At 17:59 27.10.98 -0800, you wrote:
>Erik Mooney wrote:
>> How it works? I thought we knew that. If NUSIZ0 is set to two or more
>> copies of a sprite, and RESP0 is hit during a scanline, the second and
>> later copies of the sprite will display on that line.
>
>Generally speaking, this is true for the second and later hits of RESPx
>on a line. The first hit on a line generally gives you all of the
>copies including the first. But there are some subtleties having to do
I don't think this is how it works. Look at trick18 or extra18.
The last hits to RESP0/RESP1 both generate three copies.
I think it has to do with wether you hit RESPx when a sprite is
currently displayed or not. Hitting RESPx when a sprite is
displayed, gets you all copies, hitting RESPx during the gap
or after the first sprite has been drawn omits the first copy.
The pixel at which you hit RESPx, the screen position, at which
the sprite is currently positioned and of course the value in
NUSIZx might be factors for the outcome of this trick too.
Also the resulting screen position for the additional sprites
is a complete mystery to me. For example in the grid demo the
last two copies of the sprites are overlaping into the next
scanline, where they are hit by the initializing accesses to
RESPx. As a result to this all following sprites will be
positioned at a different screen position than during the
initial scanline.
Everytime I came up with a theory about how this trick works and
did some tests to verify this theory, I got some strange results,
that just wouldn't fit in.
>P.S. I've been running unstable.bin for around 10-15 minutes, and the E
>letters are beginning to fade to completion! So they DO show up.
That is strange! I have unstable.bin running on my PAL VCS jr.
for 40 minutes now and there is absolutely nothing fading in.
Ciao, Eckhard Stolberg
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