[SDL] Loading bitmaps with transparency? (Torsten Giebl)
Patricia Curtis
patricia.curtis at gmail.com
Mon Mar 5 09:38:22 PST 2007
On 3/5/07, sdl-request at lists.libsdl.org <sdl-request at lists.libsdl.org>
wrote:
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> Hi
I don't want to get into an argument of coding styles as this is not
the place, but i do know about errors and catching them, I just showed you a
very simplistic version, just to get you going. sorry for the confusion, by
the way i have been coding since 1982 and in that time i have written 27
games, check www.unboxedgames.com for the list and i think you will be
pleasantly surprised.
Trish
Today's Topics:
>
> 1. Re: Loading bitmaps with transparency? (Torsten Giebl)
> (Bill Kendrick)
> 2. Re: Loading bitmaps with transparency? (Torsten Giebl)
> (Leo M. Cabrera)
> 3. Re: Flickering and division by zero in Windows
> (Andre de Leiradella)
> 4. Universal binary crashing on iMac (Core2Duo) system (Lijith P)
> 5. How to create an GDK window inside SDL? (Serjan Pruis)
> 6. Re: How to create an GDK window inside SDL? (Torsten Giebl)
> 7. Problem with not using fullscreen. (Chris Rajula)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 4 Mar 2007 15:00:24 -0800
> From: Bill Kendrick <nbs at sonic.net>
> Subject: Re: [SDL] Loading bitmaps with transparency? (Torsten Giebl)
> To: "A list for developers using the SDL library. (includes
> SDL-announce)" <sdl at lists.libsdl.org>
> Message-ID: <20070304230024.GE30220 at sonic.net>
> Content-Type: text/plain; charset=us-ascii
>
> On Sun, Mar 04, 2007 at 03:30:42PM +0700, Patricia Curtis wrote:
> > Its simple to use transparency just save your images as a PNG-24 which
> will
> > give you 255 levels of transparency and you don't have to do the colour
> > keying either.
> >
> > SDL_Surface * gLoadedImage = SDL_DisplayFormatAlpha(IMG_Load("
> SomePNG.png"
> > ));
>
> Bad coding style. If IMG_Load() fails for some reason (file not found,
> corrupted file, out of memory, etc.), you'll be sending a NULL ptr to
> SDL_DisplayFormatAlpha(). I imagine that'd cause a segfault
> (aka SDL parachute launch).
>
> Always check for NULL and for errors!
>
>
> Of course, if I recall, they wanted to literally load Windows BitMaP
> (.bmp)
> files, as they were in an environment where SDL_Image library (and hence
> IMG_Load(), and hence PNG support) was unavailable.
>
> So for that, use BMP with a color-key.
>
> --
> -bill!
> bill at newbreedsoftware.com
> http://www.newbreedsoftware.com/
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 04 Mar 2007 18:06:03 -0800
> From: "Leo M. Cabrera" <leo28c at gmail.com>
> Subject: Re: [SDL] Loading bitmaps with transparency? (Torsten Giebl)
> To: "A list for developers using the SDL library. (includes
> SDL-announce)" <sdl at lists.libsdl.org>
> Message-ID: <45EB7B0B.1090206 at gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> >
> > Bad coding style. If IMG_Load() fails for some reason (file not found,
> > corrupted file, out of memory, etc.), you'll be sending a NULL ptr to
> > SDL_DisplayFormatAlpha(). I imagine that'd cause a segfault
> > (aka SDL parachute launch).
> Ha, yes, I do the same thing... *embarrass*
>
> I always say; "I'll do this now, then I'll add error checking whenever I
> finish the proggy..."
>
> But when I finish it, I forget... gotta improve that. xD
>
>
> Bill Kendrick wrote:
> > On Sun, Mar 04, 2007 at 03:30:42PM +0700, Patricia Curtis wrote:
> >
> >> Its simple to use transparency just save your images as a PNG-24 which
> will
> >> give you 255 levels of transparency and you don't have to do the colour
> >> keying either.
> >>
> >> SDL_Surface * gLoadedImage = SDL_DisplayFormatAlpha(IMG_Load("
> SomePNG.png"
> >> ));
> >>
> >
> > Bad coding style. If IMG_Load() fails for some reason (file not found,
> > corrupted file, out of memory, etc.), you'll be sending a NULL ptr to
> > SDL_DisplayFormatAlpha(). I imagine that'd cause a segfault
> > (aka SDL parachute launch).
