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Assembly Source File | 1993-09-13 | 14.8 KB | 608 lines

;----------------------------------------------------------------------- ; MODULE XPOLYGON ; ; Filled Triangle function for all MODE X 256 Color resolutions ; ; Compile with Tasm. ; C callable. ; ; ****** XLIB - Mode X graphics library **************** ; ****** **************** ; ****** Written By Themie Gouthas **************** ; ; This module is based on code developed by Steve Dollind for his ; XSPACE game. ; Copyright (C) 1992 Steven Dollins -- sdollins@uiuc.edu ; ; ; egg@dstos3.dsto.gov.au ; teg@bart.dsto.gov.au ;----------------------------------------------------------------------- include xlib.inc include xpolygon.inc .data ; Plane masks for clipping left and right edges of rectangle. LeftClipPlaneMask db 00fh,00eh,00ch,008h RightClipPlaneMask db 00fh,001h,003h,007h .code ;----------------------------------------------------------------------- ; void HLineClipR ; ; Draws a horizontal line from (X1, Y) to (X2, Y). ; Uses Watcom Parameter passing convention in registers ; ; X1 in AX ; X2 in DX ; Y in CX ; Color in BX ; PageOffset in DI ; ; By Themie Gouthas - Adapted from x_fill_rect. ;----------------------------------------------------------------------- proc _HLineClipR near push di cmp dx,ax ; if (X2 < X1) then assume no line jl @@Invisible ; is visible cmp cx,[_TopClip] ; if (Y < TopClip) then no line jl @@Invisible cmp cx,[_BottomClip] ;if (Y > BottomClip) then no line jg @@Invisible mov di,[_RightClip] ;convert RightClip to pixel coords sal di,2 cmp ax,di ; if (X1 > RightClip) then no line jg @@Invisible cmp dx,di ; if (X2 > RightClip) then jle @@ClipLeft ; X2:=RightClip mov dx,di @@ClipLeft: mov di,[_LeftClip] ;convert LeftClip to pixel coords sal di,2 cmp dx,di ; if (X2 < LeftClip) then no line jl @@Invisible cmp ax,di ;if (X1 > LeftClip) then were ready to plot jge @@DoLine mov ax,di ; X1:=LeftClip jmp short @@DoLine @@Invisible: pop di ret @@DoLine: pop di ; di = PageOffset xchg cx,ax ; AX = Y, CX = X1 mov si,dx ; SI = DX = X2 mul [_ScrnLogicalByteWidth] mov dx,si ; Reset DX to X1 since mul erases DX add ax,di mov di,cx sar di,2 ; Convert to bytes add di,ax ; DI->First byte and si,03h ; look up right edge plane mask mov ah,RightClipPlaneMask[si] mov si,cx ; look up left edge plane mask and si,03h mov al,LeftClipPlaneMask[si] cmp dx,cx ; No harm in being paranoid.. jle @@Invisible2 xchg cx,dx ;CX=X2, DX=X1 dec cx and dx,not 03h sub cx,dx js @@Invisible2 shr cx,2 jnz @@MasksSet and al,ah @@MasksSet: mov dl,bl ; set BX=Plane Masks, AH=Color mov bx,ax mov ah,dl mov dx,SC_INDEX+1 ;set the Sequence Controller Index to mov al,bl out dx,al mov al,ah stosb ; Plot left byte dec cx js @@Invisible2 jz @@RightEnd mov al,0fh ; plot middle