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Blogs

On Yer Bike! (Or at least, My Bike)…

November 13, 2017 Retro Ports

Since it has been over 2 weeks since the last update, I thought I’d better post something.

Whilst I have been focusing on life off the computer lately (namely an 82km fun/charity bicycle ride) I have managed to make some progress. What I haven’t made any progress on, however, is the …

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Blogs

Flicker-be-gone! (mostly)

October 26, 2017 Retro Ports

No progress on the collision-detection bug so I decided to implement the double-buffering (page flipping) since it is almost trivial and won’t be affected by any other programming issue.

The arcade machine uses a pair of so-called “ping-pong” buffers to allow the DVG to render the frame whilst the CPU is …

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Blogs

A progress report on lack of progress.

October 24, 2017 Retro Ports

Today I had the chance to review the collision-detection code. The bad news is that I couldn’t see anything amiss. I did find a few minor issues to do with ADC/ADD but they don’t appear to be the cause of the bug. I also managed to effect a few minor …

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Blogs

A few more fixes and it’s looking good… but not perfect.

October 22, 2017 Retro Ports

Another brief update; I seem to only get to work on it in snippets atm…

I’ve fixed the ship explosion offset (same as ship offset). I also fixed a long-standing bug in the erase routine for the extra life indicators.

It’s looking pretty spot-on now as far as object placement goes, although …

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Blogs

#bug

October 21, 2017 Retro Ports

Super-brief update… I’ve fixed the ship/shot offset issue. Nothing sinister at all – simply forgot the ‘#’ character when adding the fixed pixel offsets to the accumulator!

Need to re-check the other offsets now, and fix the display issue at the bottom of the screen, and possibly add Y clipping – …

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Blogs

Code that isn’t executed has no bugs!

October 19, 2017 Retro Ports

Very brief update.

After five days away from the keyboard I decided there was only one possible reason for the erase ship routine not working… and I was right! Because I cut-and-paste the render routine and used it for the erase by replacing the video writes with CLR, it simply wasn’t …

Blogs

Size does matter

October 11, 2017 Retro Ports

Finally, I’ve implemented the exploding ship routine! I had even avoided it on the Apple IIGS version which, of course, remains incomplete at this point. It’s complicated, it’s messy, it’s slow – but I get the same results as Norbert, sans graphical bugs.

When it comes time to implement it ‘properly’ …

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Blogs

Another last word on explosions

October 11, 2017 Retro Ports

After adding the thrust (pixel) rendering, I decided to bite the bullet and implement the ship explosion to round off the port before I move on to optimisations for the Coco3.

I’ve ported all the original code, despite the fact that one of the routines isn’t required for the Coco3 (or …

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Blogs

A last word on explosions.

October 10, 2017 Retro Ports

I’ve finished the RE of the exploding ship routines, both in the original and Norbert’s emulator.

Norbert patches the explosion routine to call his routine to render a piece – using intermediate results from the caller – and then jumps back to the original routine. There’s a decent amount of code …