Problem with bob double buffering

[damex]

Hi!

I'm drawing some bobs using animtools from the Amiga Developer Docs.

I'm experiencing some flicker when moving the bobs around so I want to see if double buffering will fix the issue. However when I enable `dbuf` in the `NEWBOB` structure I get some artefacts when bobs are moving and also I get a guru meditation when I exit the program.

Any idea what might be causing the issue?

Here is a video that demonstrates the issue.

And here is the relevant part of my program:

/* 16x8, 5 planes */
ULONG chip bobData[] =
{
  0xf7008f00,0x8700a700,0xc500a700,0xd900ff00,
  0xff00a300,0x97008500,0x9f008700,0xa100ff00,
  0xf700a700,0x93008300,0xc1008300,0xe700ff00,
  0xcf00a700,0x9300a100,0xa500a300,0x8300ff00,
  0x00001800,0x08000000,0x00000000,0x00000000,
};

struct Bob *makeBobForUnit(SHORT positionX, SHORT positionY) {
  struct Bob *bob;

  /* information for the new bob
  ** structure defined in animtools.h
  */
  NEWBOB newBob = {
      (SHORT *)bobData,   /* image data               */
      1,                  /* width in WORDs           */
      8,                  /* height in lines          */
      5,                  /* image depth              */
      31,                 /* plane pick               */
      0,                  /* plane on off             */
      SAVEBACK | OVERLAY, /* vsprite flags            */
      1,                  /* dbuf (0 == FALSE)        */
      SBMDEPTH,           /* raster depth             */
      0,                  /* x position               */
      0,                  /* y position               */
      0,                  /* hit mask                 */
      0,                  /* me mask                  */
  };

  newBob.nb_X = positionX;
  newBob.nb_Y = positionY;

  if (NULL == (bob = makeBob(&newBob))) {
    printf("Error: Can't make bob for unit\n");
  }

  return bob;
}