Solider Stations

Entry posted by SpiceWare · May 8, 2014

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One issue with the station graphics is the gaps in the image which are used to create a shadow effect. They look great, but play havoc with collision testing. I built a test version, available below, that lets you move a horizontal shot around with the right joystick. It denotes a collision by changing the score to 888888:

If the shot ends up in a shadow there's nothing to collide with, so the score shows 0:

Collision tests are done row-by-row, so I got to thinking that a way to handle that would be to also consider the rows above and below the row being tested. I should be able to fill in the shadows by ANDing the above and below rows together then ORing that with the row being tested. In pseudo code that'd be (row-1 & row+1) | row.

To test the idea, I wrote a quick a command line program. It first outputs the rows of the station using ASCII graphics:

............XXXX............................XXXX..........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXX............................XXXXXXXX........................XXXX............................XXXXXXXX....................XXXXXXXX....XXXX....................XXXXXXXX....................XXXXXXXX....XXXX....................XXXXXXXX................XXXX................XXXX..................XXXX................XXXXXXXX............XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXX........XXXX....XXXX........XXXXXXXX............XXXXXXXX....XXXX........XXXX....XXXX........XXXXXXXX....XXXX....XXXXXXXX....XXXX....XXXXXXXXXXXXXXXX........XXXXXXXX....XXXX....XXXXXXXX....XXXX....XXXXXXXXXXXXXXXX........XXXXXXXX............XXXXXXXX................XXXX..................XXXX................XXXX................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXX............................XXXXXXXX........................XXXX............................XXXXXXXX........................XXXX............................XXXXXXXX................XXXX................XXXX..................XXXX................XXXXXXXX............XXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXX....XXXXXXXXXXXXXXXX........XXXXXXXX....XXXX....XXXXXXXX....XXXX........XXXX....XXXX........XXXXXXXX............XXXXXXXX....XXXX........XXXX....XXXX........XXXXXXXX....XXXX....XXXXXXXX....XXXX........XXXX....XXXX........XXXXXXXX............XXXXXXXX................XXXX..................XXXX................XXXX................XXXXXXXX....................XXXXXXXXXXXXXXXX....................XXXXXXXX....................XXXXXXXX....XXXX....................XXXXXXXX........................XXXX............................XXXXXXXX........................XXXX............................XXXXXXXX........................XXXX............................XXXXXXXX..........................................................XXXX................

then again as each row would appear for collision testing:

............XXXX............................XXXX..........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX....................XXXXXXXXXXXXXXXX................XXXXXXXXXXXXXXXX................XXXXXXXXXXXXXXXX....................XXXXXXXX................XXXX......XXXX......XXXX........XXXX......XXXX......XXXX......XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX......XXXX......XXXX......XXXX........XXXX......XXXX......XXXX................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX................XXXX......XXXX......XXXX........XXXX......XXXX......XXXX......XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX....XXXXXXXX....XXXX....XXXXXXXX......XXXX......XXXX......XXXX........XXXX......XXXX......XXXX................XXXXXXXX....................XXXXXXXXXXXXXXXX................XXXXXXXXXXXXXXXX................XXXXXXXXXXXXXXXX....................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX........................XXXXXXXX..........................XXXX............................XXXX................

The test can be found in the source in subdirectory quadtest. The results looked good, so I dropped it in. We now get a collision in the shadows: