Bitmap/Bresenham's line algorithm: Difference between revisions
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(Added Prolog implementation) |
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</lang> |
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=={{header|Prolog}}== |
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Works with SWI-prolog. |
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<lang Prolog> |
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use_module(library(pce)). |
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lindraw(X1,Y1,X2,Y2):- |
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new(Win,window("Line")), |
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new(Pix,pixmap(@nil,black,white,X2+30,Y2+30)), |
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send(Win,size,size(400,400)), |
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drwlin(Pix,X1,Y1,X2,Y2), |
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new(Bmp,bitmap(Pix)), |
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send(Win,display,Bmp,point(0,0)), |
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send(Win,open). |
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draw_recursive_line(_Pict,X,X,_DX,_DY,_Y,_D).%Don't iterate if X and X2 are the same number |
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draw_recursive_line(Pict,X,X2,DX,DY,Y,C):- |
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( C>0->%If the difference is greater than one, add Y one to Y. |
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Y1 is Y+1, |
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send(Pict,pixel(X,Y1,colour(black))), |
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C2 is C+(2*DY-2*DX); |
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Y1 is Y, |
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send(Pict,pixel(X,Y,colour(black))), |
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C2 is C+(2*DY)), |
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X0 is X+1,%The next iteration |
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draw_recursive_line(Pict,X0,X2,DX,DY,Y1,C2). |
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draw_line(Pict,X1,Y1,X2,Y2):- |
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DY is Y2-Y1, |
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DX is X2-X1, |
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D = 2*DY-DX,%The slope of the line |
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draw_recursive_line(Pict,X1,X2,DX,DY,Y1,D). |
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</lang> |
</lang> |
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