ebiten/run.go
2016-03-23 00:44:16 +09:00

173 lines
4.9 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/ui"
)
var runContext = &struct {
running bool
fps float64
newScreenWidth int
newScreenHeight int
newScreenScale int
isRunningSlowly bool
}{}
// FPS represents how many times game updating happens in a second.
const FPS = 60
// CurrentFPS returns the current number of frames per second of rendering.
//
// This value represents how many times rendering happens in 1/60 second and
// NOT how many times logical game updating (a passed function to Run) happens.
// Note that logical game updating is assured to happen 60 times in a second
// as long as the screen is active.
func CurrentFPS() float64 {
return runContext.fps
}
// IsRunningSlowly returns true if the game is running too slowly to keep 60 FPS of rendering.
// The game screen is not updated when IsRunningSlowly is true.
// It is recommended to skip heavy processing, especially drawing, when IsRunningSlowly is true.
func IsRunningSlowly() bool {
return runContext.isRunningSlowly
}
// 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
}()
if err := ui.Start(width, height, scale, title); err != nil {
return err
}
defer ui.Terminate()
glContext.Check()
graphicsContext, err := newGraphicsContext(width, height, ui.ActualScale())
if err != nil {
return err
}
frames := 0
now := ui.Now()
beforeForUpdate := now
beforeForFPS := now
for {
// TODO: setSize should be called after swapping buffers?
if 0 < runContext.newScreenWidth || 0 < runContext.newScreenHeight || 0 < runContext.newScreenScale {
changed := false
if 0 < runContext.newScreenWidth || 0 < runContext.newScreenHeight {
c := ui.SetScreenSize(runContext.newScreenWidth, runContext.newScreenHeight)
changed = changed || c
}
if 0 < runContext.newScreenScale {
c := ui.SetScreenScale(runContext.newScreenScale)
changed = changed || c
}
if changed {
w, h := runContext.newScreenWidth, runContext.newScreenHeight
if err := graphicsContext.setSize(w, h, ui.ActualScale()); err != nil {
return err
}
}
}
runContext.newScreenWidth = 0
runContext.newScreenHeight = 0
runContext.newScreenScale = 0
if err := ui.DoEvents(); err != nil {
return err
}
if ui.IsClosed() {
return nil
}
now := ui.Now()
// If beforeForUpdate is too old, we assume that screen is not shown.
runContext.isRunningSlowly = false
if int64(5*time.Second/FPS) < now-beforeForUpdate {
beforeForUpdate = now
} else {
c := float64(now-beforeForUpdate) * FPS / float64(time.Second)
runContext.isRunningSlowly = c >= 2.5
for i := 0; i < int(c); i++ {
if err := ui.DoEvents(); err != nil {
return err
}
if ui.IsClosed() {
return nil
}
if err := graphicsContext.update(f); err != nil {
return err
}
}
beforeForUpdate += int64(c) * int64(time.Second/FPS)
ui.SwapBuffers()
}
// Calc the current FPS.
now = ui.Now()
frames++
if time.Second <= time.Duration(now-beforeForFPS) {
runContext.fps = float64(frames) * float64(time.Second) / float64(now-beforeForFPS)
beforeForFPS = 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
}
// ScreenScale returns the current screen scale.
func ScreenScale() int {
return ui.ScreenScale()
}