cirno

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 Go to latest Published: Aug 28, 2021 License: MIT Imports: 5 Imported by: 4

README

Cirno GoDoc

An easy to use collision detection and resolution library written in Go programming language. The library is still in development and the API might change.

Installation

No C dependencies required to compile the library. Just use the following command to install it.

go get github.com/zergon321/cirno

Tutorial

The tutorial series explains how to use different API methods and data types of Cirno to handle everything related to collisions in games.

Examples

All the example programs using the library are located in examples directory. Pixel is required to run any of them. The most important demos are described below.

  • benchmark - a small demo application that creates 1000 rectangles, randomly moves and rotates them and serches for collisions between them. It clearly showcases quad tree in action;

  • contacts - a small demo application that showcases finding contact points between shape outlines;

  • raycast - a small demo application that showcases raycast, just like Physics2D.Raycast from Unity;

  • sliding - a small demo that showcases shapes movement with sliding collision.

Games

The most noteable game created with Cirno at the current time is a Touhou style danmaku demo. The less noteable one is a tiny platrformer level in examples directory.

Danmaku Platformer
Danmaku Platformer

If you have a game using Cirno and you want it to be present in this list, just create a new PR with your changes to the README.

Features

  • Shapes to attach to game objects to detect and resolve collisions between them:
    • circle;
    • line segment (or just line);
    • rectangle (OBB, oriented bounding box).
  • Quadtree space index
  • Raycast
  • Contacts finding methods
  • Normal computing methods
  • Movement and rotation approximation
  • Tag system

Contributing

For minor and unimportant errors such as typos please just create issues instead of PRs fixing them.

Code changes adding features, optimizations, tests and bugfixes are welcome. All the contributions in examples directory should be really small, preferrably one-file. If your game is quite big, consider placing links to it in the list of games in the README.

Documentation

Index

Constants

View Source 
const (
	// RadToDeg is a factor to transfrom radians to degrees.
	RadToDeg float64 = 180.0 / math.Pi
	// DegToRad is a factor to transform degrees to radians.
	DegToRad float64 = math.Pi / 180.0
	// Epsilon is the constant for approximate comparisons.
	Epsilon float64 = 0.000001
	// CollinearityThreshold is the constant to detect if two vectors
	// are effectively collinear.
	CollinearityThreshold float64 = 10.0
)

Variables

This section is empty.

Functions

func AdjustAngle 

func AdjustAngle(angle float64) float64

AdjustAngle adjusts the value of the angle so it is bettween 0 and 360.

func Angle 

func Angle(a, b Vector) (float64, error)

Angle returns the angle between two vectors (in degrees).

func AngleRadians 

func AngleRadians(a, b Vector) (float64, error)

AngleRadians returns the angle between two vectors (in radians).

func Approximate 

func Approximate(shape Shape, moveDiff Vector, turnDiff float64, shapes Shapes, intensity int, useTags bool) (Vector, float64, Shape, error)

Approximate attempts to move the shape in the specified direction to detect the closest point until the shape collides other shapes.

func CollisionCircleToCircle 

func CollisionCircleToCircle(a, b *Circle) (bool, error)

CollisionCircleToCircle detects if there's an intersection between two circles.

func CollisionRectangleToCircle 

func CollisionRectangleToCircle(rect *Rectangle, circle *Circle) (bool, error)

CollisionRectangleToCircle detects if there's an intersection between an oriented rectangle and a circle.

func CollisionRectangleToRectangle 

func CollisionRectangleToRectangle(a, b *Rectangle) (bool, error)

CollisionRectangleToRectangle detects if there is an intersection between two oriented rectangles.

func Cross 

func Cross(a, b Vector) float64

Cross returns the cross product of two vectors.

func Distance 

func Distance(a, b Vector) float64

Distance returns the value of distance between two points represented as vectors.

func Dot 

func Dot(a, b Vector) float64

Dot returns the dot product of two vectors.

func IntersectionLineToCircle 

func IntersectionLineToCircle(line *Line, circle *Circle) (bool, error)

IntersectionLineToCircle detects if a line and a circle do intersect.

func IntersectionLineToLine 

func IntersectionLineToLine(a, b *Line) (bool, error)

IntersectionLineToLine detects if two lines intersect.

func IntersectionLineToRectangle 

func IntersectionLineToRectangle(line *Line, rect *Rectangle) (bool, error)

IntersectionLineToRectangle detects if there's an intersection between a line and a rectangle.

func LinesDistance 

func LinesDistance(a, b *Line) (float64, error)

LinesDistance returns the shortest distance between two lines.

func ResolveCollision 

func ResolveCollision(one, another Shape, useTags bool) (bool, error)

ResolveCollision assumes types of the given shapes and detects if they collide.

func Sign 

func Sign(number float64) float64

Sign returns the sign of the number according to Epsilon.

func SquaredDistance 

func SquaredDistance(a, b Vector) float64

SquaredDistance returns the value of distance in the power of 2 between two points represented as vectors.

Types

type Circle 

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

Circle represents a geometric euclidian circle.

func NewCircle 

func NewCircle(position Vector, radius float64) (*Circle, error)

NewCircle create a new circle with the given parameters.

func (*Circle) Angle 

func (c *Circle) Angle() float64

Angle doesn't return any valuable data because there is no sense to rotate the circle.

This method is added just to match the Shape interface.

func (*Circle) AngleRadians 

func (c *Circle) AngleRadians() float64

AngleRadians doesn't return any valuable data because there is no sense to rotate the circle.

This method is added just to match the Shape interface.

func (*Circle) Center 

func (c *Circle) Center() Vector

Center returns the coordinates of the center of the circle.

func (*Circle) ContainsPoint 

func (c *Circle) ContainsPoint(point Vector) bool

ContainsPoint detects if the given point is inside the circle.

func (*Circle) Data 

func (data *Circle) Data() interface{}

Data returns whatever is saved in the data field of the shape.

func (Circle) GetIdentity 

func (t Circle) GetIdentity() int32

GetIdentity returns the valye of the shape identity.

func (Circle) GetMask 

func (t Circle) GetMask() int32

GetMask the value of the shape mask.

func (*Circle) Move 

func (c *Circle) Move(direction Vector) Vector

Move moves the circle in the specified direction.

func (*Circle) NormalTo 

func (circle *Circle) NormalTo(shape Shape) (Vector, error)

NormalTo returns the normal from the given circle to the other shape.

func (*Circle) NormalToCircle 

func (circle *Circle) NormalToCircle(other *Circle) (Vector, error)

NormalToCircle returns the normal from the given circle to the other circle.

func (*Circle) NormalToLine 

func (circle *Circle) NormalToLine(line *Line) (Vector, error)

NormalToLine returns the normal from the given circle to the line.

func (*Circle) NormalToRectangle 

func (circle *Circle) NormalToRectangle(rect *Rectangle) (Vector, error)

NormalToRectangle returns the normal from the given circle to the rectangle.

func (*Circle) Radius 

func (c *Circle) Radius() float64

Radius returns the radius og the circle.

func (*Circle) Rotate 

func (c *Circle) Rotate(angle float64) float64

Rotate does nothing to the circle because there is no sense to rotate it.

This method is added just to match the Shape interface.

func (*Circle) RotateAround 

func (c *Circle) RotateAround(angle float64, base Vector) Vector

RotateAround rotates the circle around the specified point changing the circle's position.

func (*Circle) RotateAroundRadians 

func (c *Circle) RotateAroundRadians(angle float64, base Vector) Vector

RotateAroundRadians rotates the circle around the base point at the specified angle in radians.

func (*Circle) RotateRadians 

func (c *Circle) RotateRadians(angle float64) float64

RotateRadians does nothing to the circle because there is no sense to rotate it.

This method is added just to match the Shape interface.

func (*Circle) SetAngle 

func (c *Circle) SetAngle(angle float64) float64

SetAngle does nothing to the circle because there is no sense to rotate it.

This method is added just to match the Shape interface.

func (*Circle) SetAngleRadians 

func (c *Circle) SetAngleRadians(angle float64) float64

SetAngleRadians does nothing to the circle because there is no sense to rotate it.