bytes out dx,al mov al,ah shr cx,1 rep stosw adc cx,cx rep stosb @@RightEnd: mov al,bh ; Plot right byte out dx,al mov al,ah stosb @@Invisible2: ret _HLineClipR endp ;----------------------------------------------------------------------- ; void x_triangle( int X0, int Y0, int X1, int Y1, ; int X2, int Y2, unsigned Color, unsigned PageOffset ); ; ; ; Written by S. Dollins _x_triangle proc ARG X0:word,Y0:word,X1:word,Y1:word,X2:word,Y2:word,Color:word,PageOffset:word LOCAL DX01:word, DY01:word, DX02:word, DY02:word, DX12:word, DY12:word, \ DP01:word, DP02:word, DP12:word, XA01:word, XA02:word, XA12:word=STK push bp mov bp,sp sub sp,STK push ds es si di ; Save es for polygon routine mov ax,X0 mov bx,Y0 mov cx,X1 mov dx,Y1 cmp bx,dx ; Y0,Y1 jl tri_Y0lY1 je tri_Y0eY1 xchg ax,cx ; X0,X1 xchg bx,dx ; Y0,Y1 tri_Y0lY1: cmp dx,Y2 ; Y1,Y2 jg tri_a jmp tri_sorted tri_a: xchg cx,X2 ; X1,X2 xchg dx,Y2 ; Y1,Y2 cmp bx,dx ; Y0,Y1 jge tri_b jmp tri_sorted tri_b: je tri_bot xchg ax,cx ; X0,X1 xchg bx,dx ; Y0,Y1 jmp tri_sorted tri_Y0eY1: cmp bx,Y2 ; Y0,Y2 jl tri_bot jg tri_c jmp tri_done tri_c: xchg ax,X2 ; X0,X2 xchg bx,Y2 ; Y0,Y2 jmp tri_sorted tri_bot: cmp ax,cx ; X0,X1 jl tri_bot_sorted jg tri_bot_a jmp tri_done tri_bot_a: xchg ax,cx ; X0,X1 tri_bot_sorted: cmp bx,[_BottomClip] jle tri_bot_y0ok jmp tri_done tri_bot_y0ok: mov si,Y2 cmp si,[_TopClip] jge tri_bot_y2ok jmp tri_done tri_bot_y2ok: mov X0,ax mov Y0,bx mov X1,cx mov Y1,dx mov bx,Y2 ; bx <- Y2 sub bx,Y0 ; bx <- Y2 - Y0 mov DY02,bx ; DY02 <- Y2 - Y0 mov ax,X2 ; ax <- X2 sub ax,X0 ; ax <- X2 - X0 mov DX02,ax ; DX02 <- X2 - X0 mov cx,ax ; cx <- DX02 cwd ; dx:ax <- DX02 idiv bx ; ax <- DX02 / DY02 cmp cx,0 jge short tri_bot02 dec ax ; ax <- DX02 / DY02 - 1 tri_bot02: mov XA02,ax ; XA02 <- DX02 / DY02 imul bx ; ax <- XA02 * DY02 sub cx,ax ; cx <- DX02 - XA02 * DY02 mov DP02,cx ; DP02 <- DX02 - XA02 * DY02 mov bx,Y2 ; bx <- Y2 sub bx,Y1 ; bx <- Y2 - Y1 mov DY12,bx ; DY02 <- Y2 - Y1 mov ax,X2 ; ax <- X2 sub ax,X1 ; ax <- X2 - X1 mov DX12,ax ; DX12 <- X2 - X1 mov cx,ax ; cx <- DX12 cwd ; dx:ax <- DX12 idiv bx ; ax <- DX12 / DY12 cmp cx,0 jge short tri_bot12 dec ax ; ax <- DX12 / DY12 - 1 tri_bot12: mov XA12,ax ; XA12 <- DX12 / DY12 imul bx ; ax <- XA12 * DY12 sub cx,ax ; cx <- DX12 - XA12 * DY12 mov DP12,cx ; DP12 <- DX12 - XA12 * DY12 mov ax,0 ; PL <- 0 mov bx,0 ; PS <- 0 mov cx,Y0 ; Y <- Y0 mov si,X0 mov di,X1 dec di tri_bot_loop: inc cx ; Y add ax,DP02 ; PL,DP02 jle short tri_bot_shortl sub ax,DY02 ; PL,DY02 inc si ; XL tri_bot_shortl: add si,XA02 ; XL,XA02 add bx,DP12 ; PS,DP12 jle short tri_bot_shortr sub bx,DY12 ; PS,DY12 inc di ; XS tri_bot_shortr: add di,XA12 ; XS,XA12 push di ; XS push si ; XL cmp cx,Y2 ; Y,Y2 jl short tri_bot_loop jmp tri_draw_lines tri_sorted: cmp bx,[_BottomClip] jle tri_y0ok jmp tri_done tri_y0ok: mov si,Y2 cmp si,[_TopClip] jge tri_y2ok jmp tri_done tri_y2ok: mov X0,ax mov Y0,bx mov X1,cx mov Y1,dx mov bx,dx ; bx <- Y1 sub bx,Y0 ; bx <- Y1 - Y0 mov DY01,bx ; DY01 <- Y1 - Y0 mov ax,X1 ; ax <- X1 sub ax,X0 ; ax <- X1 - X0 mov DX01,ax ; DX01 <- X1 - X0 mov cx,ax ; cx <- DX01 cwd ; dx:ax <- DX01 idiv bx ; ax <- DX01 / DY01 cmp cx,0 ; DX01 ? 