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Switch/Case problem

Started by Mullvalen Jan 28, 2006 at 12:37 PM 7 replies 1.3k views

Original Post

Jan 28, 2006 at 12:37 PM

This problem seem to be really fishy. As it it now, i have to comment out the call for the 32 bit rendering function. Else, the program will call that one too and thats no good. What could be wrong?


void fh_renderer::draw_sprite( int scrollx, int scrolly, fh_layer_list& l, SDL_Surface& dest )
{
     switch ( l.image->format->BytesPerPixel )
     {
     case 1:
          //render_8bit();
          break;
     case 2:
          //render_16bit();
          break;
     case 3:
          render_24bit( l.x - scrollx, l.y - scrolly, *l.image, dest );
          break;
     case 4:
//          render_32bit( l.x - scrollx, l.x - scrolly, *l.image, dest );
          break;
     }
}

Mullvalen

Author

Mullvalen

Jan 28, 2006 at 2:31 PM

Oh...no, the program does compile. The problem is that the program runs both case 3 and 4

Argus2

Jan 28, 2006 at 4:37 PM

And you are completely sure that 'render_24bit' will never call 'render_32bit' ?

Mullvalen

Author

Mullvalen

Jan 28, 2006 at 4:46 PM

Yep, if i comment out case 4 everything works completely fine

rip-off

Mod

445

rip-off

Jan 28, 2006 at 5:03 PM

It looks like you are using SDL for your rendering. Why do you have different functions for rendering at different bitdpeths, seeing as SDL will do this for you?

Mullvalen

Author

Mullvalen

Jan 29, 2006 at 3:54 AM

Because i want to render it front to back and SDL_BlitSurface doesnt provide that...

haegarr

271

haegarr

Jan 29, 2006 at 4:09 AM

It is unlikely that the compiler introduces a bug like the one described in the OP, but who knows... Else you have should take into account to choose another compiler.

From the shown code snippet and the given description I assume that fh_renderer::draw_sprite is called twice. If you have no debugger at hand, you could try to do something like

void fh_renderer::draw_sprite( int scrollx, int scrolly, fh_layer_list& l, SDL_Surface& dest ){     cout << "entered w/ " << l.image->format->BytesPerPixel << endl;     switch ( l.image->format->BytesPerPixel )     {     case 1:          //render_8bit();          break;     case 2:          //render_16bit();          break;     case 3:          render_24bit( l.x - scrollx, l.y - scrolly, *l.image, dest );          cout << "24 bit done\n";          break;     case 4:          render_32bit( l.x - scrollx, l.x - scrolly, *l.image, dest );          cout << "32 bit done\n";          break;     }}

From the resulting sequence of output you could determine whether
(1) the 32 bit rendering was invoked by a second invocation of fh_renderer::draw_sprite, in which case "entering w/" and "24 bit done" as well as "entering w/" and "32 bit done" would occur,
(2) by a spurious invocation from inside fh_renderer::draw_sprite, in which case "24 bit done" and "32 bit done" would occur in direct sequence, or
(3) by an invocation from outside fh_renderer::draw_sprite, in which case "32 bit done" would not occur at all.

Mullvalen

Author

Mullvalen

Jan 29, 2006 at 5:19 AM

Thanks, i found the error, seemed like the last sprite where not loaded at all, therefore had a dummy surface which was 32-bit.

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