collide

package module

v0.0.0-...-c04b3ee Latest Latest Go to latest Published: Feb 21, 2022 License: MIT Imports: 1 Imported by: 0

Details

Valid go.mod file
Redistributable license
Tagged version
Stable version
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Repository

git.sr.ht/~adnano/go-collide

README ¶

go-collide

Package collide implements 2D collision detection in Go.

This package implements collision detection only. Resolving collisions is not implemented.

Usage

import "git.sr.ht/~adnano/go-collide"

Examples

There are a few examples provided in the examples directory. To run an example:

go run examples/distance.go

Contributing

Send patches and questions to ~adnano/go-collide-devel.

Subscribe to release announcements on ~adnano/go-collide-announce.

Credits

This library is based on:

Erin Catto's Box2D
Randy Gaul's ImpulseEngine
Chanhaeng Lee's GJKPracticeBasedBox2D

The following resources explain the various algorithms used in this library.

Documentation ¶

Overview ¶

Package collide implements 2D collision detection.

Index ¶

func Cross(p, q Point) float64
func Distance(a Shape, xfa Transform, b Shape, xfb Transform) float64
func Dot(p, q Point) float64
func TimeOfImpact(simplex *Simplex, a Shape, sweepA Sweep, b Shape, sweepB Sweep) float64
type Circle
type Collision
- func Collide(a Shape, xfa Transform, b Shape, xfb Transform) *Collision
- func CollideCircleAndPolygon(a *Circle, xfa Transform, b *Polygon, xfb Transform) *Collision
- func CollideCircles(a *Circle, xfa Transform, b *Circle, xfb Transform) *Collision
- func CollidePolygonAndCircle(a *Polygon, xfa Transform, b *Circle, xfb Transform) *Collision
- func CollidePolygons(a *Polygon, xfa Transform, b *Polygon, xfb Transform) *Collision
type Point
- func CrossPS(p Point, s float64) Point
- func CrossSP(s float64, p Point) Point
- func Pt(X, Y float64) Point
- func (p Point) Add(q Point) Point
- func (p Point) Div(k float64) Point
- func (p Point) IsZero() bool
- func (p Point) Length() float64
- func (p Point) LengthSquared() float64
- func (p Point) Mul(k float64) Point
- func (p Point) Neg() Point
- func (p Point) Normalize() Point
- func (p Point) Sub(q Point) Point
type Polygon
- func NewPolygon(points ...Point) *Polygon
- func Rect(x, y, w, h float64) *Polygon
- func Rectangle(center, extents Point) *Polygon
type Rotation
- func NewRotation(theta float64) Rotation
- func (r Rotation) Mul(p Point) Point
- func (r Rotation) MulT(p Point) Point
type Shape
type Simplex
- func (s *Simplex) ClosestPoint() Point
- func (s *Simplex) GJK(a Shape, xfa Transform, b Shape, xfb Transform)
- func (s *Simplex) Metric() float64
- func (s *Simplex) ReadCache(cache *SimplexCache, a Shape, xfa Transform, b Shape, xfb Transform)
- func (s *Simplex) WitnessPoints() (Point, Point)
- func (s *Simplex) WriteCache(cache *SimplexCache)
type SimplexCache
type Sweep
- func (s Sweep) Advance(t float64) Sweep
- func (s Sweep) GetTransform(t float64) Transform
type Transform
- func NewTransform(position Point, rotation float64) Transform
- func (t Transform) Mul(p Point) Point
- func (t Transform) MulT(p Point) Point

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

func Cross ¶

func Cross(p, q Point) float64

Cross returns the cross product of p and q.

func Distance ¶

func Distance(a Shape, xfa Transform, b Shape, xfb Transform) float64

Distance returns the distance between a and b.

func Dot ¶

func Dot(p, q Point) float64

Dot returns the dot product of p and q.

func TimeOfImpact ¶

func TimeOfImpact(simplex *Simplex, a Shape, sweepA Sweep, b Shape, sweepB Sweep) float64

CCD via the local separating axis method. This seeks progression by computing the largest time at which separation is maintained.

Types ¶

type Circle ¶

type Circle struct {
	Center Point
	Radius float64
}

Circle represents a circle shape.

type Collision ¶

type Collision struct {
	Normal Point
	Depth  float64
}

Collision represents a collision.

func Collide ¶

func Collide(a Shape, xfa Transform, b Shape, xfb Transform) *Collision

Collide calculates a collision for two shapes.

func CollideCircleAndPolygon ¶

func CollideCircleAndPolygon(a *Circle, xfa Transform, b *Polygon, xfb Transform) *Collision

func CollideCircles ¶

func CollideCircles(a *Circle, xfa Transform, b *Circle, xfb Transform) *Collision

func CollidePolygonAndCircle ¶

func CollidePolygonAndCircle(a *Polygon, xfa Transform, b *Circle, xfb Transform) *Collision

func CollidePolygons ¶

func CollidePolygons(a *Polygon, xfa Transform, b *Polygon, xfb Transform) *Collision

type Point ¶

type Point struct {
	X, Y float64
}

A Point is an X, Y coordinate pair.

