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The Story of Stay Frosty 2, Part 17



As sometimes happens at the start of January, I came down with Cedar Fever - really bad allergies due to the cedar pollen. Technically they're Ashe juniper trees, but they're known in Texas as Mountain Cedar. The trees grow in the hill country (central Texas) so I don't normally get exposed to it - but when the wind blows just right (or maybe that should be just wrong :)) the pollen makes it all the way to Houston. How bad can it be? It made it here again this year and I had to take three sick days in a row off work - and I work from home. Here we are three weeks later, and I'm still not quite over it. Found out Cedar Fever started late this year, so I've actually been fighting a bug.

In spite of the allergies we still thought SF2 would be released in February, so I'd been changing my avatar (the animated one posted last time) so that each day it took 5 seconds off the initial 2:30 delay before the snowman would pop up.

batari made an update to the DPC+ driver - revised the random number generator so it would be more random, and fixed an issue with the "Copy ROM to fetcher" routine.

Over the holidays I'd watched family play test the game and made some changes based on problems they encountered. I added a new kernel to show the rescue character that Nathan suggested last time. I did it by tapping into the logic for the sprite reposition routines - there were 11 X Object Position kernels, I added a 12th kernel. The new kernel would position the sprite to a fixed location, as the animated rescue character would not move around the level, then fall into a new rescue kernel routine. The rescue kernel would skip updating the playfield, so no ice would be drawn, and use that time instead to draw a multi-color sprite. The snowman's melt trail would also not be drawn in this special rescue kernel. Neither shortcoming would be a problem for the "finished level 32" screen, but these limitations are obvious on the test done using level 1.


the upper snowman is a test of the rescue character kernel


The flicker routines are active to show the snowman and the upper fireball. Because the ice is flickering as well, the fireball loses the transparent affect that's seen with the lower fireballs. When the upper fireball is put out, the flicker routine is no longer needed so the upper ice disappears. It can still be collected though.


invisible ice


In this build the Right Difficulty switch was used to control some test routines. If set to B the snowman's gravity will be off and he'll be super floaty, so set it to A for normal performance. This was done to make it easier for Nathan to see the different images from the animation sequence and make sure I converted them correctly.

ROM (sorry, no PAL version this time):
SF2 20110113_NTSC.bin


NOTE: While the ROM works on the Harmony, it does not work in Stella.

Blog entry covers January 3 - 13, 2010


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