> >
> > Always check for NULL and for errors!
> >
> >
> > Of course, if I recall, they wanted to literally load Windows BitMaP
> (.bmp)
> > files, as they were in an environment where SDL_Image library (and hence
> > IMG_Load(), and hence PNG support) was unavailable.
> >
> > So for that, use BMP with a color-key.
> >
> >
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 04 Mar 2007 20:40:18 -0300
> From: Andre de Leiradella <leiradella at bigfoot.com>
> Subject: Re: [SDL] Flickering and division by zero in Windows
> To: sdl at lists.libsdl.org
> Message-ID: <45EB58E2.1010005 at bigfoot.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> > -- set the video mode
> > local screen = image_lib.set_video(800, 600)
> > -- load and resize the background
> > local background = image_lib.load('background.png')
> > background = background.resize(screen.width, screen.height)
> > -- evaluates a half-transparent black color
> > local transparent = image_lib.color(0, 0, 0, 128)
> > -- loop until the user presses the left mouse button
> > while true do
> > -- query the mouse
> > x, y, left = input_lib.mouse()
> > -- blit the background to the screen, covering all pixels
> > background.blit(screen, 0, 0)
> > -- fill a square with the half-transparent black
> > screen.filled_rect(10, 10, screen.width - 10, screen.width - 10,
> > transparent)
> > -- update the screen
> > screen.update()
> > -- if left mouse button was pressed, break the loop
> > if left then
> > break
> > end
> > end
> >
>
> I have found the problem. Blame me, I was setting up a one-second,
> repeating timer that was calling SDL_UpdateRect. When I removed the
> SDL_UpdateRect from the timer the flickering went away.
>
> Sorry for the noise...
>
> Andre
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 5 Mar 2007 12:23:48 +0530
> From: "Lijith P" <lijithstar at gmail.com>
> Subject: [SDL] Universal binary crashing on iMac (Core2Duo) system
> To: sdl at libsdl.org
> Message-ID:
> <bfd660b30703042253k5dfb6b34we1357743e105d69 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> HI,
>
> I am trying to built a universal binary application using xcode 2.3 and
> sdl
>
> framework..
>
> The application works finely on the ppc.. But when i try to run the
>
> application on an iMac (core2Duo) system , the application is crashing at
>
> randomly.. But when i disable one cpu , the application is running
>
> properly..
>
> My application has a main thread and a helper thread...
>
> Is there any way to schedule multiple threads in a single processor on
> a dual core
> system..
>
> Valuable suggestion regarding this are most welcome..
>
> Regards
> Lijith
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 5 Mar 2007 12:11:26 +0100
> From: Serjan Pruis <serjan at quicknet.nl>
> Subject: [SDL] How to create an GDK window inside SDL?
> To: "A list for developers using the SDL library. (includes
> SDL-announce)" <sdl at lists.libsdl.org>
> Message-ID: <200703051211.26588.serjan at quicknet.nl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> I'm trying to add an GTK/GDK window to my application,
> Does any one already done this?
> I am able to create a Xwindow with a window id so that i can give
> the window id to mplayer so it can run in a window in my app.
> But i also want to play flash files in my window and so i guess i need a
> GDK
> window.
>
> Thanks in advance.
> Serjan
>
>
> ------------------------------
>
> Message: 6
> Date: Mon, 5 Mar 2007 14:53:31 +0100
> From: "Torsten Giebl" <wizard at syntheticsw.com>
> Subject: Re: [SDL] How to create an GDK window inside SDL?
> To: "A list for developers using the SDL library. (includes
> SDL-announce)" <sdl at lists.libsdl.org>
> Message-ID:
> <ce432aba0703050553g7598f309tc7167ae5ff4cf82a at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hello !
>
>
> > I'm trying to add an GTK/GDK window to my application,
> > Does any one already done this?
> > I am able to create a Xwindow with a window id so that i can give
> > the window id to mplayer so it can run in a window in my app.
> > But i also want to play flash files in my window and so i guess i need a
> GDK
> > window.
>
>
> Sam Lantinga has done something like this :
>
> http://www.libsdl.org/projects/gtk-demo/
>
>
> CU
>
>
> ------------------------------
>
> Message: 7
> Date: Mon, 5 Mar 2007 15:45:41 +0100
> From: "Chris Rajula" <superrajula at gmail.com>
> Subject: [SDL] Problem with not using fullscreen.
