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view docs/html/sdlupdaterects.html @ 3899:081aecdb0911 SDL-1.2
From: Gabriel Gambetta
To: SDL Mailing List <sdl@libsdl.org>
Date: Fri, 17 Nov 2006 00:39:29 -0200
Subject: [SDL] Alpha blending bug - fixed?
It turns out mm5 never got the correct value. This failed :
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (sf->Ashift) );
mm5 got 0xFF000018 instead of 0x00000018. However I did this :
Uint32 ashift = sf->Ashift;
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (ashift) );
and everything worked fine.
The only thing I could find out was that ashift is 32-bit aligned but
sf->Ashift isn't:
printf("ashift %8X [%d]\n", &ashift, (int)(&ashift) % 4);
printf("sf->Ashift %8X [%d]\n", &sf->Ashift, (int)(&sf->Ashift) % 4);
ashift at BFF0E0C4 [0]
sf->Ashift at 08AFB9CD [1]
Could this be the problem? If it is, the fix is extremely trivial.
Should I submit a patch?
--Gabriel
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Tue, 21 Nov 2006 23:17:00 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_UpdateRects</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Video" HREF="video.html"><LINK REL="PREVIOUS" TITLE="SDL_UpdateRect" HREF="sdlupdaterect.html"><LINK REL="NEXT" TITLE="SDL_Flip" HREF="sdlflip.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlupdaterect.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlflip.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLUPDATERECTS" ></A >SDL_UpdateRects</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN1392" ></A ><H2 >Name</H2 >SDL_UpdateRects -- Makes sure the given list of rectangles is updated on the given screen.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN1395" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN1396" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >void <B CLASS="FSFUNC" >SDL_UpdateRects</B ></CODE >(SDL_Surface *screen, int numrects, SDL_Rect *rects);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1402" ></A ><H2 >Description</H2 ><P >Makes sure the given list of rectangles is updated on the given screen. The rectangles must all be confined within the screen boundaries (no clipping is done).</P ><P >This function should not be called while <TT CLASS="PARAMETER" ><I >screen</I ></TT > is <A HREF="sdllocksurface.html" >locked</A >.</P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B >It is adviced to call this function only once per frame, since each call has some processing overhead. This is no restriction since you can pass any number of rectangles each time.</P ><P >The rectangles are not automatically merged or checked for overlap. In general, the programmer can use his knowledge about his particular rectangles to merge them in an efficient way, to avoid overdraw.</P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1411" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlupdaterect.html" ><TT CLASS="FUNCTION" >SDL_UpdateRect</TT ></A >, <A HREF="sdlrect.html" ><SPAN CLASS="STRUCTNAME" >SDL_Rect</SPAN ></A >, <A HREF="sdlsurface.html" ><SPAN CLASS="STRUCTNAME" >SDL_Surface</SPAN ></A >, <A HREF="sdllocksurface.html" ><TT CLASS="FUNCTION" >SDL_LockSurface</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlupdaterect.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlflip.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_UpdateRect</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="video.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_Flip</TD ></TR ></TABLE ></DIV ></BODY ></HTML >