Mercurial > sdl-ios-xcode
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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 | 74212992fb08 |
children | 14717b52abc0 |
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<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> <HTML ><HEAD ><TITLE >Introduction</TITLE > </HEAD ><BODY BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" > <HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="PREFACE" ><H1 ><A NAME="AEN8" >Introduction</A ></H1 ><P >This library is designed to make it easy to write games that run on Linux, Win32 and BeOS using the various native high-performance media interfaces, (for video, audio, etc) and presenting a single source-code level API to your application. This is a fairly low level API, but using this, completely portable applications can be written with a great deal of flexibility.</P ><P >The library is loaded as a dynamically linked library on its native platform, and is currently compiled natively for Linux, compiled for Win32 using a Linux hosted GCC <A HREF="http://www.libsdl.org/Xmingw32/" TARGET="_top" >cross-compilation</A > environment, and compiled using the EGCS C++ compiler under BeOS.</P ><P >An introduction to SDL can be found online at: <A HREF="http://www.libsdl.org/intro/toc.html" TARGET="_top" >http://www.libsdl.org/intro/</A > </P ><P >There are code examples on each of the main library pages, and there are fully fleshed example C++ classes and programs in the examples archive, available on the <A HREF="http://www.libsdl.org/download.html" TARGET="_top" >SDL download page</A >.</P ><P >For an introduction to basic multi-media programming concepts, you might try some of the following links: <P ></P ><UL ><LI ><P ><A HREF="http://www.ziron.com/links/" TARGET="_top" >Game Programming Links</A ></P ></LI ><LI ><P ><A HREF="http://developer.dungeon-crawl.com/" TARGET="_top" >Game Developer Search Engine</A ></P ></LI ></UL ></P ><P >Enjoy!</P ><P > Sam Lantinga <TT CLASS="EMAIL" ><<A HREF="mailto:slouken@libsdl.org" ><A HREF="mailto:slouken@libsdl.org" TARGET="_top" >slouken@libsdl.org</A ></A >></TT ></P > <P> <br><br><HR> <H1>Table of Contents</H1> <UL> <LI><A HREF="html/index.html">Full Table of Contents</A></LI> <LI><A HREF="html/guide.html">The SDL Guide</A></LI> <LI><A HREF="html/reference.html">The SDL Reference</A></LI> <UL> <LI><A HREF="html/general.html">Initialization</A></LI> <LI><A HREF="html/video.html">Video</A></LI> <LI><A HREF="html/wm.html">Window Manager</A></LI> <LI><A HREF="html/event.html">Event Handling</A></LI> <LI><A HREF="html/joystick.html">Joystick</A></LI> <LI><A HREF="html/audio.html">Audio</A></LI> <LI><A HREF="html/cdrom.html">CDROM</A></LI> <LI><A HREF="html/thread.html">Threads</A></LI> <LI><A HREF="html/time.html">Timers</A></LI> </UL> </UL> </DIV ></BODY ></HTML >