point.go

// Copyright (c) Roman Atachiants and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for details.

package tile

import (
	"fmt"
)

const invalid = int16(-1 << 15)

var interleaveLookup = [256]int32{
	0x0000, 0x0001, 0x0004, 0x0005, 0x0010, 0x0011, 0x0014, 0x0015,
	0x0040, 0x0041, 0x0044, 0x0045, 0x0050, 0x0051, 0x0054, 0x0055,
	0x0100, 0x0101, 0x0104, 0x0105, 0x0110, 0x0111, 0x0114, 0x0115,
	0x0140, 0x0141, 0x0144, 0x0145, 0x0150, 0x0151, 0x0154, 0x0155,
	0x0400, 0x0401, 0x0404, 0x0405, 0x0410, 0x0411, 0x0414, 0x0415,
	0x0440, 0x0441, 0x0444, 0x0445, 0x0450, 0x0451, 0x0454, 0x0455,
	0x0500, 0x0501, 0x0504, 0x0505, 0x0510, 0x0511, 0x0514, 0x0515,
	0x0540, 0x0541, 0x0544, 0x0545, 0x0550, 0x0551, 0x0554, 0x0555,

	0x1000, 0x1001, 0x1004, 0x1005, 0x1010, 0x1011, 0x1014, 0x1015,
	0x1040, 0x1041, 0x1044, 0x1045, 0x1050, 0x1051, 0x1054, 0x1055,
	0x1100, 0x1101, 0x1104, 0x1105, 0x1110, 0x1111, 0x1114, 0x1115,
	0x1140, 0x1141, 0x1144, 0x1145, 0x1150, 0x1151, 0x1154, 0x1155,
	0x1400, 0x1401, 0x1404, 0x1405, 0x1410, 0x1411, 0x1414, 0x1415,
	0x1440, 0x1441, 0x1444, 0x1445, 0x1450, 0x1451, 0x1454, 0x1455,
	0x1500, 0x1501, 0x1504, 0x1505, 0x1510, 0x1511, 0x1514, 0x1515,
	0x1540, 0x1541, 0x1544, 0x1545, 0x1550, 0x1551, 0x1554, 0x1555,

	0x4000, 0x4001, 0x4004, 0x4005, 0x4010, 0x4011, 0x4014, 0x4015,
	0x4040, 0x4041, 0x4044, 0x4045, 0x4050, 0x4051, 0x4054, 0x4055,
	0x4100, 0x4101, 0x4104, 0x4105, 0x4110, 0x4111, 0x4114, 0x4115,
	0x4140, 0x4141, 0x4144, 0x4145, 0x4150, 0x4151, 0x4154, 0x4155,
	0x4400, 0x4401, 0x4404, 0x4405, 0x4410, 0x4411, 0x4414, 0x4415,
	0x4440, 0x4441, 0x4444, 0x4445, 0x4450, 0x4451, 0x4454, 0x4455,
	0x4500, 0x4501, 0x4504, 0x4505, 0x4510, 0x4511, 0x4514, 0x4515,
	0x4540, 0x4541, 0x4544, 0x4545, 0x4550, 0x4551, 0x4554, 0x4555,

	0x5000, 0x5001, 0x5004, 0x5005, 0x5010, 0x5011, 0x5014, 0x5015,
	0x5040, 0x5041, 0x5044, 0x5045, 0x5050, 0x5051, 0x5054, 0x5055,
	0x5100, 0x5101, 0x5104, 0x5105, 0x5110, 0x5111, 0x5114, 0x5115,
	0x5140, 0x5141, 0x5144, 0x5145, 0x5150, 0x5151, 0x5154, 0x5155,
	0x5400, 0x5401, 0x5404, 0x5405, 0x5410, 0x5411, 0x5414, 0x5415,
	0x5440, 0x5441, 0x5444, 0x5445, 0x5450, 0x5451, 0x5454, 0x5455,
	0x5500, 0x5501, 0x5504, 0x5505, 0x5510, 0x5511, 0x5514, 0x5515,
	0x5540, 0x5541, 0x5544, 0x5545, 0x5550, 0x5551, 0x5554, 0x5555,
}

