컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� ; ; TITLE: Star field ;WRITTEN BY: DRAEDEN ; DATE: 03/15/93 ; ; NOTES: Need 386 to execute. ; ;ASSOCIATED FILES: ; ; STARGEN.BAS => Basic program that generates a set of 'randomized' ; numbers. Creates STARRND.DW ; ; STARS.TXT => The text file that explains starfields... ; ; STARRND.DW => File that contains a set of shuffled numbers. ; Used to create 'random' star field. ; 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 DOSSEG .MODEL SMALL .STACK 200h .CODE .386 ASSUME CS:@CODE, DS:@CODE LOCALS ;=== GLOBALS ;=== Data Includes INCLUDE starrnd.dw ;file that has label StarRnd numbers ;=== DATA Structures Star_Struc STRUC X dw 0 Y dw 0 Z dw 0 OldDi dw 0 ;where to erase last dot Color db 0 ;BASE color. a number 0-16 is added to it Star_Struc ENDS StarStrucSize = 9 ;number of bytes per entry ;=== DATA ScreenWidth EQU 320 ScreenHeight EQU 200 NumRnds EQU 400 ;number of random numbers defined MaxZpos EQU 4096 MinZpos EQU 2 MaxStars EQU 190 NumColors EQU 5 ;number of Base colors in the Color Chart WarpSpeed dw 15 ;how quickly the stars move toward ya MaxWarp EQU 90 Xindex dw 30 ;index into the StarRnd chart for X & Y Yindex dw 230 ; -note they must be different; set em the same to ;see why Cindex dw 0 ;index into ColorChart ColorChart db 0,16,32,48,64,80 ;a list of base colors (-1) Stars Star_Struc MaxStars DUP (<>) ;where all the data is held NumActive dw 0 ;number of stars active Palette db 3 dup (0) ;the palette.. first entrie is BG color (black) i = 15 REPT 16 db 2*i,3*i,4*i i=i-1 ENDM i = 15 REPT 16 db 2*i,2*i,4*i i=i-1 ENDM i = 15 REPT 16 db 3*i,3*i,4*i i=i-1 ENDM i = 15 REPT 16 db 3*i,2*i,4*i i=i-1 ENDM i = 15 REPT 16 db 3*i,3*i,3*i i=i-1 ENDM i = 15 REPT 16 db 2*i,4*i,3*i i=i-1 ENDM ;=== Code Includes ;=== SUBROUTINES ;finds 1st available slot for a star and puts it there MakeStar PROC NEAR pusha mov ax,cs mov es,ax mov ds,ax cmp [NumActive],MaxStars ;is there room for another star? jae NoEmptySpace ;search for 1st available slot mov si,0 TryAgain: cmp word ptr [Stars.Z+si],0 ;is this slot empty? je GotOne ;yes, go fill it add si,StarStrucSize cmp si,MaxStars*StarStrucSize jb TryAgain jmp NoEmptySpace GotOne: ;si points to the record for the star to fill mov di,[Yindex] ;grab index for Ypos add di,di ;multiply by 2 to make it a WORD index mov ax,[StarRnd+di] ;get the number shl ax,3 ;multiply by 8- could been done in BAS file mov [Stars.Y+si],ax ;and save off the number mov di,[Xindex] ;grab index for Xpos add di,di ;... same as above, but for Xpos mov ax,[StarRnd+di] shl ax,3 mov [Stars.X+si],ax mov [Stars.Z+si],MaxZpos ;reset Zpos to the max inc [NumActive] ;we added a star so increase the counter mov di,[Cindex] ;grab the color index mov al,[ColorChart+di] ;grab the BaseColor for the star mov [Stars.Color+si],al ;save it in the record ;increase all the index pointers inc [Cindex] ;increases the color counter cmp [Cindex],NumColors jb OkColor mov [Cindex],0 OkColor: inc [Yindex] ;increases Yindex cmp [Yindex],NumRnds ;note that for this one we jb YindNotZero ; subtract NumRnds from Yindex if we sub [Yindex],NumRnds ; go off the end of the chart YindNotZero: inc [Xindex] ;increase Xindex cmp [Xindex],NumRnds ;have we gone through the entire