JohnGri Posted June 11, 2022 Share Posted June 11, 2022 (edited) I have watched several tutorials and read a few books and looked at assembly source for KABOOM. I'm still not grasping how a game can have so many objects on the screen at the same time when there is only player0, player1, missle0, missle1, and a bomb available. For example from KABOOM. Thanks to anyone that explains Edited June 11, 2022 by JohnGri more info Quote Link to comment Share on other sites More sharing options...
KevKelley Posted June 11, 2022 Share Posted June 11, 2022 Without looking, my guess would be the bombs, person, and buckets are probably repositioned sprites. You can look at it in Stella to see the breakdown. Now as for accomplishing that, I don't know how to do that outside of batari Basic. Quote Link to comment Share on other sites More sharing options...
+SpiceWare Posted June 11, 2022 Share Posted June 11, 2022 It's done by using Player(sprite) multiplexing: Quote Sprite multiplexing is a computer graphics technique where additional sprites (moving images) can be drawn on the screen, beyond the nominal maximum. ... The sprite multiplexing technique is based on the idea that while the hardware may only support a finite number of sprites, it is sometimes possible to re-use the same sprite "slots" more than once per frame or scanline. The program will first use the hardware to draw one or more sprite(s), as normal. Before the next frame (or next scanline) needs to be drawn, the software reprograms the hardware to display additional sprites, in other positions. ... On the older Atari 2600, sprite multiplexing was not intentionally designed in, but programmers discovered they could reset the TIA graphics chip to draw additional sprites on the same scanline. Displaying additional players(sprites) per frame was known about early on the Atari's life as seen in Air Sea Battle, one of the first 9 games that was available when the Atari was first released. The additional players(sprites) per scanline trick was discovered later, and was used in Galaxian to get 7 players(sprites) per scanline. The original limit is 6 per scanline, achieved by using both sprites in triplicate mode as seen in Space Invaders: You can find a disassembly of Kaboom! by @DEBRO over at MiniDig. I used this excellent disassembly to create the Kaboom! Deluxe! hack. It adds the 2 player "Pitch and Catch" variation from the 5200, where the other player controls the Mad Bomber, and a few graphical enhancements. Additionally you can use Stella's Fixed Debug Colors mode to see what objects are used to draw what parts of the screen. Use the Developer Keys to toggle this mode (CMD + . on a Mac, or ALT + . on Linux/Windows). P0 = Player 0 = Red . It's used to draw the part of the score, all bombs (and explosions), and part of the Activision Logo P1 = Player 1 = Yellow . It's used to draw part of the score, the mad bomber, all buckets, and part of the Activision Logo 5 Quote Link to comment Share on other sites More sharing options...
JohnGri Posted June 11, 2022 Author Share Posted June 11, 2022 As always the information you provide is outstanding. Thank You Quote Link to comment Share on other sites More sharing options...
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