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Masking pixels in a created pixmap

BlitzMax Forums/BlitzMax Beginners Area/Masking pixels in a created pixmap

Pete Carter(Posted 2009) [#1]
ive made a pixmap using alot of pixel writing and some use of grabimage.

Anyway i can't get the resulting image to mask. its a 128x128 isometric tile with black spaces round the edges. Ive tryed the blend modes which normally work but ive not got anywhere.

help :O)


Jesse(Posted 2009) [#2]
none of the 3d graphics commands work with pixmaps. you need to convert it to a Timage and use it that way.
image:TImage = LoadImage(pixmap:tpixmap)


_Skully(Posted 2009) [#3]
	Function SetImageMask(p_image:TImage, p_red:Int,p_green:Int,p_blue:Int)
		Local l_maskrgb:Int
		Local l_maskargb:Int
		Local l_pixelrgb:Int
		Local l_pixelraw:Int
		Local l_x:Int,l_y:Int
		Local l_pix1:TPixmap
		
		l_maskrgb = p_red Shl 16 + p_green Shl 8 + p_blue
		l_pix1 = LockImage(p_image)
		For l_x = 0 To ImageWidth(p_image)-1
			For l_y = 0 To ImageHeight(p_image)-1
				l_pixelraw = ReadPixel(l_pix1,l_x,l_y)
				l_pixelrgb = l_pixelraw & 16777215
				If l_pixelrgb = l_maskrgb Then
					' make transparent
					WritePixel(l_pix1,l_x,l_y,l_maskrgb)
				Else
					' remove transparency
					Local l_PixelNoAlpha:Int=l_pixelrgb | (255 Shl 24)
					WritePixel(l_pix1,l_x,l_y,l_PixelNoAlpha)
				End If
			Next 
		Next
		UnlockImage(p_image)
	End Function



_Skully(Posted 2009) [#4]
you can have cumulative masking by commenting out the 'remove transparency' part..

I assume you can mine the function for what you need..


Jesse(Posted 2009) [#5]
I don't think that is what he wants. I believe he is trying to display a pixmap to the screen as if he is displaying an image and the pixmap is being drawn including the black pixels to the screen which he doesn't want to happen.


_Skully(Posted 2009) [#6]
Anyway i can't get the resulting image to mask


make sure you set DYNAMICIMAGE|MASKEDIMAGE when you create the image...


Pete Carter(Posted 2009) [#7]
ok i will give all the above a go thanks for your help :O)

Pete


Pete Carter(Posted 2009) [#8]
sorry but should this mask all the bright pink pixels?

nomask:TPixmap = GrabPixmap:TPixmap(128,64,128,64)
masked:Timage = LoadImage(nomask:TPixmap,DYNAMICIMAGE|MASKEDIMAGE)

SetMaskColor(255,000,255)
SetBlend(MASKBLEND)
DrawImage(masked:Timage,0,0)



Pete Carter(Posted 2009) [#9]
got it working with black. id rather it was bright pink though as i may want black in may images.


_Skully(Posted 2009) [#10]
It should work for any color.. I currently use it to set the mask on several tilesets.

If you peek the color from the pixelmap you ensure the correct mask color


Pete Carter(Posted 2009) [#11]
I found out what it was! i had to setmaskcolor before loading the image. now it works perfect. thanks again


_Skully(Posted 2009) [#12]
Thats the proper way of doing it lol... you don't need the function if you do it that way. If you're setting mask after loading them you need the function I posted. Perhaps I should have mentioned that but I didn't know why you needed to set the mask...just that you needed to set the mask lol