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(C) Devil of eTc / Scene '99
Chanks ...
Currently, the domestic
demomake'rstve more and more
becoming popular for use
graphics output on the screen of so-called
chunks.
The advantages of this technology are great,
Among them:
- 16 shades of gray (even if
Chunks 8 * 8 we can use
attributes, then the colors become even
too much:)
- Relatively fast output to
Screen (2-3 int'a), with a rather small
scale image of the screen (no more than 3,072 b.);
However, there is a drawback, which is almost
balances the benefits:
- Significantly decreases the screen resolution
(If chunks 4 * 4 it is obvious resolution
screen will be 64 * 48 that, to put it mildly,
not enough ...);
Example chunks 4 * 4 you can see in
demos such as Refresh, Forever,
5thElement, Goa and many others.
First, consider how to derive
finished animation on the screen (the effect you
can be found in the intro Demo or Die # 01). For
This should be very animated in such a
format:
1-byte 2-byte
OOOO OOOO OOOO OOOO. . .
/ \ / \
1 Chunk 2 Chunk 3 Chunk 4 Chunk
That is, you have to convert so-
image to the first byte in the older
half of the code is the first chunk
(4 bit - 0 .. 15 shades of gray), and
the younger half of the byte code of the next
chunk, and so all of Kartika. Following her
Memory must be placed second image
pictures, then third, etc.
Here is a sample program with a detailed
description.
ORG 25000
CADR EQU 12; SIZE
LEN EQU 15; REAL_LEN = (LEN +1) * 4
HGT EQU 48
;==================================;
; Kidatel chunks by Devil / eTc / sCeNE;
; MoveR cHanKS 4 * 4 pIXels;
;==================================;
CHANKS EQU # F000; at this location will
, Is launched
; Table. Images of chunks
EI: HALT
CALL INIT_CH;, expand the floor
; Nuyu Table. chunks
CALL INITCH; initialize
; Kidatel chunks
CALL INITTAB; create a table. hell
; Ests screen
LD A, CADR; in A, the number of
; Animation frames
LD LX, A
TWERD
EI
HALT
CALL MOVCH; call the procedure
, Throwing the image of scr.
LD A, # 7F; check press
IN A, (# FE); space, and if
RRCA; lie then the output
RET NC
JR TWERD
MOVCH
; Procedure for deriving the image of the screen
MOVCH1 LD A, LX
DEC A
AND A
JR NZ, MOVCH0
LD A, CADR
LD HL, TABLCH; in HL, the address of the image
; Screen
MOVCH0 LD LX, A
XOR A
MOVCH2 LD HX, A
LD B, TABLADR [; in B, high byte
, Address table
; Address screen
ADD A, A
LD C, A
LD A, (BC)
LD D, A
INC BC
LD A, (BC)
LD E, A; in DE, address screen
PUSH DE; from which we
; Output chunks
LD B, CHANKS [; in B, high byte
, Address table
, All combinations
; Chunks
CALL PUTLIN; draw a line from
; (LEN +1) * 4 chunks
POP DE
LD A, HX; check, rather than
INC A; the last line is
CP HGT; we withdraw?
JR NZ, MOVCH2
RET
;-----------------------------;
; CREATE DITHER TABLE
To the address DTDAT are images of chunks
; Duplicated in older and younger
; Parts bytes.
; Example:
,% 1010 1010
,% 0100 0100
,% 1010 1010
,% 0000 0000
; Procedure INIT_CH deploys images
; Chunks at # F000, so that
; Get all # FF combinations of chunks.
