package sprite

import "golang.org/x/mobile/exp/sprite"

Package sprite provides a 2D scene graph for rendering and animation.

A tree of nodes is drawn by a rendering Engine, provided by another package. The OS-independent Go version based on the image package is:

golang.org/x/mobile/exp/sprite/portable

An Engine draws a screen starting at a root Node. The tree is walked depth-first, with affine transformations applied at each level.

Nodes are rendered relative to their parent.

Typical main loop:

for each frame {
	quantize time.Now() to a clock.Time
	process UI events
	modify the scene's nodes and animations (Arranger values)
	e.Render(scene, t, sz)
}

Index ¶

Package Files ¶

sprite.go

type Arranger ¶

type Arranger interface {
    Arrange(e Engine, n *Node, t clock.Time)
}

type Engine ¶

type Engine interface {
    Register(n *Node)
    Unregister(n *Node)

    LoadTexture(a image.Image) (Texture, error)

    SetSubTex(n *Node, x SubTex)
    SetTransform(n *Node, m f32.Affine) // sets transform relative to parent.

    // Render renders the scene arranged at the given time, for the given
    // window configuration (dimensions and resolution).
    Render(scene *Node, t clock.Time, sz size.Event)

    Release()
}

type Node ¶

type Node struct {
    Parent, FirstChild, LastChild, PrevSibling, NextSibling *Node

    Arranger Arranger

    // EngineFields contains fields that should only be accessed by Engine
    // implementations. It is exported because such implementations can be
    // in other packages.
    EngineFields struct {
        // TODO: separate TexDirty and TransformDirty bits?
        Dirty  bool
        Index  int32
        SubTex SubTex
    }
}

A Node is a renderable element and forms a tree of Nodes.

func (*Node) AppendChild ¶

func (n *Node) AppendChild(c *Node)

AppendChild adds a node c as a child of n.

It will panic if c already has a parent or siblings.

func (*Node) RemoveChild ¶

func (n *Node) RemoveChild(c *Node)

RemoveChild removes a node c that is a child of n. Afterwards, c will have no parent and no siblings.

It will panic if c's parent is not n.

type SubTex ¶

type SubTex struct {
    T   Texture
    R   image.Rectangle
}

type Texture ¶

type Texture interface {
    Bounds() (w, h int)
    Download(r image.Rectangle, dst draw.Image)
    Upload(r image.Rectangle, src image.Image)
    Release()
}

Directories ¶