Program Plasma_;
uses crt;
type lrgarr = array[0..65534]of byte;
const
pal : array[1..384]of byte =
( 0, 0, 0,48,48,48, 1, 0,43, 1, 3,43, 2, 5,44, 2, 7,44, 3, 9,
45, 4,11,46, 5,13,47, 6,15,48, 7,17,49, 8,19,50, 9,21,51,10,
22,52,11,24,52,12,26,54,13,28,54,14,30,56,15,32,56,16,34,58,
17,34,58,17,36,58,18,38,60,19,40,60,20,42,62,21,44,62,10,31,
0,11,31, 0,11,31, 1,11,32, 1,12,32, 1,12,32, 2,12,33, 2,13,
33, 2,14,33, 3,15,33, 3,15,34, 3,15,34, 4,15,35, 4,16,35, 4,
16,35, 5,16,36, 5,17,36, 5,17,36, 6,18,37, 6,18,38, 7,19,38,
8,20,39, 8,20,40, 9,21,40,10,22,41,10,22,42,11,23,42,12,24,
43,12,24,44,13,25,44,14,25,45,14,26,46,15,27,46,16,27,47,17,
28,47,18,28,48,19,29,49,19,30,49,20,30,50,21,31,51,21,32,51,
22,32,52,23,33,53,23,34,53,24,34,54,25,35,55,25,36,55,26,36,
56,27,37,57,27,38,57,27,39,57,27,41,57,27,42,57,27,43,57,27,
44,57,27,45,57,27,46,57,27,47,57,27,49,57,27,50,57,27,51,57,
27,52,57,27,53,57,27,55,57,27,56,57,27,57,57,27,58,57,27,58,
57,26,58,57,25,58,57,24,58,56,23,58,55,22,58,54,20,58,53,19,
58,51,18,58,50,17,58,50,16,58,49,15,58,48,14,58,47,13,58,46,
12,58,45,11,58,44,11,58,44,10,58,43,10,58,42, 9,57,41, 8,57,
40, 8,56,39, 7,56,38, 6,55,37, 5,55,35, 4,54,33, 4,54,31, 2,
32,32,32,63,63,63,63,63,63,63,63,63,63,63,63,48,48,48,63,63,
63,63,63,63);
var
mp,scr : ^lrgarr;
rng : array[0..320]of byte;
dir,i,x,y : integer;
function ncol(mc,n,dvd : integer): integer;
var loc : integer;
begin
loc:=(mc+n-random(2*n)) div dvd; ncol:=loc;
if loc>250 then ncol:=250; if loc<5 then ncol:=5
end;
procedure plasma(x1,y1,x2,y2 : word);
var xn,yn,dxy,p1,p2,p3,p4 : word;
begin
if (x2-x1<2) and (y2-y1<2) then EXIT;
p1:=mp^[256*y1+x1]; p2:=mp^[256*y2+x1]; p3:=mp^[256*y1+x2];
p4:=mp^[256*y2+x2]; xn:=(x2+x1) shr 1; yn:=(y2+y1) shr 1;
dxy:=5*(x2-x1+y2-y1) div 3;
if mp^[256*y1+xn]=0 then mp^[256*y1+xn]:=ncol(p1+p3,dxy,2);
if mp^[256*yn+x1]=0 then mp^[256*yn+x1]:=ncol(p1+p2,dxy,2);
if mp^[256*yn+x2]=0 then mp^[256*yn+x2]:=ncol(p3+p4,dxy,2);
if mp^[256*y2+xn]=0 then mp^[256*y2+xn]:=ncol(p2+p4,dxy,2);
mp^[256*yn+xn]:=ncol(p1+p2+p3+p4,dxy,4);
plasma(x1,y1,xn,yn); plasma(xn,y1,x2,yn);
plasma(x1,yn,xn,y2); plasma(xn,yn,x2,y2);
end;
procedure draw(xp,yp,dir : integer);
var z,zobs,ix,iy,iy1,iyp,ixp,x,y,s,csf,snf,mpc,i,j : integer;
begin
fillchar(rng,sizeof(rng),200); zobs:=100+mp^[256*yp+xp];
csf:=round(256*cos(dir/180*pi)); snf:=round(256*sin(dir/180*pi));
fillchar(scr^,64000,0);
for iy:=yp to yp+55 do
begin
iy1:=1+2*(iy-yp); s:=4+300 div iy1;
for ix:=xp+yp-iy to xp-yp+iy do
begin
ixp:=xp+((ix-xp)*csf+(iy-yp)*snf) div 256;
iyp:=yp+((iy-yp)*csf-(ix-xp)*snf) div 256;
x:=160+360*(ix-xp) div iy1;
if (x>=0) and (x+s<=318) then
begin
z:=mp^[256*iyp+ixp]; mpc:=z shr 1;
if z<47 then z:=46; y:=100+(zobs-z)*30 div iy1;
if (y<=199) and (y>=0) then
for j:=x to x+s do
begin
for i:=y to rng[j] do scr^[320*i+j]:=mpc;
if y<rng[j] then rng[j]:=y
end;
end;
end;
end;
move(scr^,mem[$A000:0],64000);
end;
begin
randomize; x:=0; y:=0; dir:=0; new(mp); fillchar(mp^,65535,0);
new(scr); mp^[$0000]:=128; plasma(0,0,256,256);
asm xor ax,ax; mov al,$13; int $10; end;
port[$3C8]:=0; for i:=1 to 384 do port[$3C9]:=pal[i];
repeat
dir:=dir mod 360; draw(x,y,dir);
case readkey of
#0 : case readkey of
#75 : dec(dir,10);
#77 : inc(dir,10);
#72 : begin y:=y+round(4*cos(dir/180*pi));
x:=x+round(4*sin(dir/180*pi)); end;
#80 : begin y:=y-round(4*cos(dir/180*pi));
x:=x-round(4*sin(dir/180*pi)); end;
end;
#27 : begin asm xor ax,ax; mov al,$3; int $10; end; HALT end
end
until false;
end.
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