Clock is responsible for providing a real time and a virtual time, real time starts from 0 to increment, and hardware clock is synchronized; virtual time is also incremented by MS from 0, but does not necessarily synchronize with real time.
To get system.currenttimemillies (), the system hardware has a counter. When the computer starts, the counter starts every 1 ms 1 ms 1, System.currentTimeMillies () Returns from the boot to the current MS. We don't need to know time seconds, just need an incremental integer timing.
Clock changes C code in Marshall "Game Programming Gems 3", main member variables: thermistime: System.currentTimeMillies () SystemTime: The system time of the game, that is, the THISTIME is converted to the time VirtualTime incremented from 0: Virtual time, increment from 0, but does not sync with real time
code show as below:
Package game.Engine.core;
Class clock {
// Clock Whether it runs:
Private boolean running;
// Current HardWare Clock:
Private int thistime;
// Record The Last Hardware Clock When Calling Stop ():
Private Int lasttime;
// SystemTIME starts increment from 0, and hardware clock synchronization:
Private int systemtime;
// Systemoffset is the difference between the hardware clock and the SystemTime:
Private Int systemoffset;
// SYSTEMTIME to be stopped last time:
PRIVATE INT PAUSEAT;
// VirtualTime Starts from 0.
Private Int VirtualTime;
// VirtualOffset Records How long The clock paused:
Private Int VirtualOffset;
Private int framestart;
PRIVATE INT FRAMEEND;
PRIVATE INT FRAMECOUNT;
Public clock () {
RESET ();
}
// Reset the clock:
Public void reset () {
Running = false;
// Get The Hardware Clock:
THISTIME = (int) system.currenttimemillis ();
Lasttime = thistime;
// and systemtime starts from 0:
SystemTime = 0;
Systemoffset = thermistime;
Pauseat = 0;
// init Virtual Time:
VirtualTime = 0;
Virtualoffset = 0;
// init frame time:
FrameStart = 0;
Framed = 0;
Framecount = 0;
}
// Synchronize Hardware Clock:
Private void update () {
Lasttime = thistime;
THISTIME = (int) system.currenttimemillis ();
// increable the systemtime:
SystemTIME = (thisTime - lasttime);
// Start CLOCK:
Public void start () {
IF (! Running) {
Running = true;
Update ();
VirtualOffset = (SystemTime - Pauseat);
System.out.println ("[START]");
}
}
// Stop Clock:
Public void stop () {
IF (Running) {
Running = false;
Update ();
Pauseat = systemtime;
System.out.println ("[STOP] AT" Pauseat);
}
}
// Clock Whether it runs:
Public boolean isrunning () {
Return this.running;
}
// Start Frame:
Public void beginframe () {
IF (Running) {
Update ();
Framecount ;
Framestart = frameend;
Framed = systemtime - virtualoffset;
VirtualTime = framestart;
System.out.println ("[Beginframe] Virtual Time =" VirtualTime ", SystemTime =" SystemTime);
}
}
// End the Virtual Time to Frame:
Public void advancetoend () {
IF (Running) {
VirtualTime = frameend;
System.out.println ("[AdvanceToend] Virtual Time =" VirtualTime);
}
}
Public int getVirtualTime () {
Return VirtualTime;
}
// Get system time:
Public int getSystemTime () {
Update ();
Return SystemTime;
}
// Get Frame Start Time:
Public int getframestart () {
Return Framestart;
}
// Get the end time of the frame:
Public int getframeend () {
Return FrameEnd;
}
Public int getFramecount () {
Return Framecount;
}
}
Reference: Marshall: "Game Programming Gems 3"
to be continued :)
