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Different recursive approach with bezier curve.

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This commit is contained in:
Brad Nelson
2022-03-11 21:23:21 -08:00
parent 2099d1a3d8
commit 1b09f7a2b0
1 changed files with 25 additions and 34 deletions
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59
examples/bezier_test.fs
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@ -39,6 +39,7 @@ scanlines max-scanlines cells erase
;
: row-span ( y -- a ) cells scanlines + ;
: add-edge { x y }
y 0< y max-scanlines >= or if exit then
y row-span { yp }
begin yp @ while
x yp @ ->edge @ <= if
@ -65,53 +66,43 @@ scanlines max-scanlines cells erase
;
: draw-spans max-scanlines 0 do i draw-row loop ;
: 2span { a b -- n } a b max a b min - ;
: 3span { a b c -- n } a b max c max a b min c min - ;
: raw-bezier 0 0 { x1 y1 x2 y2 x3 y3 d xn yn }
y1 d rshift y2 d rshift y3 d rshift 3span 2 < if
y1 d rshift y3 d rshift 2span if
y1 y3 = if
x1 x3 + 2/ d lshift y1 d rshift add-edge
exit
then
y1 y3 < if
x1 x3 x1 - y1 1 d lshift 1- and y3 y1 - */ - d rshift
y1 d rshift add-edge
else
x3 x1 x3 - y3 1 d lshift 1- and y1 y3 - */ - d rshift
y3 d rshift add-edge
then
then
else
x1 x2 2* + x3 + to xn
y1 y2 2* + y3 + to yn
x1 4* y1 4* x1 x2 + 2* y1 y2 + 2* xn yn d 2 + recurse
xn yn x2 x3 + 2* y2 y3 + 2* x3 4* y3 4* d 2 + recurse
then
;
: 0.<< ( n -- n ) 16 lshift ;
: 0.>> ( n -- n ) 16 rshift ;
(
: line 0 0 { x1 y1 x2 y2 dx dy }
: line ( x1 y1 x2 y2 )
0 0 0 0 { x1 y1 x2 y2 dx dy sy ey }
y1 y2 > if
y1 y2 to y1 to y2
x1 x2 to x1 to x2
then
y2 y1 - 0.>> to dy
x2 x1 - to dx
y1 0.>> to sy
y2 0.>> to ey
ey sy - to dy
dy 0 ?do
x1 dx i dy */ + 0.>> y1 0.>> i + add-edge
x1 dx i dy */ + 0.>> sy i + add-edge
loop
;
)
: bezier 0 raw-bezier ;
: distance2 { x1 y1 x2 y2 } x1 x2 - dup * y1 y2 - dup * + ;
: line ( x1 y1 x2 y2 ) 2dup bezier ;
: raw-bezier 0 0 { x1 y1 x2 y2 x3 y3 d xn yn }
d 0< if
x1 y1 x3 y3 line
else
x1 x2 2* + x3 + 2/ 2/ to xn
y1 y2 2* + y3 + 2/ 2/ to yn
x1 y1 x1 x2 + 2/ y1 y2 + 2/ xn yn d 1- recurse
xn yn x2 x3 + 2/ y2 y3 + 2/ x3 y3 d 1- recurse
then
;
: bezier 10 raw-bezier ;
0 value pen-x 0 value pen-y
: move-to { x y } x to pen-x y to pen-y ;
: line-to { x y } pen-x pen-y x y line x y move-to ;
: bezier-to { x' y' x y } pen-x pen-y x' y' x y bezier x y move-to ;
: move-to { x y } x 0.<< to pen-x y 0.<< to pen-y ;
: line-to { x y } pen-x pen-y x 0.<< y 0.<< line x y move-to ;
: bezier-to { x' y' x y } pen-x pen-y x' 0.<< y' 0.<< x 0.<< y 0.<< bezier x y move-to ;
-1 -1 window