ebiten/internal/clock/clock.go

155 lines
3.2 KiB
Go
Raw Normal View History

2017-07-13 17:28:28 +02:00
// Copyright 2017 The Ebiten Authors
//
// 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 clock
import (
"time"
2017-07-13 17:28:28 +02:00
"github.com/hajimehoshi/ebiten/internal/sync"
)
const FPS = 60
2017-07-13 17:28:28 +02:00
var (
2017-08-05 17:52:12 +02:00
primaryTime int64
lastPrimaryTime int64
frames int64
logicalTime int64
currentFPS float64
lastFPSUpdated int64
framesForFPS int64
ping func()
m sync.Mutex
2017-07-13 17:28:28 +02:00
)
func CurrentFPS() float64 {
m.Lock()
v := currentFPS
m.Unlock()
return v
}
func RegisterPing(pingFunc func()) {
m.Lock()
ping = pingFunc
m.Unlock()
}
2017-08-05 17:52:12 +02:00
// ProceedPrimaryTimer increments the primary time by a frame.
func ProceedPrimaryTimer() {
2017-07-13 17:28:28 +02:00
m.Lock()
2017-08-05 17:52:12 +02:00
primaryTime++
2017-07-13 17:28:28 +02:00
m.Unlock()
}
func updateFPS(now int64) {
if lastFPSUpdated == 0 {
lastFPSUpdated = now
}
framesForFPS++
if time.Second > time.Duration(now-lastFPSUpdated) {
return
}
currentFPS = float64(framesForFPS) * float64(time.Second) / float64(now-lastFPSUpdated)
lastFPSUpdated = now
framesForFPS = 0
}
// Update updates the inner clock state and returns an integer value
// indicating how many logical frames the game should update.
2017-08-05 19:12:23 +02:00
func Update() int {
2017-07-13 17:28:28 +02:00
m.Lock()
defer m.Unlock()
2017-08-05 19:12:23 +02:00
n := now()
if ping != nil {
ping()
}
2017-08-05 17:52:12 +02:00
// Initialize logicalTime if needed.
if logicalTime == 0 {
2017-08-05 19:12:23 +02:00
logicalTime = n
2017-08-05 17:52:12 +02:00
}
2017-08-05 19:12:23 +02:00
t := n - logicalTime
2017-08-05 17:52:12 +02:00
if t < 0 {
return 0
}
count := 0
2017-08-23 19:30:43 +02:00
// Logical clock:
// A clock that updated based on the number of frames.
2017-08-05 17:52:12 +02:00
//
2017-08-23 19:30:43 +02:00
// System clock:
// A clock that offered by the OS.
//
// Primary clock:
// A clock that is used in the higher priority over the system clock.
// Primary time is usually an audio time.
// Primary time might not exist when e.g. audio is not used.
// When sync is true, the logical time is forced to sync with the system clock.
sync := false
2017-08-05 17:52:12 +02:00
if primaryTime > 0 && lastPrimaryTime != primaryTime {
2017-08-23 19:30:43 +02:00
// If the primary clock is updated, use this.
2017-08-05 17:52:12 +02:00
if frames < primaryTime {
count = int(primaryTime - frames)
}
2017-08-05 17:52:12 +02:00
lastPrimaryTime = primaryTime
sync = true
} else {
// Use system clock when
// 1) Inc() is not called, or
2017-08-23 19:30:43 +02:00
// 2) the primary clock is not updated yet.
// As the primary clock can be updated discountinuously, the system clock is still needed.
if t > 5*int64(time.Second)/FPS {
2017-08-05 17:23:31 +02:00
// The previous time is too old.
2017-08-05 17:52:12 +02:00
// Let's force to sync the logical time with the OS clock.
sync = true
} else {
count = int(t * FPS / int64(time.Second))
}
}
// Stabilize FPS.
if count == 0 && (int64(time.Second)/FPS/2) < t {
count = 1
}
if count == 2 && (int64(time.Second)/FPS*3/2) > t {
count = 1
}
if count > 3 {
count = 3
}
frames += int64(count)
2017-08-05 17:52:12 +02:00
if sync {
2017-08-05 19:12:23 +02:00
logicalTime = n
2017-08-05 17:52:12 +02:00
} else {
logicalTime += int64(count) * int64(time.Second) / FPS
2017-08-05 17:52:12 +02:00
}
2017-08-05 19:12:23 +02:00
updateFPS(n)
2017-08-05 17:52:12 +02:00
return count
2017-07-13 17:28:28 +02:00
}