Whats brewing in the Lab ?

First optimizations

March 15, 2004

I'v replaced the 4 direction variables with a single variable. Thats 4 bytes into 1 nyble. Not only am I saving RAM but also a lot of loading and storing opcodes which equels rom space and kernel time.
The phantom zero is now gone. I'v changed the position of the number sprites in Chr-Rom
so the zero is now blank. A stop-gap solution I know. But as long as it works ..... :)

direction	ds 1 ;UDLR0000 	

;Up        	ds 1
;Down       	ds 1
;Left       	ds 1
;Right      	ds 1

Movment

March 14, 2004

As promised here is the latest source code and rom.
I'm doing my testing in Nintendulator, FCEU and Nestopia (when it works :( )
I'v implemented control and rudimentry boundry checking.
If you keep pressing a direction you can cross the boundry's
I'v also implemented the Afterburner on button A
The phantom zero is still hanging around. Looks like I'll have to ask on NESdev about that. It's starting to bug me.

Going up.

Ship	March 13, 2004

Just when I thought I'd be giving up and persuing another aspect of the game I suddenly realized how it all works.
You know the feeling, Staring at a problem so long it loses all meaning and then suddenly BAM you know exactly what to do.
4 days straigt (well nights, but whatever :) ) and I finaly have my first milestone. The ship will move diagonaly across the screen from upper left to lower right.
The nose of the ship has to be 8 pixles in front of the rear so I'm using 2 index variables.
I'll be adding control next and the source will be out when I get the sprites turning in the direction of the pad.
For now you can see my creation moving across the screen There is a phantom zero in the top left hand corner I'm hoping simply clearing the Nametable at startup will fix this.
If it's in the source release you'll know it didn't and you can debug it for me (pretty please)

Ship being persued by phantom zero

Control

March 12, 2004

Well I've been having a lot of problems with the sprites. It seems that no matter what I write to Ptable1 (which is where Sprites are supposed to be located) I can't get my ship sprite displayed.

Anyway I've implemented some rudimentary control and linked it to the sprites index byte.
so the sprite changes to the next sprite in the pattern table every frame. it's a bit fast but I'm not debouncing it just yet.

I'll be releasing the first milestone as a ZIP file with the rom and sourcecode.
Basicaly I want the ship to be controlable. Not in a gamplay sense just 100% freedom of movement ;)

sprites
��� ��� dc.b� $00,$00,$00,$00
��� ��� dc.b� $00,$00,$00,$08

16x16

C O L O U R S

Background� #$01 (Blue)
Ship������� #$39 (yellowish)
Missile���� #$14 (Purple)
dots������� #$30 (white)
walls������ #$21 (Aqua)

Possible colour values.

16x16 Sprite

March 11, 2004

I'v got a 16x16 sprite on the screen.
It's just 2 8x16 sprites next to each other
Next step is to make it look like our ship and to figure out why the background colour is always dark blue now.
I think it has something to do with placing the sprite graphics in the chr-rom, but it's not being loaded (into the correct sprites anyway)

(No this isn't a
�port of Adventure)

Background

March 10, 2004

This is it so far. I have a screen display and can change the background colour. It's a good starting point but not a milestone.
I'll just be concentrating on drawing the graphics first then move onto game logic afterwards.

� Blue screen of life

The Lab is now open

March 8, 2004

My first project here will be a port of� the 1980 Taito game Space Chaser.
The first thing I'm going to do is play this game until my eyes bleed.
the whole time wondering "How can I do that?"

LATER THAT DAY ........
O.k my eyes are officially bleeding and I still haven't passed the first stage.
This game is friggin HARD.
And apparently later levels have multiple missiles and enemies.

===================
C O M P A R I S O N
===================
A r c a d e
Screen Size : 224x248
Sprite size : 11x11

N E S
Screen Size : 32x30 tiles (256x240 pixels)
Sprite size : 8x8 or 8x16��

Looks like I'v got enough resolution to pull off the Playfeild
The playfeild is roughly 21 tiles high by 18 tiles wide. It might be a little bigger .
The sprites are going to need some special attention. I could use 2 8x16 sprites and be able to keep the same sprites from the arcade. Of course I don't know how I'd do this yet ... which is the whole point of this project.
Time to do a little research.....

Hopefully this project will help add some more stuff to the code vault. ;)

Contact me at Happy_Dude [at] Bocnet.com.au

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