Abductor

[fizgog]

Finally finished major project at work, so I have more time for the Beeb


Started disassembling the VIC20 game Abductor, by getting it run on the Beeb first in Mode 7 and then using the dissembler from the Beeb's emulators as they are a lot better.

Probably about 50% disassembled, but it seems to be fully working, albeit in Mode 7.

In game video can be seen here
https://youtu.be/h8FAXUt5Vws

[Arcadian]

Nice fast shooter! Will look forward to this! (I think you should 'release' the Mode 7 port too, or include it as a hidden Easter Egg!).

I remember spotting the attached [variant] Abductor cover in with a bunch of BBC Micro tapes on ebay a number of years back, got all excited because I thought it might have been an unknown BBC Micro port but it turned out to be the Vic 20 version (I didn't buy it thankfully!).

[fizgog]

Could possibly have a Mode7 version when finished.

I was thinking going down the the route of Galaforce 2 where you can switch between Mode 1 and Mode 5, as not a lot of other games do that.

Moved a lot of code out into a constants file, which allowed me to centre the display better in Mode 7

Video is here, if you want to watch a demonstration

https://www.youtube.com/watch?v=Bzy8V_FQzK0

This is what it looks like in Mode 7 at the moment

[fizgog]

Disassembled about 90% of the game, so thought I'd make a start on the proper Beeb version

Example Front end screen with ability to switch between Mode 1 and 5
This shows the hud and title using more than 4 colours ion Mode 1/5
Falling down white stars

Video is here, if you are interested
https://youtu.be/whzexGDcuVI

[Arcadian]

Title screen and blinking/scrolling stars look the business!

The mode switching is a great touch, I'd have loved to see more games take this approach back in the day (I was always well impressed with Spy Hunter, wished Arcadians had a similar feature!). The switching looks great in your Abductor port already!

Looking forward to the next update!!

[fizgog]

Started to add beeb sprites
Added player ship with left and right movement
Added humanoids
Added alien sprites with partial movement, (need to finish disassembling the last of the ZP values)

Video is here
https://youtu.be/m2jFdlS9I9k

[fizgog]

Added 6 colour Mode 1 loader image
Stopped stars from going below the ground
Some more work on the alien attack patterns (still needs seem work)

NB Slowed down animation for testing purposes

Mode 1/Mode 5 toggle also needs fixing as it toggles to fast

Video is here

https://youtu.be/qRd-PIm-m9U

[nicolagiacobbe]

Thanks for the effort, it is always nice to follow the development of new code. I just watched the video and there appears to be a strange pattern on the attack wave leaving the enemy sprites behind, it is how it should behave or is just a temporary solution?

[fizgog]

Thanks for the effort, it is always nice to follow the development of new code. I just watched the video and there appears to be a strange pattern on the attack wave leaving the enemy sprites behind, it is how it should behave or is just a temporary solution?

No it’s not supposed to do that, I need to add the humanoid capture code and disassemble a bit more of the alien code

[fizgog]

Started to add humanoid movement with skull drop

https://youtu.be/ky-U5cEjrvU

[fizgog]

Started to map out the wave data last night, as it will need changing to fit into the 20x32 beeb display

This is from level 1

Code: Select all

;----------------------------------------------------------------------------
; Wave Data ; L1B38
;----------------------------------------------------------------------------
; 5 waves of data
; Each wave is terminated by $00
; first 4 bytes are alien character frames (max 4 frames)
; Each level is 40 bytes

; Second value is generated from the first value using 4 ROR A
; Example $33 becomes $63

