green >0 Then
                                   col_des_green = 1
                              End If
                              
                              If col_des_red >fade_red Then 
                                   col_des_red = col_des_red -fade_red
                              ElseIf col_des_red >0 Then
                                   col_des_red = 1
                              End If
                              
                              val =((255 -col_des_blue) /2) 
                              If col_src_blue >val Then
                                   col_src_blue =col_src_blue -val 
                              Else
                                   col_src_blue =1
                              End If
                              
                              val =((255 -col_des_green) /2)
                              If col_src_green >val Then
                                   col_src_green =col_src_green -val
                              Else
                                   col_src_green =1
                              End If
                              
                              val =((255 -col_des_red) /2)
                              If col_src_red >val Then
                                   col_src_red =col_src_red -val
                              Else
                                   col_src_red =1
                              End If
                              
                              ; assign the destination var with the brightest pixel.
                              If col_src_blue Then ; limit this col.
                                   If col_src_blue >col_des_blue Then 
                                        col_des_blue =col_src_blue +((col_src_blue -col_des_blue) /2)
                                   End If
                              End If
                              
                              If col_src_green Then ; limit col.
                                   If col_src_green >col_des_green Then 
                                        col_des_green =col_src_green +((col_src_green -col_des_green) /2)
                                   End If
                              End If
                              
                              If col_src_red Then ; limit col.
                                   If col_src_red >col_des_red Then 
                                        col_des_red =col_src_red +((col_src_red -col_des_red) /2)
                                   End If
                              End If
                              
                              ; use shl to reformat bits, ready for assignment.
                              col_des_green =col_des_green Shl 8
                              col_des_red =col_des_red Shl 16
                              
                              ; build rgb pixel.
                              rgb_des =col_des_blue
                              rgb_des =rgb_des +col_des_green
                              rgb_des =rgb_des +col_des_red
                              
                              If rgb_des Then WritePixelFast dest_x +x, dest_y + y, rgb_des
                         End If
                    Next
               Next
          Else
               ;     >> Copy source image to default buffer with transparancy <<
               
               For y = 0 To ImgHeight -1
                    For x = 0 To ImgWidth -1
                         rgb_src = ReadPixelFast( x, y, ImageBuffer( par_fxImage )) And $FFFFFF
                         If Not rgb_src = 0 Then
                              col_src_blue = rgb_src And 255
                              col_src_green = ( rgb_src And 65280 )
                              col_src_red = ( rgb_src And 16711680 )
                              
                              rgb_des = ReadPixelFast( dest_x +x, dest_y + y ) And $FFFFFF
                              col_des_blue = rgb_des And 255
                              col_des_green = ( rgb_des And 65280 )
                              col_des_red = ( rgb_des And 16711680 )
                              
                              If col_src_blue >col_des_blue Then
                                   rgb_des =col_src_blue 
                              Else
                                   rgb_des =col_des_blue
                              End If
                              If col_src_green >col_des_green Then
                                   rgb_des =rgb_des +col_src_green 
                              Else
                                   rgb_des =rgb_des +col_des_green
                              End If
                              If col_src_red >col_des_red Then
                                   rgb_des =rgb_des +col_src_red 
                              Else
                                   rgb_des =rgb_des +col_des_red
                              End If
                              
                              If rgb_des Then WritePixelFast dest_x +x, dest_y + y, rgb_des
                         End If
                    Next
               Next
          End If
     Else
          ;     >> Copy source image (faded) to default buffer <<
          
          For y = 0 To ImgHeight -1
               For x = 0 To ImgWidth -1
                    rgb_src = ReadPixelFast( x, y, ImageBuffer( par_fxImage )) And $FFFFFF
                    If Not rgb_src = 0 Then
                         col_src_blue = rgb_src And 255
                         col_src_green = ( rgb_src And 65280 )
                         col_src_red = ( rgb_src And 16711680 )
                         
                         ; use shl/shr to get bits in right format.
                         col_src_green =col_src_green Shr 8
                         col_src_red =col_src_red Shr 16
                         
                         If col_src_blue >fade_blue Then 
                              col_src_blue = col_src_blue -fade_blue 
                         ElseIf col_src_blue >0 Then
                              col_src_blue = 1
                         End If
                         
                         If col_src_green >fade_green Then 
                              col_src_green = col_src_green -fade_green
                         ElseIf col_src_green >0 Then
                              col_src_green = 1
                         End If
                         
                         If col_src_red >fade_red Then 
                              col_src_red = col_src_red -fade_red
                         ElseIf col_src_red >0 Then
                              col_src_red = 1
                         End If
                         
                         ; use shr/shl to reformat bits.
                         col_src_green =col_src_green Shl 8
                         col_src_red =col_src_red Shl 16
                         rgb_des =col_src_blue +col_src_green +col_src_red
                         
                         ;If rgb_des Then WritePixelFast dest_x +x, dest_y + y, rgb_des, FrontBuffer()     Bug fix [16th Dec 2004].
                         If rgb_des Then WritePixelFast dest_x +x, dest_y + y, rgb_des, GraphicsBuffer()
                    End If
               Next
          Next
     End If
     
     UnlockBuffer ImageBuffer( par_fxImage )
     UnlockBuffer GraphicsBuffer()
End Function ;     fnImg_Sfx_ScrnBuffer%( 
 )

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