[Closed] add one bitmap to another as alpha

@DennisT:the goal is # texture file with alpha as a final (tga, png, tiff, …)

Specifically a 32 bit tga that is then passed ( via hiddenDoscommand ) to a command line .dds converter
(AMD’s TheCompressonator )

@PolyTools3D :
tried your script and it does work.
But why does this use of rendermap preserve alpha while my previous attempt does not?

is it because of the use of the ” into: ” parameter?

max script help says:

If you specify the optional into: argument, the function renders the map into the supplied bitmap, taking size and other attributes from the existing bitmap. If you don’t, a new bitmap value is created using the size: and fileName: arguments in its creation.

so it appears that by using [into:<bitmap>] alpha is preserved
without [into:<bitmap>] render map generates only an rgb bitmap.

my .NET-fu is too weak for bitmap operations.
I am experiencing no issues saving .tga from mxs.
It may be slower but faster than manually building game textures in photoshop et al.

@Mambo4: Yes, it may be a bug in the function, I can’t tell. But if you create the bitmap first it renders the alpha channel.

If you need to do bitmap manipulation (in this case or for other projects), I think it would be better to move ahead with .Net. Max is very limited in this field.

Although you can’t directly save .TGA file from .Net (as Denis mentioned), you could save a .PNG, open it in max and save it as .TGA.

I suspect the whole process will be slower in .Net, but you get much more options to manipulating the images.

Well, I do wish to improve my Dot Net Fu.

would you suggest starting with the MSDN page for the bitmap class? ?

My guess is that I’d create a dotNetObject or dotNetClass in mxs and use the methods and properties documented to do stuff…am I close to the mark?

You might also want to check the Graphics Class, which allows further image manipulation MSDN Graphics Class.

Here is a quick code to resize an existing bitmap and save it as .TGA as you described.

(
 	
 fn ResizeNetBitmap inputFileName outputFileName factor =
 (
 	sourceImg = (dotnetclass "System.Drawing.Image").FromFile inputFileName
 
 	imgBits   = sourceImg.PixelFormat
 	imgWidth  = sourceImg.Width * factor
 	imgHeight = sourceImg.Height * factor
 
 	destImg = dotnetobject "System.Drawing.Bitmap" imgWidth imgHeight imgBits
 	graphic =  (dotnetclass "System.Drawing.Graphics").fromImage destImg
 	
 	graphic.CompositingQuality = graphic.CompositingQuality.HighQuality
 	graphic.SmoothingMode	  = graphic.SmoothingMode.HighQuality
 	graphic.InterpolationMode  = graphic.InterpolationMode.HighQualityBicubic	
 	
 	rect = dotnetobject "System.Drawing.Rectangle" 0 0 imgWidth imgHeight
 	graphic.DrawImage sourceImg rect
 	
 	tempFileName = outputFileName +".png"
 	destImg.Save tempFileName
 		
 	sourceImg.Dispose()
 	destImg.Dispose()
 	graphic.Dispose()
 	
 	-- Set TGA properties
 	Targa.setColorDepth   32
 	Targa.setCompressed   true
 	Targa.setAlphaSplit   false
 	Targa.setPreMultAlpha false
 
 	tempImg = openBitMap tempFileName
 	close tempImg
 	deleteFile tempFileName
 
 	outputBitmap = copy tempImg
 	outputBitmap.filename = outputFileName		
 	
 	save outputBitmap
 	close outputBitmap
 	
 	freeSceneBitmaps()
 	gc light:true
 )
 
 ResizeNetBitmap @"C:	est.tif" @"C:	est_out.tga" 0.5
 
 )

thanks a bunch!