ebiten/run.go

159 lines
4.0 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 (
"time"
"github.com/hajimehoshi/ebiten/internal/audio"
"github.com/hajimehoshi/ebiten/internal/ui"
)
var runContext = &struct {
running bool
fps float64
newScreenWidth int
newScreenHeight int
newScreenScale int
}{}
// CurrentFPS returns the current number of frames per second.
func CurrentFPS() float64 {
return runContext.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 guaranteed to be called 60 times a second
// even if a rendering frame is skipped.
// f is not called when the screen is not shown.
func Run(f func(*Image) error, width, height, scale int, title string) error {
runContext.running = true
defer func() {
runContext.running = false
}()
actualScale, err := ui.Start(width, height, scale, title)
if err != nil {
return err
}
defer ui.Terminate()
ui.ExecOnUIThread(func() {
glContext.Check()
})
graphicsContext, err := newGraphicsContext(width, height, actualScale)
if err != nil {
return err
}
frames := 0
gameTime := ui.Now()
before := ui.Now()
for {
if 0 < runContext.newScreenWidth || 0 < runContext.newScreenHeight || 0 < runContext.newScreenScale {
changed := false
actualScale := 0
if 0 < runContext.newScreenWidth || 0 < runContext.newScreenHeight {
c, a := ui.SetScreenSize(runContext.newScreenWidth, runContext.newScreenHeight)
changed = changed || c
actualScale = a
}
if 0 < runContext.newScreenScale {
c, a := ui.SetScreenScale(runContext.newScreenScale)
changed = changed || c
// actualScale of SetScreenState is more reliable than one of SetScreenSize
actualScale = a
}
if changed {
w, h := runContext.newScreenWidth, runContext.newScreenHeight
if err := graphicsContext.setSize(w, h, actualScale); err != nil {
return err
}
}
}
runContext.newScreenWidth = 0
runContext.newScreenHeight = 0
runContext.newScreenScale = 0
audio.Tick()
if err := ui.DoEvents(); err != nil {
return err
}
if ui.IsClosed() {
return nil
}
now := ui.Now()
// If gameTime is too old, we assume that screen is not shown.
if int64(5*time.Second/60) < now-gameTime {
gameTime = now
}
for gameTime < now {
gameTime += int64(time.Second / 60)
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
}
ui.SwapBuffers()
// Calc the current FPS.
now = ui.Now()
frames++
if time.Second <= time.Duration(now-before) {
runContext.fps = float64(frames) * float64(time.Second) / float64(now-before)
before = now
frames = 0
}
}
}
// SetScreenSize changes the (logical) size of the screen.
// This doesn't affect the current scale of the screen.
func SetScreenSize(width, height int) {
if !runContext.running {
panic("SetScreenSize must be called during Run")
}
if width <= 0 || height <= 0 {
panic("width and height must be positive")
}
runContext.newScreenWidth = width
runContext.newScreenHeight = height
}
// SetScreenSize changes the scale of the screen.
func SetScreenScale(scale int) {
if !runContext.running {
panic("SetScreenScale must be called during Run")
}
if scale <= 0 {
panic("scale must be positive")
}
runContext.newScreenScale = scale
}