0 jge short tri_psl01 dec ax ; ax <- DX01 / DY01 - 1 tri_psl01: mov XA01,ax ; XA01 <- DX01 / DY01 imul bx ; ax <- XA01 * DY01 sub cx,ax ; cx <- DX01 - XA01 * DY01 mov DP01,cx ; DP01 <- DX01 - XA01 * DY01 mov bx,Y2 ; bx <- Y2 sub bx,Y0 ; bx <- Y2 - Y0 mov DY02,bx ; DY02 <- Y2 - Y0 mov ax,X2 ; ax <- X2 sub ax,X0 ; ax <- X2 - X0 mov DX02,ax ; DX02 <- X2 - X0 mov cx,ax ; cx <- DX02 cwd ; dx:ax <- DX02 idiv bx ; ax <- DX02 / DY02 cmp cx,0 jge short tri_psl02 dec ax ; ax <- DX02 / DY02 - 1 tri_psl02: mov XA02,ax ; XA02 <- DX02 / DY02 imul bx ; ax <- XA02 * DY02 sub cx,ax ; cx <- DX02 - XA02 * DY02 mov DP02,cx ; DP02 <- DX02 - XA02 * DY02 mov bx,Y2 ; bx <- Y2 sub bx,Y1 ; bx <- Y2 - Y1 jle short tri_const_computed mov DY12,bx ; DY12 <- Y2 - Y1 mov ax,X2 ; ax <- X2 sub ax,X1 ; ax <- X2 - X1 mov DX12,ax ; DX12 <- X2 - X1 mov cx,ax ; cx <- DX12 cwd ; dx:ax <- DX12 idiv bx ; ax <- DX12 / DY12 cmp cx,0 jge short tri_psl12 dec ax ; ax <- DX12 / DY12 - 1 tri_psl12: mov XA12,ax ; XA12 <- DX12 / DY12 imul bx ; ax <- XA12 * DY12 sub cx,ax ; cx <- DX12 - XA12 * DY12 mov DP12,cx ; DP12 <- DX12 - XA12 * DY12 tri_const_computed: mov ax,DX01 imul word ptr DY02 mov bx,ax mov cx,dx ; DX01 * DY02 in cx:bx mov ax,DX02 imul word ptr DY01 ; DX02 * DY01 in dx:ax cmp cx,dx jg tri_pt1rt jl tri_pt1lt cmp bx,ax ja tri_pt1rt jb tri_pt1lt jmp tri_done ;------------------------------------ ; Short sides are on the left ; tri_pt1lt: mov ax,0 ; PL <- 0 mov bx,0 ; PS <- 0 mov cx,Y0 ; Y <- Y0 mov si,X0 mov di,si dec si tri_lt_loop: inc cx ; Y add ax,DP02 ; PL,DP02 jle short tri_lt_shortl sub ax,DY02 ; PL,DY02 inc si ; XL tri_lt_shortl: add si,XA02 ; XL,XA02 add bx,DP01 ; PS,DP01 jle short tri_lt_shortr sub bx,DY01 ; PS,DY01 inc di ; XS tri_lt_shortr: add di,XA01 ; XS,XA01 push si ; XL push di ; XS cmp cx,Y1 ; Y,Y1 jl short tri_lt_loop jmp short tri_lb_start tri_lb_loop: inc cx ; Y add ax,DP02 ; PL,DP02 jle short tri_lb_shortl sub ax,DY02 ; PL,DY02 inc si ; XL tri_lb_shortl: add si,XA02 ; XL,XA02 add bx,DP12 ; PS,DP12 jle short tri_lb_shortr sub bx,DY12 ; PS,DY12 inc di ; XS tri_lb_shortr: add di,XA12 ; XS,XA12 push si ; XL push di ; XS tri_lb_start: cmp cx,Y2 ; Y,Y2 jl tri_lb_loop jmp short tri_draw_lines ;------------------------------------ ; short sides are on the right ; tri_pt1rt: mov ax,0 ; PL <- 0 mov bx,0 ; PS <- 0 mov cx,Y0 ; Y <- Y0 mov si,X0 mov di,si dec di tri_rt_loop: inc cx ; Y add ax,DP02 ; PL,DP02 jle short tri_rt_shortl