chart? jb XindNotZero ;nope... ;This clever bit of code makes more use out of the chart by increasing Yindex ; one additional unit each time Xindex goes through the entire chart... the ; result is nearly NumRND^2 random non-repeating points inc [Yindex] ;yes, so change Yindex so that we get a mov ax,[Yindex] ;new set of random (x,y) cmp ax,[Xindex] ;does Xindex = Yindex? jne NotTheSame ;if the index were the same, you'd see ;a graph of the line Y = X, not good... inc [Yindex] ;if they are the same, inc Yindex again NotTheSame: mov [Xindex],0 ;reset Xindex to 0 XindNotZero: ;all done making the star... NoEmptySpace: popa ret MakeStar ENDP DisplayStars PROC NEAR pusha mov ax,cs mov ds,ax mov ax,0a000h mov es,ax mov si,0 DispLoop: mov cx,[Stars.Z+si] or cx,cx ;if Zpos = 0 then this star is dead... je Cont ;continue to the next one- skip this one mov di,[Stars.OldDi+si] ;grab old Di mov byte ptr es:[di],0 ;erase the star cmp cx,MinZpos jl TermStar ;if Zpos < MinZpos then kill the star mov ax,[Stars.Y+si] movsx dx,ah ;'multiply' Ypos by 256 shl ax,8 idiv cx ;and divide by Zpos add ax,ScreenHeight/2 ;center it on the screen mov di,ax cmp di,ScreenHeight ;see if the star is in range. jae PreTermStar ; If not, kill it imul di,ScreenWidth ; DI = Y*ScreenWidth mov ax,[Stars.X+si] movsx dx,ah ;multiply Xpos by 256 shl ax,8 idiv cx ;and divide by Zpos add ax,ScreenWidth/2 ;center it on the screen cmp ax,ScreenWidth ;are we inside the screen boundries? jae PreTermStar add di,ax ; DI = Y * ScreenWidth + X mov [Stars.OldDi+si],di ;save old di ;calculate the color below add ch,cs:[Stars.Color+si] ;i'm dividing cx (the zpos) by 256 and ; putting the result in ch and adding ; the base color to it in one instruction mov es:[di],ch ;put the dot on the screen mov ax,cs:[WarpSpeed] sub cs:[Stars.Z+si],ax ;move the stars inward at WarpSpeed Cont: add si,StarStrucSize ;point to next record cmp si,MaxStars*StarStrucSize ;are we done yet? jb DispLoop popa ret PreTermStar: mov [Stars.Z+si],1 ;this is here so that the star will get erased jmp short Cont ;next time through if I just went off and killed ;the star, it would leave a dot on the screen TermStar: mov [Stars.Z+si],0 ;this actually kills the star, after it has dec [NumActive] ;been erased jmp short Cont DisplayStars ENDP ;=== CODE START: mov ax,cs mov ds,ax mov es,ax mov ax,0013h ;set vid mode 320x200x256 graph int 10h mov dx,offset Palette mov ax,1012h ; WRITE palette mov bx,0 mov cx,256 ;write entire palette int 10h ;doesn't matter if we didnt define it all StarLoop: call MakeStar ;make stars 2x as thick call MakeStar mov dx,3dah VRT: in al,dx test al,8 jnz VRT ;wait until Verticle Retrace starts NoVRT: in al,dx test al,8 jz NoVRT ;wait until Verticle Retrace Ends call DisplayStars mov ah,1 ;check to see if a char is ready int 16h jz StarLoop ;nope, continue mov ah,0 int 16h ;get the character & put in AX cmp al,"+" ;compare ASCII part (al) to see what was pressed jne NotPlus inc [WarpSpeed] cmp [WarpSpeed],MaxWarp jbe StarLoop mov [WarpSpeed],MaxWarp jmp StarLoop NotPlus: cmp al,"-" jne NotMinus dec [WarpSpeed] cmp [WarpSpeed],0 jge StarLoop mov [WarpSpeed],0 Jmp StarLoop NotMinus: mov ax,0003h ;set 80x25x16 char mode int 10h mov ax,4c00h ;return control to DOS int 21h END START