Commodore Amiga A2000 - Figure 3-5 Interlacing; Figure 3-6 Effect of Interlaced Mode on Edges of Objects

line 1_________________________
| _________________________ |\
| _________________________ | \
| _________ | \
| Field 1 | \ __________________
| _________ | \ |___|______________|___Line 1
| _________________________ | >|___|______________|___
| _________________________ | / | | | Line 2
|___________________________| / | | Video display|
/ | | (400 lines) |
line 1_________________________ / | | |
| _________________________ | |__\|/_____________|
| _________________________ |
| _________ |
| Field 2 | (same physical space as used
| _________ | by a 200 line noninterlaced
| _________________________ | display)
| _________________________ |
|___________________________|
Figure 3-5: Interlacing
Even though interlaced mode requires a modest amount of extra work in setting registers
(as you will see later on in this section), it provides fine tuning that is needed for certain
graphics effects. Consider the diagonal line in Figure 3-6 as it appears in non-interlaced
and interlaced modes. Interlacing eliminates much of the jaggedness or "staircasing" in
the edges of the line.
Figure 3-6: Effect of Interlaced Mode on Edges of Objects
When you use the special blitter DMA channel to draw lines or polygons onto an interlaced
playfield, the playfield is treated as one display, rather than as odd and even fields.
Therefore, you still get the smoother edges provided by interlacing.
- 44 Playfield Hardware -