sf::BlendMode Class Reference

Blending modes for drawing. More...

#include <SFML/Graphics/BlendMode.hpp>

Public Types
enum	Factor {   Zero , One , SrcColor , OneMinusSrcColor ,   DstColor , OneMinusDstColor , SrcAlpha , OneMinusSrcAlpha ,   DstAlpha , OneMinusDstAlpha }
	Enumeration of the blending factors. More...
enum	Equation {   Add , Subtract , ReverseSubtract , Min ,   Max }
	Enumeration of the blending equations. More...

Public Member Functions
	BlendMode ()
	Default constructor.
	BlendMode (Factor sourceFactor, Factor destinationFactor, Equation blendEquation=Add)
	Construct the blend mode given the factors and equation.
	BlendMode (Factor colorSourceFactor, Factor colorDestinationFactor, Equation colorBlendEquation, Factor alphaSourceFactor, Factor alphaDestinationFactor, Equation alphaBlendEquation)
	Construct the blend mode given the factors and equation.

Public Attributes
Factor	colorSrcFactor
	Source blending factor for the color channels.
Factor	colorDstFactor
	Destination blending factor for the color channels.
Equation	colorEquation
	Blending equation for the color channels.
Factor	alphaSrcFactor
	Source blending factor for the alpha channel.
Factor	alphaDstFactor
	Destination blending factor for the alpha channel.
Equation	alphaEquation
	Blending equation for the alpha channel.

Related Symbols
(Note that these are not member symbols.)
bool	operator== (const BlendMode &left, const BlendMode &right)
	Overload of the == operator.
bool	operator!= (const BlendMode &left, const BlendMode &right)
	Overload of the != operator.

Detailed Description

Blending modes for drawing.

sf::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 sf namespace:

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

In SFML, a blend mode can be specified every time you draw a sf::Drawable object to a render target. It is part of the sf::RenderStates compound that is passed to the member function sf::RenderTarget::draw().

See also

sf::RenderStates, sf::RenderTarget

Definition at line 41 of file BlendMode.hpp.

Member Enumeration Documentation

Equation

enum sf::BlendMode::Equation

Enumeration of the blending equations.

The equations are mapped directly to their OpenGL equivalents, specified by glBlendEquation() or glBlendEquationSeparate().

Enumerator
Add	Pixel = Src * SrcFactor + Dst * DstFactor.
Subtract	Pixel = Src * SrcFactor - Dst * DstFactor.
ReverseSubtract	Pixel = Dst * DstFactor - Src * SrcFactor.
Min	Pixel = min(Dst, Src)
Max	Pixel = max(Dst, Src)

Definition at line 69 of file BlendMode.hpp.

Factor

enum sf::BlendMode::Factor

Enumeration of the blending factors.

The factors are mapped directly to their OpenGL equivalents, specified by glBlendFunc() or glBlendFuncSeparate().

Enumerator
Zero	(0, 0, 0, 0)
One	(1, 1, 1, 1)
SrcColor	(src.r, src.g, src.b, src.a)
OneMinusSrcColor	(1, 1, 1, 1) - (src.r, src.g, src.b, src.a)
DstColor	(dst.r, dst.g, dst.b, dst.a)
OneMinusDstColor	(1, 1, 1, 1) - (dst.r, dst.g, dst.b, dst.a)
SrcAlpha	(src.a, src.a, src.a, src.a)
OneMinusSrcAlpha	(1, 1, 1, 1) - (src.a, src.a, src.a, src.a)
DstAlpha	(dst.a, dst.a, dst.a, dst.a)
OneMinusDstAlpha	(1, 1, 1, 1) - (dst.a, dst.a, dst.a, dst.a)

Definition at line 49 of file BlendMode.hpp.

Constructor & Destructor Documentation

BlendMode() [1/3]

sf::BlendMode::BlendMode

(

)

Default constructor.

Constructs a blending mode that does alpha blending.

BlendMode() [2/3]

sf::BlendMode::BlendMode	(	Factor	sourceFactor,
		Factor	destinationFactor,
		Equation	blendEquation = Add )

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.
blendEquation	Specifies how to combine the source and destination colors and alpha.

BlendMode() [3/3]

sf::BlendMode::BlendMode	(	Factor	colorSourceFactor,
		Factor	colorDestinationFactor,
		Equation	colorBlendEquation,
		Factor	alphaSourceFactor,
		Factor	alphaDestinationFactor,
		Equation	alphaBlendEquation )

Construct the blend mode given the factors and equation.

Parameters

colorSourceFactor	Specifies how to compute the source factor 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 Symbol Documentation

operator!=()

bool operator!= ( const BlendMode & left, const BlendMode & right )

related

Overload of the != operator.

Parameters

left	Left operand
right	Right operand

Returns

True if blending modes are different, false if they are equal

operator==()

bool operator== ( const BlendMode & left, const BlendMode & right )

related

Overload of the == operator.

Parameters

left	Left operand
right	Right operand

Returns

True if blending modes are equal, false if they are different

Member Data Documentation

alphaDstFactor

Factor sf::BlendMode::alphaDstFactor

Destination blending factor for the alpha channel.

Definition at line 121 of file BlendMode.hpp.

alphaEquation

Equation sf::BlendMode::alphaEquation

Blending equation for the alpha channel.

Definition at line 122 of file BlendMode.hpp.

alphaSrcFactor

Factor sf::BlendMode::alphaSrcFactor

Source blending factor for the alpha channel.

Definition at line 120 of file BlendMode.hpp.

colorDstFactor

Factor sf::BlendMode::colorDstFactor

Destination blending factor for the color channels.

Definition at line 118 of file BlendMode.hpp.

colorEquation

Equation sf::BlendMode::colorEquation

Blending equation for the color channels.

Definition at line 119 of file BlendMode.hpp.

colorSrcFactor

Factor sf::BlendMode::colorSrcFactor

Source blending factor for the color channels.

Definition at line 117 of file BlendMode.hpp.

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The documentation for this class was generated from the following file:

• BlendMode.hpp