mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-28 12:48:54 +01:00
106 lines
2.1 KiB
Go
106 lines
2.1 KiB
Go
// Copyright 2016 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package loop
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import (
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"errors"
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"time"
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"github.com/hajimehoshi/ebiten/internal/clock"
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"github.com/hajimehoshi/ebiten/internal/sync"
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)
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const FPS = clock.FPS
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func CurrentFPS() float64 {
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if theRunContext == nil {
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return 0
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}
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return theRunContext.getCurrentFPS()
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}
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type runContext struct {
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currentFPS float64
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framesForFPS int64
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lastFPSUpdated int64
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m sync.RWMutex
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}
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var (
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theRunContext *runContext
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contextInitCh = make(chan struct{})
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)
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func (c *runContext) getCurrentFPS() float64 {
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c.m.RLock()
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v := c.currentFPS
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c.m.RUnlock()
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return v
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}
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func (c *runContext) updateFPS(fps float64) {
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c.m.Lock()
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c.currentFPS = fps
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c.m.Unlock()
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}
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func Start() error {
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// TODO: Need lock here?
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if theRunContext != nil {
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return errors.New("loop: The game is already running")
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}
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theRunContext = &runContext{}
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n := now()
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theRunContext.lastFPSUpdated = n
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close(contextInitCh)
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return nil
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}
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func End() {
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theRunContext = nil
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}
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type Updater interface {
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Update(updateCount int) error
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}
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func Update(u Updater) error {
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<-contextInitCh
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return theRunContext.update(u)
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}
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func (c *runContext) update(u Updater) error {
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n := now()
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count := clock.Update(n)
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if err := u.Update(count); err != nil {
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return err
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}
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c.framesForFPS++
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// Calc the current FPS.
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if time.Second > time.Duration(n-c.lastFPSUpdated) {
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return nil
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}
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currentFPS := float64(c.framesForFPS) * float64(time.Second) / float64(n-c.lastFPSUpdated)
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c.updateFPS(currentFPS)
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c.lastFPSUpdated = n
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c.framesForFPS = 0
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return nil
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}
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