This method is added just to match the Shape interface.

func (*Circle) SetData 

func (data *Circle) SetData(newData interface{})

SetData assigns new data to the shape.

func (*Circle) SetIdentity 

func (t *Circle) SetIdentity(newIdentity int32)

SetIdentity assigns a new value to the tag identity.

func (*Circle) SetMask 

func (t *Circle) SetMask(newMask int32)

SetMask assigns a new value to the tag mask.

func (*Circle) SetPosition 

func (c *Circle) SetPosition(pos Vector) Vector

SetPosition sets the circle position to the given coordinates.

func (Circle) ShouldCollide 

func (t Circle) ShouldCollide(other Shape) (bool, error)

ShouldCollide returns true if the shape should collide another one accodring to their tags.

func (*Circle) TypeName 

func (c *Circle) TypeName() string

TypeName returns the name of the shape type.

type Line 

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

Line represents a geometric euclidian line segment from p to q.

func NewLine 

func NewLine(p Vector, q Vector) (*Line, error)

NewLine returns a new line segment with the given parameters.

func (*Line) Angle 

func (l *Line) Angle() float64

Angle returns the rotation angle of the line (un degrees).

func (*Line) AngleRadians 

func (l *Line) AngleRadians() float64

AngleRadians returns the rotation angle of the line (un radians).

func (*Line) Center 

func (l *Line) Center() Vector

Center returns the coordinates of the middle point between p and q.

func (*Line) CollinearTo 

func (l *Line) CollinearTo(other *Line) (bool, error)

CollinearTo returns true if the lines are collinear, and false otherwise.

func (*Line) ContainsPoint 

func (l *Line) ContainsPoint(point Vector) bool

ContainsPoint detects if the point lies on the line.

func (*Line) Data 

func (data *Line) Data() interface{}

Data returns whatever is saved in the data field of the shape.

func (*Line) GetBoundingBox 

func (l *Line) GetBoundingBox() (Vector, Vector)

GetBoundingBox returns the bounding box for the line.

func (Line) GetIdentity 

func (t Line) GetIdentity() int32

GetIdentity returns the valye of the shape identity.

func (Line) GetMask 

func (t Line) GetMask() int32

GetMask the value of the shape mask.

func (*Line) Length 

func (l *Line) Length() float64

Length returns the length of the line.

func (*Line) Move 

func (l *Line) Move(direction Vector) Vector

Move moves the line in the specified direction and returns its new position.

func (*Line) NormalTo 

func (line *Line) NormalTo(shape Shape) (Vector, error)

NormalTo returns the normal from the given line to the other shape.

func (*Line) NormalToCircle 

func (line *Line) NormalToCircle(circle *Circle) (Vector, error)

NormalToCircle returns the normal from the given line to the circle.

func (*Line) NormalToLine 

func (line *Line) NormalToLine(other *Line) (Vector, error)

NormalToLine returns the normal from the given line to the other line.

func (*Line) NormalToRectangle 

func (line *Line) NormalToRectangle(rect *Rectangle) (Vector, error)

NormalToRectangle returns the normal from the given line to the rectangle.

func (*Line) Orientation 

func (l *Line) Orientation(point Vector) int

Orientation returns 0 if the point is collinear to the line, 1 if orientation is clockwise, -1 if orientation is counter-clockwise.

func (*Line) P 

func (l *Line) P() Vector

P returns the starting point of the line.

func (*Line) ParallelTo 

func (l *Line) ParallelTo(other *Line) (bool, error)

ParallelTo checks if two line segments are collinear but don't lie on the same line.

func (*Line) ProjectPoint 

func (l *Line) ProjectPoint(point Vector) Vector

ProjectPoint returns the projection of the point onto the line.

func (*Line) Q 

func (l *Line) Q() Vector

Q returns the ending point of the line.

func (*Line) Rotate 

func (l *Line) Rotate(angle float64) float64

Rotate rotates the line at the specified angle (in degrees).

Returns the rotation angle of the line (in degrees).

func (*Line) RotateAround 

func (l *Line) RotateAround(angle float64, base Vector) Vector

RotateAround rotates the line around the base point.

func (*Line) RotateAroundRadians 

func (l *Line) RotateAroundRadians(angle float64, base Vector) Vector

RotateAroundRadians rotates the line around the base point at the angle in radians.

func (*Line) RotateRadians 

func (l *Line) RotateRadians(angle float64) float64

RotateRadians rotates the line at the specified angle (in radians).

