Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_SetAlpha.3 @ 1438:1f4f09641645
Date: Sun, 26 Feb 2006 11:25:09 +0900
From: Hayashi Naoyuki
Subject: Re: [SDL] CVS stable again, please update SDL ports
Some problems are caused on Tru64 UNIX.
If applying SDL12-osf1.path, these problems are fixed.
1. configure-script say "recursive mutexes... no" and "pthread
semaphores... no".
checking for pthreads... yes
checking for recursive mutexes... no
checking for pthread semaphores... no
This is because it compiled without pthread_cflags and pthread_lib when
checking recursive mutexes and pthread semaphores.
2. Compiling src/audio/mme/SDL_mmeaudio.c fails.
cc: Severe: ./src/audio/mme/SDL_mmeaudio.c, line 25: Cannot find file
<mme_api.h> specified in #include directive. (noinclfilef)
#include <mme_api.h>
-^
This is because BUILD_CFLAGS is wrong.
3. Compiling src/cdrom/osf/SDL_syscdrom.c fails.
cc: Warning: ./src/cdrom/osf/SDL_syscdrom.c, line 176: Too few actual
parameters in the invocation of the macro "SDL_stack_alloc". (toofewactuals)
cdpath = SDL_stack_alloc(len);
------------------------------------^
cc: Error: ./src/cdrom/osf/SDL_syscdrom.c, line 176: Invalid expression.
(badexpr)
cdpath = SDL_stack_alloc(len);
-----------------^
SDL_stack_alloc is defined in include/SDL_stdinc.h.
#define SDL_stack_alloc(type, count) (type*)alloca(sizeof(type)*count)
4. Linking fails if running configure with --enable-x11-shared=yes.
/usr/ccs/bin/ld:
Warning: Unresolved:
p_XData32
5. Compiling src/video/x11/SDL_x11dyn.c fails if running configure with
--enable-x11-shared=no.
cc: Error: ./src/video/x11/SDL_x11sym.h, line 149: In this statement,
"_SmtBufferOverflow" is not declared. (undeclared)
SDL_X11_SYM(1,void,_SmtBufferOverflow,(Display *dpy,register smtDisplayPtr))
^
cc: Error: ./src/video/x11/SDL_x11sym.h, line 150: In this statement,
"_SmtBufferOverflow" is not declared. (undeclared)
SDL_X11_SYM(1,void,_SmtBufferOverflow,(Display *dpy,register smtDisplayPtr))
^
cc: Error: ./src/video/x11/SDL_x11sym.h, line 150: In this statement,
"_SmtIpError" is not declared. (undeclared)
SDL_X11_SYM(1,void,_SmtIpError,(Display *dpy,register smtDisplayPtr, int))
^
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 26 Feb 2006 04:54:01 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
|---|---|
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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1 .TH "SDL_SetAlpha" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_SetAlpha\- Adjust the alpha properties of a surface | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBint \fBSDL_SetAlpha\fP\fR(\fBSDL_Surface *surface, Uint32 flag, Uint8 alpha\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 .RS | |
| 12 \fBNote: | |
| 13 .PP | |
| 14 This function and the semantics of SDL alpha blending have changed since version 1\&.1\&.4\&. Up until version 1\&.1\&.5, an alpha value of 0 was considered opaque and a value of 255 was considered transparent\&. This has now been inverted: 0 (\fBSDL_ALPHA_TRANSPARENT\fP) is now considered transparent and 255 (\fBSDL_ALPHA_OPAQUE\fP) is now considered opaque\&. | |
| 15 .RE | |
| 16 .PP | |
|
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17 \fBSDL_SetAlpha\fP is used for setting the per-surface alpha value and/or enabling and disabling alpha blending\&. |
| 0 | 18 .PP |
|
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19 The\fBsurface\fR parameter specifies which surface whose alpha attributes you wish to adjust\&. \fBflags\fR is used to specify whether alpha blending should be used (\fBSDL_SRCALPHA\fP) and whether the surface should use RLE acceleration for blitting (\fBSDL_RLEACCEL\fP)\&. \fBflags\fR can be an OR\&'d combination of these two options, one of these options or 0\&. If \fBSDL_SRCALPHA\fP is not passed as a flag then all alpha information is ignored when blitting the surface\&. The \fBalpha\fR parameter is the per-surface alpha value; a surface need not have an alpha channel to use per-surface alpha and blitting can still be accelerated with \fBSDL_RLEACCEL\fP\&. |
