Dragon Demos

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A collection of work-in-progress (or possibly destined to remain proof-of-concept) Dragon software.

• Horizontal Scrolling
• Line Drawing
• Vertical Scrolling

Horizontal Scrolling

Horizontally scrolling shooter demo. Technical features:

• 42 bytes per line video mode.
• Smooth horizontal scroll with sprites updated at full PAL screen rate.
• Utilises FAST CPU rate while outside the active area. This avoids display corruption and allows plenty of RAM refresh each during each frame.
• Dynamic sprite compilation: over a series of frames, compact sprite data is "compiled" into machine code that draws directly to the screen. This means sprites can be drawn very quickly, while allowing more sprites to be stored in the compact format.

• scroll.dsk disk image.

This disk image is "dual boot": it should work on both the Dragon (using DragonDOS) and the CoCo (RSDOS). Keys are W, S, A, D and Enter. P pauses, and within pause mode, Break will restart the demo level. Some number keys adjust options like player speed and firing rate.

Line Drawing

An Asteroids-esque environment demonstrating line drawing. All the vector offsets are precalculated, but line drawing is done properly. Keys A and S allow rotation of the ship, but nothing else works.

• line.bin DragonDOS binary.
• linec.bin CoCo binary (old versions of XRoar will only directly load this type).

Vertical Scrolling

Fast full-height vertical scroll, albeit in a lower resolution. Not very much CPU time left after this, not sure it could be turned into a game really. Keys (in the CoCo keymap only!) are W, S, A, D and Enter.

• vscroll.bin CoCo binary.

Updated 17 Jul 2010