dango

package module
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 Go to latest Published: Aug 1, 2025 License: MIT Imports: 21 Imported by: 0

README

Dango

Dango is a collection of functions that can be used with Ebitengine

data.go - FS

embedded file system

Commonly used function to load files from embedded file system Example:

import "github.com/iatearock/dango"
//go:embed assets/*
var data embed.FS
vfs = dango.NewFS(data)

// example usage
img, err := vfs.GetImage("assets/images/red.png") // *ebiten.Image
ff, err := vfs.GetFontFace("assets/font/red.ttf") // font.Face
str, err := vfs.GetCSV("assets/csv/red.csv") // [][]string
byte, err := vfs.ReadFile("assets/csv/red.txt") // []byte

camera

Adopted from ebiten camera example: https://github.com/hajimehoshi/ebiten/tree/main/examples/camera

cam := &dango.Camera{}  // setup camera 
cam.SetViewPort(w, h)
cam.Update() // update when position/rotation/zoom/viewport change

spriteOp := &ebiten.DrawImageOptions{}  // init options, and then apply sprite's transformation to spriteOp
spriteOP.GeoM.Concat(cam.GeoM()) // multiply sprite's matrix to camera matrix
screen.Draw(sprite, spriteOp)

screenX, screenY := cam.WorldToScreen(worldX, worldY) // transform coordinates

scene

Scene manager adopted from ebiten Block example Handle transition between scenes that implement Update() and Draw(*ebiten.Image)

id

Simple unique id generator, concurrency safe, I think.

bitmasks

bits.go provide bitmask functions with mutex lock Example:

const {
	s1 = 1 << iota
	s2
	s3
    s4
}

b = NewBits()
b.Set(s2|s3)
b.Has(s1|s2)  // true, matched any bit
b.HasAll(s1|s2) // false, need to match all bits

Neon light

Add neon light effect to an image

Neon adds color c within light pixels away from any pixels with 255 for alpha channel. Gaussian blur is applied with sqaure of width blur, and sigma as Gaussian standard deviation If origin, original image is draw on top of new image If resize, new image will be larger due to Gaussian effect on the edge

img := LoadPNG("input.png") // import a png file to *image.RGBA

d := 2 // add colour up to 2 pixels aways, from existing pixel with 255 in alpha channel
k := 3 // 3x3 kernal size for Gaussian blurring
s := 1 // standard deviation for Gaussian kernal
yellow := color.RGBA{255,255,0,255}
origin := true // draw original image on top of the result
resize := false // remove edge pixel produced by the Gaussin kernal, i.e. false to return same image size as the input

dango.Neon(img, d, k, s, yellow, origin, resize)

Input image:input Result image:result with neon light effect

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func AddWidth 

func AddWidth(img *image.RGBA, dist int, c color.RGBA) *image.RGBA

AddWidth light effect to any pixel with 255 in alpha channle within `dist` from the pixels

func Blur 

func Blur(img *image.RGBA, size int, kernal []float64) *image.RGBA

Return a new image applying Gaussian Blur Note, for my purpose, the reutrn image size is larger by the size of the kernal, to capture the entire bluring effect

func Clamp 

func Clamp(f, min, max float64) float64

func Clamp01 

func Clamp01(f float64) float64

func ConsolePrompt 

func ConsolePrompt(text string) string

ConsolePrompt takes a text prompt, wait for and return user input

func Convolution 

func Convolution(img *image.RGBA, x, y, size int) []color.RGBA

Return the RGBA values of kernal with `size` x `size` in a list

func DistanceTolerance 

func DistanceTolerance(a, b f64.Vec2, epsilon float64) bool

DistanceTolerance check if two 2D positions are close enough

func DrawRect 

func DrawRect(w, h, t, edge int, c color.RGBA) *image.RGBA

DrawRect with width, height, thickness, tansparent edge

func EqualFloat 

func EqualFloat(a, b, tolerance float64) bool

func G 

func G(x, y, sigma float64) float64

G calculates kernal value with Gaussian distribution at point x, y

func InvertMatrix 

func InvertMatrix(m []float64) ([]float64, bool)

InvertMatrix computes the inverse of a 4x4 matrix.

func Kernal 

func Kernal(size int, sigma float64) []float64

Create a gaussian kernal, each row is appended to previous row

func Lerp 

func Lerp(f1, f2, t float64) float64

func LerpConst 

func LerpConst(f1, f2, d float64) float64

func LoadPNG 

func LoadPNG(name string) *image.RGBA

Read img from path

func MatrixMultiplication 

func MatrixMultiplication(a, b []float64) []float64

func MatrixVectorMultiplication 

func MatrixVectorMultiplication(a, b []float64) []float64

func Neon 

func Neon(img *image.RGBA, light, blur int, sigma float64,
	c color.RGBA, origin, resize bool) *image.RGBA

Neon add neon light effect of an image, Neon adds color `c` within `light` pixels away from any pixels with 255 for alpha channel. Gaussian blur is applied with sqaure of width `blur`, and `sigma` as Gaussian standard deviation If `origin`, original image is draw on top of new image If `resize`, new image will be larger due to Gaussian effect on the edge

func Paint 

func Paint(img *image.RGBA, x, y, radius int, c color.RGBA)

Paint add colour to pixel radius away from x, y

func PosToUint 

func PosToUint(p uint) uint

Convert bit position to uint, right most bit is bit 1,

func SegmentsIntersect 

func SegmentsIntersect(x1, y1, x2, y2, x3, y3, x4, y4 float64) (float64, float64, error)

SegmentsIntersect find intersection point between line pt1 to pt2 and pt3 and pt4 return error if no intersection

func SimpleAlphaComposite 

func SimpleAlphaComposite(s, b color.RGBA) color.RGBA

Simple Alpha Composite source with background pixel https://www.w3.org/TR/compositing-1/#simplealphacompositing

func Tolerance 

func Tolerance(a, b, epsilon float64) bool

Tolerance check if a and b is close and within epsilon

func WritePNG 

func WritePNG(path string, img image.Image) error

Write img to path

Types

type Bits 

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

func NewBits 

func NewBits() *Bits

func (*Bits) Clear 

func (b *Bits) Clear(n uint)

func (*Bits) Has 

func (b *Bits) Has(n uint) bool

Has matches any bit position

func (*Bits) HasAll 

func (b *Bits) HasAll(n uint) bool

HasAll matches all bit positions

func (*Bits) Set 

func (b *Bits) Set(n uint)

func (*Bits) String 

func (b *Bits) String() string

func (*Bits) Toggle 

func (b *Bits) Toggle(n uint)

func (*Bits) Value 

func (b *Bits) Value() uint

type Camera 

type Camera struct {
	ViewPort   f64.Vec2 // viewport should be the same as the window size/resolution
	Position   f64.Vec2 // points camera to `Position` in the world
	ZoomFactor int
	Rotation   float64
	// contains filtered or unexported fields
}

Camera projects world to Screen

func (*Camera) GeoM 

func (c *Camera) GeoM() ebiten.GeoM

Ebiten GeoM, usage sprite.GeoM.Concat(camera.GeoM)

func (*Camera) GetPosition 

func (c *Camera) GetPosition() (float64, float64)

GetPosition return x, y

func (*Camera) IsPointInViewport 

func (c *Camera) IsPointInViewport(wx, wy float64) bool

IsPointInViewport check is a point in on screen

func (*Camera) Matrix 

func (c *Camera) Matrix() ebiten.GeoM

Matrix return current camera matrix

func (*Camera) Pan 

func (c *Camera) Pan(x, y float64)

func (*Camera) Render 

func (c *Camera) Render(screen, world *ebiten.Image)

Render draw `world` image on screen

func (*Camera) Reset 

func (c *Camera) Reset()

func (*Camera) Rotate 

func (c *Camera) Rotate(a float64)

func (*Camera) Scale 

func (c *Camera) Scale() float64

func (*Camera) ScreenToWorld 

func (c *Camera) ScreenToWorld(posX, posY int) (float64, float64)

func (*Camera) SetPosition 

func (c *Camera) SetPosition(x, y float64)

SetPosition moves camera to location x, y

func (*Camera) SetViewPort 

func (c *Camera) SetViewPort(w, h int)

SetViewPort set the size of the window

func (*Camera) SpriteGeoMConcat 

func (c *Camera) SpriteGeoMConcat(sprite ebiten.GeoM) ebiten.GeoM

DEPRECATED, Concat camera's matrix with m

func (*Camera) String 

func (c *Camera) String() string

func (*Camera) Update 

func (c *Camera) Update()

UpdateMatrix when position/rotation/zoom changes

func (*Camera) WorldToScreen 

func (c *Camera) WorldToScreen(wx, wy float64) (float64, float64)

func (*Camera) WorldToScreen32 

func (c *Camera) WorldToScreen32(wx, wy float64) (float32, float32)

