· Commodore 64Two drawings, a Sunday, and a C64
Off schedule, and for once it isn't my own stuff. Matteo85 is just starting out with Commodore 64 graphics and sent me two drawings: a SUV and a frog. The question behind them was a concrete one, do these work?, and that kind of question is answered faster by running the drawings than by discussing them.
So in a couple of hours, in the gaps of a Sunday, I put them on the road. Out came an endless run: you drive, you avoid the frogs, a frog you pass alive is worth points and one you flatten costs a life, and you get three. You accelerate, you brake, you sound the horn, and the horn scatters the frogs for a second. There's no finish line. The name, Save The Frogs, is his.
The interesting part, though, isn't the game, it's what it was there to explain. A sprite on this machine is understood far sooner by watching one move than by reading its definition, so I wrote it out properly: C64 sprites, explained by putting them on the road. Eight drawings the video chip moves on its own with the CPU redrawing nothing, the 24 by 21 grid, one colour of your own plus two borrowed from every other sprite, the 63 bytes used inside a 64-byte block, the shadow that isn't drawn but computed by four lines of code, the ninth-bit trap that teleports your object halfway across the screen, and the thing that matters most: why the road isn't a sprite.
The tutorial also has an eight-minute video telling the whole path, from pixels to game, with Italian subtitles, plus the PRG to load in VICE or on a real machine.