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diff --git a/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/blendfunc.gl b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/blendfunc.gl new file mode 100644 index 000000000..7afec2732 --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/blendfunc.gl @@ -0,0 +1,264 @@ +_C_ License Applicability. Except to the extent portions of this file are +_C_ made subject to an alternative license as permitted in the SGI Free +_C_ Software License B, Version 1.1 (the "License"), the contents of this +_C_ file are subject only to the provisions of the License. You may not use +_C_ this file except in compliance with the License. You may obtain a copy +_C_ of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 +_C_ Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: +_C_ +_C_ http://oss.sgi.com/projects/FreeB +_C_ +_C_ Note that, as provided in the License, the Software is distributed on an +_C_ "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS +_C_ DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND +_C_ CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A +_C_ PARTICULAR PURPOSE, AND NON-INFRINGEMENT. +_C_ +_C_ Original Code. The Original Code is: OpenGL Sample Implementation, +_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, +_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. +_C_ Copyright in any portions created by third parties is as indicated +_C_ elsewhere herein. All Rights Reserved. +_C_ +_C_ Additional Notice Provisions: The application programming interfaces +_C_ established by SGI in conjunction with the Original Code are The +_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released +_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version +_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X +_C_ Window System(R) (Version 1.3), released October 19, 1998. This software +_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation +_C_ published by SGI, but has not been independently verified as being +_C_ compliant with the OpenGL(R) version 1.2.1 Specification. +_C_ +_C_ The first character in this file must be an '_'! +_C_ Anything on a line after _C_ is ignored +_define(_filters,tbl|eqn)_C_ +_C_ eqn is automatically replaced with neqn for nroff +_header(BlendFunc, specify pixel arithmetic) +_names(BlendFunc) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1) +Specifies how the red, green, blue, +and alpha source blending factors are computed. +The following symbolic constants are accepted: +_const(ZERO), +_const(ONE), +_const(DST_COLOR), +_const(ONE_MINUS_DST_COLOR), +_const(SRC_ALPHA), +_const(ONE_MINUS_SRC_ALPHA), +_const(DST_ALPHA), +_const(ONE_MINUS_DST_ALPHA), and +_const(SRC_ALPHA_SATURATE). +The initial value is _const(ONE). +.TE + +Additionally, if the _arbstring(imaging) extension is supported, the +following constants are accepted: +_const(CONSTANT_COLOR), +_const(ONE_MINUS_CONSTANT_COLOR), +_const(CONSTANT_ALPHA), +_const(ONE_MINUS_CONSTANT_ALPHA). +_phead(_param2) +Specifies how the red, green, blue, +and alpha destination blending factors are computed. +Eight symbolic constants are accepted: +_const(ZERO), +_const(ONE), +_const(SRC_COLOR), +_const(ONE_MINUS_SRC_COLOR), +_const(SRC_ALPHA), +_const(ONE_MINUS_SRC_ALPHA), +_const(DST_ALPHA), and +_const(ONE_MINUS_DST_ALPHA). +The initial value is _const(ZERO). +.TE + +Additionally, if the _arbstring(imaging) extension is supported, the +following constants are accepted: +_const(CONSTANT_COLOR), +_const(ONE_MINUS_CONSTANT_COLOR), +_const(CONSTANT_ALPHA), +_const(ONE_MINUS_CONSTANT_ALPHA). +.SH DESCRIPTION +In RGBA mode, 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 _cmnd(Enable) and _cmnd(Disable) with argument _const(BLEND) +to enable and disable blending. +.P +_cmnd defines the operation of blending when it is enabled. +_param1 specifies which of nine methods is used to scale the +source color components. +_param2 specifies which of eight methods is used to scale the +destination color components. +The eleven possible methods are described in the following table. +Each method defines four scale factors, +one each for red, green, blue, and alpha. +.P +In the table and in subsequent equations, source and destination +color components are referred to as +$(R sub s , G sub s , B sub s , A sub s )$ and +$(R sub d , G sub d , B sub d , A sub d )$. +The color specified by _cmnd(BlendColor) is referred to as +$(R sub c , G sub c , B sub c , A sub c )$. +They are understood to have integer values between 0 and +$(k sub R , k sub G , k sub B , k sub A )$, +where +.P +.RS +.ce +$k sub c ~=~ 2 sup m sub c - 1$ +.RE +.P +and +$(m sub R , m sub G , m sub B , m sub A )$ +is