BlitImageAlphaSubImage

BlitImageAlphaSubImage ThisImage, Xpos, Ypos, BlendImage

Parameters:     ThisImage = The Index of the image you wish to draw     Xpos = The X coordinate to draw this image     Ypos = The Y coordinate to draw this image     BlendImage = The index of the image to you wish to Alpha Subtract from the primary image before drawing

Returns: NONE

BlitImageAlphaSubImage is similar to the DrawImage function, except it has post processing. What it does, is it takes two images (of the same size) and uses Alpha Subtraction to blend them together before drawing them. The Pixels are calculated by Subtracting the blend image from the primary image. Neither image is modified during the process though.       To create equivalent functionally, you'd need three images. The two images you wish to draw blended and third to store the temporary blended state. So we'd first copy the src image #1 to image 3, then blend src image 2 onto image 3 and finally draw image 3 to it's destination.       The combined processing is not just to save you a few lines of code, it's actually a more optimal way of performing this action. FACTS:      * BlitImageAlphaSubImage is only intend for drawing FX or AFX formatted surfaces.      * BlitImageAlphaSubImage doesn't support mask & alpha channel transparency.

Example Source: Download This Example ; Inlude the Blit Image functions   #Include "BlitImage"    ; Create an FX image the size of the screen   MyImage=NewFXImage(GetScreenWidth(),GetScreenHeight())       ; Create a second  FX image the size of the screen ; we'll be using to blend with our other image   Backdrop=NewFXImage(GetScreenWidth(),GetScreenHeight())    ; fill the backdrop with something so we can see it   Tile=LoadNewFxImage("..\../Media/bg22.jpg")   RenderToImage Backdrop   TileImage Tile,0,0,false       ; Set Fps of the program   SetFPS 30    ; enable Vsync to remove any tearing from the refresh   ScreenVsync on         Col=$803030       ; Start of Demo loop   Do          ; redirect all drawing to this image      RenderToImage MyImage                  If MouseButton()<>0 Then Col=RndRGB()          ; draw a circle at the mouses current position      CircleC MouseX(),MouseY(),100, true,Col          ; redirect all drawing to screen back buffer      RenderToScreen          ; To do combined Blit (copy) our Image.  This    ; version subtracts the pixels in the blend    ; image (MyImage) from the backdrop.  So it's    ; a basic form lighting effect.      BlitImageAlphaSubImage(BackDrop,0,0,MyImage)                ; Display Message      Text 0,0,"USing BlitImageAlphaSubImage to create a simple coloured light effect"      Text 0,20,"Press the Mouse Button"          ; flip the back buffer to the front, so the user can see it      Sync         Loop

Related Info:	BlitImageAlpha50Colour | BlitImageClear | Box | DrawAlphaImage | DrawImage | InkMode :

(c) Copyright 2002 - 2024 - Kevin Picone - PlayBASIC.com