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Demo or Die #02
31 июля 1999 |
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Demo-Building - The implementation of plasma sizes of 2x2.
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Wolf of eTc / Scene
Implementation of the plasma size 2x2
(As in BooM trackmo)
Write this article, I made
interest of some people to the plasma size
2x2, in our FunTop'ovskoy demo - BooM
trackmo.
I hasten to add that this effect
very easy to implement. Its size
is about 150 bytes (excluding tables and
data). In the demo itself, the data for
implementation of the 2x2 plasma were established in advance
and take in the form of neupakovanom about 26kb
(!). In my opinion a lot, but I do not
meant to make fans
demomeykerstva long wait.
So how does this all done?
First we need to create
normal plasma size 128x96
(256/2x192/2) - this is due to the fact that
point we will have the size 2x2. At what
plasma must be constructed in 256
color (ie bytes per point).
For those who do not know how one
normal plasma, read the rest
can skip the next paragraph.
The algorithm is very simple. First, create
a grid of points in the buffer with some tasks
step, where the color of a point will be
random variable (0 to maximum
color values, such as "chunks" -
16). Then in the middle of each
square write the arithmetic mean
one of the two numbers (color values)
which are recorded at the vertices of
square. In the center of the square write
arithmetic mean of the four
flowers in the four vertices of a square. And so
continue recursively, until no
fill the entire buffer, ie until
reduced to the minimum squares
size. As a result, we have
plasma.
There is another way to build a plasma
but this plasma I call - a sine wave.
In my opinion, this is a plazmochka
BestView (by Ivan Roshchin) in screensaver'e
(As custodian of the screen).
I'm doing it this way:
round (n) - rounded to the nearest whole number
values.
z1: = 0.25; z2: = 0.125; {all sorts of factors}
for y: = 0 to 95 do {} elevation of plasma
for x: = 0 to 127 do {width} of the plasma
c: = round (32 * sin (x * z1/pi) * sin ((x) *
z2/pi) +32 * cos (y * z1/pi)); {proper
formula for the plasma}
As you can see here, depending on the
coordinates X and Y, the function will have
a result that matches the color
point with the same coordinates.
Having such a plasma size 128x96
(Total length 12,288), create a data
Our unpretentious effect.
For clarity, we will do this by
Pascal, but who knows, I think
after such source quickly to it
get used to it, especially with my
comments.
plasma [1 .. 128.1 .. 96] - an array of
128x96, which houses our plasma;
data [1 .. 12 288 * 2] - an array which will
stored the coordinates of the plasma;
data_len [1 .. 256] - an array, where it will
contains information about the number of
dorisovuyuschihsya points per frame.
A little bit about the syntax of Pascal:
inc (n) - to increase the variable n to 1;
dec (n) - to reduce the variable n to 1;
plasma [x, y]: = C - Record the variable C,
in a cell array with coordinates x, y;
i: = 1;
j: = 1;
for phase: = 1 to 256 do
begin
len: = 0;
for y: = 1 to 96 do
for x: = 1 to 128 do
begin
if plasma [x, y] = 0 then
begin
data [i]: = x;
inc (i);
data [i]: = y;
inc (i);
inc (len);
end;
inc (plasma [x, y]);
end;
data_len [j]: = len;
inc (j);
end;
This procedure examines each
pixel plasma to zero color. Namely,
writes the buffer coordinates (X and Y)
each of the zero point and the second buffer
number of points found in one
passage. So do 256 times. This is due to
the fact that the plasma is used for byte
pixel.
; (C) CopyRight by Wolf / eTc / Scene 1998
; From BooM trackmo
ORG 25000
; Throw the picture (black)
LD HL, SCR
LD DE, # 4000
LD BC, 6144
LDIR
, Paint it some color
LD HL, # 5800
INC DE
LD BC, 767
LD (HL), 28
LDIR
; Create a table of addresses screen
LD HL, TAB
LD DE, # 4000
LD B, 96; (192 / 2) as 2x2 points
CRUNCH1 LD (HL), E
INC HL
LD (HL), D
INC HL
; Procedure for calculating the addresses of the screen through
; Two lines
INC D
INC D
LD A, D
AND 7
JR NZ, DONE
LD A, E
ADD A, 32
LD E, A
JR C, DONE
LD A, D
SUB 8
LD D, A
DONE
DJNZ CRUNCH1
; Actually very beginning
EI
START LD A, 4; show all
OUT (# FE), A; how much it
HALT; "eating" time
XOR A
OUT (# FE), A
TIME LD A, 0; loop counter
DEC A; initialization
JR NZ, COOL
LD HL, TABLEN; set options
LD (F1 +1), HL; if the counter has gone
LD HL, DATA; on the second circle
LD (F2 +1), HL
XOR A
COOL LD (TIME +1), A
F1 LD DE, TABLEN
F2 LD HL, DATA
LD A, (DE); how many points to draw
LD B, A
INC DE
LD (F1 +1), DE
OR A
JR Z, NO_P
PRN PUSH BC
LD A, (HL); \ = x
INC HL; |-coordinates
LD E, (HL); / = y
INC HL
PUSH HL
LD L, E
CALL PLOT; Draw point
POP HL
POP BC
DJNZ PRN; draw on
NO_P
LD (F2 +1), HL
LD A, # 7F; poll gap
IN A, (# FE)
RRA
JP C, START
RET; Output:)
; Procedure for drawing points, size 2x2
; When drawing, the point xor'itsya.
; A = x, L = y
; (C) By Wolf / eTc / Scene 1998
PLOT
LD H, TAB [
PUSH AF
LD A, L
ADD A, A
LD L, A
POP AF
LD E, (HL)
INC HL
LD D, (HL)
LD L, A
RRCA
RRCA
AND # 3F
ADD A, E
LD E, A
LD H, D
LD A, L
LD L, E
AND 3
LD D, (TAB +256) [
LD E, A
LD A, (DE)
LD E, A
XOR (HL)
LD (HL), A
INC H
LD A, E
XOR (HL)
LD (HL), A
RET
; Table lengths
TABLEN INCB "tablen"
; Address table screen
ORG ($ -1) / 256 * 256 +256
TAB
4-points and options
ORG TAB +256
DB 128 +64.32 +16.8 +4.1 +2
, "Slonyachie" data
DATA INCB "data"
; Layback etc group
SCR INCB "etcgroup"
Alexandr Kulik (Wolf) 2:4635 / 8.18 @ FidoNet
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