====== SHBlendModes ======
---- dataentry extension ----
type          : extension
author_mail   : shilo86@gmail.com Shilo White
description   : A category that allows blend modes via presets or custom blends.
lastupdate_dt : 2012-03-11
compatible    : v1.X
depends       : 
tags          : blend, blending, mode, blend mode
homepage_url  : https://gist.github.com/2019733
download_url  : https://gist.github.com/gists/2019733/download
----

===== Properties =====
=== blendMode ===
An integer that specifies a preset blend mode. The initial value is SHBlendModeAuto.
<code>@property (nonatomic, assign) SHBlendMode blendMode;</code>
See [[shblendmodes#presets|presets]] for valid values.

=== blendModeName ===
A readonly string that describes what blending mode is in use. The initial value is "auto".
<code>@property (nonatomic, readonly) NSString *blendModeName;</code>

=== blendModeSourceFactor ===
An integer that specifies how the red, green, blue, and alpha source blending factors are computed. The following symbolic constants are accepted: GL_ZERO, GL_ONE, GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA, and GL_SRC_ALPHA_SATURATE. The initial value is GL_ZERO.
<code>@property (nonatomic, assign) GLenum blendModeSourceFactor;</code>
Changing this property will automatically set "blendMode" property to SHBlendModeCustom.

=== blendModeDestinationFactor ===
An integer that specifies how the red, green, blue, and alpha destination blending factors are computed. Eight symbolic constants are accepted: GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, and GL_ONE_MINUS_DST_ALPHA. The initial value is GL_ZERO.
<code>@property (nonatomic, assign) GLenum blendModeDestinationFactor;</code>
Changing this property will automatically set "blendMode" property to SHBlendModeCustom.

===== Instance Methods =====
=== setBlendModeSourceFactor:destinationFactor:===
Sets the blend mode source factor and destination source factor. See [[shblendmodes#blendModeSourceFactor|blendModeSourceFactor]] and [[shblendmodes#blendModeDestinationFactor|blendModeDestinationFactor]].
<code>- (void)setBlendModeSourceFactor:(GLenum)blendModeSourceFactor destinationFactor:(GLenum)blendModeDestinationFactor;</code>
Calling this method will automatically set "blendMode" property to SHBlendModeCustom.

===== Presets =====
  * **SHBlendModeAuto** - Blend mode will automatically be handled by Sparrow. (Default)
  * **SHBlendModeNormal** - The source and destination alpha value will blend normally.
  * **SHBlendModeInverseMask** - The source alpha will be 100% and the destination alpha value will be 0%. This preset is only useful for drawing an object into a SPRenderTexture.
  * **SHBlendModeErase** - Erases the pixels behind the object's bound, or if it is a SPImage, the pixels behind it will be erased based on the alpha value of each pixel inside the SPImage.
  * **SHBlendModeCustom** - Allows you to specify the blend source factor and blend destination factor manually.
  * More presets to come...

===== Source Code =====
%gist(2019733)%