the number of red, +green, +blue, +and alpha bitplanes. +.P +Source and destination scale factors are referred to as +$(s sub R , s sub G , s sub B , s sub A )$ and +$(d sub R , d sub G , d sub B , d sub A )$. +The scale factors described in the table, +denoted $(f sub R , f sub G , f sub B , f sub A )$, +represent either source or destination factors. +All scale factors have range [0,\ 1]. +.P +.TS +center; +lb cb +l c . +_ +Parameter $(f sub R , ~~ f sub G , ~~ f sub B , ~~ f sub A )$ +_ +_const(ZERO) $(0, ~0, ~0, ~0 )$ +_const(ONE) $(1, ~1, ~1, ~1 )$ +_const(SRC_COLOR) $(R sub s / k sub R , ~G sub s / k sub G , ~B sub s / k sub B , ~A sub s / k sub A )$ +_const(ONE_MINUS_SRC_COLOR) $(1, ~1, ~1, ~1 ) ~-~ (R sub s / k sub R , ~G sub s / k sub G , ~B sub s / k sub B , ~A sub s / k sub A )$ +_const(DST_COLOR) $(R sub d / k sub R , ~G sub d / k sub G , ~B sub d / k sub B , ~A sub d / k sub A )$ +_const(ONE_MINUS_DST_COLOR) $(1, ~1, ~1, ~1 ) ~-~ (R sub d / k sub R , ~G sub d / k sub G , ~B sub d / k sub B , ~A sub d / k sub A )$ +_const(SRC_ALPHA) $(A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A )$ +_const(ONE_MINUS_SRC_ALPHA) $(1, ~1, ~1, ~1 ) ~-~ (A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A )$ +_const(DST_ALPHA) $(A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A )$ +_const(ONE_MINUS_DST_ALPHA) $(1, ~1, ~1, ~1 ) ~-~ (A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A )$ +_const(SRC_ALPHA_SATURATE) $(i, ~i, ~i, ~1 )$ +_const(CONSTANT_COLOR) $(R sub c, G sub c, B sub c, A sub c)$ +_const(ONE_MINUS_CONSTANT_COLOR) $(1, ~1, ~1, ~1 ) ~-~ (R sub c, G sub c, B sub c, A sub c)$ +_const(CONSTANT_ALPHA) $(A sub c, A sub c, A sub c, A sub c)$ +_const(ONE_MINUS_CONSTANT_ALPHA) $(1, ~1, ~1, ~1 ) ~-~ (A sub c, A sub c, A sub c, A sub c)$ +_ +.TE +.sp +In the table, +.P +.RS +.nf +.IP +$i ~=~ min (A sub s , ~k sub A ~-~ A sub d ) ~/~ k sub A$ +.fi +.RE +.P +To determine the blended RGBA values of a pixel when drawing in RGBA mode, +the system uses the following equations: +.P +.RS +.nf +.IP +$R sub d ~=~ mark min ( k sub R, ~R sub s~s sub R~+~R sub d~d sub R )$ +$G sub d ~=~ lineup min ( k sub G, ~G sub s~s sub G~+~G sub d~d sub G )$ +$B sub d ~=~ lineup min ( k sub B, ~B sub s~s sub B~+~B sub d~d sub B )$ +$A sub d ~=~ lineup min ( k sub A, ~A sub s~s sub A~+~A sub d~d sub A )$ +.fi +.RE +.P +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 _param1 is _const(SRC_ALPHA), +_param2 is _const(ONE_MINUS_SRC_ALPHA), +and $A sub s$ is equal to $k sub A$, +the equations reduce to simple replacement: +.P +.RS +.nf +.IP +$R sub d ~=~ mark R sub s$ +$G sub d ~=~ lineup G sub s$ +$B sub d ~=~ lineup B sub s$ +$A sub d ~=~ lineup A sub s$ +.fi +.RE +.P +.SH EXAMPLES +.P +Transparency is best implemented using blend function +(_const(SRC_ALPHA), _const(ONE_MINUS_SRC_ALPHA)) +with primitives sorted from farthest to nearest. +Note that this transparency calculation does not require +the presence of alpha bitplanes in the frame buffer. +.P +Blend function +(_const(SRC_ALPHA), _const(ONE_MINUS_SRC_ALPHA)) +is also useful for rendering antialiased points and lines +in arbitrary order. +.P +Polygon antialiasing is optimized using blend function +.br +(_const(SRC_ALPHA_SATURATE), _const(ONE)) +with polygons sorted from nearest to farthest. +(See the _cmnd(Enable), _cmnd(Disable) reference page and the +_const(POLYGON_SMOOTH) argument for information on polygon antialiasing.) +Destination alpha bitplanes, +which must be present for this blend function to operate correctly, +store the accumulated coverage. +.SH NOTES +Incoming (source) alpha is correctly thought of as a material opacity, +ranging from 1.0 ($K sub A$), representing complete opacity, +to 0.0 (0), representing complete +transparency. +.P +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 _cmnd(DrawBuffer).) +.P +Blending affects only RGBA rendering. +It is ignored by color index renderers. +.P +_const(CONSTANT_COLOR), _const(ONE_MINUS_CONSTANT_COLOR), +_const(CONSTANT_ALPHA), _const(ONE_MINUS_CONSTANT_ALPHA) are only +available if the _arbstring(imaging) is supported by your implementation. +.SH ERRORS +_const(INVALID_ENUM) is generated if either _param1 or _param2 is not an +accepted value. +.P +_const(INVALID_OPERATION) is generated if _cmnd +is executed between the execution of _cmnd(Begin) +and the corresponding execution of _cmnd(End). +.SH ASSOCIATED GETS +_cmnd(Get) with argument _const(BLEND_SRC) +.br +_cmnd(Get) with argument _const(BLEND_DST) +.br +_cmnd(IsEnabled) with argument _const(BLEND) +.br +.SH SEE ALSO +_cmnd(AlphaFunc), +_cmnd(BlendColor), +_cmnd(BlendEquation), +_cmnd(Clear), +_cmnd(DrawBuffer), +_cmnd(Enable), +_cmnd(LogicOp), +_cmnd(StencilFunc) |