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Bitmap/Bresenham's line algorithm: Difference between revisions
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ENDPROC</lang>
[[File:bresenham_bbc.gif]]
=={{header|BASIC}}==
<lang basic>
1500 REM === Draw a line. Ported from C version
1510 REM Inputs are X1, Y1, X2, Y2: Destroys value of X1, Y1
1520 DX = ABS(X2 - X1):SX = -1:IF X1 < X2 THEN SX = 1
1530 DY = ABS(Y2 - Y1):SY = -1:IF Y1 < Y2 THEN SY = 1
1540 ER = -DY:IF DX > DY THEN ER = DX
1550 ER = INT(ER / 2)
1560 PLOT X1,Y1:REM This command may differ depending on BASIC dialect
1570 IF X1 = X2 AND Y1 = Y2 THEN RETURN
1580 E2 = ER
1590 IF E2 > -DX THEN ER = ER - DY:X1 = X1 + SX
1600 IF E2 < DY THEN ER = ER + DX:Y1 = Y1 + SY
1610 GOTO 1560
</lang>
=={{header|Batch File}}==
<lang dos>@echo off
setlocal enabledelayedexpansion
set width=87
set height=51
mode %width%,%height%
set "grid="
set /a resolution=height*width
for /l %%i in (1,1,%resolution%) do (
set "grid=!grid! "
)
call :line 1 1 5 5
call :line 9 30 60 7
call :line 9 30 60 50
call :line 52 50 32 1
echo:%grid%
pause>nul
exit
:line
set x1=%1
set y1=%2
set x2=%3
set y2=%4
set /a dx=x2-x1
set /a dy=y2-y1
if %dx% neq 0 set /a o=y1 - ( x1 * dy / dx )
if %x1% leq %x2% (
if %x1% geq %width% goto :eof
if %x2% lss 0 goto :eof
if %x1% lss 0 (
if %dx% neq 0 set y1=%o%
set x1=0
)
if %x2% geq %width% (
set /a x2= width - 1
if %dx% neq 0 set /a "y2= x2 * dy / dx + o"
)
) else (
if %x2% geq %width% goto :eof
if %x1% lss 0 goto :eof
if %x2% lss 0 (
if %dx% neq 0 set y2=%o%
set x2=0
)
if %x1% geq %width% (
set /a x1=width - 1
if %dx% neq 0 set /a "y1= x1 * dy / dx + o"
)
)
if %y1% leq %y2% (
if %y1% geq %height% goto :eof
if %y2% lss 0 goto :eof
if %y1% lss 0 (
set y1=0
if %dx% neq 0 set /a x1= - o * dx /dy
)
if %y2% geq %height% (
set /a y2=height-1
if %dx% neq 0 set /a "x2= (y2 - o) * dx /dy"
)
) else (
if %y2% geq %height% goto :eof
if %y1% lss 0 goto :eof
if %y2% lss 0 (
set y2=0
if %dx% neq 0 set /a "x2= - o * dx /dy"
)
if %y1% geq %height% (
set /a y1=height-1
if %dx% neq 0 set /a "x1= (y1 - o) * dx /dy"
)
)
set stepy=1
set stepx=1
set /a dx=x2-x1
set /a dy=y2-y1
if %dy% lss 0 set /a "dy=-dy","stepy=-1"
if %dx% lss 0 set /a "dx=-dx","stepx=-1"
set /a "dy <<= 1"
set /a "dx <<= 1"
if %dx% gtr %dy% (
set /a "fraction=dy-(dx>>1)"
set /a "cursor=y1*width + x1"
for /l %%x in (%x1%,%stepx%,%x2%) do (
set /a cursorP=cursor+1
for /f "tokens=1-2" %%g in ("!cursor! !cursorP!") do set "grid=!grid:~0,%%g!Û!grid:~%%h!"
if !fraction! geq 0 (
set /a y1+=stepy
set /a cursor+=stepy*width
set /a fraction-=dx
)
set /a fraction+=dy
set /a cursor+=stepx
)
) else (
set /a "fraction=dx-(dy>>1)"
set /a "cursor=y1*width + x1"
for /l %%y in (%y1%,%stepy%,%y2%) do (
set /a cursorP=cursor+1
for /f "tokens=1-2" %%g in ("!cursor! !cursorP!") do set "grid=!grid:~0,%%g!Û!grid:~%%h!"
if !fraction! geq 0 (
set /a x1+=stepx
set /a cursor+=stepx
set /a fraction-=dy
)
set /a fraction+=dx
set /a cursor+=width*stepy
)
)
goto :eof</lang>
=={{header|C}}==
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