Returns the rotation angle of the line (in radians).

func (*Line) SameLineWith 

func (l *Line) SameLineWith(other *Line) (bool, error)

SameLineWith returns true if two line segments lie on the same line.

func (*Line) SetAngle 

func (l *Line) SetAngle(angle float64) float64

SetAngle sets the rotation angle of the line to the specified value (in degrees).

func (*Line) SetAngleRadians 

func (l *Line) SetAngleRadians(angle float64) float64

SetAngleRadians sets the rotation angle of the line to the specified value (in radians).

func (*Line) SetData 

func (data *Line) SetData(newData interface{})

SetData assigns new data to the shape.

func (*Line) SetIdentity 

func (t *Line) SetIdentity(newIdentity int32)

SetIdentity assigns a new value to the tag identity.

func (*Line) SetMask 

func (t *Line) SetMask(newMask int32)

SetMask assigns a new value to the tag mask.

func (*Line) SetPosition 

func (l *Line) SetPosition(pos Vector) Vector

SetPosition sets the position of the line to the given coordinates.

func (Line) ShouldCollide 

func (t Line) ShouldCollide(other Shape) (bool, error)

ShouldCollide returns true if the shape should collide another one accodring to their tags.

func (*Line) SquaredLength 

func (l *Line) SquaredLength() float64

SquaredLength returns the length of the line in the power of 2.

func (*Line) TypeName 

func (l *Line) TypeName() string

TypeName returns the name of the shape type.

type Rectangle 

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

Rectangle represents an oriented euclidian rectangle.

func NewRectangle 

func NewRectangle(position Vector, width, height, angle float64) (*Rectangle, error)

NewRectangle returns a new rectangle with specified parameters.

func (*Rectangle) Angle 

func (r *Rectangle) Angle() float64

Angle returns the angle of the rectangle (in degrees).

func (*Rectangle) AngleRadians 

func (r *Rectangle) AngleRadians() float64

AngleRadians returns the angle of the rectangle (in radians).

func (*Rectangle) Center 

func (r *Rectangle) Center() Vector

Center returns the coordinates of the center of the rectangle.

func (*Rectangle) ContainsPoint 

func (r *Rectangle) ContainsPoint(point Vector) bool

ContainsPoint detects if the given point is inside the rectangle.

func (*Rectangle) Data 

func (data *Rectangle) Data() interface{}

Data returns whatever is saved in the data field of the shape.

func (Rectangle) GetIdentity 

func (t Rectangle) GetIdentity() int32

GetIdentity returns the valye of the shape identity.

func (Rectangle) GetMask 

func (t Rectangle) GetMask() int32

GetMask the value of the shape mask.

func (*Rectangle) Height 

func (r *Rectangle) Height() float64

Height returns the height of the rectangle.

func (*Rectangle) Max 

func (r *Rectangle) Max() Vector

Max returns the upper right point of the rectangle with no rotation.

func (*Rectangle) Min 

func (r *Rectangle) Min() Vector

Min returns the lower left point of the rectangle with no rotation.

func (*Rectangle) Move 

func (r *Rectangle) Move(direction Vector) Vector

Move moves the rectangle in the specified direction; returns its new position.

func (*Rectangle) NormalTo 

func (rect *Rectangle) NormalTo(shape Shape) (Vector, error)

NormalTo returns the normal from the given rectangle to the other shape.

func (*Rectangle) NormalToCircle 

func (rect *Rectangle) NormalToCircle(circle *Circle) (Vector, error)

NormalToCircle returns the normal from the given rectangle to the circle.

func (*Rectangle) NormalToLine 

func (rect *Rectangle) NormalToLine(line *Line) (Vector, error)

NormalToLine returns the normal between the given rectangle and the line.

func (*Rectangle) NormalToRectangle 

func (rect *Rectangle) NormalToRectangle(other *Rectangle) (Vector, error)

NormalToRectangle returns the normal from the given rectangle to the other rectangle.

func (*Rectangle) Rotate 

func (r *Rectangle) Rotate(angle float64) float64

Rotate rotates the whole rectangle at the specified angle (in degrees).