var deinterleaveLookup = [256]int16{
	0x0, 0x1, 0x1, 0x1, 0x2, 0x3, 0x3, 0x3,
	0x2, 0x3, 0x3, 0x3, 0x2, 0x3, 0x3, 0x3,
	0x4, 0x5, 0x5, 0x5, 0x6, 0x7, 0x7, 0x7,
	0x6, 0x7, 0x7, 0x7, 0x6, 0x7, 0x7, 0x7,
	0x4, 0x5, 0x5, 0x5, 0x6, 0x7, 0x7, 0x7,
	0x6, 0x7, 0x7, 0x7, 0x6, 0x7, 0x7, 0x7,
	0x4, 0x5, 0x5, 0x5, 0x6, 0x7, 0x7, 0x7,
	0x6, 0x7, 0x7, 0x7, 0x6, 0x7, 0x7, 0x7,

	0x8, 0x9, 0x9, 0x9, 0xa, 0xb, 0xb, 0xb,
	0xa, 0xb, 0xb, 0xb, 0xa, 0xb, 0xb, 0xb,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,

	0x8, 0x9, 0x9, 0x9, 0xa, 0xb, 0xb, 0xb,
	0xa, 0xb, 0xb, 0xb, 0xa, 0xb, 0xb, 0xb,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,

	0x8, 0x9, 0x9, 0x9, 0xa, 0xb, 0xb, 0xb,
	0xa, 0xb, 0xb, 0xb, 0xa, 0xb, 0xb, 0xb,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
	0xc, 0xd, 0xd, 0xd, 0xe, 0xf, 0xf, 0xf,
	0xe, 0xf, 0xf, 0xf, 0xe, 0xf, 0xf, 0xf,
}

// deinterleavePoint decodes the interleaved values.
func deinterleavePoint(code int) (p Point) {
	p.X = (deinterleaveLookup[code&0x55]) |
		(deinterleaveLookup[(code>>8)&0x55] << 4) |
		(deinterleaveLookup[(code>>16)&0x55] << 8) |
		(deinterleaveLookup[(code>>24)&0x55] << 12)

	p.Y = (deinterleaveLookup[code&0xaa]) |
		(deinterleaveLookup[(code>>8)&0xaa] << 4) |
		(deinterleaveLookup[(code>>16)&0xaa] << 8) |
		(deinterleaveLookup[(code>>24)&0xaa] << 12)
	return
}

// -----------------------------------------------------------------------------

// Point represents a 2D coordinate.
type Point struct {
	X int16 // X coordinate
	Y int16 // Y coordinate
}

func unpackPoint(v uint32) Point {
	return At(int16(v>>16), int16(v))
}

// At creates a new point at a specified x,y coordinate.
func At(x, y int16) Point {
	return Point{X: x, Y: y}
}

// String returns string representation of a point.
func (p Point) String() string {
	return fmt.Sprintf("%v,%v", p.X, p.Y)
}

// Integer returns a packed 32-bit integer representation of a point.
func (p Point) Integer() uint32 {
	return (uint32(p.X) << 16) | (uint32(p.Y) & 0xffff)
}

// Interleave bits of x and y, so that all of thebits of x are in the even
// positions and y in the odd (Morton Number).
func (p Point) Interleave() int32 {
	// see: https://graphics.stanford.edu/~seander/bithacks.html
	// and: https://github.com/golang/geo/blob/master/s2/interleave.go
	return (interleaveLookup[p.X&0xff]) |
		(interleaveLookup[(p.X>>8)&0xff] << 16) |
		(interleaveLookup[p.Y&0xff] << 1) |
		(interleaveLookup[(p.Y>>8)&0xff] << 17)
}

// Equal compares two points and returns true if they are equal.
func (p Point) Equal(other Point) bool {
	return p.X == other.X && p.Y == other.Y
}

// Add adds two points together.
func (p Point) Add(p2 Point) Point {
	return Point{p.X + p2.X, p.Y + p2.Y}
}

// Subtract subtracts the second point from the first.
func (p Point) Subtract(p2 Point) Point {
	return Point{p.X - p2.X, p.Y - p2.Y}
}

// Multiply multiplies two points together.
func (p Point) Multiply(p2 Point) Point {
	return Point{p.X * p2.X, p.Y * p2.Y}
}

