Bitmap/Bresenham's line algorithm: Difference between revisions
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Using the data storage type defined on the [[Bitmap]] page for raster graphics images, draw a line given two points with [[wp:Bresenham's line algorithm|Bresenham's line algorithm]].
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=={{header|360 Assembly}}==
{{trans|Rexx}}
<lang 360asm>* Bitmap/Bresenham's line algorithm - 13/05/2019
BRESENH CSECT
USING BRESENH,R13 base register
B 72(R15) skip savearea
DC 17F'0' savearea
SAVE (14,12) save previous context
ST R13,4(R15) link backward
ST R15,8(R13) link forward
LR R13,R15 set addressability
LA R10,DATAXY @dataxy
LA R8,1 p=1
DO WHILE=(C,R8,LE,=A(POINTS)) do p=1 to points
L R6,0(R10) x=dataxy((p-1)*2+1)
L R7,4(R10) y=dataxy((p-1)*2+2)
IF C,R8,EQ,=F'1' THEN if p=1 then
ST R6,MINX minx=x
ST R6,MAXX maxx=x
ST R7,MINY miny=y
ST R7,MAXY maxy=y
ENDIF , endif
IF C,R6,LT,MINX THEN if x<minx then
ST R6,MINX minx=x
ENDIF , endif
IF C,R6,GT,MAXX THEN if x>maxx then
ST R6,MAXX maxx=x
ENDIF , endif
IF C,R7,LT,MINY THEN if y<miny then
ST R7,MINY miny=y
ENDIF , endif
IF C,R7,GT,MAXY THEN if y>maxy then
ST R7,MAXY maxy=y
ENDIF , endif
LA R10,8(R10) @dataxy+=8
LA R8,1(R8) p++
ENDDO , enddo p
L R1,MINX minx
S R1,=A(BORDER*2) -border*2
ST R1,MINX minx=minx-border*2
L R1,MAXX maxx
A R1,=A(BORDER*2) +border*2
ST R1,MAXX maxx=maxx+border*2
L R1,MINY miny
S R1,=A(BORDER) -border
ST R1,MINY miny=miny-border
L R1,MAXY maxy
A R1,=A(BORDER) +border
ST R1,MAXY maxy=maxy+border
L R1,MINX minx
LCR R1,R1 -
A R1,=F'1' +1
ST R1,OX ox=-minx+1
L R1,MINY miny
LCR R1,R1 -
A R1,=F'1' +1
ST R1,OY oy=-miny+1
LA R1,HMAPX hbound(map,1)
S R1,OX wx=hbound(map,1)-ox
IF C,R1,LT,MAXX THEN if maxx>wx then
ST R1,MAXX maxx=wx
ENDIF , endif
LA R1,HMAPY hbound(map,2)
S R1,OY wy=hbound(map,2)-oy
IF C,R1,LT,MAXY THEN if maxy>wy then
ST R1,MAXY maxy=wy
ENDIF , endif
L R6,MINX x=minx
DO WHILE=(C,R6,LE,MAXX) do x=minx to maxx
L R1,OY oy
BCTR R1,0 1
MH R1,=AL2(HMAPX) dim(x)
AR R1,R6 x
A R1,OX ox
LA R1,MAP-1(R1) map(0+oy,x+ox)
MVC 0(1,R1),=C'-' map(0+oy,x+ox)='-'
A R6,=F'1' x++
ENDDO , enddo x
L R7,MINY y=miny
DO WHILE=(C,R7,LE,MAXY) do y=miny to maxy
LR R1,R7 y
A R1,OY +oy
BCTR R1,0 -1
MH R1,=AL2(HMAPX) *dim(x)
A R1,OX +ox
LA R1,MAP-1(R1) @map(y+oy,0+ox)
MVC 0(1,R1),=C'|' map(y+oy,0+ox)='|'
A R7,=F'1' y++
ENDDO , enddo y
L R1,OY +oy
BCTR R1,0 -1
MH R1,=AL2(HMAPX) *dim(x)
A R1,OX +ox
LA R1,MAP-1(R1) @map(0+oy,0+ox)
MVC 0(1,R1),=C'+' map(0+oy,0+ox)='+'
LA R10,POINTS points
BCTR R10,0 pn=points-1
