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view docs/man3/SDL_GLattr.3 @ 1543:98f9b16f565c
From: "Alex Volkov"
Date: Thu, 10 Nov 2005 21:53:40 -0500
Subject: [SDL] BUG[?]: 32bpp RGBA->RGB colorkey blit, no SDL_SRCALPHA
It seems there is either a documentation vs. reality mismatch or a real bug
in SDL_blit_N.c:BlitNtoNKey().
The exact blit in question is a 32bpp RGBA->RGB, where RGBA has SDL_COLORKEY
and *no* SDL_SRCALPHA flags. The doc in SDL_video.h states:
* RGBA->RGB:
* SDL_SRCALPHA not set:
* copy RGB.
* if SDL_SRCCOLORKEY set, only copy the pixels matching the
* RGB values of the source colour key, ignoring alpha in the
* comparison.
BlitNtoNKey(), however, forgets to "ignore alpha in the comparison". The
documentation makes perfect sense, so I think it is the code that is faulty.
The attached patch corrects the code.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 15 Mar 2006 15:43:15 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_GLattr" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_GLattr\- SDL GL Attributes .SH "ATTRIBUTES" .TP 20 \fBSDL_GL_RED_SIZE\fP Size of the framebuffer red component, in bits .TP 20 \fBSDL_GL_GREEN_SIZE\fP Size of the framebuffer green component, in bits .TP 20 \fBSDL_GL_BLUE_SIZE\fP Size of the framebuffer blue component, in bits .TP 20 \fBSDL_GL_ALPHA_SIZE\fP Size of the framebuffer alpha component, in bits .TP 20 \fBSDL_GL_DOUBLEBUFFER\fP 0 or 1, enable or disable double buffering .TP 20 \fBSDL_GL_BUFFER_SIZE\fP Size of the framebuffer, in bits .TP 20 \fBSDL_GL_DEPTH_SIZE\fP Size of the depth buffer, in bits .TP 20 \fBSDL_GL_STENCIL_SIZE\fP Size of the stencil buffer, in bits .TP 20 \fBSDL_GL_ACCUM_RED_SIZE\fP Size of the accumulation buffer red component, in bits .TP 20 \fBSDL_GL_ACCUM_GREEN_SIZE\fP Size of the accumulation buffer green component, in bits .TP 20 \fBSDL_GL_ACCUM_BLUE_SIZE\fP Size of the accumulation buffer blue component, in bits .TP 20 \fBSDL_GL_ACCUM_ALPHA_SIZE\fP Size of the accumulation buffer alpha component, in bits .SH "DESCRIPTION" .PP While you can set most OpenGL attributes normally, the attributes list above must be known \fIbefore\fP SDL sets the video mode\&. These attributes a set and read with \fI\fBSDL_GL_SetAttribute\fP\fR and \fI\fBSDL_GL_GetAttribute\fP\fR\&. .SH "SEE ALSO" .PP \fI\fBSDL_GL_SetAttribute\fP\fR, \fI\fBSDL_GL_GetAttribute\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01