// Divide divides the first point by the second.
func (p Point) Divide(p2 Point) Point {
	return Point{p.X / p2.X, p.Y / p2.Y}
}

// MultiplyScalar multiplies the given point by the scalar.
func (p Point) MultiplyScalar(s int16) Point {
	return Point{p.X * s, p.Y * s}
}

// DivideScalar divides the given point by the scalar.
func (p Point) DivideScalar(s int16) Point {
	return Point{p.X / s, p.Y / s}
}

// Within checks if the point is within the specified bounding box.
func (p Point) Within(nw, se Point) bool {
	return p.X >= nw.X && p.Y >= nw.Y && p.X <= se.X && p.Y <= se.Y
}

// WithinRect checks if the point is within the specified bounding box.
func (p Point) WithinRect(box Rect) bool {
	return p.X >= box.Min.X && p.Y >= box.Min.Y && p.X <= box.Max.X && p.Y <= box.Max.Y
}

// WithinSize checks if the point is within the specified bounding box
// which starts at 0,0 until the width/height provided.
func (p Point) WithinSize(size Point) bool {
	return p.X >= 0 && p.Y >= 0 && p.X < size.X && p.Y < size.Y
}

// Move moves a point by one in the specified direction.
func (p Point) Move(direction Direction) Point {
	return p.MoveBy(direction, 1)
}

// MoveBy moves a point by n in the specified direction.
func (p Point) MoveBy(direction Direction, n int16) Point {
	switch direction {
	case North:
		return Point{p.X, p.Y + n}
	case NorthEast:
		return Point{p.X + n, p.Y + n}
	case East:
		return Point{p.X + n, p.Y}
	case SouthEast:
		return Point{p.X + n, p.Y - n}
	case South:
		return Point{p.X, p.Y - n}
	case SouthWest:
		return Point{p.X - n, p.Y - n}
	case West:
		return Point{p.X - n, p.Y}
	case NorthWest:
		return Point{p.X - n, p.Y + n}
	default:
		return p
	}
}

// DistanceTo calculates manhattan distance to the other point
func (p Point) DistanceTo(other Point) uint32 {
	return abs(int32(p.X)-int32(other.X)) + abs(int32(p.Y)-int32(other.Y))
}

func abs(n int32) uint32 {
	if n < 0 {
		return uint32(-n)
	}
	return uint32(n)
}

// -----------------------------------------------------------------------------

// Rect represents a rectangle
type Rect struct {
	Min Point // Top left point of the rectangle
	Max Point // Bottom right point of the rectangle
}

// NewRect creates a new rectangle
// left,top,right,bottom correspond to x1,y1,x2,y2
func NewRect(left, top, right, bottom int16) Rect {
	return Rect{Min: At(left, top), Max: At(right, bottom)}
}

// Contains returns whether a point is within the rectangle or not.
func (r *Rect) Contains(p Point) bool {
	return p.X >= r.Min.X && p.Y >= r.Min.Y && p.X <= r.Max.X && p.Y <= r.Max.Y
}

// Intersects returns whether a rectangle intersects with another rectangle or not.
func (r *Rect) Intersects(box Rect) bool {
	return !(box.Max.X < r.Min.X || box.Min.X > r.Max.X || box.Max.Y < r.Min.Y || box.Min.Y > r.Max.Y)
}

// Size returns the size of the rectangle
func (r *Rect) Size() Point {
	return Point{
		X: r.Max.X - r.Min.X,
		Y: r.Max.Y - r.Min.Y,
	}
}

// -----------------------------------------------------------------------------

// Diretion represents a direction
type Direction byte

// Various directions
const (
	North Direction = iota
	NorthEast
	East
	SouthEast
	South
	SouthWest
	West
	NorthWest
)

// String returns a string representation of a direction
func (v Direction) String() string {
	switch v {
	case North:
		return "🡱N"
	case NorthEast:
		return "🡵NE"
	case East:
		return "🡲E"
	case SouthEast:
		return "🡶SE"
	case South:
		return "🡳S"
	case SouthWest:
		return "🡷SW"
	case West:
		return "🡰W"
	case NorthWest:
		return "🡴NW"
	default:
		return ""
	}
}