brett@umd5.umd.edu (Brett Bourbin) (05/31/89)
I was wondering how the first Boing! demo did the movement of the
ball? I know that the program draws the ball in small increments, in different
colors, and then uses color rotations to make the ball spin.
I have heard that the demo changed the copper list to alter the
starting location of the bitplanes holding the ball image to move it up and
down. Is this true, and if so, does it alter the hardware copper list on the
fly or the ViewPort and MakeVPort(), MrgCop(), LoadView()?
The reason I ask is because I need to write a program that uses a
specialized user copper list that changes the background color every scanline.
After the list is built, it needs to rotate the colors up and down the screen
to simulate motion. Now, if there was a copper instruction to move a value
from a table or location into one of the hardware color registers, then there
would not be a problem. What I feel I must do now is alter the hardware list
for each of the MOVE #nnnn,COLOR00 entries.
Can I legally create a View and build my own copper list and place
its address in the structure, so a call to LoadView() will display my tricks,
or should I use UCopper instructions to wait for the first line, change the
color, wait for the second line, etc? If I do it this way, can I legally
search for MY color register 0 changes and alter the hardware list on the
fly?
[It is so hard not to go directly to the hardware when you know you can
solve the task in a matter of minutes by doing so. 8^) ]
--
--Brett S Bourbin, Instructional Computing Programs -- Univ of Maryland
Computer Science Center, College Park, MD 20742
INTERNET: brett@umd5.umd.edu BIX: brettb DELPHI: brettbpage%swap@Sun.COM (Bob Page) (06/01/89)
brett@umd5.umd.edu (Brett Bourbin) wrote: >I was wondering how the first Boing! demo did the movement of the ball? The first one? You mean the one that said "Amiga Inc" in the background? >I know that the program draws the ball in small increments, in different >colors, and then uses color rotations to make the ball spin. Yep. You can catch some of that by keeping the boing screen to front and watching it draw the ball. Also by bringing up a palette tool and looking at the pen colors. >I have heard that the demo changed the copper list to alter the starting >location of the bitplanes holding the ball image to move it up and down. I heard it too. To quote a famous duck: "I cheated my ass off!" >[It is so hard not to go directly to the hardware when you know you can >solve the task in a matter of minutes by doing so. 8^) ] Good thing you got that smiley in there! ..bob