English Amiga Board - View Single Post

Mrs Beanbag · 17 January 2016, 19:11

yes, never use two wait vbls or you'll just slow things down, but that's not what i said.

Double buffering creates two screen buffers, the bobs are drawn to the invisible buffer, and then the buffers are swapped, so you never see the screen half-way through the drawing. It prevents flickering of bobs and other animation.

If you are using "screen copy" to scroll the screen around, the bob drawing routine might get confused, because the stored background behind the bobs will be wrong, so you will need to turn "bob update off" and "autoback 0" and do manual "bob clear"/"bob draw" operations to make it work. Clear the bobs, then scroll, then draw the bobs. Then "screen swap" and "wait vbl".

17 January 2016, 19:11	#8
Mrs Beanbag Glastonbridge Software Join Date: Jan 2012 Location: Edinburgh/Scotland Posts: 2,243	yes, never use two wait vbls or you'll just slow things down, but that's not what i said. Double buffering creates two screen buffers, the bobs are drawn to the invisible buffer, and then the buffers are swapped, so you never see the screen half-way through the drawing. It prevents flickering of bobs and other animation. If you are using "screen copy" to scroll the screen around, the bob drawing routine might get confused, because the stored background behind the bobs will be wrong, so you will need to turn "bob update off" and "autoback 0" and do manual "bob clear"/"bob draw" operations to make it work. Clear the bobs, then scroll, then draw the bobs. Then "screen swap" and "wait vbl". Last edited by Mrs Beanbag; 17 January 2016 at 19:17.