87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package canvas
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import (
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"syscall/js"
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"time"
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"git.kirsle.net/go/render/event"
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)
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// Engine implements a rendering engine targeting an HTML canvas for
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// WebAssembly targets.
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type Engine struct {
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canvas Canvas
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startTime time.Time
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width int
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height int
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ticks uint32
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// Private fields.
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events *event.State
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running bool
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textures map[string]*Texture // cached texture PNG images
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// Event channel. WASM subscribes to events asynchronously using the
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// JavaScript APIs, whereas SDL2 polls the event queue which orders them
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// all up for processing. This channel will order and queue the events.
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queue chan Event
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}
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// New creates the Canvas Engine.
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func New(canvasID string) (*Engine, error) {
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canvas := GetCanvas(canvasID)
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engine := &Engine{
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canvas: canvas,
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startTime: time.Now(),
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events: event.NewState(),
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width: canvas.ClientW(),
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height: canvas.ClientH(),
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queue: make(chan Event, 1024),
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textures: map[string]*Texture{},
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}
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return engine, nil
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}
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// WindowSize returns the size of the canvas window.
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func (e *Engine) WindowSize() (w, h int) {
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// Good time to recompute it first?
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var (
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window = js.Global().Get("window")
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width = window.Get("innerWidth").Int()
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height = window.Get("innerHeight").Int()
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)
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e.canvas.Value.Set("width", width)
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e.canvas.Value.Set("height", height)
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return e.canvas.ClientW(), e.canvas.ClientH()
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}
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// GetTicks returns the number of milliseconds since the engine started.
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func (e *Engine) GetTicks() uint32 {
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ms := time.Since(e.startTime) * time.Millisecond
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return uint32(ms)
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}
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// TO BE IMPLEMENTED...
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func (e *Engine) Setup() error {
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return nil
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}
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func (e *Engine) Present() error {
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return nil
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}
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// Delay for a moment.
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func (e *Engine) Delay(delay uint32) {
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time.Sleep(time.Duration(delay) * time.Millisecond)
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}
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// Teardown tasks.
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func (e *Engine) Teardown() {}
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func (e *Engine) Loop() error {
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return nil
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}
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