LA R9,DATAXY @dataxy
LA R8,1 p=1
DO WHILE=(CR,R8,LE,R10) do p=1 to points-1
L R6,0(R9) x=dataxy((p-1)*2+1)
L R7,4(R9) y=dataxy((p-1)*2+2)
L R4,8(R9) xf=dataxy(p*2+1)
L R5,12(R9) yf=dataxy(p*2+2)
LR R2,R4 xf
SR R2,R6 -x
LPR R2,R2 abs()
ST R2,DX dx=abs(xf-x)
LR R2,R5 xf
SR R2,R7 -y
LPR R2,R2 abs()
ST R2,DY dy=abs(yf-y)
IF CR,R6,LT,R4 THEN if x<xf then
MVC SX,=F'1' sx=+1
ELSE , else
MVC SX,=F'-1' sx=-1
ENDIF , endif
IF CR,R7,LT,R5 THEN if y<yf then
MVC SY,=F'1' sy=+1
ELSE , else
MVC SY,=F'-1' sy=-1
ENDIF , endif
L R2,DX dx
S R2,DY -dy
ST R2,ERR err=dx-dy
LOOP EQU * loop forever
LR R1,R7 y
A R1,OY +oy
BCTR R1,0 -1
MH R1,=AL2(HMAPX) *dim(x)
AR R1,R6 +x
A R1,OX +ox
LA R1,MAP-1(R1) @map(y+oy,x+ox)
MVC 0(1,R1),=C'X' map(y+oy,x+ox)='X'
CR R6,R4 if x=xf
BNE STAYDO ~
CR R7,R5 if y=yf
BE EXITLOOP if x=xf and y=yf then leave loop
STAYDO L R0,ERR err
A R0,ERR err+err
ST R0,ERR2 err2=err+err
L R0,DY dy
LCR R0,R0 -dy
IF C,R0,LT,ERR2 THEN if err2>-dy then
A R0,ERR -dy+err
ST R0,ERR err=err-dy
A R6,SX x=x+sx
ENDIF , endif
L R0,DX dx
IF C,R0,GT,ERR2 THEN if err2<dx then
L R0,ERR err
A R0,DX +dx
ST R0,ERR err=err+dx
A R7,SY y=y+sy
ENDIF , endif
B LOOP endloop
EXITLOOP LA R9,8(R9) @dataxy+=2
LA R8,1(R8) p++
ENDDO , enddo p
LA R9,MAP+(HMAPX*HMAPY)-HMAPX @map
L R7,MAXY y=maxy
DO WHILE=(C,R7,GE,MINY) do y=maxy to miny by -1
MVC PG(HMAPX),0(R9) output map(x,*)
XPRNT PG,L'PG print buffer
S R9,=A(HMAPX) @pg
S R7,=F'1' y--
ENDDO , enddo y
L R13,4(0,R13) restore previous savearea pointer
RETURN (14,12),RC=0 restore registers from calling sav
BORDER EQU 2 border size
POINTS EQU (MAP-DATAXY)/L'DATAXY/2
HMAPX EQU 24 dim(map,1)
HMAPY EQU 20 dim(map,2)
DATAXY DC F'1',F'8',F'8',F'16',F'16',F'8',F'8',F'1',F'1',F'8'
MAP DC (HMAPX*HMAPY)CL1'.' map(hmapx,hmapy)
OX DS F
OY DS F
MINX DS F
MAXX DS F
MINY DS F
MAXY DS F
DX DS F
DY DS F
SX DS F
SY DS F
ERR DS F
ERR2 DS F
PG DC CL80' ' buffer
REGEQU
END BRESENH </lang>
{{out}}
<pre>
...|....................
...|....................
...|.......X............
...|......X.X...........
...|.....X...X..........
...|....X.....X.........
...|...X.......X........
...|...X........X.......
...|..X..........X......
...|.X............X.....
...|X..............X....
...|.X............X.....
...|..X..........X......
...|...X.......XX.......
...|....X.....X.........
...|.....X...X..........
...|......X.X...........
...|.......X............
---+--------------------
...|....................
</pre>
=={{header|Ada}}==
Line 75 ⟶ 290:
H
</pre>
=={{header|ALGOL 68}}==
{{trans|Ada}}
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