func CrossPS ¶

func CrossPS(p Point, s float64) Point

func CrossSP ¶

func CrossSP(s float64, p Point) Point

func Pt ¶

func Pt(X, Y float64) Point

Pt is shorthand for Point{X, Y}.

func (Point) Add ¶

func (p Point) Add(q Point) Point

Add returns the vector p+q.

func (Point) Div ¶

func (p Point) Div(k float64) Point

Div returns the vector p/k.

func (Point) IsZero ¶

func (p Point) IsZero() bool

IsZero reports whether the point has zero length.

func (Point) Length ¶

func (p Point) Length() float64

Length returns the length of the vector p.

func (Point) LengthSquared ¶

func (p Point) LengthSquared() float64

LengthSquared returns the squared length of the vector p.

func (Point) Mul ¶

func (p Point) Mul(k float64) Point

Mul returns the vector p*k.

func (Point) Neg ¶

func (p Point) Neg() Point

Neg returns the vector -p.

func (Point) Normalize ¶

func (p Point) Normalize() Point

Normalize returns the unit vector in the direction of p.

func (Point) Sub ¶

func (p Point) Sub(q Point) Point

Sub returns the vector p-q.

type Polygon ¶

type Polygon struct {
	Points  []Point
	Normals []Point
}

Polygon represents a collection of points.

func NewPolygon ¶

func NewPolygon(points ...Point) *Polygon

NewPolygon returns a polygon with the given points specified in clockwise order.

func Rect ¶

func Rect(x, y, w, h float64) *Polygon

Rect is shorthand for Rectangle(Point{x, y}, Point{w/2, h/2}).

func Rectangle ¶

func Rectangle(center, extents Point) *Polygon

Rectangle returns a rectangular polygon shape with the given center and half extents.

type Rotation ¶

type Rotation struct {
	Sin, Cos float64
}

Rotation represents a rotation.

func NewRotation ¶

func NewRotation(theta float64) Rotation

NewRotation returns a new rotation of theta radians.

func (Rotation) Mul ¶

func (r Rotation) Mul(p Point) Point

Mul returns the vector p rotated.

func (Rotation) MulT ¶

func (r Rotation) MulT(p Point) Point

MulT returns the vector p inverse rotated.

type Shape ¶

type Shape interface {
	// contains filtered or unexported methods
}

Shape represents a shape.

type Simplex ¶

type Simplex struct {
	// contains filtered or unexported fields
}

Simplex represents a simplex.

func (*Simplex) ClosestPoint ¶

func (s *Simplex) ClosestPoint() Point

ClosestPoint returns the closest point on the simplex to the origin.

func (*Simplex) GJK ¶

func (s *Simplex) GJK(a Shape, xfa Transform, b Shape, xfb Transform)

GJK implements the Gilbert-Johnson-Keerthi distance algorithm.

func (*Simplex) Metric ¶

func (s *Simplex) Metric() float64

Metric returns a metric that identifies this simplex.

func (*Simplex) ReadCache ¶

func (s *Simplex) ReadCache(cache *SimplexCache, a Shape, xfa Transform, b Shape, xfb Transform)

ReadCache populates the simplex from the cache.

func (*Simplex) WitnessPoints ¶

func (s *Simplex) WitnessPoints() (Point, Point)

WitnessPoints returns the witness points on the original shapes.

func (*Simplex) WriteCache ¶

func (s *Simplex) WriteCache(cache *SimplexCache)

WriteCache populates the cache.

type SimplexCache ¶

type SimplexCache struct {
	// contains filtered or unexported fields
}

SimplexCache is used to speed up repeated calls to distance functions.

type Sweep ¶

type Sweep struct {
	P0, P1 Point   // position
	R0, R1 float64 // rotation
}

A Sweep interpolates between two positions and orientations.

func (Sweep) Advance ¶

func (s Sweep) Advance(t float64) Sweep

Advance advances the position and rotation to time t.

func (Sweep) GetTransform ¶

func (s Sweep) GetTransform(t float64) Transform

GetTransform returns the transform at time t.

type Transform ¶

type Transform struct {
	Position Point
	Rotation Rotation
}

A Transform represents translation and rotation.

func NewTransform ¶

func NewTransform(position Point, rotation float64) Transform

NewTransform returns a Transform with the given position and rotation.

func (Transform) Mul ¶

func (t Transform) Mul(p Point) Point

Mul returns the transformation of the vector p.

func (Transform) MulT ¶

func (t Transform) MulT(p Point) Point

MulT returns the inverse transformation of the vector p.

Source Files ¶

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