Slordax 0.8A RELEASED

DigiTan · Post by **DigiTan** » Thu 24 Mar, 2005 4:37 am

Scrolling backgrounds...I like the sound of that. There's a little-known TI-82 game called Alpha-10 that made some really nice use of scrolling backdrops. Okay--so it got a bad review from Sam Heald, but I really liked the parallex illusion; it created a good sense of altitude and speed.

If you wanted to go one further, you could try doing just a little side-scrolling as the player manuvers left and right. Just implement it using bit shift and rotate instructions. Then sit back and watch those beta-testers pivot in their chairs against those imaginary G-forces.

Spengo · Post by **Spengo** » Thu 24 Mar, 2005 6:26 am

Wait, I don't understand. What the heck is that thing?

Shadow Phoenix · Post by **Shadow Phoenix** » Thu 24 Mar, 2005 4:25 pm

DigiTan wrote: If you wanted to go one further, you could try doing just a little side-scrolling as the player manuvers left and right. Just implement it using bit shift and rotate instructions. Then sit back and watch those beta-testers pivot in their chairs against those imaginary G-forces.

bit shift?
rotate?
i still cant do a _PointOn =(

DigiTan · Post by **DigiTan** » Thu 24 Mar, 2005 5:17 pm

Mainly, it's just a useful way to side-scroll without a tilemap. In Alpha-10, the programmer used a bitmapped background and added ldi commands to scroll the "terrian" image down. What I'm saying is you can do a similar horizontal effect by rotating the bitmap left and right with the shop--as well as vertically like Alpha-10 does.

The (unoptimised) code below will do this. If you declare HL as a pointer to part of your display mem, it will rotate every pixel on that row left 1 pixel--giving the illusion of strafing to the right. Of course, the same thing can be done for right-scrolling.

Code: Select all

RIGHT_ROTATE:			; Special thanks to CrASH_Man
 push hl
  SLA (HL)                      ; 96-bit shift left
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
  RL  (HL)
  DEC HL
 pop hl
 ret nc
 ld a,(hl)
 or %00000001
 ld (hl),a
 ret

Also, if used in the context below, the ROTATE code will move the entire screen. And unlike the hardware scroll, it won't leave a white gap at the edge of the screen. It's in 82 ASM, but the concept pretty much applies across the board...

Code: Select all

scroller_loop1:
 ld b,64                        ; Picture is 64 pixels high
 ld hl,GRAPH_MEM+767            ; Start at end of picture and move backwards
scroller_loop0:
 call RIGHT_ROTATE              ; Rotate the row by 1 pixel
 dec hl                         ; Move up one row...
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 dec hl
 djnz scroller_loop0      ; Loop until all 16 row are rotated
 call CR_GRBCopy                ; Refresh the picture
...
 jr scroller_loop1

Shadow Phoenix · Post by **Shadow Phoenix** » Thu 24 Mar, 2005 8:28 pm

DigiTan wrote:Mainly, it's just a useful way to side-scroll without a tilemap. In Alpha-10, the programmer used a bitmapped background and added ldi commands to scroll the "terrian" image down. What I'm saying is you can do a similar horizontal effect by rotating the bitmap left and right with the shop--as well as vertically like Alpha-10 does.

The (unoptimised) code below will do this. If you declare HL as a pointer to part of your display mem, it will rotate every pixel on that row left 1 pixel--giving the illusion of strafing to the right. Of course, the same thing can be done for right-scrolling.

I cant do that yet.
gimme some time

i am still fighting with loops

DigiTan · Post by **DigiTan** » Fri 25 Mar, 2005 8:18 pm

Well, I guess it's not too important to add that now. If you decide to, just use the code above.

Shadow Phoenix · Post by **Shadow Phoenix** » Wed 20 Apr, 2005 11:09 pm

once the menu *bug* will be resolved I will post alpha 0.8.

Shadow Phoenix · Post by **Shadow Phoenix** » Thu 21 Apr, 2005 12:15 am

http://www.geocities.com/karavaev@sbcgl ... lordax.zip
8 kbts 3 files.

kalan_vod · Post by **kalan_vod** » Thu 21 Apr, 2005 3:12 am

looks great, is there any shooting?

also there are a few bugs, like if you dont use alpha and press somthing else it will freeze.

Jim e · Post by **Jim e** » Thu 21 Apr, 2005 1:00 pm

I just tried it, not bad, I didn't know if the grey would work for a shooter, but looks good. Some more bugs need to get worked though.
Some times it messed up at the menu, also the ship would crash into nothing and freeze. But with some work I can see this happening.

Shadow Phoenix · Post by **Shadow Phoenix** » Thu 21 Apr, 2005 3:30 pm

I have disabled the shooting :/ evil stacks.
the crashing boundary is behind to the left of enemies.

Spengo · Post by **Spengo** » Thu 21 Apr, 2005 4:39 pm

one time, it seemed as tho it crashed randomly, and then after that, every time I turned it on, it just showed a crash and froze.

Shadow Phoenix · Post by **Shadow Phoenix** » Thu 21 Apr, 2005 10:56 pm

as soon as the evil stacks will give away I will post it here

DJ_O · Post by **DJ_O** » Sun 08 May, 2005 8:39 pm

progress (with stacks and the game)?

necro · Post by **necro** » Mon 09 May, 2005 2:07 pm

How stable is it?

MaxCoderz

Slordax 0.8A RELEASED

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