WorldToScreen32 return x, y in float32, ebiten screen drawing use float32

func (*Camera) ZoomIn 

func (c *Camera) ZoomIn(n int)

func (*Camera) ZoomOut 

func (c *Camera) ZoomOut(n int)

type Camera3D 

type Camera3D struct {
	// contains filtered or unexported fields
}

func NewCamera3D 

func NewCamera3D(pos, lookAt Vector3, fov, w, h float64) *Camera3D

func (*Camera3D) FOV 

func (cam *Camera3D) FOV(delta float64)

change fov, need to call Update() the camear manually

func (*Camera3D) LineToScreen 

func (cam *Camera3D) LineToScreen(a Vector3, b Vector3) ([]float32, bool)

give screen coordinates of 2 points {x1 y1 z1 w1 x2 y2 z2 w2}, i.e. point1 [0] v[1], and point2 v[4] v[5] if one point is behind the Camera3D, it will return move that point to where the line intersect with the clip plan if both points are behind, it will return both points as { 0, 0, 0, -1} return boolean indicates if the line is in front of the Camera3D

func (*Camera3D) Move 

func (cam *Camera3D) Move(dir Vector3)

move the Camera3D

func (*Camera3D) Pitch 

func (cam *Camera3D) Pitch(rad float64)

pitch the Camera3D, need to call Update() the Camera3D manually

func (*Camera3D) PosToScreen 

func (cam *Camera3D) PosToScreen(p Vector3) []float32

convert world position to screen coordinate

func (*Camera3D) PrintCombineMatrix 

func (cam *Camera3D) PrintCombineMatrix() string

func (*Camera3D) PrintMatrix 

func (cam *Camera3D) PrintMatrix(m []float64) string

print a 4 x 4 matrix

func (*Camera3D) PrintProjectionMatrix 

func (cam *Camera3D) PrintProjectionMatrix() string

func (*Camera3D) PrintVector 

func (cam *Camera3D) PrintVector(m []float64) string

print a 4 x 1 vector

func (*Camera3D) PrintViewMatrix 

func (cam *Camera3D) PrintViewMatrix() string

func (*Camera3D) PrintViewportMatrix 

func (cam *Camera3D) PrintViewportMatrix() string

func (*Camera3D) Update 

func (cam *Camera3D) Update()

call after changeing Camera3D parameters

func (*Camera3D) UpdateCamera3D 

func (cam *Camera3D) UpdateCamera3D(pos, lookAt Vector3, fov, w, h float64)

func (*Camera3D) WorldToScreen 

func (cam *Camera3D) WorldToScreen(p []float64) []float64

convert world position to screen coordinate

func (*Camera3D) Yaw 

func (cam *Camera3D) Yaw(rad float64)

rotate the Camera3D, need to call Update() the Camera3D manually

type EmbedFS 

type EmbedFS interface {
	fs.ReadDirFS
	fs.ReadFileFS
}

type FS 

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

func NewFS 

func NewFS(filesystem EmbedFS) *FS

func (*FS) GetFontFace 

func (f *FS) GetFontFace(path string, size, dpi float64) (font.Face, error)

func (*FS) GetGoTextFaceSource 

func (f *FS) GetGoTextFaceSource(path string) *text.GoTextFaceSource

func (*FS) GetImage 

func (f *FS) GetImage(path string) (*ebiten.Image, error)

func (*FS) GetRGBA 

func (f *FS) GetRGBA(path string) (*image.RGBA, error)

func (*FS) MustGetFontFace 

func (f *FS) MustGetFontFace(path string, size, dpi float64) font.Face

func (*FS) MustGetImage 

func (f *FS) MustGetImage(path string) *ebiten.Image

func (*FS) MustReadCSV 

func (f *FS) MustReadCSV(path string) [][]string

func (*FS) MustReadFile 

func (f *FS) MustReadFile(path string) []byte

func (*FS) Open 

func (f *FS) Open(path string) (fs.File, error)

func (*FS) ReadCSV 

func (f *FS) ReadCSV(path string) ([][]string, error)

ReadCSV return list of rows, only use for small file

func (*FS) ReadDir 

func (f *FS) ReadDir(path string) ([]fs.DirEntry, error)

func (*FS) ReadFile 

func (f *FS) ReadFile(path string) ([]byte, error)

type ID 

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

func NewIDGenerator 

func NewIDGenerator() *ID

func (*ID) Current 

func (i *ID) Current() int

func (*ID) NewID 

func (i *ID) NewID() int

func (*ID) Reset 

func (i *ID) Reset()

func (*ID) SetCurrent 

func (i *ID) SetCurrent(n int)

Up to the caller to ensure id is still unique

type Scene 

type Scene interface {
	Update() error
	Draw(screen *ebiten.Image)
}

type SceneManager 

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

func NewSceneManager 

func NewSceneManager(w, h, transitionFrames int) *SceneManager

Create new scene manager, where w - screen width, h - screen height, transitionFrames - number of frames to transit between scenes

func (*SceneManager) Draw 

func (s *SceneManager) Draw(r *ebiten.Image)

func (*SceneManager) GoTo 

func (s *SceneManager) GoTo(scene Scene)

func (*SceneManager) Update 

func (s *SceneManager) Update() error

type Vector 

type Vector struct {
	X, Y float64
}

func ForAngle 

func ForAngle(a float64) Vector

ForAngle returns the unit length vector for the given angle (in radians).

