Page 143 - DCAP303_MULTIMEDIA_SYSTEMS

Unit 8: Fundamental of Animations

8.3 animation techniques notes

8.3.1 Blitting

Blitting is the process of taking rectangles from off-screen drawing surfaces and copying them
onto primary or secondary drawing surfaces. Blitting is much like taking pieces of a jigsaw puzzle
and assembling the finished product on a table.
8.3.2 page flipping and Back Buffering

Page flipping is the process of cycling through the drawing surfaces, or pages. In back buffering,
you populate these surfaces with new frames of information. With these two techniques, you can
create true animation by creating a frame, displaying the frame, creating the secondary surface,
and then displaying it.
Before the flip occurs, users see a single vehicle going east. What they are seeing at that point
is the primary surface. While this is going on, the secondary surface is being redrawn with an
additional vehicle, a little bit larger, going west. When the flip occurs, the users’ view is changed
to the secondary surface. In essence, the secondary surface in the previous frame is now the
primary surface, and vice versa. Users now see both the vehicles. Since the car going east will
have travelled off the screen in the next frame, you remove it from the secondary surface. The
secondary surface is now redrawn to get ready for the next flip.

8.3.3 palette Cycling
Palette cycling can best be visualized by imagining a painter’s palette. Painters use a palette of
colours to create their paintings. Just imagine what would happen if they changed a few of the
colours on their palettes to new colours, and that change resulted in the colours in their painting
automatically changing, too. You would have the same painting, but with a few colours changed.
If you continued to do that, some of the images in the painting would look animated, simply
because you had changed their colours over and over. This effect is called palette animation, and
this technique can be used to create psychedelic effects such as those popular in the 1970s. You
can also use it to create fading effects on objects and text to give the impression that they are
appearing or disappearing.

Give the use of page flipping and back buffering with the suitable example.

self assessment

Choose the correct answer:
1. ………………… is the essence of animation.
( a) Timing (b) Arcs
( c) Anticipation (d) Exaggeration
2. Action in animation usually occurs in .............. sections.
( a) four (b) three
( c) two (d) None of these
3. Rigid objects can still squash and stretch in a way.
( a) True (b) False

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