Blending modes for drawing. More...

#include <gf/Blend.h>

Public Member Functions
constexpr	BlendMode ()
	Default constructor. More...

constexpr	BlendMode (BlendFactor sourceFactor, BlendFactor destinationFactor, BlendEquation equation=BlendEquation::Add)
	Construct the blend mode given the factors and equation. More...

constexpr	BlendMode (BlendFactor colorSourceFactor, BlendFactor colorDestinationFactor, BlendEquation colorBlendEquation, BlendFactor alphaSourceFactor, BlendFactor alphaDestinationFactor, BlendEquation alphaBlendEquation)
	Construct the blend mode given the factors and equation. More...

Public Attributes
BlendFactor	colorSrcFactor
	Source blending factor for the color channels. More...

BlendFactor	colorDstFactor
	Destination blending factor for the color channels. More...

BlendEquation	colorEquation
	Blending equation for the color channels. More...

BlendFactor	alphaSrcFactor
	Source blending factor for the alpha channel. More...

BlendFactor	alphaDstFactor
	Destination blending factor for the alpha channel. More...

BlendEquation	alphaEquation
	Blending equation for the alpha channel. More...

Related Functions
(Note that these are not member functions.)
constexpr bool	operator== (const BlendMode &lhs, const BlendMode &rhs)
	Equality operator. More...

Detailed Description

Blending modes for drawing.

gf::BlendMode is a class that represents a blend mode. A blend mode determines how the colors of an object you draw are mixed with the colors that are already in the buffer.

The class is composed of 6 components, each of which has its own public member variable:

color source factor (colorSrcFactor)
color destination Factor (colorDstFactor)
color blend equation (colorEquation)
alpha source factor (alphaSrcFactor)
alpha destination factor (alphaDstFactor)
alpha blend equation (alphaEquation)

The source factor specifies how the pixel you are drawing contributes to the final color. The destination factor specifies how the pixel already drawn in the buffer contributes to the final color.

The color channels RGB (red, green, blue; simply referred to as color) and A (alpha; the transparency) can be treated separately. This separation can be useful for specific blend modes, but most often you won't need it and will simply treat the color as a single unit.

The blend factors and equations correspond to their OpenGL equivalents. In general, the color of the resulting pixel is calculated according to the following formula (src is the color of the source pixel, dst the color of the destination pixel, the other variables correspond to the public members, with the equations being + or - operators):

dst.rgb = colorSrcFactor * src.rgb (colorEquation) colorDstFactor * dst.rgb

dst.a = alphaSrcFactor * src.a (alphaEquation) alphaDstFactor * dst.a

All factors and colors are represented as floating point numbers between 0 and 1. Where necessary, the result is clamped to fit in that range.

The most common blending modes are defined as constants in the gf::PredefinedBlendMonde namespace:

gf::BlendMode alphaBlending          = gf::BlendAlpha;
gf::BlendMode additiveBlending       = gf::BlendAdd;
gf::BlendMode multiplicativeBlending = gf::BlendMultiply;
gf::BlendMode noBlending             = gf::BlendNone;

A blend mode can be specified every time you draw a gf::Drawable object to a gf::RenderWindow. It is part of the gf::RenderStates compound that is passed to the member function gf::RenderTarget::draw().

See also: gf::BlendFactor, gf::BlendEquation, gf::RenderStates, gf::RenderWindow

Constructor & Destructor Documentation

constexpr gf::BlendMode::BlendMode ( )

inline

Default constructor.

Constructs a blending mode that does alpha blending.

constexpr gf::BlendMode::BlendMode	(	BlendFactor	sourceFactor,
		BlendFactor	destinationFactor,
		BlendEquation	equation = `BlendEquation::Add`
	)

inline

Construct the blend mode given the factors and equation.

This constructor uses the same factors and equation for both color and alpha components. It also defaults to the Add equation.

Parameters

sourceFactor	Specifies how to compute the source factor for the color and alpha channels.
destinationFactor	Specifies how to compute the destination factor for the color and alpha channels.
equation	Specifies how to combine the source and destination colors and alpha.

constexpr gf::BlendMode::BlendMode	(	BlendFactor	colorSourceFactor,
		BlendFactor	colorDestinationFactor,
		BlendEquation	colorBlendEquation,
		BlendFactor	alphaSourceFactor,
		BlendFactor	alphaDestinationFactor,
		BlendEquation	alphaBlendEquation
	)

inline

Construct the blend mode given the factors and equation.

Parameters

colorSourceFactor	Specifies how to compute the source function for the color channels.
colorDestinationFactor	Specifies how to compute the destination factor for the color channels.
colorBlendEquation	Specifies how to combine the source and destination colors.
alphaSourceFactor	Specifies how to compute the source factor.
alphaDestinationFactor	Specifies how to compute the destination factor.
alphaBlendEquation	Specifies how to combine the source and destination alphas.

Friends And Related Function Documentation

constexpr bool operator==	(	const BlendMode &	lhs,
		const BlendMode &	rhs
	)

Parameters

lhs	First blend mode
rhs	Second blend mode

Returns: True if the blend modes are the same

Member Data Documentation

BlendFactor gf::BlendMode::alphaDstFactor

Destination blending factor for the alpha channel.

BlendEquation gf::BlendMode::alphaEquation

Blending equation for the alpha channel.

BlendFactor gf::BlendMode::alphaSrcFactor

Source blending factor for the alpha channel.

BlendFactor gf::BlendMode::colorDstFactor

Destination blending factor for the color channels.

BlendEquation gf::BlendMode::colorEquation

Blending equation for the color channels.

BlendFactor gf::BlendMode::colorSrcFactor

Source blending factor for the color channels.

Public Member Functions

Public Attributes

Related Functions

Detailed Description

Constructor & Destructor Documentation

Friends And Related Function Documentation

Member Data Documentation