Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Use markdown style lists

Browse source
This commit is contained in:
James Gregory 2013-12-31 07:31:51 +11:00
commit 307b59584f
17 changed files with 120 additions and 120 deletions
Download patch file Download diff file Expand all files Collapse all files

32
45-06.md
View file

@ -40,22 +40,22 @@ Serge didn't care to do all that bookkeeping in his animation
applications, so he came up with the following approach, which I've
reworded, amplified, and slightly modified in the summary here:
**1.**  Set the start address to display page 0.
1. Set the start address to display page 0.
**2.**  Draw to page 1.
2. Draw to page 1.
**3.**  Set the start address to display page 1 (the newly drawn page),
then wait for the leading edge of vertical sync, at which point the page
has flipped and it's safe to modify page 0.
3. Set the start address to display page 1 (the newly drawn page),
then wait for the leading edge of vertical sync, at which point the page
has flipped and it's safe to modify page 0.
**4.**  Copy, via the latches, from page 1 to page 0 the areas that
changed from the previous screen to the current one.
4. Copy, via the latches, from page 1 to page 0 the areas that
changed from the previous screen to the current one.
**5.**  Set the start address to display page 0, which is now identical
to page 1, then wait for the leading edge of vertical sync, at which
point the page has flipped and it's safe to modify page 1.
5. Set the start address to display page 0, which is now identical
to page 1, then wait for the leading edge of vertical sync, at which
point the page has flipped and it's safe to modify page 1.
**6.**  Go to step 2.
6. Go to step 2.
The great benefit of Serge's approach is that the only page that is ever
actually drawn to (as opposed to being block-copied to) is page 1. Only
@ -74,14 +74,14 @@ less-experienced animation programmers.
An interesting variation on Serge's approach doesn't page flip nor wait
for vertical sync:
**1.**  Set the start address to display page 0.
1. Set the start address to display page 0.
**2.**  Draw to page 1.
2. Draw to page 1.
**3.**  Copy, via the latches, the areas that changed from the last
screen to the current one from page 1 to page 0.
3. Copy, via the latches, the areas that changed from the last
screen to the current one from page 1 to page 0.
**4.**  Go to step 2.
4. Go to step 2.
This approach totally eliminates page flipping, which can consume a
great deal of time. The downside is that images may shear for one frame