Aliens Unleashed

23rd March 2020

Last Saturday, I mentioned about the problems I had with the alien movement patterns, where I made things a lot harder for myself. Especially the previous weekend. This weekend, I started on working on the alien movement groups. After Saturday's major change of the code and pointers. After following the Starfysh code, I finally got somewhere and I am now ready to continue with working on the alien movement groups.

Alien movement is based on time instead of position. Once the timer table has reached the end, the next group of aliens can spawn. I have a lot more groups of aliens to work on, which will take some time time to make. Or should I say, a lot of time to make. Especially when the total number of enemy sprites drawn result to 26. I have used the border cycle on screen as a clock, so I can count which byte the table is read at, and also where I should time out the aliens to stop them wrapping across the screen.

On the plus side, since the game preview was released Summer last year. The majority of the game code is still there. Although at the moment I have disabled the collision, in order to test the aliens for their movement.

The new set of tables are as follows:

enemy1framelo !byte <Frame_AlienType2 ;Store low-byte of alien frame
enemy1framehi !byte >Frame_AlienType2 ;Store hi-byte of alien frame 
enemy1colour  !byte $0a               ;Store colour of alien
enemy1startx  !byte $0c               ;Start X-Position   
enemy1starty  !byte $f0               ;Start Y-Position
enemy1score   !byte $01               ;Amount of points to score
enemy1lives   !byte $01               ;Number or hits to kill alien
enemy1time    !byte $18,$18,$18,$1c,$18,$18,$18,$18 ;Timed movement
enemy1speedx  !byte $00,$00,$00,$00,$00,$00,$00,$00 ;Speed of movement accordingly X
enemy1speedy  !byte $fe,$fe,$fe,$fe,$00,$00,$00,$00 ;"                             Y

Aliens in self-isolation

21st March 2020
 
This post is a quick update on the Cruiser-X 79 project. Unfortunately, once again I made things much harder for myself. Last week's post caused me more trouble on the project, instead of making things easier for myself. So once again I deleted all of the alien movement/spawning code which I started last week. I made an alternative plan for the aliens, which is to basically use a timed movement, similar to Starfysh, rather than a positional movement trigger. . This will reduce the amount of programming I would have to do for each enemy. On the plus side, the Starfysh method is a whole lot easier to master. Mind you, I will be using more than just 4 bytes on the table to move those alien groups. Wish me luck :)

Where have all the aliens gone?

14th March 2020

Great news. Cruiser-X 79 continues this month. Today has been quite a long session. You might probably notice that the game was delayed for a very long time over several months period. This was mainly because of some other game projects I was working on. Happy Blocks DX, Amazon Tales, Mega Tank Blasta, Toxic (2020 Edition). Amazon Tales was made as a practice piece in order to attempt to develop custom enemy movement patterns which didn't require wasting $200 bytes of data. Plus I wanted to add a mixed batch of enemies in to the game project.

Since the game engine in Amazon Tales was successful. I have decided to try a similar attempt for Cruiser-X 79. In order to do that. I have to start the enemies attack patterns from scratch. Before I could do that, I had to delete the existing alien attack patterns. Therefore on today's build of the project, I concentrated on setting up table values per enemy type.

For example:

Alien1SpawnX = The starting horizontal position for the alien to spawn from
Alien1SpawnY = The vertical horizontal position for the alien to spawn from
Alien1Dir = Direction for the alien to move whilst in operation. 0 = Up, 1=Down, 2=Left,3=Right. This consists of a table of 8 bytes (Since the aliens are supposed to switch to the next direction every time a path limit has been reached).
Alien1Speed = Speed of the alien which is moving, once again 8 bytes.
Alien1ChangePosition = Horizontal or Vertical position in which the alien must reach before it can change to the next direction (or leave the screen)
Alien1ObjectLo = Low byte of the animation frame read from the sprite animation subroutine
Alien1ObjectHi = Hi byte of the animation frame read from the sprite animation subroutine
Alien1Colour = Alien sprite colour
Alien1Lives = Amount of lives the alien has before it can be destroyed
Alien1Score =  Multiple number of points to be scored per alien destroyed

I also made different lo/hi byte tables which should somewhere in the game code (once implemented) copy the self-modifying pointers in to the correct self-modifying code. For example, after the last change position has been breached, and all aliens are off set. A new group should spawn.

For now, there's no aliens in this current build, because the code needs to be started from scratch. This will be continued during my next coding session on this game project.