; %00000000 - NONE
; %00000001 - LEFT
; %00000010 - RIGHT
; %00000011 - (LEFT RIGHT Cancel)
; %00000100 - UP
; %00000101 - UP LEFT
; %00000110 - UP RIGHT
; %00000111 - UP (LEFT RIGHT Cancel)
; %00001000 - DOWN
; %00001001 - DOWN LEFT
; %00001010 - DOWN RIGHT
; %00001011 - DOWN (LEFT RIGHT Cancel)
;----------------------------------------------------------------------------
.waveData
        ;EQUB $09,$0A,$0B,$0C ; alien sprite1 frame 1-4
        EQUS "1111"                     ; Use Beebs character set
        ; Following expanded out
        ;EQUB $33,$62,$22,$22
        ;EQUB $22,$22,$22,$22,$22,$2A,$AA,$89
        ;EQUB $91,$15,$6A,$A8,$88,$88,$99,$91
        ;EQUB $55,$51,$98,$88,$88,$A2,$26,$44
        ;EQUB $45,$55,$55,$54,$46,$66,$62
        ;EQUB $00                        ; Terminator

        EQUB $33    ;                           , $63 %01100011 - (LEFT RIGHT Cancel)
        EQUB $62    ; $62 %01100010 - RIGHT     , $46 %01000110 - UP RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $22    ; $22 %00100010 - RIGHT     , $42 %01000010 - RIGHT 
        EQUB $2A    ; $2A %00101010 - DOWN RIGHT, $42 %01000010 - RIGHT 
        EQUB $AA    ; $AA %10101010 - DOWN RIGHT, $4A %01001010 - DOWN RIGHT 
        EQUB $89    ; $89 %10001001 - DOWN LEFT , $28 %00101000 - DOWN 
        EQUB $91    ; $91 %10010001 - UP LEFT   , $29 %00101001 - DOWN LEFT 
        EQUB $15    ; $15 %00001111 - NONE      , $A1 %10100001 - LEFT
        EQUB $6A    ; $6A %00001111 - NONE      , $A1 %10100001 - LEFT
        EQUB $A8    ; $A8 %10101000 - DOWN      , $08 %00001000 - DOWN
        EQUB $88    ; $88 %10001000 - DOWN      , $08 %00001000 - DOWN
        EQUB $88    ; $88 %10001000 - DOWN      , $08 %00001000 - DOWN
        EQUB $99    ; $99 %10011001 - DOWN LEFT , $29 %00101001 - DOWN LEFT
        EQUB $91    ; $91 %10010001 - LEFT      , $29 %00101001 - DOWN LEFT   
        EQUB $55    ; $55 %01010101 - UP LEFT   , $A5 %10100101 - UP LEFT
        EQUB $51    ; $51 %01010101 - UP LEFT   , $25 %00100101 - UP LEFT
        EQUB $98    ; $98 %10011000 - DOWN      , $09 %00001001 - DOWN LEFT
        EQUB $88    ; $88 %10001000 - DOWN      , $08 %00001000 - DOWN
        EQUB $88    ; $88 %10001000 - DOWN      , $08 %00001000 - DOWN
        EQUB $A2    ; $A2 %10100010 - RIGHT     , $4A %01001010 - DOWN RIGHT
        EQUB $26    ; $26 %00100110 - UP RIGHT  , $C2 %11000010 - RIGHT
        EQUB $44    ; $44 %01000100 - UP        , $84 %10000100 - UP
        EQUB $45    ; $45 %01000101 - UP LEFT   , $A4 %10100100 - UP
        EQUB $55    ; $55 %01010101 - UP LEFT   , $A5 %10100101 - UP LEFT 
        EQUB $55    ; $55 %01010101 - UP LEFT   , $A5 %10100101 - UP LEFT
        EQUB $54    ; $54 %01010100 - UP        , $85 %10000101 - UP LEFT
        EQUB $66    ; $66 %01100110 - UP RIGHT  , $C6 %11000110 - UP RIGHT
        EQUB $62    ; $62 %01100010 - RIGHT     , $46 %01000110 - UP RIGHT
        EQUB $00    ; Terminator

Which can be seen in this image

NB I did notice a bug in the original, seems you cannot protect the first humanoid as the ship cannot travel to the furthest left space

[fizgog]

Testing level 1 alien attack pattern

https://youtu.be/9VARB7wtgic

[fizgog]

Bit more work done

Added level 2 sprites and attack pattern
Plugged humanoid code back in, so aliens can take them and drop them as skulls


https://youtu.be/UinJJyGiEp0


Slight bug, leaving alien sprites behind when they begin the dives