|
|
Эта страница руководства является частью версии 5.0 Инструментов XCodeПолучить эти инструменты:
Если Вы выполняете версию Инструментов XCode кроме 5,0, просматриваете документацию локально:
Читать страницы руководстваСтраницы руководства предназначаются как справочник для людей, уже понимающих технологию.
|
GLBLENDFUNCSEPARATE(3G) OpenGL 3.3 GLBLENDFUNCSEPARATE(3G)
NAME
glBlendFuncSeparate - specify pixel arithmetic for RGB and alpha components separately
C SPECIFICATION
void glBlendFuncSeparate(GLenum srcRGB, GLenum dstRGB, GLenum srcAlpha, GLenum dstAlpha);
PARAMETERS
srcRGB
Specifies how the red, green, and blue blending factors are computed. The initial value is
GL_ONE.
dstRGB
Specifies how the red, green, and blue destination blending factors are computed. The initial
value is GL_ZERO.
srcAlpha
Specified how the alpha source blending factor is computed. The initial value is GL_ONE.
dstAlpha
Specified how the alpha destination blending factor is computed. The initial value is GL_ZERO.
DESCRIPTION
Pixels can be drawn using a function that blends the incoming (source) RGBA values with the RGBA
values that are already in the frame buffer (the destination values). Blending is initially disabled.
Use glEnable() and glDisable() with argument GL_BLEND to enable and disable blending.
glBlendFuncSeparate defines the operation of blending when it is enabled. srcRGB specifies which
method is used to scale the source RGB-color components. dstRGB specifies which method is used to
scale the destination RGB-color components. Likewise, srcAlpha specifies which method is used to
scale the source alpha color component, and dstAlpha specifies which method is used to scale the
destination alpha component. The possible methods are described in the following table. Each method
defines four scale factors, one each for red, green, blue, and alpha.
In the table and in subsequent equations, first source, second source and destination color
components are referred to as R s0 G s0 B s0 A s0, R s1 G s1 B s1 A s1, and R d G d B d A d,
respectively. The color specified by glBlendColor() is referred to as R c G c B c A c. They are
understood to have integer values between 0 and k R k G k B k A, where
and m R m G m B m A is the number of red, green, blue, and alpha bitplanes.
Source and destination scale factors are referred to as s R s G s B s A and d R d G d B d A. All
scale factors have range 0 1.
+----------------------------------+--------------------------------------------+----------------------------------------+
| | | |
| Parameter | RGB | Alpha |
| | Factor | Factor |
| | | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ZERO | 0 | 0 |
| | 0 | |
| | 0 | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE | 1 | 1 |
| | 1 | |
| | 1 | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_SRC_COLOR | R | A |
| | s0 | s0 |
| | | |
| | k | k |
| | R | A |
| | | |
| | | |
| | | |
| | G | |
| | s0 | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | s0 | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_SRC_COLOR | 1 | 1 |
| | 1 | - |
| | 1 | |
| | 1 | A |
| | | s0 |
| | - | |
| | | k |
| | | A |
| | R | |
| | s0 | |
| | | |
| | k | |
| | R | |
| | | |
| | | |
| | | |
| | G | |
| | s0 | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | s0 | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_DST_COLOR | R | A |
| | d | d |
| | | |
| | k | k |
| | R | A |
| | | |
| | | |
| | | |
| | G | |
| | d | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | d | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_DST_COLOR | 1 | 1 |
| | 1 | - |
| | 1 | |
| | | A |
| | - | d |
| | | |
| | | k |
| | R | A |
| | d | |
| | | |
| | k | |
| | R | |
| | | |
| | | |
| | | |
| | G | |
| | d | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | d | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_SRC_ALPHA | A | A |
| | s0 | s0 |
| | | |
| | k | k |
| | A | A |
| | | |
| | | |
| | | |
| | A | |
| | s0 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s0 | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_SRC_ALPHA | 1 | 1 |
| | 1 | - |
| | 1 | |
| | | A |
| | - | s0 |
| | | |
| | | k |
| | A | A |
| | s0 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s0 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s0 | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_DST_ALPHA | A | A |
| | d | d |
| | | |
| | k | k |
| | A | A |
| | | |
| | | |
| | | |
| | A | |
| | d | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | d | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_DST_ALPHA | 1 | 1 |
