SDLx::Sprite rotation artifacts and size limitation
Hi, Running Strawberry Perl on Win 7 x64 I have installed SDL and Alien::SDL from CPAN (selecting option 1) and I'm writing a twin stick shooter game for fun. I have three questions: 1) When rotating sprites using the -rotation() method the sprites often get a line of artifact noise along one of the sides, usually the right and/or bottom edge of the original sprite. The effect is not constant and the original sprites are all 100% transparent at the edges so I believe the artifacts are introduced by the rotation algorithm. Or is it? 2) After experimenting with different sprite sizes, it seems that there's a limit somewhere. When attempting to load a sprite that's too large, I get a seemingly valid sprite object that just doesn't seem to render anything. Is there a known size limit to sprites or could this be a driver issue? Or am I overlooking something? 3) How exactly does the 'alpha_key' property work? I tried setting it to the ubiquitous bright purple (FF00FF) but this just caused half my sprites to become completely invisible. When using PNG files with an alpha channel, using a key color seems pointless to me, which makes the POD example code somewhat confusing: # spawning can include almost all of the above: my $sprite = SDLx::Sprite-new( image = 'hero.png', # or surface = SDL::Surface rect= SDL::Rect,# or x = $x, y = $y clip= SDL::Rect, alpha_key = SDL::Color, # or [$r, $g, $b] alpha = 1, rotation = 45, # degrees ); If anyone is interested in a sneak peek, here's the code: http://floyd.atc.no/Programming/Perl/IfItMoves/2012-04-23.zip Suggestions are welcome :-) -- Andreas Lund (fl...@atc.no) Tel: +47 90077162 #include disclaimer.h Look at you hacker, panting and sweating as you run through my corridors. How can you challenge a perfect immortal machine? -- SHODAN, System Shock
Re: SDLx::Sprite rotation artifacts and size limitation
Hi Andreas, Am 23.04.2012 09:53, schrieb Andreas Lund: Hi, Running Strawberry Perl on Win 7 x64 I have installed SDL and Alien::SDL from CPAN (selecting option 1) and I'm writing a twin stick shooter game for fun. I have three questions: 1) When rotating sprites using the -rotation() method the sprites often get a line of artifact noise along one of the sides, usually the right and/or bottom edge of the original sprite. The effect is not constant and the original sprites are all 100% transparent at the edges so I believe the artifacts are introduced by the rotation algorithm. Or is it? Do you have a screenshot? I just can think of problems when anti-aliasing and transparency come together... 2) After experimenting with different sprite sizes, it seems that there's a limit somewhere. When attempting to load a sprite that's too large, I get a seemingly valid sprite object that just doesn't seem to render anything. Is there a known size limit to sprites or could this be a driver issue? Or am I overlooking something? See http://sdl.perl.org/SDL-GFX-Rotozoom.html, I believe width+height must be less than 16384. 3) How exactly does the 'alpha_key' property work? I tried setting it to the ubiquitous bright purple (FF00FF) but this just caused half my sprites to become completely invisible. When using PNG files with an alpha channel, using a key color seems pointless to me, which makes the POD example code somewhat confusing: # spawning can include almost all of the above: my $sprite = SDLx::Sprite-new( image = 'hero.png', # or surface = SDL::Surface rect= SDL::Rect,# or x = $x, y = $y clip= SDL::Rect, alpha_key = SDL::Color, # or [$r, $g, $b] alpha = 1, rotation = 45, # degrees ); Ya, alpha and blitting is not the easiest things as someone might think. If you have a png file with alpha channel, and applying an alpha color key to it should reset the alpha channel. At least that is what I would expect. You cant mix the alpha channel and alpha key. If anyone is interested in a sneak peek, here's the code: http://floyd.atc.no/Programming/Perl/IfItMoves/2012-04-23.zip Will have a look then ;o) Cheers, FROGGS Suggestions are welcome :-) -- Andreas Lund (fl...@atc.no) Tel: +47 90077162 #include disclaimer.h Look at you hacker, panting and sweating as you run through my corridors. How can you challenge a perfect immortal machine? -- SHODAN, System Shock
Re: SDLx::Sprite rotation artifacts and size limitation
Mon, 23 Apr 2012 20:56:21 +0200, Tobias Leich em...@froggs.de wrote: Hi again, Its quit cool, but I'm not that good when it comes to do two things at the same time ;o) I can't see anything strange when rotating the player-sprite. The problem isn't constant but it's very annoying when it does appear. I've posted an example screenshot here: http://floyd.atc.no/Programming/Perl/IfItMoves/SDL-Sprite-artifacts.png Tip: If you have downloaded the code, try setting $cheatmode = 1 to become immortal. You can now hit TAB a few times to spawn more enemies. -- Andreas Lund (fl...@atc.no) Tel: +47 90077162 #include disclaimer.h Look at you hacker, panting and sweating as you run through my corridors. How can you challenge a perfect immortal machine? -- SHODAN, System Shock
