ebiten/run.go

90 lines
2.3 KiB
Go

// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ebiten
import (
"github.com/hajimehoshi/ebiten/internal/audio"
"github.com/hajimehoshi/ebiten/internal/graphics/internal/opengl"
"github.com/hajimehoshi/ebiten/internal/ui"
"time"
)
var fps = 0.0
// CurrentFPS returns the current number of frames per second.
func CurrentFPS() float64 {
return fps
}
// Run runs the game.
// f is a function which is called at every frame.
// The argument (*Image) is the render target that represents the screen.
//
// This function must be called from the main thread.
//
// The given function f is expected to be called 60 times a second,
// but this is not strictly guaranteed.
// If you need to care about time, you need to check current time every time f is called.
func Run(f func(*Image) error, width, height, scale int, title string) error {
actualScale, err := ui.Start(width, height, scale, title)
if err != nil {
return err
}
defer ui.Terminate()
var graphicsContext *graphicsContext
ui.Use(func(c *opengl.Context) {
graphicsContext, err = newGraphicsContext(c, width, height, actualScale)
})
if err != nil {
return err
}
frames := 0
t := time.Now().UnixNano()
for {
if err := ui.DoEvents(); err != nil {
return err
}
if ui.IsClosed() {
return nil
}
if err := graphicsContext.preUpdate(); err != nil {
return err
}
if err := f(graphicsContext.screen); err != nil {
return err
}
if err := graphicsContext.postUpdate(); err != nil {
return err
}
// TODO: I'm not sure this is 'Update'. Is 'Tick' better?
audio.Update()
ui.SwapBuffers()
if err != nil {
return err
}
// Calc the current FPS.
now := time.Now().UnixNano()
frames++
if time.Second <= time.Duration(now-t) {
fps = float64(frames) * float64(time.Second) / float64(now-t)
t = now
frames = 0
}
}
}