| | 1 | - |
| | 1 | |
| | | A |
| | - | d |
| | | |
| | | k |
| | A | A |
| | d | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | d | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | d | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_CONSTANT_COLOR | R | A |
| | c | c |
| | | |
| | G | |
| | c | |
| | | |
| | B | |
| | c | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_CONSTANT_COLOR | 1 | 1 |
| | 1 | - |
| | 1 | A |
| | | c |
| | - | |
| | | |
| | R | |
| | c | |
| | | |
| | G | |
| | c | |
| | | |
| | B | |
| | c | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_CONSTANT_ALPHA | A | A |
| | c | c |
| | | |
| | A | |
| | c | |
| | | |
| | A | |
| | c | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_CONSTANT_ALPHA | 1 | 1 |
| | 1 | - |
| | 1 | A |
| | | c |
| | - | |
| | | |
| | A | |
| | c | |
| | | |
| | A | |
| | c | |
| | | |
| | A | |
| | c | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_SRC_ALPHA_SATURATE | i | 1 |
| | i | |
| | i | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_SRC1_COLOR | R | A |
| | s1 | s1 |
| | | |
| | k | k |
| | R | A |
| | | |
| | | |
| | | |
| | G | |
| | s1 | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | s1 | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_SRC_COLOR | 1 | 1 |
| | 1 | - |
| | 1 | |
| | 1 | A |
| | | s1 |
| | - | |
| | | k |
| | | A |
| | R | |
| | s1 | |
| | | |
| | k | |
| | R | |
| | | |
| | | |
| | | |
| | G | |
| | s1 | |
| | | |
| | k | |
| | G | |
| | | |
| | | |
| | | |
| | B | |
| | s1 | |
| | | |
| | k | |
| | B | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_SRC1_ALPHA | A | A |
| | s1 | s1 |
| | | |
| | k | k |
| | A | A |
| | | |
| | | |
| | | |
| | A | |
| | s1 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s1 | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
|GL_ONE_MINUS_SRC_ALPHA | 1 | 1 |
| | 1 | - |
| | 1 | |
| | | A |
| | - | s1 |
| | | |
| | | k |
| | A | A |
| | s1 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s1 | |
| | | |
| | k | |
| | A | |
| | | |
| | | |
| | | |
| | A | |
| | s1 | |
| | | |
| | k | |
| | A | |
+----------------------------------+--------------------------------------------+----------------------------------------+
In the table,
To determine the blended RGBA values of a pixel, the system uses the following equations:
Despite the apparent precision of the above equations, blending arithmetic is not exactly specified,
because blending operates with imprecise integer color values. However, a blend factor that should be
equal to 1 is guaranteed not to modify its multiplicand, and a blend factor equal to 0 reduces its
multiplicand to 0. For example, when srcRGB is GL_SRC_ALPHA, dstRGB is GL_ONE_MINUS_SRC_ALPHA, and A
s is equal to k A, the equations reduce to simple replacement:
NOTES
Incoming (source) alpha is correctly thought of as a material opacity, ranging from 1.0 (K A),
representing complete opacity, to 0.0 (0), representing complete transparency.
When more than one color buffer is enabled for drawing, the GL performs blending separately for each
enabled buffer, using the contents of that buffer for destination color. (See glDrawBuffer().)
When dual source blending is enabled (i.e., one of the blend factors requiring the second color input
is used), the maximum number of enabled draw buffers is given by GL_MAX_DUAL_SOURCE_DRAW_BUFFERS,
which may be lower than GL_MAX_DRAW_BUFFERS.
ERRORS
GL_INVALID_ENUM is generated if either srcRGB or dstRGB is not an accepted value.
ASSOCIATED GETS
glGet() with argument GL_BLEND_SRC_RGB
glGet() with argument GL_BLEND_SRC_ALPHA
glGet() with argument GL_BLEND_DST_RGB
glGet() with argument GL_BLEND_DST_ALPHA
glIsEnabled() with argument GL_BLEND
SEE ALSO
glBlendColor(), glBlendFunc(), glBlendEquation(), glClear(), glDrawBuffer(), glEnable(), glLogicOp(),
glStencilFunc()
COPYRIGHT
Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software
B License. For details, see http://oss.sgi.com/projects/FreeB/.
OpenGL 3.3 03/08/2011 GLBLENDFUNCSEPARATE(3G)
|
Сообщение о проблемах
Способ сообщить о проблеме с этой страницей руководства зависит от типа проблемы:
- Ошибки содержания
- Ошибки отчета в содержании этой документации к проекту OpenGL.
- Отчеты об ошибках
- Сообщите об ошибках в функциональности описанного инструмента или API через Генератор отчетов Ошибки.
- Форматирование проблем
- Отчет, форматирующий ошибки в интерактивной версии этих страниц со ссылками на отзыв ниже.