AllocScreenBuffer() - doesn't want to allocate bitmap.

[mateusz_s]

I am making a triple buffering using ChangeScreenBuffer() function.

It looks like AllocScreenBuffer() doesn't want to allocate bitmap for it when the parameter is 0.

The code below doesnt work as it should. I can fill only first buffor that is linked to screen bitmap, and the other two buffers are blank, and I can't fill them. Like the bitmaps werent allocated, but the pointers are not NULL; So the result is that only one frame is filled with rendered content and two frames are blank. So the screen flickers.

        // INIT

	// create two message ports
	struct MsgPort* APP_port_disp = CreateMsgPort();
	struct MsgPort* APP_port_safe = CreateMsgPort();
	
	// declare Screen Buffer structure
	struct ScreenBuffer* APP_screen_buffer[3];

	// first buffer - the bitmap won't be allocated - it will use screens bitmap
	APP_screen_buffer[0] = AllocScreenBuffer(APP_screen, NULL, SB_SCREEN_BITMAP);

	// second and third buffer - the bitmaps will be allocated
	APP_screen_buffer[1] = AllocScreenBuffer(APP_screen, NULL, 0);
	APP_screen_buffer[2] = AllocScreenBuffer(APP_screen, NULL, 0);

	// link with message ports
	for (int i = 0; i < 3; i++)
	{
		APP_screen_buffer[i]->sb_DBufInfo->dbi_DispMessage.mn_ReplyPort = APP_port_disp;
       	APP_screen_buffer[i]->sb_DBufInfo->dbi_SafeMessage.mn_ReplyPort = APP_port_safe;
	}
	
	// init buffer switcher
	int APP_current_frame_buffer = 1;
	int APP_next_frame_buffer = 2;


        // LOOP

        while (APP_main_loop)
        {
	....

      ChangeScreenBuffer(APP_screen, APP_screen_buffer[APP_current_frame_buffer]);

      // lock bitmap adress and put it in my engine buffer: EM_prefs.output_buffer_32
      APTR handle = LockBitMapTags(APP_screen_buffer[APP_next_frame_buffer]->sb_BitMap, LBMI_BASEADDRESS (ULONG)&EM_prefs.output_buffer_32, TAG_DONE);
	
        // render frame in engine				         
       EM_Update_And_Render(&APP_main_loop);
       UnLockBitMap(handle);

	// increment APP_current_frame_buffer
	APP_current_frame_buffer++;
	if (APP_current_frame_buffer > 2) APP_current_frame_buffer = 0;

	// increment APP_next_frame_buffer
	APP_next_frame_buffer++;
	if (APP_next_frame_buffer > 2) APP_next_frame_buffer = 0;
}

Then I allocated BitMaps manually and linked them to screen buffers. And everything works..
I just added this in INIT part. Free bitmaps that should be allocated by AllocScrennBuffer, and alloca my own botmaps:

FreeBitMap(APP_screen_buffer[1]->sb_BitMap);
FreeBitMap(APP_screen_buffer[2]->sb_BitMap);

struct BitMap* bm1 = AllocBitMap(320,200,32,BMF_DISPLAYABLE , &APP_screen->BitMap );
APP_screen_buffer[1]->sb_BitMap = bm1;

struct BitMap* bm2 = AllocBitMap(320,200,32,BMF_DISPLAYABLE , &APP_screen->BitMap );
APP_screen_buffer[2]->sb_BitMap = bm2;

Am I doing something wrong? or this is an API bug?
Thanks!

[Thomas Richter]

Maybe the following example from the P96 test corpus helps.

[mateusz_s]

Originally Posted by Thomas Richter

Maybe the following example from the P96 test corpus helps.

Thank You Thomas, that a really big exmaple, I must analyze it carefully..

[mateusz_s]

Originally Posted by Thomas Richter

Maybe the following example from the P96 test corpus helps.

ps. Should I see something on the screen? I just see empty Intuition Screen..

ohh, ok. Q,S,R on keyboard