mirror of
https://github.com/genxium/DelayNoMore
synced 2024-12-26 03:39:00 +00:00
425 lines
12 KiB
Go
425 lines
12 KiB
Go
package resolv
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import (
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"math"
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)
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type Shape interface {
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// Intersection tests to see if a Shape intersects with the other given Shape. dx and dy are delta movement variables indicating
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// movement to be applied before the intersection check (thereby allowing you to see if a Shape would collide with another if it
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// were in a different relative location). If an Intersection is found, a ContactSet will be returned, giving information regarding
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// the intersection.
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Intersection(dx, dy float64, other Shape) *ContactSet
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// Bounds returns the top-left and bottom-right points of the Shape.
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Bounds() (Vector, Vector)
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// Position returns the X and Y position of the Shape.
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Position() (float64, float64)
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// SetPosition allows you to place a Shape at another location.
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SetPosition(x, y float64)
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// Clone duplicates the Shape.
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Clone() Shape
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}
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// A Line is a helper shape used to determine if two ConvexPolygon lines intersect; you can't create a Line to use as a Shape.
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// Instead, you can create a ConvexPolygon, specify two points, and set its Closed value to false.
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type Line struct {
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Start, End Vector
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}
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func NewLine(x, y, x2, y2 float64) *Line {
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l := &Line{}
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l.Start = Vector{x, y}
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l.End = Vector{x2, y2}
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return l
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}
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func (line *Line) Normal() Vector {
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dy := line.End[1] - line.Start[1]
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dx := line.End[0] - line.Start[0]
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return Vector{dy, -dx}.Unit()
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}
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// IntersectionPointsLine returns the intersection point of a Line with another Line as a Vector. If no intersection is found, it will return nil.
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func (line *Line) IntersectionPointsLine(other *Line) Vector {
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det := (line.End[0]-line.Start[0])*(other.End[1]-other.Start[1]) - (other.End[0]-other.Start[0])*(line.End[1]-line.Start[1])
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if det != 0 {
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// MAGIC MATH; the extra + 1 here makes it so that corner cases (literally, lines going through corners) works.
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// lambda := (float32(((line.Y-b.Y)*(b.X2-b.X))-((line.X-b.X)*(b.Y2-b.Y))) + 1) / float32(det)
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lambda := (((line.Start[1] - other.Start[1]) * (other.End[0] - other.Start[0])) - ((line.Start[0] - other.Start[0]) * (other.End[1] - other.Start[1])) + 1) / det
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// gamma := (float32(((line.Y-b.Y)*(line.X2-line.X))-((line.X-b.X)*(line.Y2-line.Y))) + 1) / float32(det)
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gamma := (((line.Start[1] - other.Start[1]) * (line.End[0] - line.Start[0])) - ((line.Start[0] - other.Start[0]) * (line.End[1] - line.Start[1])) + 1) / det
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if (0 < lambda && lambda < 1) && (0 < gamma && gamma < 1) {
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// Delta
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dx := line.End[0] - line.Start[0]
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dy := line.End[1] - line.Start[1]
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// dx, dy := line.GetDelta()
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return Vector{line.Start[0] + (lambda * dx), line.Start[1] + (lambda * dy)}
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}
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}
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return nil
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}
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type ConvexPolygon struct {
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Points *RingBuffer
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X, Y float64
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Closed bool
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}
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// NewConvexPolygon creates a new convex polygon from the provided set of X and Y positions of 2D points (or vertices). Should generally be ordered clockwise,
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// from X and Y of the first, to X and Y of the last. For example: NewConvexPolygon(0, 0, 10, 0, 10, 10, 0, 10) would create a 10x10 convex
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// polygon square, with the vertices at {0,0}, {10,0}, {10, 10}, and {0, 10}.
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func NewConvexPolygon(points ...float64) *ConvexPolygon {
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cp := &ConvexPolygon{}
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cp.Points = NewRingBuffer(6) // I don't expected more points to be coped with in this particular game
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cp.Closed = true
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cp.AddPoints(points...)
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return cp
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}
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func (cp *ConvexPolygon) GetPointByOffset(offset int32) Vector {
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if cp.Points.Cnt <= offset {
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return nil
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}
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return cp.Points.GetByFrameId(cp.Points.StFrameId + offset).(Vector)
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}
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func (cp *ConvexPolygon) Clone() Shape {
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newPoly := NewConvexPolygon()
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newPoly.X = cp.X
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newPoly.Y = cp.Y
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for i := int32(0); i < cp.Points.Cnt; i++ {
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newPoly.Points.Put(cp.GetPointByOffset(i))
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}
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newPoly.Closed = cp.Closed
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return newPoly
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}
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// AddPoints allows you to add points to the ConvexPolygon with a slice or selection of float64s, with each pair indicating an X or Y value for
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// a point / vertex (i.e. AddPoints(0, 1, 2, 3) would add two points - one at {0, 1}, and another at {2, 3}).