> To: sdl at lists.libsdl.org
> Message-ID:
> <630acb5b0703050645k6ba6d1dxccb7a71b538a5541 at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hello there!
>
> I have written a small testing-program that uses OpenGL and creates a
> window, but I have a small problem, namely that I can't get it not to use
> fullscreen.
> Using the program to draw a circle or whatever works just fine, but I
> can't
> get it to create a windowed window...
>
> I have the program divided into three separate files. One program-file,
> one
> class-file and one file containing the functions for the class.
> I appreciate any help.
>
> Thank you.
>
> /Chris
>
> Here we go:
> window.h:
> #ifndef _draw_h
> #define _draw_h
>
> class window{
> private:
> int height;
> int width;
> int depth;
> bool debug;
> bool fullscreen;
> public:
> window();
> window(int w, int h, int d, bool fs);
> void SDLInit();
> void Event();
> ~window();
> };
>
> #endif
>
> window.cpp:
> #ifdef WIN32
> #include <windows.h>
> #endif
>
> #include <iostream>
> #include <SDL.h>
> #include <GL/gl.h>
> #include <GL/glu.h>
> #include "window.h"
>
> window::window(){
> debug = 1;
> width = 640;
> height = 480;
> depth = 32;
> fullscreen = false;
> if(debug == 1)
> std::cout << "Height, width, and depth specified.\n";
> }
>
> window::window(int w,int h,int d,bool fs){
> if(fs == true) fullscreen = true;
> else fullscreen = false;
> if(h == 0) h = 1;
> if(w == 0) w = 1;
> if(d == 0) d = 32;
> width = w;
> height = h;
> depth = d;
> if(debug == 1)
> std::cout << "Height, width, and depth specifically
> specified.\n";
> }
>
>
> void window::SDLInit(){
> int error;
> // Just initialize everything and check for errors. Keep it simple,
> stupid. FIXME Check the error flag.
> error = SDL_Init(SDL_INIT_EVERYTHING);
> // std::cout << SDL_GetError();
> // I keep getting "Failed loading DPMSDisable:
> /usr/lib/libX11.so.6:
> undefined symbol" here.
> // It has something to do with SDLinitializing video, but I don't
> think it's a problem.
>
> // Here we set the different attributes for the drawing context.
> SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); // Double
> buffering.
> (Draw on offscreen buffer, then move to screen.)
> SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, depth); // Depth of the
> buffer.
> // Be sure to allocate space for the different colors to 8 bits,
> since we use a depth of 32 bits. FIXME (8/colour for 32bit depth!)
> SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8); // Red
> colour.
> SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8); // Green colour.
> SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8); // Blue
> colour.
> SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8); // Transparency.
> // Creating an SDL surface.
> Uint32 flags; // Used for choosing how the drawing context should
> act.
> if(fullscreen == true) flags = SDL_OPENGL | SDL_FULLSCREEN;
> else flags = SDL_OPENGL;
> SDL_Surface* drawContext;
> // Create the OpenGL draw context.
> drawContext = SDL_SetVideoMode(width,height,depth,flags);
> }
>
> void window::Event(){
> SDL_Event event;
> bool exit = false;
> while((!exit) && (SDL_WaitEvent(&event))) {
> switch(event.type) {
> case SDL_KEYDOWN:
> exit = true;
> break;
> case SDL_MOUSEBUTTONDOWN:
> exit = true;
> break;
> }
> }
> }
>
> window::~window(){
> SDL_Quit();
> }
>
> test.cpp:
> #include <iostream>
> #include "window.h"
>
> int main(int argc, char *argv[]){
> bool fs = true;
> window window;
> //window window(100,100,32,fs);
> window.SDLInit();
> // The main function should here call some different stuff.
> // Preferences();
> // It should enable or disable antialiasing and such, and read
> values from a file of user preferences.
> // It should also call a specific first-run-function to set the
> initial values for the user.
> window.Event();
> return 0;
> }
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> End of SDL Digest, Vol 3, Issue 10
> **********************************
>
--
In a time of universal deceit, telling the truth is a revolutionary act.
Trish & Thy also Available on
Skype tranmaithy63,
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