(Blitz3dSDK) PNG Texture Colorizer And Alpha Modifier

This code has been declared by its author to be Public Domain code.

(Blitz3dSDK) PNG Texture Colorizer And Alpha Modifier by JesseJoh

2013

I'm pretty proud of this one - even though it's small, it works well with the Blitz3DSdK.

Basically you pass the function a texture, and values to add or subtract from each of the channels. If you were to enter -20 for the blue and green channels, your texture would become redder. Just like with other Blitz3D commands such as TurnEntity - entering 0 for a modifier value will induce no change on that channel.

This also works with PNG textures that have alpha channels :) For me, I performed the colorize a bunch of times before loading a character and it reasonably quick too.

My purpose was to be able to change the color of clothing on a character.

' Usage
' modify_texture_rgba( <input texture>, <r modifier (-255 to 255)>, <g modifier (-255 to 255)>, <b modifier (-255 to 255)>, <a modifier (-255 to 255)> )
'
' For example, if you entered -20 for the green and blue modifiers, your texture would get redder.
Function modify_texture_rgba(texture, r_modifier, g_modifier, b_modifier, a_modifier)
	
	' Lock texture buffer for fast operation
	bbLockBuffer(bbTextureBuffer(texture))
	
	' Loop through the texture
	For Local y = 0 To bbTextureHeight(texture) - 1
		For Local x = 0 To bbTextureWidth(texture) - 1
		
			' Get RGBA
			Local rgba_value = bbReadPixelFast(x, y, bbTextureBuffer(texture))
			
			' Get individual values
			Local a = (rgba_value Shr 24) & $FF
			Local r = (rgba_value Shr 16) & $FF
			Local g = (rgba_value Shr 8) & $FF
			Local b = rgba_value & $FF
			
			' Red modifications
			If r_modifier > 0 Then
				If r + r_modifier < 255 Then
					r = r + r_modifier
				Else
					r = 255
				End If
			End If
			If r_modifier < 0 Then
				If r + r_modifier > 0 Then
					r = r + r_modifier
				Else
					r = 0
				End If
			End If
			
			' Green modifications
			If g_modifier > 0 Then
				If g + g_modifier < 255 Then
					g = g + g_modifier
				Else
					g = 255
				End If
			End If
			If g_modifier < 0 Then
				If g + g_modifier > 0 Then
					g = g + g_modifier
				Else
					g = 0
				End If
			End If
			
			' Blue modifications
			If b_modifier > 0 Then
				If b + b_modifier < 255 Then
					b = b + b_modifier
				Else
					b = 255
				End If
			End If
			If b_modifier < 0 Then
				If b + b_modifier > 0 Then
					b = b + b_modifier
				Else
					b = 0
				End If
			End If
			
			' Alpha modifications
			If a_modifier > 0 Then
				If a + a_modifier < 255 Then
					a = a + a_modifier
				Else
					a = 255
				End If
			End If
			If a_modifier < 0 Then
				If a + a_modifier > 0 Then
					a = a + a_modifier
				Else
					a = 0
				End If
			End If
		
			' Make it RGBA Again
			Local new_rgba = (a Shl 24 | r Shl 16 | g Shl 8 | b)
			
			' Write the pixel to the texture
			bbWritePixelFast(x, y, new_rgba, bbTextureBuffer(texture))
	
		Next
	Next
	
	' Unlock the texture buffer
	bbUnlockBuffer(bbTextureBuffer(texture))

End Function

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