Re: [stella] 11 Invaders "Reloaded"

[christophertumber@xxxxxxxxxx]

> Attached is an early tech demo, which shows 11 invaders/row. The demo
> does *NOT* work well on any emulator! (Yet? :-)

Thomas,

I wish you all the luck in the world, but there are a few things I didn't have a chance to mention in our previous conversation that you really should realise (Previously Thomas and I have been discussing this in email, however I've just gone out of town so it was a very broef convo).

Space Instigators was originally intended to be an 11x5 game. The decision to drop down to 9x5 was an extremely difficult one. The whole point of the project was to do a proper 11x5 so I only made this change after a huge amount of consideration and angst.

The reason Space Instigators dropped from 11x5 to 9x5 was twofold.

First, is the vertical size of the formation. Using the multi sprite trick causes a shift in the vertical positioning of sprites. Space Instigators is unable to use the leftmost 1/5 or so of the screen for the aliens. Because of this, in order to center things, I also did not use the rightmost 1/5 or so of the screen. This mean't that with a full compliment of 11 aliens, there was VERY little space for vertical movement. I think there were 3 or 4 vertical positions.

You've overcome this problem using the illegal HMOVE trickery, however, so did Erik Mooney's old demo years ago. (In fact since Erik's works properly on emus and presumably on Kool-Aid man affected 2600's I'd suggest that you're not yet as far along as he got). When I did Space Instigators, it was only after I'd made the decision to drop to 9x5 that I realised Erik had found a way around it. And I think I asked Eckard about it or something and he explained the theory, but at the time since it was all undocumented and I'd only been working with the 2600 a few months I decided to just let it go.

(To be contined)

Chris...




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