func (Vector) Add 

func (v Vector) Add(other Vector) Vector

func (Vector) CheckAxis 

func (v Vector) CheckAxis(v1, p, n Vector) bool

func (Vector) Clamp 

func (v Vector) Clamp(length float64) Vector

func (Vector) Clone 

func (v Vector) Clone() Vector

func (Vector) ClosestDist 

func (v Vector) ClosestDist(v1 Vector) float64

func (Vector) ClosestPointOnSegment 

func (v Vector) ClosestPointOnSegment(a, b Vector) Vector

func (Vector) ClosestT 

func (v Vector) ClosestT(b Vector) float64

func (Vector) Cross 

func (v Vector) Cross(other Vector) float64

Cross calculates the 2D vector cross product analog. The cross product of 2D vectors results in a 3D vector with only a z component. This function returns the magnitude of the z value.

func (Vector) Distance 

func (v Vector) Distance(other Vector) float64

func (Vector) DistanceSq 

func (v Vector) DistanceSq(other Vector) float64

func (Vector) Dot 

func (v Vector) Dot(other Vector) float64

func (Vector) Equal 

func (v Vector) Equal(other Vector) bool

func (Vector) Length 

func (v Vector) Length() float64

func (Vector) LengthSq 

func (v Vector) LengthSq() float64

func (Vector) Lerp 

func (v Vector) Lerp(other Vector, t float64) Vector

func (Vector) LerpConst 

func (v Vector) LerpConst(other Vector, d float64) Vector

func (Vector) LerpT 

func (v Vector) LerpT(b Vector, t float64) Vector

func (Vector) Mult 

func (v Vector) Mult(s float64) Vector

func (Vector) Near 

func (v Vector) Near(other Vector, d float64) bool

func (Vector) Neg 

func (v Vector) Neg() Vector

func (Vector) Normalize 

func (v Vector) Normalize() Vector

func (Vector) Perp 

func (v Vector) Perp() Vector

func (Vector) PointGreater 

func (v Vector) PointGreater(b, c Vector) bool

func (Vector) Project 

func (v Vector) Project(other Vector) Vector

func (Vector) ReversePerp 

func (v Vector) ReversePerp() Vector

func (Vector) Rotate 

func (v Vector) Rotate(other Vector) Vector

func (Vector) SLerp 

func (v Vector) SLerp(other Vector, t float64) Vector

func (Vector) SlerpConst 

func (v Vector) SlerpConst(other Vector, a float64) Vector

func (Vector) String 

func (v Vector) String() string

func (Vector) Sub 

func (v Vector) Sub(other Vector) Vector

func (Vector) ToAngle 

func (v Vector) ToAngle() float64

func (Vector) Unrotate 

func (v Vector) Unrotate(other Vector) Vector

type Vector3 

type Vector3 struct {
	X, Y, Z float64
}

func SliceToVector 

func SliceToVector(a []float64) Vector3

take first 3 element as x, y, z

func (Vector3) Add 

func (a Vector3) Add(b Vector3) Vector3

a add b

func (Vector3) Angle 

func (a Vector3) Angle(b Vector3) float64

Angle returns the angle in radians between two vectors.

func (Vector3) Cross 

func (a Vector3) Cross(b Vector3) Vector3

a cross b

func (Vector3) DistanceSq 

func (a Vector3) DistanceSq(b Vector3) float64

func (Vector3) Dot 

func (a Vector3) Dot(b Vector3) float64

func (Vector3) Length 

func (v Vector3) Length() float64

func (Vector3) LengthSq 

func (v Vector3) LengthSq() float64

func (Vector3) Lerp 

func (a Vector3) Lerp(b Vector3, t float64) Vector3

func (Vector3) Mult 

func (a Vector3) Mult(t float64) Vector3

a * float64

func (Vector3) Negate 

func (v Vector3) Negate() Vector3

func (Vector3) Normalize 

func (v Vector3) Normalize() Vector3

func (Vector3) Slerp 

func (a Vector3) Slerp(b Vector3, t float64) Vector3

Slerp performs Spherical Linear Interpolation between two vectors. It's ideal for smoothly rotating a direction vector. Both vectors should be normalized for the best results.

func (Vector3) Sub 

func (a Vector3) Sub(b Vector3) Vector3

a subtract b

func (Vector3) ToSlice 

func (a Vector3) ToSlice() []float64

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