Action
Specify pixel arithmetic.
Syntax
BlendFunc src, dst
Remarks
src |
Specifies how the source blending factor is computed. One of ZERO, ONE, SRC_ALPHA, DST_ALPHA,ONE_MINUS_SRC_ALPHA or ONE_MINUS_DST_ALPHA. |
dst |
Specifies how the destination blending factor is computed, One of ZERO, ONE, SRC_ALPHA, DST_ALPHA,ONE_MINUS_SRC_ALPHA or ONE_MINUS_DST_ALPHA. |
The blend function controls how new color values are combined with the values already in the color buffer.
Given a pixel value source and a previous value in the color buffer destination, the computed color is:
source × src + destination × dst
for each color channel: red, green, blue and alpha.
For more details please refer to the FT800 Series Programmer Guide.PDF from FTDI.
See also
Example
' Pseudocode
' The default blend function of (SRC_ALPHA, ONE_MINUS_SRC_ALPHA) causes drawing
' to overlay the destination using the alpha value
Begin_G BITMAPS
Vertex2II 50, 30, 31, &H47
Color_A 128
Vertex2II 60, 40, 31, &H47
' A destination factor of zero means that destination pixels are not used
Begin_G BITMAPS
BlendFunc SRC_ALPHA, ZERO
Vertex2II 50, 30, 31, &H47
Color_A 128
Vertex2II 60, 40, 31, &H47
' Using the source alpha to control how much of the destination to keep
Begin_G BITMAPS
BlendFunc ZERO, SRC_ALPHA
Vertex2II 60, 40, 31, &H47
