const sqDist = ( x0 , y0 , x1 , y1 ) => { return ( y1 - y0 ) ** 2 + ( x1 - x0 ) ** 2 ; } ; const simplifyDist = ( xs , ys , epsilon ) => { const epsilonSq = epsilon ** 2 ; const keep = new Uint8Array ( xs . length ) ; let prevX = xs [ 0 ] ; let prevY = ys [ 0 ] ; let keptLength = 1 ; keep [ 0 ] = 1 ; keep [ keep . length - 1 ] = 1 ; for ( let i = 1 ; i < xs . length ; i ++ ) { const x = xs [ i ] ; const y = ys [ i ] ; if ( sqDist ( x , y , prevX , prevY ) > epsilonSq ) { keep [ i ] = 1 ; prevX = x ; prevY = y ; keptLength ++ ; } } const simplifiedXs = ( new Float64Array ( keptLength ) as any ) as number [ ] ; const simplifiedYs = ( new Float64Array ( keptLength ) as any ) as number [ ] ; let i = 0 ; for ( let j = 0 ; j < keep . length ; j ++ ) { if ( keep [ j ] === 1 ) { simplifiedXs [ i ] = xs [ j ] ; simplifiedYs [ i ] = ys [ j ] ; i ++ ; } } return [ simplifiedXs , simplifiedYs ] as const ; } ; const sqSegmentDist = ( x0 , y0 , x1 , y1 , x2 , y2 ) => { let x = x0 ; let y = y0 ; let dx = x1 - x0 ; let dy = y1 - y0 ; if ( dx !== 0 || dy !== 0 ) { const t = ( ( x2 - x ) * dx + ( y2 - y ) * dy ) / ( dx * dx + dy * dy ) ; if ( t > 1 ) { x = x1 ; y = y1 ; } else if ( t > 0 ) { x += dx * t ; y += dy * t ; } } dx = x2 - x ; dy = y2 - y ; return dx * dx + dy * dy ; } ; const simplifyDouglasPeuckerHelper = ( xs , ys , epsilonSq , i0 , i1 , keep ) => { const indexStack = [ ] ; indexStack . push ( { i0 , i1 } ) ; while ( indexStack . length ) { const { i0 , i1 } = indexStack . pop ( ) ! ; const x0 = xs [ i0 ] ; const y0 = ys [ i0 ] ; const x1 = xs [ i1 ] ; const y1 = ys [ i1 ] ; let maxIndex = 0 ; let maxDist = - 1 ; for ( let i = i0 + 1 ; i < i1 ; i ++ ) { const sqDist = sqSegmentDist ( x0 , y0 , x1 , y1 , xs [ i ] , ys [ i ] ) ; if ( sqDist > maxDist ) { maxIndex = i ; maxDist = sqDist ; } } if ( maxDist > epsilonSq ) { keep [ maxIndex ] = 1 ; if ( maxIndex - i0 > 1 ) { indexStack . push ( { i0 , i1 : maxIndex } ) ; } if ( i1 - maxIndex > 1 ) { indexStack . push ( { i0 : maxIndex , i1 } ) ; } } } } ; const simplifyDouglasPeucker = ( xs , ys , epsilon ) => { const keep = new Uint8Array ( xs . length ) ; const sqEpsilon = epsilon * epsilon ; keep [ 0 ] = 1 ; keep [ keep . length - 1 ] = 1 ; simplifyDouglasPeuckerHelper ( xs , ys , sqEpsilon , 0 , keep . length - 1 , keep ) ; let resultLength = 0 ; for ( let j = 0 ; j < keep . length ; j ++ ) { if ( keep [ j ] === 1 ) { resultLength ++ ; } } const xsResult = new Float64Array ( resultLength ) ; const ysResult = new Float64Array ( resultLength ) ; let i = 0 ; for ( let j = 0 ; j < keep . length ; j ++ ) { if ( keep [ j ] === 1 ) { xsResult [ i ] = xs [ j ] ; ysResult [ i ] = ys [ j ] ; i ++ ; } } return [ xsResult , ysResult ] as const ; } ; export const simplifyForNormalizedData = ( xs , ys , epsilon ) => { const [ _xs , _ys ] = simplifyDist ( xs , ys , epsilon ) ; const [ __xs , __ys ] = simplifyDouglasPeucker ( _xs , _ys , epsilon ) ; return ( [ __xs , __ys ] as any ) as [ number [ ] , number [ ] ] ; } ;