sub ax,DY02 ; PL,DY02 inc si ; XL tri_rt_shortl: add si,XA02 ; XL,XA02 add bx,DP01 ; PS,DP01 jle short tri_rt_shortr sub bx,DY01 ; PS,DY01 inc di ; XS tri_rt_shortr: add di,XA01 ; XS,XA01 push di ; XS push si ; XL cmp cx,Y1 ; Y,Y1 jl short tri_rt_loop jmp short tri_rb_start tri_rb_loop: inc cx ; Y add ax,DP02 ; PL,DP02 jle short tri_rb_shortl sub ax,DY02 ; PL,DY02 inc si ; XL tri_rb_shortl: add si,XA02 ; XL,XA02 add bx,DP12 ; PS,DP12 jle short tri_rb_shorts sub bx,DY12 ; PS,DY12 inc di ; XS tri_rb_shorts: add di,XA12 ; XS,XA12 push di ; XS push si ; XL tri_rb_start: cmp cx,Y2 ; Y,Y2 jl short tri_rb_loop ;------------------------------------ ; Draw the horizontal lines ; tri_draw_lines: mov cx,SCREEN_SEG ;point ES to video segment mov es,cx mov dx,SC_INDEX ;set the Sequence Controller Index to mov al,MAP_MASK ; point to the Map Mask register out dx,al line_loop: pop ax pop dx cmp ax,dx jg tri_draw_next mov bx,Color mov cx,Y2 add dx,2 mov di,PageOffset call _HLineClipR tri_draw_next: dec word ptr Y2 dec word ptr DY02 jnz line_loop tri_done: pop di si es ds mov sp,bp pop bp ret _x_triangle endp ;----------------------------------------------------------------------- ; void x_polygon( VERTEX vertices[], int num_vertices,unsigned Color, ; unsigned PageOffset ); ; ; Where VERTEX is defined as: ; ; typedef struct { ; int X; ; int Y; ; } far VERTEX; ; ; ; Written by T. Gouthas ; ; ; ; Note: This is just a quick hack of a generalized polygon routine. ; The way it works is by splitting up polygons into triangles and ; drawing each individual triangle. ; ; Obviously this is not as fast as it could be, but for polygons of ; 4 vertices it should perform quite respectably. ; ; Warning: Only works for convex polygons (convex polygons are such ; that if you draw a line from any two vertices, every point on that ; line will be within the polygon) ; ; _x_polygon proc ARG vertices:dword,numvertices:word,Color:word,PageOffset:word LOCAL x0:word,y0:word,tri_count:word=STK push bp mov bp,sp sub sp,STK push di si mov cx,numvertices cmp cx,3 jl @@Done sub cx,3 mov tri_count,cx ; Number of triangles to draw les di,vertices ; ES:DI -> Vertices mov ax,es:[di] ; Save first vertex mov x0,ax mov ax,es:[di+2] mov y0,ax ; Set up permanent parameter stack frame for ; triangle parameters mov ax,PageOffset push ax mov ax,Color push ax sub sp,12 mov si,sp @@NextTriangle: add di,4 mov ax,es:[di] ; Vertex 2 mov ss:[si],ax mov ax,es:[di+2] mov ss:[si+2],ax mov ax,es:[di+4] ; Vertex 1 mov ss:[si+4],ax mov ax,es:[di+6] mov ss:[si+6],ax mov ax,x0 ; Vertex 0: The first vertex is mov ss:[si+8],ax ; part of every triangle mov ax,y0 mov ss:[si+10],ax call _x_triangle dec tri_count jns @@NextTriangle add sp,16 ; Remove triangle stack frame @@Done: pop si di mov sp,bp pop bp ret _x_polygon endp end