| 0 | 20 .PP |
| 21 .RS | |
| 22 \fBNote: | |
| 23 .PP | |
| 24 The per-surface alpha value of 128 is considered a special case and is optimised, so it\&'s much faster than other per-surface values\&. | |
| 25 .RE | |
| 26 .PP | |
| 27 Alpha effects surface blitting in the following ways: | |
| 28 .TP 20 | |
| 29 RGBA->RGB with \fBSDL_SRCALPHA\fP | |
| 30 The source is alpha-blended with the destination, using the alpha channel\&. \fBSDL_SRCCOLORKEY\fP and the per-surface alpha are ignored\&. | |
| 31 .TP 20 | |
| 32 RGBA->RGB without \fBSDL_SRCALPHA\fP | |
| 33 The RGB data is copied from the source\&. The source alpha channel and the per-surface alpha value are ignored\&. | |
| 34 .TP 20 | |
| 35 RGB->RGBA with \fBSDL_SRCALPHA\fP | |
|
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Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
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36 The source is alpha-blended with the destination using the per-surface alpha value\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. The alpha channel of the copied pixels is set to opaque\&. |
| 0 | 37 .TP 20 |
| 38 RGB->RGBA without \fBSDL_SRCALPHA\fP | |
|
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Sam Lantinga <slouken@lokigames.com>
parents:
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diff
changeset
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39 The RGB data is copied from the source and the alpha value of the copied pixels is set to opaque\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. |
| 0 | 40 .TP 20 |
| 41 RGBA->RGBA with \fBSDL_SRCALPHA\fP | |
| 42 The source is alpha-blended with the destination using the source alpha channel\&. The alpha channel in the destination surface is left untouched\&. \fBSDL_SRCCOLORKEY\fP is ignored\&. | |
| 43 .TP 20 | |
| 44 RGBA->RGBA without \fBSDL_SRCALPHA\fP | |
| 45 The RGBA data is copied to the destination surface\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
| 46 .TP 20 | |
| 47 RGB->RGB with \fBSDL_SRCALPHA\fP | |
| 48 The source is alpha-blended with the destination using the per-surface alpha value\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
| 49 .TP 20 | |
| 50 RGB->RGB without \fBSDL_SRCALPHA\fP | |
| 51 The RGB data is copied from the source\&. If \fBSDL_SRCCOLORKEY\fP is set, only the pixels not matching the colorkey value are copied\&. | |
|
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parents:
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diff
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52 .PP |
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53 .RS |
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54 \fBNote: |
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55 .PP |
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56 Note that RGBA->RGBA blits (with SDL_SRCALPHA set) keep the alpha of the destination surface\&. This means that you cannot compose two arbitrary RGBA surfaces this way and get the result you would expect from "overlaying" them; the destination alpha will work as a mask\&. |
|
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57 .PP |
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58 Also note that per-pixel and per-surface alpha cannot be combined; the per-pixel alpha is always used if available |
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59 .RE |
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60 .SH "RETURN VALUE" |
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61 .PP |
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62 This function returns \fB0\fR, or \fB-1\fR if there was an error\&. |
| 0 | 63 .SH "SEE ALSO" |
| 64 .PP | |
| 65 \fI\fBSDL_MapRGBA\fP\fR, \fI\fBSDL_GetRGBA\fP\fR, \fI\fBSDL_DisplayFormatAlpha\fP\fR, \fI\fBSDL_BlitSurface\fP\fR | |
|
181
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Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
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66 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |