Bitmap/Bresenham's line algorithm: Difference between revisions
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=={{header|ALGOL 68}}== |
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<pre> |
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MODE IMAGE = [16,16]PIXEL, |
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POINT = STRUCT(INT x,y), |
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PIXEL = STRUCT(SHORT BITS red,green,blue); |
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PIXEL black = (16r00, 16r00, 16r00), |
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red = (16rff, 16r00, 16r00), |
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green = (16r00, 16rff, 16r00), |
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blue = (16r00, 16r00, 16rff), |
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white = (16rff, 16rff, 16rff); |
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PROC fill = (REF IMAGE image, PIXEL color)VOID: |
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BEGIN |
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FOR x TO 1 UPB image DO |
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FOR y TO 2 UPB image DO |
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image[x,y] := color |
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OD |
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OD |
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END; |
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PROC line = (REF IMAGE picture, POINT start, stop, PIXEL color)VOID: |
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BEGIN |
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REAL dx = ABS (x OF stop - x OF start); |
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REAL dy = ABS (y OF stop - y OF start); |
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REAL err; |
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INT x := x OF start; |
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INT y := y OF start; |
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INT step x := 1; |
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INT step y := 1; |
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IF x OF start > x OF stop THEN |
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step x := -1 |
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FI; |
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IF y OF start > y OF stop THEN |
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step y := -1 |
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FI; |
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IF dx > dy THEN |
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err := dx / 2.0; |
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WHILE x /= x OF stop DO |
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picture[x,y] := color; |
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err -:= dy; |
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IF err < 0.0 THEN |
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y +:= step y; |
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err +:= dx |
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FI; |
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x +:= step x |
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OD |
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ELSE |
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err := dy / 2.0; |
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WHILE y /= y OF stop DO |
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picture[x,y] := color; |
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err := err - dx; |
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IF err < 0.0 THEN |
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x +:= step x; |
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err +:= dy |
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FI; |
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y +:= step y |
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OD |
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FI; |
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picture[x,y] := color # ensure dots to be drawn # |
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END # line #; |
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### |
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the test program's |
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### |
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REF IMAGE x = LOC[1:16, 1:16]PIXEL; |
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BEGIN |
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fill (x, white); |
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line (x, ( 1, 8), ( 8,16), black); |
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line (x, ( 8,16), (16, 8), black); |
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line (x, (16, 8), ( 8, 1), black); |
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line (x, ( 8, 1), ( 1, 8), black); |
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printf(($n(UPB x)(3(16r2d))l$, x)) |
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END |
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</pre> |
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Output: |
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<pre> |
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ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffffffffffffffff000000ffffff000000ffffffffffffffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffffffffff000000ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000000000ffffffffffffffffffffffff |
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ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff |
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ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffff |
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ffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffff |
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000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000 |
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ffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffff |
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ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffff |
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ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff |
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ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffff |
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ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffffffffff000000ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffffffffffffffff000000ffffff000000ffffffffffffffffffffffffffffffffffffffffff |
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ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff |
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</pre> |
</pre> |
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Revision as of 13:14, 18 January 2009
Bitmap/Bresenham's line algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
You are encouraged to solve this task according to the task description, using any language you may know.
Using the data storage type defined on this page for raster graphics images, draw a line given 2 points with the Bresenham's algorithm (definition on Wikipedia).
Ada
<ada> procedure Line (Picture : in out Image; Start, Stop : Point; Color : Pixel) is
DX : constant Float := abs Float (Stop.X - Start.X); DY : constant Float := abs Float (Stop.Y - Start.Y); Err : Float; X : Positive := Start.X; Y : Positive := Start.Y; Step_X : Integer := 1; Step_Y : Integer := 1;
begin
if Start.X > Stop.X then Step_X := -1; end if; if Start.Y > Stop.Y then Step_Y := -1; end if; if DX > DY then Err := DX / 2.0; while X /= Stop.X loop Picture (X, Y) := Color; Err := Err - DY; if Err < 0.0 then Y := Y + Step_Y; Err := Err + DX; end if; X := X + Step_X; end loop; else Err := DY / 2.0; while Y /= Stop.Y loop Picture (X, Y) := Color; Err := Err - DX; if Err < 0.0 then X := X + Step_X; Err := Err + DY; end if; Y := Y + Step_Y; end loop; end if; Picture (X, Y) := Color; -- Ensure dots to be drawn
end Line; </ada> The test program's <ada>
X : Image (1..16, 1..16);
begin
Fill (X, White); Line (X, ( 1, 8), ( 8,16), Black); Line (X, ( 8,16), (16, 8), Black); Line (X, (16, 8), ( 8, 1), Black); Line (X, ( 8, 1), ( 1, 8), Black); Print (X);
</ada> sample output
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ALGOL 68
MODE IMAGE = [16,16]PIXEL, POINT = STRUCT(INT x,y), PIXEL = STRUCT(SHORT BITS red,green,blue); PIXEL black = (16r00, 16r00, 16r00), red = (16rff, 16r00, 16r00), green = (16r00, 16rff, 16r00), blue = (16r00, 16r00, 16rff), white = (16rff, 16rff, 16rff); PROC fill = (REF IMAGE image, PIXEL color)VOID: BEGIN FOR x TO 1 UPB image DO FOR y TO 2 UPB image DO image[x,y] := color OD OD END; PROC line = (REF IMAGE picture, POINT start, stop, PIXEL color)VOID: BEGIN REAL dx = ABS (x OF stop - x OF start); REAL dy = ABS (y OF stop - y OF start); REAL err; INT x := x OF start; INT y := y OF start; INT step x := 1; INT step y := 1; IF x OF start > x OF stop THEN step x := -1 FI; IF y OF start > y OF stop THEN step y := -1 FI; IF dx > dy THEN err := dx / 2.0; WHILE x /= x OF stop DO picture[x,y] := color; err -:= dy; IF err < 0.0 THEN y +:= step y; err +:= dx FI; x +:= step x OD ELSE err := dy / 2.0; WHILE y /= y OF stop DO picture[x,y] := color; err := err - dx; IF err < 0.0 THEN x +:= step x; err +:= dy FI; y +:= step y OD FI; picture[x,y] := color # ensure dots to be drawn # END # line #; ### the test program's ### REF IMAGE x = LOC[1:16, 1:16]PIXEL; BEGIN fill (x, white); line (x, ( 1, 8), ( 8,16), black); line (x, ( 8,16), (16, 8), black); line (x, (16, 8), ( 8, 1), black); line (x, ( 8, 1), ( 1, 8), black); printf(($n(UPB x)(3(16r2d))l$, x)) END
Output:
ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffff000000ffffff000000ffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffff000000ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000000000ffffffffffffffffffffffff ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffff ffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffff 000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000 ffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffff ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffff ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffff000000ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffff000000ffffff000000ffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffff
C
<C>#define plot(x, y) put_pixel_clip(img, x, y, r, g, b)
- define swap_uint(a, b) do{ unsigned int tmp; tmp = a; a = b; b = tmp; }while(0)
void draw_line(
image img, unsigned int x0, unsigned int y0, unsigned int x1, unsigned int y1, color_component r, color_component g, color_component b )
{
unsigned short steep; steep = abs(y1 - y0) > abs(x1 - x0); if (steep) { swap_uint(x0, y0); swap_uint(x1, y1); } if (x0 > x1) { swap_uint(x0, x1); swap_uint(y0, y1); } { int deltax = x1 - x0; int deltay = abs(y1 - y0); int error = deltax / 2; int ystep; int y = y0; int x; if (y0 < y1) ystep = 1; else ystep = -1; for (x = x0; x <= x1; ++x) { if (steep) plot(y,x); else plot(x,y); error = error - deltay; if (error < 0) { y = y + ystep; error = error + deltax; } } }
}
- undef swap_uint
- undef plot</C>
Forth
defer steep \ noop or swap defer ystep \ 1+ or 1- : line ( x0 y0 x1 y1 color bmp -- ) { color bmp } rot swap ( x0 x1 y0 y1 ) 2dup - abs >r 2over - abs r> < if ['] swap \ swap use of x and y else 2swap ['] noop then is steep ( y0 y1 x0 x1 ) 2dup > if swap 2swap swap \ ensure x1 > x0 else 2swap then ( x0 x1 y0 y1 ) 2dup > if ['] 1- else ['] 1+ then is ystep over - abs { y deltay } swap 2dup - dup { deltax } 2/ rot 1+ rot ( error x1+1 x0 ) do color i y steep bmp b! deltay - dup 0< if y ystep to y deltax + then loop drop ;
5 5 bitmap value test 0 test bfill 1 0 4 1 red test line 4 1 3 4 red test line 3 4 0 3 red test line 0 3 1 0 red test line test bshow cr ** * ** * * ** * ** ok
MAXScript
fn plot img coord steep col = ( if steep then ( swap coord[1] coord[2] ) setPixels img coord col ) fn drawLine img start end col = ( local steep = (abs (end.y - start.y)) > (abs (end.x - start.x)) if steep then ( swap start.x start.y swap end.x end.y ) if start.x > end.x then ( swap start.x end.x swap start.y end.y ) local deltaX = end.x - start.x local deltaY = abs (end.y - start.y) local error = deltaX / 2.0 local yStep = -1 local y = start.y if start.y < end.y then ( yStep = 1 ) for x in start.x to end.x do ( plot img [x, y] steep col error -= deltaY if error < 0 then ( y += yStep error += deltaX ) ) img ) myBitmap = bitmap 512 512 color:(color 0 0 0) myBitmap = drawLine myBitmap [0, 511] [511, 0] #((color 255 255 255)) display myBitmap
OCaml
<ocaml>let draw_line ~img ~color ~p0:(x0,y0) ~p1:(x1,y1) =
let steep = abs(y1 - y0) > abs(x1 - x0) in
let plot = if steep then (fun x y -> put_pixel img color y x) else (fun x y -> put_pixel img color x y) in
let x0, y0, x1, y1 = if steep then y0, x0, y1, x1 else x0, y0, x1, y1 in let x0, x1, y0, y1 = if x0 > x1 then x1, x0, y1, y0 else x0, x1, y0, y1 in
let delta_x = x1 - x0 and delta_y = abs(y1 - y0) in let error = -delta_x / 2 and y_step = if y0 < y1 then 1 else -1 in let rec loop x y error = plot x y; if x <= x1 then let error = error + delta_y in let y, error = if error > 0 then (y + y_step), (error - delta_x) else y, error in loop (succ x) y error in loop x0 y0 error
- </ocaml>
Vedit macro language
// Daw a line using Bresenham's line algorithm. // #1=x1, #2=y1; #3=x2, #4=y2 :DRAW_LINE: if (#4-#2 < #1-#3) { // dy < -dx ? #99=#1; #1=#3; #3=#99 // swap start and end points #99=#2; #2=#4; #4=#99 } #31 = abs(#3-#1) // x distance #32 = abs(#4-#2) // y distance if (#32 > #31) { // steep angle, step by Y #33 = #32 / 2 // error distance if (#1 < #3) { #34=1 } else { #34=-1 } // x step while (#2 <= #4) { Call("DRAW_PIXEL") // #1=x, #2=y #33 -= #31 if (#33 < 0) { #1 += #34 // move right #33 += #32 } #2++ // move up } } else { // not steep, step by X #33 = #31 / 2 if (#2 < #4) { #34=1 } else { #34=-1 } // y step while (#1 <= #3) { Call("DRAW_PIXEL") #33 -= #32 if (#33 < 0) { #2 += #34 // move up #33 += #31 } #1++ // move right } } return