AndrewW wrote:
Polygon-fills would surely be too slow on the BBC for a game like Zarch?
Aha - hence my talking about cheating
Polygon fills can be slow particularly if you're also trying to do hidden surface removal and shading. But using approximation techniques and lookup tables to cut out the number crunching, you can get visual effects that are convincing.
For example, if you know that any given vertex of your landscape can only be one of 10 different heights off sea level, then you can easily do a lookup table that defines the gradient to join two adjacent 'tiles', and it then becomes a hybrid of a line drawing and raster plot to actually plot four tiles with a shared vertex.
You can apply simply linear transformation on a known shadow (say your ship can have 50 different positions - define those as little sprites, and the shadow as a polygon.
...etc.
I'd really love to have a bash at knocking this together again if I don't find the source for my previous effort. But I can't see myself having the time to even think about it for another year at least!