smk::BlendMode Struct Reference

#include <BlendMode.hpp>

Description

Blending modes for drawing.

When drawing something into a smk::RenderTarget, the smk::BlendMode represents how the colors are mixed with the colors already in the color buffer.

Commonly used BlendMode

SMK provides 6 predefined common BlendMode:

smk::BlendMode::Replace;   // dst = src
smk::BlendMode::Add;       // dst += src
smk::BlendMode::Subtract; // dst -= src
smk::BlendMode::Multiply;  // dst *= src
smk::BlendMode::Alpha;     // dst = src * a + dest * (1 - a)
smk::BlendMode::Invert;    // dst = 1 - dst

Example:

sprite.SetBlendMode(smk::BlendMode::Add);

Custom BlendMode:

This struct wrap all the parameters used by: https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glBlendEquation.xhtml

They define how the destination "dst" pixel is computed, knowing the source "src" pixel value.

dst.rgb = equation_rgb(src_rgb * src.rgb, dst_rgb / src.rgb)
dst.alpha = equation_alpha(src_alpha * src.alpha, dst_alpha / src.alpha)

Example

smk::BlendMode blend_mode = {
    GL_FUNC_ADD, // equation_rgb
    GL_FUNC_ADD, // equation_alpha
    GL_ONE,      // src_rgb factor
    GL_ZERO,     // dst_rgb factor
    GL_ONE,      // src_alpha factor
    GL_ZERO,     // dst_alpha factor
};
sprite.SetBlendMode(blend_mode);

Definition at line 62 of file BlendMode.hpp.

Public Member Functions
bool	operator== (const BlendMode &) const
bool	operator!= (const BlendMode &) const

Public Attributes
GLenum	equation_rgb = GL_FUNC_ADD
GLenum	equation_alpha = GL_FUNC_ADD
GLenum	src_rgb = GL_SRC_ALPHA
GLenum	dst_rgb = GL_ONE_MINUS_SRC_ALPHA
GLenum	src_alpha = GL_ONE
GLenum	dst_alpha = GL_ONE

Static Public Attributes
static const BlendMode	Replace
	destination = source. More...
static const BlendMode	Add
	destination += source. More...
static const BlendMode	Subtract
	destination -= source. More...
static const BlendMode	Multiply
	destination *= source More...
static const BlendMode	Alpha
	destination = source * source.a + destination * (1 - souce.a) More...
static const BlendMode	Invert
	destination = 1 - destination More...

Member Function Documentation

operator!=()

bool smk::BlendMode::operator!=

(

const BlendMode &

o

)

const

Definition at line 60 of file BlendMode.cpp.

                                                   {
  return !operator==(o);
}

operator==()

bool smk::BlendMode::operator==

(

const BlendMode &

o

)

const

Definition at line 51 of file BlendMode.cpp.

                                                   {
  return equation_rgb == o.equation_rgb &&      //
         equation_alpha == o.equation_alpha &&  //
         src_rgb == o.src_rgb &&                //
         dst_rgb == o.dst_rgb &&                //
         src_alpha == o.src_alpha &&            //
         dst_alpha == o.dst_alpha;              //
}

Member Data Documentation

Add

const BlendMode smk::BlendMode::Add

static

Initial value:

= {
    GL_FUNC_ADD, GL_FUNC_ADD, GL_SRC_ALPHA, GL_ONE, GL_ONE, GL_ONE,
}

destination += source.

Examples

framebuffer.cpp.

Definition at line 65 of file BlendMode.hpp.

Alpha

const BlendMode smk::BlendMode::Alpha

static

Initial value:

= {
    GL_FUNC_ADD,  GL_FUNC_ADD,
    GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,
    GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,
}

destination = source * source.a + destination * (1 - souce.a)

Definition at line 68 of file BlendMode.hpp.

dst_alpha

GLenum smk::BlendMode::dst_alpha = GL_ONE

Definition at line 79 of file BlendMode.hpp.

dst_rgb

GLenum smk::BlendMode::dst_rgb = GL_ONE_MINUS_SRC_ALPHA

Definition at line 77 of file BlendMode.hpp.

equation_alpha

GLenum smk::BlendMode::equation_alpha = GL_FUNC_ADD

Definition at line 73 of file BlendMode.hpp.

equation_rgb

GLenum smk::BlendMode::equation_rgb = GL_FUNC_ADD

Definition at line 72 of file BlendMode.hpp.

Invert

const BlendMode smk::BlendMode::Invert

static

Initial value:

= {
    GL_FUNC_ADD,
    GL_FUNC_ADD,
    GL_ONE_MINUS_DST_COLOR,
    GL_ZERO,
    GL_ONE_MINUS_SRC_ALPHA,
    GL_ZERO,
}

destination = 1 - destination

Definition at line 69 of file BlendMode.hpp.

Multiply

const BlendMode smk::BlendMode::Multiply

static

Initial value:

= {
    GL_FUNC_ADD, GL_FUNC_ADD, GL_DST_COLOR, GL_ZERO, GL_DST_ALPHA, GL_ZERO,
}

destination *= source

Definition at line 67 of file BlendMode.hpp.

Replace

const BlendMode smk::BlendMode::Replace

static

Initial value:

= {
    GL_FUNC_ADD, GL_FUNC_ADD, GL_ONE, GL_ZERO, GL_ONE, GL_ZERO,
}

destination = source.

Definition at line 64 of file BlendMode.hpp.

src_alpha

GLenum smk::BlendMode::src_alpha = GL_ONE

Definition at line 78 of file BlendMode.hpp.

src_rgb

GLenum smk::BlendMode::src_rgb = GL_SRC_ALPHA

Definition at line 76 of file BlendMode.hpp.

Subtract

const BlendMode smk::BlendMode::Subtract

static

Initial value:

= {
    GL_FUNC_REVERSE_SUBTRACT,
    GL_FUNC_REVERSE_SUBTRACT,
    GL_ONE,
    GL_ONE,
    GL_ONE,
    GL_ONE,
}

destination -= source.

Definition at line 66 of file BlendMode.hpp.

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The documentation for this struct was generated from the following files:

• /home/arthursonzogni/programmation/real/smk/include/smk/BlendMode.hpp
• /home/arthursonzogni/programmation/real/smk/src/smk/BlendMode.cpp