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https://gitlab.com/sheaf/metabrush.git
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use the correct tangent vector for stroke joins
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sheaf
parent
3916fe2656
commit
d4561ad549
14
app/Main.hs
14
app/Main.hs
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@ -102,7 +102,7 @@ testDocuments = IntMap.fromList
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{ displayName = "Document 1"
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, filePath = Nothing
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, unsavedChanges = False
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, strokes = [ Stroke ( circle ( PointData Normal ( razor $ BrushPointData Normal ) ) ) "Circle" True ( unsafeUnique 0 )
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, strokes = [ Stroke ( circle ( PointData Normal ( rect $ BrushPointData Normal ) ) ) "Circle" True ( unsafeUnique 0 )
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]
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, bounds = AABB ( Point2D 0 0 ) ( Point2D 100 100 )
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, viewportCenter = Point2D 50 50
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@ -157,6 +157,18 @@ razor d = Seq.fromList
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pp p = PathPoint p d
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cp p = ControlPoint p d
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rect :: forall a. a -> Seq ( StrokePoint a )
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rect d = Seq.fromList
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[ pp ( Point2D 20 5 )
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, pp ( Point2D 20 -5 )
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, pp ( Point2D -20 -5 )
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, pp ( Point2D -20 5 )
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, pp ( Point2D 20 5 )
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]
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where
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pp :: Point2D Double -> StrokePoint a
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pp p = PathPoint p d
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--------------------------------------------------------------------------------
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main :: IO ()
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@ -137,7 +137,7 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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_ -> False
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fwd, bwd :: Seq ( StrokePoint () )
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( fwd, bwd ) = go tgt_start spt0 ( spt1 :<| spts )
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( fwd, bwd ) = go spt0 ( spt1 :<| spts )
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(<~>)
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:: ( Monoid a, Monoid b )
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@ -149,6 +149,7 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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-- Connecting paths at a point of discontinuity of the tangent vector direction (G1 discontinuity).
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-- This happens at corners of the brush path (including endpoints of an open brush path, where the tangent flips direction).
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joinAndContinue :: Vector2D Double -> StrokePoint d -> Seq ( StrokePoint d ) -> ( Seq ( StrokePoint () ), Seq ( StrokePoint () ) )
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--joinAndContinue tgt sp sps = go sp sps
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joinAndContinue _ _ Empty
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-- Closed curve.
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| isClosed
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@ -164,52 +165,52 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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)
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joinAndContinue tgt sp0 ( sp1 :<| sps )
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| tgt' `parallel` tgt
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= go tgt sp0 ( sp1 :<| sps )
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= go sp0 ( sp1 :<| sps )
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| let
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ptOffset :: Vector2D Double
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ptOffset = Point2D 0 0 --> coords sp0
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= ( ptOffset • joinWithBrush ( withTangent tgt brush0 ) ( withTangent tgt' brush0 ) brush0
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, ptOffset • joinWithBrush ( withTangent ( (-1) *^ tgt' ) brush0 ) ( withTangent ( (-1) *^ tgt ) brush0 ) brush0
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)
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<~> go tgt sp0 ( sp1 :<| sps )
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<~> go sp0 ( sp1 :<| sps )
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where
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tgt' :: Vector2D Double
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tgt' = coords sp0 --> coords sp1
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brush0 :: Seq ( StrokePoint () )
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brush0 = removePointData $ brushShape @x sp0
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go :: Vector2D Double -> StrokePoint d -> Seq ( StrokePoint d ) -> ( Seq ( StrokePoint () ), Seq ( StrokePoint () ) )
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go _ _ Empty = ( Empty, Empty )
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go :: StrokePoint d -> Seq ( StrokePoint d ) -> ( Seq ( StrokePoint () ), Seq ( StrokePoint () ) )
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go _ Empty = ( Empty, Empty )
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-- Line.