Returns the new angle of the rectangle (in degrees).

func (*Rectangle) RotateAround 

func (r *Rectangle) RotateAround(angle float64, base Vector) Vector

RotateAround rotates the rectangle around the specified base point.

func (*Rectangle) RotateAroundRadians 

func (r *Rectangle) RotateAroundRadians(angle float64, base Vector) Vector

RotateAroundRadians rotates the rectangle around the specified base point at the angle in radians.

func (*Rectangle) RotateRadians 

func (r *Rectangle) RotateRadians(angle float64) float64

RotateRadians rotates the whole rectangle at the specified angle (in radians).

Returns the new angle of the rectangle (in radians).

func (*Rectangle) SetAngle 

func (r *Rectangle) SetAngle(angle float64) float64

SetAngle sets the angle of the rectangle to the given value (in degrees).

func (*Rectangle) SetAngleRadians 

func (r *Rectangle) SetAngleRadians(angle float64) float64

SetAngleRadians sets the angle of the rectangle to the given value (in radians).

func (*Rectangle) SetData 

func (data *Rectangle) SetData(newData interface{})

SetData assigns new data to the shape.

func (*Rectangle) SetIdentity 

func (t *Rectangle) SetIdentity(newIdentity int32)

SetIdentity assigns a new value to the tag identity.

func (*Rectangle) SetMask 

func (t *Rectangle) SetMask(newMask int32)

SetMask assigns a new value to the tag mask.

func (*Rectangle) SetPosition 

func (r *Rectangle) SetPosition(pos Vector) Vector

SetPosition sets the position of the rectangle to the given coordinates.

func (Rectangle) ShouldCollide 

func (t Rectangle) ShouldCollide(other Shape) (bool, error)

ShouldCollide returns true if the shape should collide another one accodring to their tags.

func (*Rectangle) TypeName 

func (r *Rectangle) TypeName() string

TypeName returns the name of the shape type.

func (*Rectangle) Vertices 

func (r *Rectangle) Vertices() [4]Vector

Vertices returns the array of the rectangle vertices.

func (*Rectangle) Width 

func (r *Rectangle) Width() float64

Width returns the width of the rectangle.

type Shape 

type Shape interface {
	// Common methods.
	TypeName() string
	Center() Vector
	Angle() float64
	AngleRadians() float64
	Move(Vector) Vector
	Rotate(float64) float64
	RotateRadians(float64) float64
	RotateAround(float64, Vector) Vector
	RotateAroundRadians(float64, Vector) Vector
	SetPosition(Vector) Vector
	SetAngle(float64) float64
	SetAngleRadians(float64) float64
	ContainsPoint(Vector) bool
	NormalTo(Shape) (Vector, error)

	// Tag-related methods.
	GetIdentity() int32
	SetIdentity(int32)
	GetMask() int32
	SetMask(int32)
	ShouldCollide(Shape) (bool, error)

	// Data-related methods.
	Data() interface{}
	SetData(data interface{})
	// contains filtered or unexported methods
}

Shape represents a shape in the space.

type Shapes 

type Shapes map[Shape]none

Shapes represents a list of shapes.

func (Shapes) Contains 

func (shapes Shapes) Contains(shape Shape) (bool, error)

Contains checks if the list of shapes contains the given shape.

func (Shapes) Copy 

func (shapes Shapes) Copy() Shapes

Copy returns a new hash set with same shapes.

func (Shapes) FilterByCollision 

func (shapes Shapes) FilterByCollision(shape Shape) (Shapes, error)

FilterByCollision returns all the shapes that should collide or get collided by the given shape.

func (Shapes) FilterByCollisionLeft 

func (shapes Shapes) FilterByCollisionLeft(shape Shape) (Shapes, error)

FilterByCollisionLeft returns all the shapes that should collide the given shape.

func (Shapes) FilterByCollisionRight 

func (shapes Shapes) FilterByCollisionRight(shape Shape) (Shapes, error)

FilterByCollisionRight returns all the shapes the given shape should collide.

func (Shapes) FilterByIdentity 

func (shapes Shapes) FilterByIdentity(identity int32) Shapes

FilterByIdentity returns all the shapes matching the specified identity template.

func (Shapes) FilterByMask 

func (shapes Shapes) FilterByMask(mask int32) Shapes

FilterByMask returns all the shapes matching the specified mask template.

func (Shapes) Insert 

func (shapes Shapes) Insert(shapesToInsert ...Shape) error

Insert adds the given shape in the set of shapes.

func (Shapes) Items 

func (shapes Shapes) Items() []Shape

Items returns the list all the shapes from the set.

