Admin at 20:14, 12 December 2014

2014-12-12T20:14:59Z

Admin: Created page with "= Action = Specify pixel arithmetic. =
2014-12-12T20:12:27Z

Created page with "= Action = Specify pixel arithmetic. = Action =

Specify pixel arithmetic.

 

 

= Syntax =

BlendFunc  src, dst 

 

 

= Remarks =
<div style="padding: 0px; margin: 0px;">
{| cellspacing="0" cellpadding="0" border="0" style="border: none; border-spacing: 0px; border-collapse: collapse;"
|- style="vertical-align: top;"
| valign="top" width="101" style="width: 101px; border: 2px solid rgb(0, 0, 0);" |
src

| valign="top" width="808" style="width: 808px; border: 2px solid rgb(0, 0, 0);" |
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.

|- style="vertical-align: top;"
| valign="top" width="101" style="width: 101px; border: 2px solid rgb(0, 0, 0);" |
dst

| valign="top" width="808" style="width: 808px; border: 2px solid rgb(0, 0, 0);" |
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.

|}
</div>
 

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 =

[[Color_A]]

 

 

= Example =

← Older revision		Revision as of 20:14, 12 December 2014
Line 63:		Line 63:

	= <span class="f_Header">Example</span> =		= <span class="f_Header">Example</span> =
		+
		+	<source lang="bascomavr">
		+	' 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
		+	</source> [[File:Clip0096.png\|center\|Clip0096.png]] <source lang="bascomavr">
		+	' 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
		+	</source> [[File:Clip0097.png\|center\|Clip0097.png]] <source lang="bascomavr">
		+	' 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
		+	</source> [[File:Clip0098.png\|center\|Clip0098.png]]
		+
		+
		+
		+	<br/>{{Languages}}
		+
		+	[[Category:FT800 Commands]]