Jeskyně by Řrřola [web]
; ES v
; J K E (The Cavern)
; YN
; a 128-byte intro by rrrola <rrrola@gmail.com>
; greets to everyone who thinks squarish tunnels are 27.32395% cooler
org 100h ; assume ah=bx=0 cx=255 si=100h di=sp=-2
mov al,93h ; int16[100h] = -27728 = BIG
push 09FCEh ; screen-aligning trick from Puls
pop es
int 10h ; mode 320x200 without clearing the screen
; bx = sp+2 = time = ptr to current metaball position (-= 16 each frame)
M fninit ; { } = fpu stack
inc cx ; cx=1 (256 on first frame: precompute states, set palette)
N mov bp,8 ; Create a new state for the 4 metaballs: m[i].x, m[i].y
S xchg ax,bx
mul word[bp+si] ; frequencies = { int16[108h]...int16[101h] }
mov bx,sp ; dx = time * frequency[i] / 65536
push dx ; bx = sp+2
fild word[bx+di]
fdiv dword[byte si-100h+C-2] ; -111.498
fsin ; {position = sin(time * frequency[i] / 65536 / -111.498)}
fimul word[si]
fistp word[bx] ; int16[bx] = BIG*position
dec bp
jnz S
mov dx,3C9h ; palette[i].rgb = [2*i 2*i-8 max(i-1,0)]
mov ax,cx
out dx,al ; blue uses running index from last time
dec dx
out dx,al
inc dx
add al,al
out dx,al
sub al,8
out dx,al
loop N
mov [di],es ; uint32[-4]=9FCE0059h ah=cx=bp=0 dx=3C9h
; x = int0_16[-3] ~ -0.5..0.5 (+= 0.003125 each column)
; y = int0_16[-2] ~ -0.4..0.4 (+= 0.00390625 each row)
X xor ax,ax ; For 29 layers
mov al,29 ; al=layer=29 carry=0 ZF=1
push bp ; store pixel address to [bx-4]
lea bp,[bx+si] ; go back 32 frames (32 * 16 bytes/frame = 0x200 = bx+si+si)
Z fldl2t ; Sum 4 metaball potentials: carry=0 ZF=(initial pass ? 1 : 0)
fimul word[bp+si] ; load metaball coord (m[i].y or m[i].x) * 3.322
lea bp,[bp+di] ; =sub bp,2 without modifying carry or ZF
jz I ; initial pass: skip computing absolute differences
fsub st3
fabs
I cmc ; load both coords; loop using carry
jc Z
jz J ; initial pass: {cy=m[0].y cx=m[0].x}, skip to J
faddp st1 ; otherwise: {dy=|m[i].y-cy| dx=|m[i].x-cx| sum cy cx}
fidivr word[si]
fsubp st1 ; {sum+=-BIG/(dy+dx) cy cx}
add al,40h
jnc Z ; loop 4 times (al is never zero here, so ZF=0)
fistp word[bx+di]; If we're inside the isosurface: go to next layer
cmp [bx+di],dh ; carry = ((int16)sum<3 ? 1 : 0)
J dec ax ; ZF = (--layer==0 ? 1 : 0), carry unchanged
fiadd word[di]
fild word[di-1]
C faddp st2
fld1 ; {sum=1 cy+=y cx+=x}
jnbe Z ;-) if (!initial pass && ((int)sum>=3 || --layer==0)) break
fninit ; { }
xor al,1Fh ; al = 31-al (use 3Fh to get blue->white)
pop bp
add word[di-2],0CCCDh ; advance x, y and address
adc word[di],cx ;cx=0
inc bp
mov [es:bp+si],al ; Draw pixel: al = depth = color
jnz X ; do all 65536 pixels
in al,60h
dec ax ;ah=0
jne M
int 20h ; can't use ret
[ back to the prod ]