func (Shapes) Merge 

func (shapes Shapes) Merge(otherShapes Shapes) error

Merge adds all the shapes from the other set to the current set.

func (Shapes) Remove 

func (shapes Shapes) Remove(shape Shape) error

Remove removes the specified shape from the set.

type Space 

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

Space represents a geometric space with shapes within it.

func NewSpace 

func NewSpace(
	subdivisionFactor, shapesInArea int, width,
	height float64, min, max Vector, useTags bool,
) (
	*Space, error,
)

NewSpace creates a new empty space with the given parameters.

func (*Space) Add 

func (space *Space) Add(shapes ...Shape) error

Add adds a new shape in the space.

func (*Space) AdjustShapePosition 

func (space *Space) AdjustShapePosition(shape Shape) error

AdjustShapePosition changes the position of the shape if it's out of bounds.

func (*Space) Boxcast 

func (space *Space) Boxcast(rect *Rectangle) (Shapes, error)

Boxcast casts a box in the space and returns all the shapes overlapped by this box.

func (*Space) Cells 

func (space *Space) Cells() map[*Rectangle]Shapes

Cells returns all the cells the space is subdivided to.

func (*Space) Circlecast 

func (space *Space) Circlecast(circle *Circle) (Shapes, error)

Circlecast casts a circle in the space and returns all the shapes overlapped by the circle.

func (*Space) Clear 

func (space *Space) Clear() error

Clear removes all shapes from the space.

func (*Space) CollidedBy 

func (space *Space) CollidedBy(shape Shape) (Shapes, error)

CollidedBy returns the set of shapes collided by the given shape.

func (*Space) CollidingShapes 

func (space *Space) CollidingShapes() (map[Shape]Shapes, error)

CollidingShapes returns the dictionary where key is a shape and value is the set of shapes colliding with the key shape.

func (*Space) CollidingWith 

func (space *Space) CollidingWith(shape Shape) (Shapes, error)

CollidingWith returns the set of shapes colliding with the given shape.

func (*Space) Contains 

func (space *Space) Contains(shape Shape) (bool, error)

Contains returns true if the shape is within the space, and false otherwise.

func (*Space) InBounds 

func (space *Space) InBounds(shape Shape) (bool, error)

InBounds detects if the center the given shape is within the space bounds.

func (*Space) Max 

func (space *Space) Max() Vector

Max returns the max point of the space.

func (*Space) Min 

func (space *Space) Min() Vector

Min returns the min point of the space.

func (*Space) Raycast 

func (space *Space) Raycast(origin, direction Vector, distance float64, mask int32) (Shape, Vector, error)

Raycast casts a ray in the space and returns the hit shape closest to the origin of the ray.

Ray cannot hit against the shape within which it's located.

func (*Space) Rebuild 

func (space *Space) Rebuild() error

Rebuild rebuilds the space's index of fhapes in purpose to optimize it.

func (*Space) Remove 

func (space *Space) Remove(shapes ...Shape) error

Remove removes the shape from the space.

func (*Space) Shapes 

func (space *Space) Shapes() Shapes

Shapes returns the list of all shapes within the space.

func (*Space) Update 

func (space *Space) Update(shape Shape) (map[Vector]Shapes, error)

Update should be called on the shape whenever it's moved within the space.

func (*Space) UseTags 

func (space *Space) UseTags() bool

UseTags indicates whether the space relies on tags for collision detection.

func (*Space) WouldBeCollidedBy 

func (space *Space) WouldBeCollidedBy(shape Shape, moveDiff Vector, turnDiff float64) (Shapes, error)

WouldBeCollidedBy returns all the shapes that would be collided by the given shape if it moved in the specified direction.

func (*Space) WouldBeCollidingWith 

func (space *Space) WouldBeCollidingWith(shape Shape, moveDiff Vector, turnDiff float64) (Shapes, error)

WouldBeCollidingWith returns all the shapes that would be colliding the given one if it moved in the specified direction.

type Vector 

type Vector struct {
	X float64
	Y float64
}

Vector represents a 2-dimensional vector.

func Contact 

func Contact(one, other Shape) ([]Vector, error)

Contact returns the contact points between two given shapes (if they exist).

func ContactCircleToCircle 

func ContactCircleToCircle(one, other *Circle) ([]Vector, error)