; Byte address indicates the number
; Chunk and byte for byte number in
; Chunk (from # 0400 bytes)
INIT_CH
LD HL, CHANKS
CRDT0 LD A, L: AND # F0
.2 RRCA
LD DE, DTDAT
ADD A, E: LD E, A
ADC A, D: SUB E: LD D, A
LD B, 4
CRDT1 LD A, (DE): INC DE
AND # F0
LD (HL), A: INC H
DJNZ CRDT1
LD A, L: AND # 0F
.2 RLCA
LD DE, DTDAT +4
ADD A, E: LD E, A
ADC A, D: SUB E: LD D, A
LD B, 4
CRDT2 DEC DE: LD A, (DE)
AND # 0F
DEC H: OR (HL)
LD (HL), A
DJNZ CRDT2
INC L: JR NZ, CRDT0
RET
DTDAT; 16 COLORS DITHER DATA
DB # 00, # 00, # 00, # 00
DB # 00, # 00, # 00, # 00
DB # 88, # 00, # 00, # 00
DB # 88, # 00, # 22, # 00
DB # AA, # 00, # 22, # 00
DB # AA, # 00, # AA, # 00
DB # AA, # 44, # AA, # 00
DB # AA, # 44, # AA, # 11
DB # AA, # 55, # AA, # 55
DB # AA, # DD, # AA, # 77
DB # AA, # 77, # AA, # FF
DB # AA, # FF, # AA, # FF
DB # AA, # FF, # BB, # FF
DB # EE, # FF, # BB, # FF
DB # EE, # FF, # FF, # FF
DB # FF, # FF, # FF, # FF
; Descent to 4 lines on the screen down
DOW_DE4 LD A, 4
ADD A, D
LD D, A
AND 7
RET NZ
LD A, E
ADD A, 32
LD E, A
RET C
LD A, D
SUB 8
LD D, A
RET
;--------------------------- INITTAB LD DE, # 4000; create table
LD HL, TABLADR; Address Screen
LD B, 48; fast rasINITT1 LD (HL), D; couple addresses
INC HL
LD (HL), E
INC HL
CALL DOW_DE4
DJNZ INITT1
RET
;---------------------------; Procedure is created kidatel line
; Chunks of kidatelya four chunks
, (Those same four chunks are thrown in
; Screen procedure PUTLIN)
INITCH LD B, LEN
LD HL, PUTLIN
LD DE, ENDPL
INITC1 PUSH BC
LD BC, ENDPL-PUTLIN
LDIR; reproduce a piece of
POP BC; PUTLIN to ENDPL
DJNZ INITC1; LEN times
LD A, # C9; a RET at the end
LD (DE), A
RET
;---------------------------
ORG ($ -1) / 256 * 256 +256
TABLCH; ship animation
INCB "ANIM"
ORG ($ -1) / 256 * 256 +256
TABLADR DS 48 * 2; buffer under Table.
; Address screen
;---------------------------; Everything here is quite simple:
; In HL - the image of the screen
; B - byte table
; Chunks (ie, B = # F0)
; DE - address on the screen
PUTLIN
LD C, (HL); take in C, the code chunk
INC HL; in BC, we address
; Image chunk
LD A, (BC); toss 1-byte
LD (DE), A; chunk of the table
; Screen
INC D; dropping down
; Screen
INC B; go to the next
; Shem byte
LD A, (BC): LD (DE), A: INC D, B
; As 2-byte
LD A, (BC): LD (DE), A: INC D, B
; As 3-byte
LD A, (BC): LD (DE), A: INC E
; After the 4-th byte We turn right on
; Screen, grab the code and the next chunk
; Begin to climb.
LD C, (HL)
INC HL
LD A, (BC): LD (DE), A: DEC D, B
LD A, (BC): LD (DE), A: DEC D, B
LD A, (BC): LD (DE), A: DEC D, B
LD A, (BC): LD (DE), A
INC E
ENDPL
However, we considered the ideal, ie when
We have a single byte codes of two,
neighboring chunks. This can be achieved in
rare cases (animation, plasma), most often we
we have one code by one byte. In this
If kidatel slightly modified and
unfortunately, becomes significantly
Brake: (
PUT_LIN
; HL = BUFFER - the same buffer in which you
, Are forming an image before displaying on the
; Screen
; HL '= ADDR_SCREEN - address on the screen
; B = TAB [- table bytes are shifted by 4 bits
; Right
; D '= CHANKS [- byte chunks table
LD C, (HL); take the code chunk
LD A, (BC); Tab. shifts its
, 4 bits to the right
INC L
LD C, (HL); take the following code
; Chunk
OR C; get in one byte
; Codes of two neighboring
; Chunks
, Then everything on vysheopisanomu algorithm
INC L
EXX
LD E, A
LD A, (DE)
LD (HL), A
INC H
INC D
LD A, (DE)
LD (HL), A
INC H
INC D
LD A, (DE)
LD (HL), A
INC H
INC D
LD A, (DE)
LD (HL), A
INC L
EXX
LD C, (HL)
LD A, (BC)
INC L
LD C, (HL)
OR C
INC L
EXX
LD E, A
LD A, (DE)
LD (HL), A
DEC H
DEC D
LD A, (DE)
LD (HL), A
DEC H
DEC D
LD A, (DE)
LD (HL), A
DEC H
DEC D
LD A, (DE)
LD (HL), A
INC L
EXX
That's all. If anything is unclear, the questions
send to the address 2:4536 / 100.128 @ FidoNet to
Sergey Movchan.
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