mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
146 lines
3.0 KiB
Go
146 lines
3.0 KiB
Go
// Copyright 2017 The Ebiten Authors
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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 clock
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import (
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"time"
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"github.com/hajimehoshi/ebiten/internal/sync"
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)
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const FPS = 60
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var (
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primaryTime int64
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lastPrimaryTime int64
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frames int64
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logicalTime int64
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currentFPS float64
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lastFPSUpdated int64
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framesForFPS int64
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ping func()
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m sync.Mutex
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)
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func CurrentFPS() float64 {
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m.Lock()
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v := currentFPS
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m.Unlock()
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return v
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}
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func RegisterPing(pingFunc func()) {
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m.Lock()
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ping = pingFunc
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m.Unlock()
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}
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// ProceedPrimaryTimer increments the primary time by a frame.
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func ProceedPrimaryTimer() {
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m.Lock()
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primaryTime++
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m.Unlock()
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}
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func updateFPS(now int64) {
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if lastFPSUpdated == 0 {
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lastFPSUpdated = now
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}
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framesForFPS++
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if time.Second > time.Duration(now-lastFPSUpdated) {
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return
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}
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currentFPS = float64(framesForFPS) * float64(time.Second) / float64(now-lastFPSUpdated)
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lastFPSUpdated = now
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framesForFPS = 0
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}
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// Update updates the inner clock state and returns an integer value
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// indicating how many logical frames the game should update.
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func Update(now int64) int {
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m.Lock()
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defer m.Unlock()
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if ping != nil {
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ping()
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}
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// Initialize logicalTime if needed.
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if logicalTime == 0 {
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logicalTime = now
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}
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t := now - logicalTime
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if t < 0 {
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return 0
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}
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count := 0
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// There are two time lines: one is the logical time and the other is the system clock.
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//
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// Usually logical time is updated based on the number of frames, but
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// when sync is true, the logical time is forced to sync with the system clock.
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sync := false
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if primaryTime > 0 && lastPrimaryTime != primaryTime {
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// If the primary time is updated, use this.
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if frames < primaryTime {
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count = int(primaryTime - frames)
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}
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lastPrimaryTime = primaryTime
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sync = true
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} else {
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// Use system clock when
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// 1) Inc() is not called, or
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// 2) the primary time is not updated yet.
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// As the primary time can be updated discountinuously,
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// the system clock is still needed.
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if t > 5*int64(time.Second)/FPS {
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// The previous time is too old.
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// Let's force to sync the logical time with the OS clock.
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sync = true
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} else {
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count = int(t * FPS / int64(time.Second))
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}
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}
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// Stabilize FPS.
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if count == 0 && (int64(time.Second)/FPS/2) < t {
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count = 1
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}
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if count == 2 && (int64(time.Second)/FPS*3/2) > t {
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count = 1
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}
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if count > 3 {
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count = 3
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}
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frames += int64(count)
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if sync {
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logicalTime = now
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} else {
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logicalTime += int64(count) * int64(time.Second) / FPS
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}
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updateFPS(now)
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return count
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}
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