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func (cp *ConvexPolygon) AddPoints(vertexPositions ...float64) {
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for v := 0; v < len(vertexPositions); v += 2 {
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// "resolv.Vector" is an alias of "[]float64", thus already a pointer type
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cp.Points.Put(Vector{vertexPositions[v], vertexPositions[v+1]})
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}
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}
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func (cp *ConvexPolygon) UpdateAsRectangle(x, y, w, h float64) bool {
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// This function might look ugly but it's a fast in-place update!
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if 4 != cp.Points.Cnt {
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panic("ConvexPolygon not having exactly 4 vertices to form a rectangle#1!")
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}
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for i := int32(0); i < cp.Points.Cnt; i++ {
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thatVec := cp.GetPointByOffset(i)
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if nil == thatVec {
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panic("ConvexPolygon not having exactly 4 vertices to form a rectangle#2!")
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}
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switch i {
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case 0:
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thatVec[0] = x
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thatVec[1] = y
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case 1:
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thatVec[0] = x + w
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thatVec[1] = y
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case 2:
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thatVec[0] = x + w
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thatVec[1] = y + h
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case 3:
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thatVec[0] = x
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thatVec[1] = y + h
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}
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}
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return true
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}
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// Lines returns a slice of transformed Lines composing the ConvexPolygon.
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func (cp *ConvexPolygon) Lines() []*Line {
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vertices := cp.Transformed()
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linesCnt := len(vertices)
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if !cp.Closed {
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linesCnt -= 1
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}
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lines := make([]*Line, linesCnt)
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for i := 0; i < linesCnt; i++ {
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start, end := vertices[i], vertices[0]
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if i < len(vertices)-1 {
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end = vertices[i+1]
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}
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line := NewLine(start[0], start[1], end[0], end[1])
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lines[i] = line
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}
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return lines
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}
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// Transformed returns the ConvexPolygon's points / vertices, transformed according to the ConvexPolygon's position.
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func (cp *ConvexPolygon) Transformed() []Vector {
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transformed := make([]Vector, cp.Points.Cnt)
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for i := int32(0); i < cp.Points.Cnt; i++ {
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point := cp.GetPointByOffset(i)
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transformed[i] = Vector{point[0] + cp.X, point[1] + cp.Y}
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}
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return transformed
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}
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// Bounds returns two Vectors, comprising the top-left and bottom-right positions of the bounds of the
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// ConvexPolygon, post-transformation.
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func (cp *ConvexPolygon) Bounds() (Vector, Vector) {
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transformed := cp.Transformed()
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topLeft := Vector{transformed[0][0], transformed[0][1]}
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bottomRight := topLeft.Clone()
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for i := 0; i < len(transformed); i++ {
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point := transformed[i]
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if point[0] < topLeft[0] {
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topLeft[0] = point[0]
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} else if point[0] > bottomRight[0] {
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bottomRight[0] = point[0]
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}
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if point[1] < topLeft[1] {
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topLeft[1] = point[1]
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} else if point[1] > bottomRight[1] {
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bottomRight[1] = point[1]
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}
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}
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return topLeft, bottomRight
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}
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// Position returns the position of the ConvexPolygon.
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func (cp *ConvexPolygon) Position() (float64, float64) {
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return cp.X, cp.Y
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}
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// SetPosition sets the position of the ConvexPolygon. The offset of the vertices compared to the X and Y position is relative to however
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// you initially defined the polygon and added the vertices.
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func (cp *ConvexPolygon) SetPosition(x, y float64) {
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cp.X = x
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cp.Y = y
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}
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// SetPositionVec allows you to set the position of the ConvexPolygon using a Vector. The offset of the vertices compared to the X and Y
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// position is relative to however you initially defined the polygon and added the vertices.
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func (cp *ConvexPolygon) SetPositionVec(vec Vector) {
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cp.X = vec.X()
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cp.Y = vec.Y()
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}
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// Move translates the ConvexPolygon by the designated X and Y values.
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func (cp *ConvexPolygon) Move(x, y float64) {
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cp.X += x
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cp.Y += y
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}
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// MoveVec translates the ConvexPolygon by the designated Vector.
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func (cp *ConvexPolygon) MoveVec(vec Vector) {
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cp.X += vec.X()
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cp.Y += vec.Y()
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}
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// SATAxes returns the axes of the ConvexPolygon for SAT intersection testing.
