Amiga 500 demo featuring the following technical highlights:
- Assembly programming on the Motorola 68000 for calculating 3D-rotation of the globe.
- Heavy use of the Blitter to achieve parallax scrolling, also called 2.5D-scrolling. Note that the clouds move right while the left moves to the left (the further away the slower).
- Considering the five bitplanes and the arbitrariness of the image sizes, the achieved frame rate of 5+ really stands out.
- In comparison, Shadow of the Beast has a 20+ frame rate but relies on the several restrictions regarding the object overlap that is only partially alleviated by the double playfield setup.
- Color cycling for the river plain during vertical blank by the Copper.
- The sky has a color gradiant obtained by the Copper list during horizontal blanks.
The pixel art looks strangely familiar... I do not own any of used images. The demo was a purely educational endeavour to have fun while exploring the possibilities of Amiga's OCS.
The easiest way is to put the repository into a mounted directory of an emulated A500 and to invoke the executable which is provided for convenience.
cd bin
Demo
At the start, the precalculation of the animation lasts about two minutes. So you need to be patient.
The sources are also included. Within your assembly IDE, you need to assemble src/Demo and start it from the src folder (relative pathes at work...).
By the way, press the mouse button to stop the demo.
I made this demo in order to achieve the same effects as Shadow of the Beast and the likes before actually understanding the tricks applied (and their restrictions).
