Re: [AL] prob with ALLEGRO_FULLSCREEN

[Neil R. <no...@co...>]

On 13/07/2012 9:33 AM, Frédéric Drouillon wrote:
> hello,
>
> i begin with allegro 5 and it is the most beautifull library i know : like
> nithrill in the mines of Moria...
>
> I use allegro 5.0.7 and i meet a problem with playing in FULLLSCREEN different
> kinds of drawings : the display is blurred a little like a very old TV and
> whatever the resolution. I link with allegro-5.0.7-monolith-mt-debug and
> allegro-5.0.7-monolith-mt
>
> i work with cobeblock and Mingw32, windows 7, Dell XPS15 with a NVIDIA GeForce
> GT 420M video card.
>
> May be i do some thing wrong ?  here is the code i test :
>
> /*******************************************************************/
> #include <allegro5/allegro.h>
> #include <allegro5/allegro_native_dialog.h>
> #include <allegro5/allegro_primitives.h>
>
> void erreur(const char*txt)
> {
>       al_show_native_message_box( NULL, "Erreur", txt ,NULL, NULL, 0);
>       exit(EXIT_FAILURE);
> }
>
> int main()
> {
> ALLEGRO_DISPLAY*display;
> ALLEGRO_KEYBOARD_STATE key;
> ALLEGRO_DISPLAY_MODE mode;
>
>       if(!al_init())
>           erreur("initialisation");
>
>       if (!al_init_primitives_addon())
>           erreur("init primitives");
>
>       if(!al_install_keyboard())
>           erreur("install keyboard");
>
>      // to have destop résolution
>       al_get_display_mode(al_get_num_display_modes()-1, &mode);
>
>       // THE FULLSCREEN DOESN'T WORK PROPERLY
>       al_set_new_display_flags(ALLEGRO_FULLSCREEN);
>
>       display=al_create_display(mode.width,mode.height);
>       if (!display)
>           erreur("create_display");
>       int scrx=al_get_display_width(display);
>       int scry=al_get_display_height(display);
>
>
>       do{
>
>               al_get_keyboard_state(&key);
>
>               int x1=rand()%scrx;
>               int y1=rand()%scry;
>               int x2=rand()%scrx;
>               int y2=rand()%scry;
>
>               ALLEGRO_COLOR color =
> al_map_rgba(rand()%255,rand()%255,rand()%255,rand()%255);
>               float thickness = rand()%10 - 5;
>
>
>               if (al_key_down(&key,ALLEGRO_KEY_F1))
>                   al_draw_line(x1, y1, x2, y2, color, thickness);
>
>               al_flip_display();
>
>
>       }while (!al_key_down(&key,ALLEGRO_KEY_ESCAPE));
>
>       al_destroy_display(display);
> }
>
>
>
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I recommend using ALLEGRO_FULLSCREEN_WINDOW which will use the person's 
desktop resolution.

There is a bug in Allegro 5.0.7 where there is lag in 
ALLEGRO_FULLSCREEN, someone identified what was the likely cause of it 
on allegro.cc in a topic I started.

Trent Gamblin stated: "I think the latest release has a bug in d3d where 
the reference driver gets used as a fallback, which is extremely slow. 
It is fixed in svn."

Since switching to ALLEGRO_FULLSCREEN_WINDOW and adding in the following 
function to set up translations it works fine.  Plus a fullscreen window 
has the added benefit of having faster ALT+TABS and such.

a5_scale_screen.c:
*
// Scale Screen:
//    Sets up transforms in order to fit any resolution
//    onto an ALLEGRO_FULLSCREEN_WINDOW.
//
// (Special thanks to Matthew Leverton for help with this!)

#include <allegro5/allegro.h>

// usage: a5_scale_screen(BUFFER_WIDTH, BUFFER_HEIGHT, display_width, 
display_height);
void a5_scale_screen(int bw, int bh, int dw, int dh)
{
   ALLEGRO_TRANSFORM t;

   // Calculate the horizontal and vertial aspect ratios
   const float HAR = dw/(float)bw;
   const float VAR = dh/(float)bh;

   // The aspect ratio, x-offset and y-offset (in pixels)
   float ar, ox, oy;


   if (bw == dw && bh == dh)
   {
     // 1:1, just reset everything
     al_identity_transform(&t);
     al_use_transform(&t);
     al_set_clipping_rectangle(0, 0, bw, bh);
   }
   else
   {
     // Choose the smaller aspect ratio
     if (HAR < VAR)
     {
       // horizontal bars on the top and bottom
       ar = HAR;
       ox = 0;
       oy = (dh - (ar * bh)) / 2.0;
     }
     else
     {
       // vertical bars on the left and right
       ar = VAR;
       ox = (dw - (ar * bw)) / 2.0;
       oy = 0;
     }

     // set up the transformation to scale and translate
     al_build_transform(&t, ox, oy, ar, ar, 0);
     al_use_transform(&t);

     // make sure nothing is drawn into the black bars
     al_set_clipping_rectangle(ox, oy, ar * bw, ar * bh);
   }
}*

And the header I use for it:

a5_scale_screen.h:

*#ifndef _a5_scale_screen_h_
#define _a5_scale_screen_h_

// usage: a5_scale_screen(BUFFER_WIDTH, BUFFER_HEIGHT, display_width, 
display_height);
void a5_scale_screen(int bw, int bh, int dw, int dh);

#endif //_scale_screen_h_*

You use this with a fullscreen window to set up whatever resolution you 
wish inside that window and it will look and act just like a fullscreen 
mode.

I also used the following code as well after using the above function:

*al_set_new_bitmap_flags(ALLEGRO_MAG_LINEAR | ALLEGRO_VIDEO_BITMAP);
al_set_blender(ALLEGRO_ADD, ALLEGRO_ONE, ALLEGRO_INVERSE_ALPHA);
al_set_new_display_option(ALLEGRO_SAMPLE_BUFFERS, 1, ALLEGRO_SUGGEST);
al_set_new_display_option(ALLEGRO_SAMPLES, 4, ALLEGRO_SUGGEST);


*Hope this helps.