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go tgt0 sp0 ( sp1 :<| sps )
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go sp0 ( sp1 :<| sps )
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| PathPoint {} <- sp1
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, let
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p0, p1, fop0, fop1, bop0, bop1 :: Point2D Double
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p0 = coords sp0
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p1 = coords sp1
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fop0 = offset ( withTangent tgt0 ( brushShape @x sp0 ) ) • p0
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fop1 = offset ( withTangent tgt0 ( brushShape @x sp1 ) ) • p1
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bop0 = offset ( withTangent ( (-1) *^ tgt0 ) ( brushShape @x sp0 ) ) • p0
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bop1 = offset ( withTangent ( (-1) *^ tgt0 ) ( brushShape @x sp1 ) ) • p1
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tgt1 :: Vector2D Double
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tgt1 = p0 --> p1
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fop0 = offset ( withTangent tgt ( brushShape @x sp0 ) ) • p0
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fop1 = offset ( withTangent tgt ( brushShape @x sp1 ) ) • p1
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bop0 = offset ( withTangent ( (-1) *^ tgt ) ( brushShape @x sp0 ) ) • p0
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bop1 = offset ( withTangent ( (-1) *^ tgt ) ( brushShape @x sp1 ) ) • p1
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tgt :: Vector2D Double
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tgt = p0 --> p1
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brush :: Double -> Seq ( StrokePoint () )
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brush t = lerpBrush t ( brushShape @x sp0 ) ( brushShape @x sp1 )
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fwdPts, bwdPts :: [ Point2D Double ]
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fwdPts
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= [ ( offset $ withTangent tgt0 $ brush t )
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= [ ( offset $ withTangent tgt $ brush t )
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• ( lerp @( Vector2D Double ) t p0 p1 )
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| t <- [0.1,0.2..0.9]
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]
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bwdPts
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= [ ( offset $ withTangent ( (-1) *^ tgt0 ) $ brush t ) •
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= [ ( offset $ withTangent ( (-1) *^ tgt ) $ brush t ) •
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( lerp @( Vector2D Double ) t p0 p1 )
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| t <- [0.9,0.8..0.1]
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]
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= ( fitCurve fop0 tgt0 fwdPts fop1 tgt0, fitCurve bop1 ( (-1) *^ tgt1 ) bwdPts bop0 ( (-1) *^ tgt0 ) )
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<~> joinAndContinue tgt1 sp1 sps
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= ( fitCurve fop0 tgt fwdPts fop1 tgt, fitCurve bop1 ( (-1) *^ tgt ) bwdPts bop0 ( (-1) *^ tgt ) )
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<~> joinAndContinue tgt sp1 sps
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-- Quadratic Bézier curve.
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go tgt0 sp0 ( sp1 :<| sp2 :<| sps )
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go sp0 ( sp1 :<| sp2 :<| sps )
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| ControlPoint {} <- sp1
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, PathPoint {} <- sp2
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, let
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@ -221,7 +222,8 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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fop2 = offset ( withTangent tgt2 ( brushShape @x sp2 ) ) • p2
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bop0 = offset ( withTangent ( (-1) *^ tgt0 ) ( brushShape @x sp0 ) ) • p0
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bop2 = offset ( withTangent ( (-1) *^ tgt2 ) ( brushShape @x sp2 ) ) • p2
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tgt2 :: Vector2D Double
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tgt0, tgt2 :: Vector2D Double
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tgt0 = p0 --> p1
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tgt2 = p1 --> p2
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bez :: Quadratic.Bezier ( Point2D Double )
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bez = Quadratic.Bezier { .. }
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@ -242,7 +244,7 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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= ( fitCurve fop0 tgt0 fwdPts fop2 tgt2, fitCurve bop2 ( (-1) *^ tgt2 ) bwdPts bop0 ( (-1) *^ tgt0 ) )
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<~> joinAndContinue tgt2 sp2 sps
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-- Cubic Bézier curve.
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go tgt0 sp0 ( sp1 :<| sp2 :<| sp3 :<| sps )
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go sp0 ( sp1 :<| sp2 :<| sp3 :<| sps )
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| ControlPoint {} <- sp1
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, ControlPoint {} <- sp2
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, PathPoint {} <- sp3
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@ -256,7 +258,8 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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fop3 = offset ( withTangent tgt3 ( brushShape @x sp3 ) ) • p3
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bop0 = offset ( withTangent ( (-1) *^ tgt0 ) ( brushShape @x sp0 ) ) • p0
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bop3 = offset ( withTangent ( (-1) *^ tgt3 ) ( brushShape @x sp3 ) ) • p3
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tgt3 :: Vector2D Double
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tgt0, tgt3 :: Vector2D Double
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tgt0 = p0 --> p1
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tgt3 = p2 --> p3
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bez :: Cubic.Bezier ( Point2D Double )
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bez = Cubic.Bezier { .. }
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@ -276,7 +279,7 @@ stroke allPts@( spt0 :<| spt1 :<| spts )
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]
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= ( fitCurve fop0 tgt0 fwdPts fop3 tgt3, fitCurve bop3 ( (-1) *^ tgt3 ) bwdPts bop0 ( (-1) *^ tgt0 ) )
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<~> joinAndContinue tgt3 sp3 sps
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go _ p0 ps = error $ "stroke: unrecognised stroke type\n" <> show ( p0 :<| ps )
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go p0 ps = error $ "stroke: unrecognised stroke type\n" <> show ( p0 :<| ps )
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-----------------------------------
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-- Various utility functions
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