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func (cp *ConvexPolygon) SATAxes() []Vector {
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lines := cp.Lines()
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axes := make([]Vector, len(lines))
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for i, line := range lines {
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axes[i] = line.Normal()
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}
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return axes
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}
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// PointInside returns if a Point (a Vector) is inside the ConvexPolygon.
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func (polygon *ConvexPolygon) PointInside(point Vector) bool {
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pointLine := NewLine(point[0], point[1], point[0]+999999999999, point[1])
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contactCount := 0
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for _, line := range polygon.Lines() {
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if line.IntersectionPointsLine(pointLine) != nil {
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contactCount++
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}
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}
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return contactCount == 1
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}
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type ContactSet struct {
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Points []Vector // Slice of Points indicating contact between the two Shapes.
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MTV Vector // Minimum Translation Vector; this is the vector to move a Shape on to move it outside of its contacting Shape.
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Center Vector // Center of the Contact set; this is the average of all Points contained within the Contact Set.
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}
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func NewContactSet() *ContactSet {
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cs := &ContactSet{}
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cs.Points = []Vector{}
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cs.MTV = Vector{0, 0}
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cs.Center = Vector{}
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return cs
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}
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// LeftmostPoint returns the left-most point out of the ContactSet's Points slice. If the Points slice is empty somehow, this returns nil.
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func (cs *ContactSet) LeftmostPoint() Vector {
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var left Vector
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for _, point := range cs.Points {
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if left == nil || point[0] < left[0] {
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left = point
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}
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}
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return left
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}
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// RightmostPoint returns the right-most point out of the ContactSet's Points slice. If the Points slice is empty somehow, this returns nil.
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func (cs *ContactSet) RightmostPoint() Vector {
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var right Vector
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for _, point := range cs.Points {
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if right == nil || point[0] > right[0] {
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right = point
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}
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}
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return right
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}
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// TopmostPoint returns the top-most point out of the ContactSet's Points slice. If the Points slice is empty somehow, this returns nil.
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func (cs *ContactSet) TopmostPoint() Vector {
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var top Vector
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for _, point := range cs.Points {
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if top == nil || point[1] < top[1] {
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top = point
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}
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}
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return top
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}
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// BottommostPoint returns the bottom-most point out of the ContactSet's Points slice. If the Points slice is empty somehow, this returns nil.
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func (cs *ContactSet) BottommostPoint() Vector {
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var bottom Vector
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for _, point := range cs.Points {
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if bottom == nil || point[1] > bottom[1] {
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bottom = point
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}
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}
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return bottom
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}
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// Intersection tests to see if a ConvexPolygon intersects with the other given Shape. dx and dy are delta movement variables indicating
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// movement to be applied before the intersection check (thereby allowing you to see if a Shape would collide with another if it
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// were in a different relative location). If an Intersection is found, a ContactSet will be returned, giving information regarding
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// the intersection.
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func (cp *ConvexPolygon) Intersection(dx, dy float64, other Shape) *ContactSet {
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contactSet := NewContactSet()
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ogX := cp.X
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ogY := cp.Y
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cp.X += dx
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cp.Y += dy
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if poly, isPoly := other.(*ConvexPolygon); isPoly {
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for _, line := range cp.Lines() {
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for _, otherLine := range poly.Lines() {
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if point := line.IntersectionPointsLine(otherLine); point != nil {
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contactSet.Points = append(contactSet.Points, point)
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}
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}
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}
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}
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if len(contactSet.Points) > 0 {
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// Do nothing
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} else {
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contactSet = nil
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}
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cp.X = ogX
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cp.Y = ogY
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return contactSet
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}
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// NewRectangle returns a rectangular ConvexPolygon with the vertices in clockwise order. In actuality, an AABBRectangle should be its own
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// "thing" with its own optimized Intersection code check.
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func NewRectangle(x, y, w, h float64) *ConvexPolygon {
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return NewConvexPolygon(
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x, y,
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x+w, y,
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x+w, y+h,
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x, y+h,
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)
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}
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type Projection struct {
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Min, Max float64
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}
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// Overlapping returns whether a Projection is overlapping with the other, provided Projection. Credit to https://www.sevenson.com.au/programming/sat/
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func (projection Projection) Overlapping(other Projection) bool {
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return projection.Overlap(other) > 0
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}
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// Overlap returns the amount that a Projection is overlapping with the other, provided Projection. Credit to https://dyn4j.org/2010/01/sat/#sat-nointer
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func (projection Projection) Overlap(other Projection) float64 {
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return math.Min(projection.Max, other.Max) - math.Max(projection.Min, other.Min)
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}
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// IsInside returns whether the Projection is wholly inside of the other, provided Projection.
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func (projection Projection) IsInside(other Projection) bool {
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return projection.Min >= other.Min && projection.Max <= other.Max
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}
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