Monday, 3 July 2017

A shot in the dark

Shots, as it turns out, are rendered in the display list as zero-length vectors with scale=7 and maximum brightness and thus can be uniquely identified.

So I simply added a check for such in my DVG emulation code and now have shots being displayed for both player and saucer. I added some crude keyboard mappings for fire and left/right rotate, and I can coin up, start a game and take aim at asteroids and destroy them.

Player's ship is yet to be rendered, but asteroids can still be destroyed

That leaves player ship and player explosion. The latter consists of component vector commands copied and patched from the DVG ROM routine. In theory, they are the only two remaining objects in the display list, and it may yet be possible to distinguish between the two... something I need to experiment with in order to confirm. It would be really, really nice if I didn't have to patch the original game - even if just for this exercise - and be able to render all the game graphics!

But next task is to get Norbert's player ship bitmaps converted and displayed in the correct orientation.

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