ContactCircleToCircle returns the contact point between two circles (if it exists).

func ContactLineToCircle 

func ContactLineToCircle(line *Line, circle *Circle) ([]Vector, error)

ContactLineToCircle returns the contact points between the line and the circle (if they exist).

func ContactLineToLine 

func ContactLineToLine(one, other *Line) ([]Vector, error)

ContactLineToLine returns the contact point between two lines (if it exists).

func ContactLineToRectangle 

func ContactLineToRectangle(line *Line, rect *Rectangle) ([]Vector, error)

ContactLineToRectangle returns the contacts between the line and the rectangle (if they exist).

func ContactRectangleToCircle 

func ContactRectangleToCircle(rect *Rectangle, circle *Circle) ([]Vector, error)

ContactRectangleToCircle returns the contacts between the rectangle and the circle (if they exist).

func ContactRectangleToRectangle 

func ContactRectangleToRectangle(one, other *Rectangle) ([]Vector, error)

ContactRectangleToRectangle returns the contacts between two rectangles (if they exist).

func Down 

func Down() Vector

Down is the vector {0; -1}.

func Left 

func Left() Vector

Left is the vector {-1; 0}.

func NewVector 

func NewVector(x, y float64) Vector

NewVector returns a new vector with the given coordinates. 

func Right() Vector

Right is the vector {1; 0}.

func Up 

func Up() Vector

Up is the vector {0; 1}.

func Zero 

func Zero() Vector

Zero is the vector {0; 0}.

func (Vector) Add 

func (v Vector) Add(other Vector) Vector

Add returns the sum of two vectors.

func (Vector) ApproximatelyEqual 

func (v Vector) ApproximatelyEqual(other Vector) bool

ApproximatelyEqual returns true if the vector is approximately equal to the other one, and false otherwise.

func (Vector) CollinearTo 

func (v Vector) CollinearTo(other Vector) (bool, error)

CollinearTo indicates if the given vector is collinear to the other vector.

func (Vector) Magnitude 

func (v Vector) Magnitude() float64

Magnitude returns the length of the vector.

func (Vector) MultiplyBy 

func (v Vector) MultiplyBy(other Vector) Vector

MultiplyBy multiplies components of the first vector by the components of the other vector.

func (Vector) MultiplyByScalar 

func (v Vector) MultiplyByScalar(scalar float64) Vector

MultiplyByScalar returns the vector multiplied by the specified scalar.

func (Vector) Normalize 

func (v Vector) Normalize() (Vector, error)

Normalize returns a normalized vector with magnitude of 1.

func (Vector) PerpendicularClockwise 

func (v Vector) PerpendicularClockwise() Vector

PerpendicularClockwise returns a new vector perpendicular to the given one and turned in a clockwise direction relatively to it.

func (Vector) PerpendicularCounterClockwise 

func (v Vector) PerpendicularCounterClockwise() Vector

PerpendicularCounterClockwise returns a new vector perpendicular to the given one and turned in a clockwise direction relatively to it.

func (Vector) Project 

func (v Vector) Project(axis Vector) Vector

Project returns vector v projected onto the axis.

func (Vector) Rotate 

func (v Vector) Rotate(angle float64) Vector

Rotate returns the vector rotated at an angle of n degrees.

func (Vector) RotateAround 

func (v Vector) RotateAround(angle float64, base Vector) Vector

RotateAround returns the vector rotated at an angle of n degrees around the base vector.

func (Vector) RotateAroundRadians 

func (v Vector) RotateAroundRadians(angle float64, base Vector) Vector

RotateAroundRadians returns the vector totated at an angle of n radians around the base vector.

func (Vector) RotateRadians 

func (v Vector) RotateRadians(angle float64) Vector

RotateRadians returns the vector totated at an angle of n radians.

func (Vector) SquaredMagnitude 

func (v Vector) SquaredMagnitude() float64

SquaredMagnitude returns the vectors's magnitude in the power of 2.

func (Vector) Subtract 

func (v Vector) Subtract(other Vector) Vector

Subtract returns the difference of two vectors.

Source Files

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Directories

Path Synopsis
examples
benchmark
black_box
brownian_motion
contacts
platformer
raycast
rotate_around
shapes
sliding
tagged_particles

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