Working currently on the player graphic. I wanted the player to be able to have a temporary shield, so I designed two definite states, with and without shields, which will be rotated with the character set providing the animation. I am also reorganising the display list to something more proper for horizontal scrolling.
Next, I will be working on the most basic player movement.
-Thom
I am slowly progressing. I have the first DLI routine set in place to set the colors. Had to use a chain of routines each modifying the DLI vector at the end of each pass. Because I had to make four distinct color changes, I decided to hard-code them into the routine, so that I could minimise the number of cycles being done. I will be modifying the look of the screen layout from here, but now I have something i can work with and mould to look the way I want it to look.
You may have noticed I
Decided for my first game to be a Space Invaders type game. Did some initial sketching in Envision, and am now posting the results of my work.
The graphics are meant for antic mode 4 displays, with each line setting a DLI to change the color palette of each line essentially doing a hue change.. I chose to use all four colors for a shaded look rather than a non-shaded flat but colourful look.
What do you guys think?
<-- editing the characters
<-- doing a basic tile test.
Ahhh, some nice DRY evening reading.. The Atari 400/800 hardware manual. Continuing my quest for getting a grasp on the whole system... I found this paragraph in section 2 slightly amusing....
Translation: shit man, we know it's possible if you're god's gift to 6502 assembler, otherwise man. Sheesh, we don't know. *Shrug*
After fixing the little display list weirdness, it works now. A tight locked interrupt loop that changes the color of every four lines (more or less) via a display list interrupt, using an increment inside the interrupt routine to change a page zero counter. It runs very fast, so it tends to strobe.. Now i need to learn proper delaying techniques. I will be tweaking this routine to make the effect not so perceptively fast, but at least it works. Yay :-)
-Thom
2puck.zip
I am currently trying to build a simple demo program that uses a DLI that increments the color registers. I am thinking if i just increment the zero page registers when the interrupt occurs, I will get a sort of ripple effect. But right now, somehow, the low bit of my LMS instruction is getting obliterated, grr a load instruction going wrong.
have attached the code i am working on.
-Thom
p.s. wow, i went 12 hours without realising i didn't even upload the attachment... go me!2puck.zi
Still reading...and I've come across something in De Re Atari that has me a bit curious. I have cross posted this to the forum, but, I am posting it here too for my journal....
In the book De Re Atari, Chris Crawford talks about moving the player vertically through memory. It's very straightforward...
of special note, is that next to last sentence in the paragraph.
If high speed is necessary, the loop can be trimmed to move only the image bytes themselves rather than the whole p
Not much accomplished tonight, spent much of my time basically testing out the memory clearing routine, and reading both Atari Roots and De Re Atari, trying to get a handle on the conceptual model of the system. Will try some basic player missile graphics stuff tomorrow night.
-Thom
After much deliberation, I finally managed to get the memory clear/fill function debugged.
;
; FILL PAGES MACRO
;
; %1 = beginning page to fill
; %2 = number of pages to fill (should be - 1)
; %3 = byte to fill with (e.g. $00)
;
; $CC = 00 for top of page boundary
; $CD = page currently being filled
; $D5 = corresponding to ending page
;
.MACRO CLRP
STCL LDA %1
STA $CD
LDA #00
STA $CC
LDY #0
LDA $CD
ADC #%2
STA $D5
CRLP LDA %3
DEY
STA ($CC),Y
BNE CRLP
INC $CD
LDA $CD
CMP $
Ok, well, got my memory clearing routine to work properly, was just a few little typos. Basically was very easy. I had decided to make two separate macros that were self contained for clearing single and multiple pages becase the addition of clearing multiple pages was just a few instructions more, and didn't make sense to loop back through re-setting everything for each individual page....
I have made a couple small test programs just going through loops and setting values, just trying to g
It's so strange to be coming back to this platform, after not seeing it since 1989. I completely missed the eastern european renaissance that occurred in the early to mid 1990s (which is still happening even today.), and am amazed to see just what has been created for the ANTIC based Atari systems since I left.
It seems I am not the only person who has decided to come back, After combing the posts here on this site, there are a lot of developers pumping out things here too! Wow, a Rally-X ga
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