Chapter II - The Playfield Hardware
Contents
- 1 INTRODUCTION
- 2 PLAYFIELD HARDWARE
- 3 HOW TO SELECT THE COLOR OF PLAYFIELD ELEMENTS
- 4 SELECTING COMBINATIONS OF BIT-PLANES
- 5 HOW BIT-PLANE DATA IS STORED IN MEMORY
- 6 WHERE IS THE BIT-PLANE DATA STORED
- 7 HOW TO CONTROL THE SIZE OF THE DISPLAY
- 8 DETERMINING HOW MUCH DISPLAY MEMORY IS NEEDED
- 9 SCROLLING THE PLAYFIELDS
- 10 HOW PLAYFIELDS INTERACT WITH OTHER ELEMENTS
- 11 PLAYFIELD SELECTION COLOR CHARTS
INTRODUCTION
There are two basic parts to the display which you see on the screen:
- Things which move, called "sprites", and
- Things which don't move, called "playfields" or playfield objects.
A playfield is the backdrop against which the sprites may be displayed or with which the sprites can interact. A playfield object is simply a smaller subsection of the playfield which is considered by the software to be an object of some kind.
Even though playfield objects are classed as non-moving object, these objects can appear to move by using a technique called playfield animation. The chapter titled "THE BLITTER" shows that playfield objects can be rapidly redrawn on the screen, while saving and restoring the background onto which they are drawn, to give the illusion of motion. Much of the demonstration software which you may have already seen uses this animation technique.
This chapter concentrates on the playfield hardware itself. It shows you what defines a playfield, how its colors are specified, how it is controlled, and how other parts of the computer interact with the playfield hardware.
WHAT TOPICS ARE COVERED IN THIS CHAPTER
This chapter covers:
- How to define playfield resolution
- How to select the color of the playfield elements using one or more bit-planes
- How Hold & Modify mode increases your choice of onscreen colors available
- How to use the bit-planes as a single playfield, or how to split the static display into two independently controllable playfields.
- How to control the size of the static display.
- How to determine how much memory space is used by the display
- What part of the display memory actually appears on the screen
- How to smoothly scroll (move the playfield) in either a horizontal or vertical direction
- How the playfield display interacts with other parts of the Amiga Personal Computer
