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screen flickering

 
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kennethdm



Joined: 24 Jan 2006
Posts: 8
PostPosted: Thu May 25, 2006 12:20 am    Post subject: screen flickering Reply with quote
Hi, I am currently updating my program to use background images instead of just plain rectangles filled with a certain color. I'm no psp expert on this, so I kept it simple for starters, the next piece of code just figures out what game mode the player wants, before the loop, an image is loaded and put on the screen, but for some reason, when i use an image as background, the screen flickers every time flipScreen is called, a problem which I didn't have when I just used plain rectangles (no I am not reloading the image every time, I'm not THAT stupid ;))

anyway, here's my code, any possible suggestions anyone?

P.S. the "pauze" function is just something that calls sceDisplayWaitVblankStart(); for a certain amount of time so the HOME button can be pushed

Code:

#include <stdlib.h>
#include <psppower.h>
#include <pspdisplay.h>
#include <pspctrl.h>
#include <pspkernel.h>
#include <pspdebug.h>
#include <pspgu.h>
#include <png.h>
#include <stdio.h>

#include "graphics.h"
#include "functies.h"

PSP_MODULE_INFO("test", 0, 1, 1);

#define RGB(r, g, b) ((r)|((g)<<8)|((b)<<16))
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y))
#define RIJEN 6
#define CIRKELS 4

/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
          sceKernelExitGame();
          return 0;
}

/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
          int cbid;

          cbid = sceKernelCreateCallback("Exit Callback", exit_callback, NULL);
          sceKernelRegisterExitCallback(cbid);

          sceKernelSleepThreadCB();

          return 0;
}

/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
          int thid = 0;

          thid = sceKernelCreateThread("update_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
          if(thid >= 0) {
                    sceKernelStartThread(thid, 0, 0);
          }

          return thid;
}

void pauze(int lengte)
{
int i = 0;

  for(i=0; i<lengte; i++) {
    sceDisplayWaitVblankStart();
  }     
}

int main(void) {

SetupCallbacks();
initGraphics();

int venster = 0;
SceCtrlData pad;  //input

while(1)
{
//begin main loop

        if(venster == 0)
        {
        //kies spelmodus
            char buffer[200];
             Image* ourImage;
             sprintf(buffer, "test.png");
             ourImage = loadImage(buffer);
             int xafb = 0;
             int yafb = 0;

             while (xafb < 480)
             {
               while (yafb < 272)
               {
                  blitAlphaImageToScreen(0 ,0 ,32 , 32, ourImage, xafb, yafb);
                  yafb += 32;
               }
               xafb += 32;
               yafb = 0;
             }
             flipScreen();
             
             venster = 1;
         
             while(1)
             {
             // aantal spelers loop
                 
           sceCtrlReadBufferPositive(&pad, 1);
           if(pad.Buttons & PSP_CTRL_DOWN) {
            if(venster == 1) {
              venster++;
            }
            pauze(10);
           } else 
           if(pad.Buttons & PSP_CTRL_UP) {
            if(venster == 2) {
              venster--;
            }
            pauze(10);
           }  else 
           if(pad.Buttons & PSP_CTRL_CROSS) {
            pauze(10);
            break;
           }
           
           fillScreenRect(RGB(0,50,50),100,50,280,86);
           printTextScreen(130,60,"1 Player",RGB(255,255,255));
           printTextScreen(130,80,"2 Players",RGB(255,255,255));
           if (venster == 1) {
            printTextScreen(115,60,"->",RGB(255,255,255));
           } else {
            printTextScreen(115,80,"->",RGB(255,255,255));
           }
           flipScreen();
           pauze(1);
           //einde aantal spelers loop
          }
                 
        //einde kies spelmodus
        }

        if(venster == 1)
        {
          while(1)
          {
            pauze(10);
          }
        }
       
        if(venster == 2)
        {
          while(1)
          {
            pauze(10);
          }
        }

//einde main loop
}



          return 0;
}
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BlackDiamond



Joined: 02 Jul 2005
Posts: 16
Location: Paris, FRANCE
PostPosted: Thu May 25, 2006 12:44 am    Post subject: Reply with quote
Shouldn't you load your image in both buffers? (draw, flip, then draw again)
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kennethdm



Joined: 24 Jan 2006
Posts: 8
PostPosted: Thu May 25, 2006 12:47 am    Post subject: Reply with quote
BlackDiamond wrote:
Shouldn't you load your image in both buffers? (draw, flip, then draw again)


I don't think I follow you, can you elaborate your suggestion further?
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Wil



Joined: 23 Feb 2005
Posts: 15
Location: Las Vegas
PostPosted: Thu May 25, 2006 3:01 am    Post subject: Reply with quote
Draw everything to a single 480x272 (or 512x512) image, and then just draw that single image to screen before you flip.
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Fanjita



Joined: 28 Sep 2005
Posts: 217
PostPosted: Thu May 25, 2006 3:09 am    Post subject: Reply with quote
You're flipping the screen immediately after blitting the image, but before drawing the other output.

Wait till you've drawn everything, then flip.
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Saotome



Joined: 03 Apr 2004
Posts: 182
PostPosted: Thu May 25, 2006 4:49 am    Post subject: Reply with quote
Nah, it's even simpler ;)

You have two buffers. You draw the background to one of the buffers. Then you go into the main loop and flip between those two buffers, the one with the background image and the empty/black one, that causes the screen to flicker.
The solution shouldn't be that hard to find out...

OK, a little hint: draw the background image to both buffers ;)
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BlackDiamond



Joined: 02 Jul 2005
Posts: 16
Location: Paris, FRANCE
PostPosted: Thu May 25, 2006 4:58 am    Post subject: Reply with quote
Thanks Saotome, that's what I meant.
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kennethdm



Joined: 24 Jan 2006
Posts: 8
PostPosted: Thu May 25, 2006 6:56 pm    Post subject: Reply with quote
thnx all, had figured it out before reading all this, reply took too long (well, not really, but I couldn't wait :)), anyway, thnx for the effort
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