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Diffstat (limited to 'src/lib/JEDI-SDL/SDL/Pas/sdlticks.pas')
| -rw-r--r-- | src/lib/JEDI-SDL/SDL/Pas/sdlticks.pas | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/src/lib/JEDI-SDL/SDL/Pas/sdlticks.pas b/src/lib/JEDI-SDL/SDL/Pas/sdlticks.pas new file mode 100644 index 00000000..a479b493 --- /dev/null +++ b/src/lib/JEDI-SDL/SDL/Pas/sdlticks.pas @@ -0,0 +1,197 @@ +unit sdlticks; +{ + $Id: sdlticks.pas,v 1.2 2006/11/08 08:22:48 savage Exp $ + +} +{******************************************************************************} +{ } +{ JEDI-SDL : Pascal units for SDL - Simple DirectMedia Layer } +{ SDL GetTicks Class Wrapper } +{ } +{ } +{ The initial developer of this Pascal code was : } +{ Dominique Louis <Dominique@SavageSoftware.com.au> } +{ } +{ Portions created by Dominique Louis are } +{ Copyright (C) 2004 - 2100 Dominique Louis. } +{ } +{ } +{ Contributor(s) } +{ -------------- } +{ Dominique Louis <Dominique@SavageSoftware.com.au> } +{ } +{ Obtained through: } +{ Joint Endeavour of Delphi Innovators ( Project JEDI ) } +{ } +{ You may retrieve the latest version of this file at the Project } +{ JEDI home page, located at http://delphi-jedi.org } +{ } +{ The contents of this file are used with permission, subject to } +{ the Mozilla Public License Version 1.1 (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.mozilla.org/MPL/MPL-1.1.html } +{ } +{ Software distributed under the License is distributed on an } +{ "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or } +{ implied. See the License for the specific language governing } +{ rights and limitations under the License. } +{ } +{ Description } +{ ----------- } +{ SDL Window Wrapper } +{ } +{ } +{ Requires } +{ -------- } +{ SDL.dll on Windows platforms } +{ libSDL-1.1.so.0 on Linux platform } +{ } +{ Programming Notes } +{ ----------------- } +{ } +{ } +{ } +{ } +{ Revision History } +{ ---------------- } +{ } +{ September 23 2004 - DL : Initial Creation } +{ + $Log: sdlticks.pas,v $ + Revision 1.2 2006/11/08 08:22:48 savage + updates tp sdlgameinterface and sdlticks functions. + + Revision 1.1 2004/09/30 22:35:47 savage + Changes, enhancements and additions as required to get SoAoS working. + +} +{******************************************************************************} + +interface + +uses + sdl; + +type + TSDLTicks = class + private + FStartTime : UInt32; + FTicksPerSecond : UInt32; + FElapsedLastTime : UInt32; + FFPSLastTime : UInt32; + FLockFPSLastTime : UInt32; + public + constructor Create; + destructor Destroy; override; // destructor + + {***************************************************************************** + Init + If the hi-res timer is present, the tick rate is stored and the function + returns true. Otherwise, the function returns false, and the timer should + not be used. + *****************************************************************************} + function Init : boolean; + + {*************************************************************************** + GetGetElapsedSeconds + Returns the Elapsed time, since the function was last called. + ***************************************************************************} + function GetElapsedSeconds : Single; + + {*************************************************************************** + GetFPS + Returns the average frames per second. + If this is not called every frame, the client should track the number + of frames itself, and reset the value after this is called. + ***************************************************************************} + function GetFPS : single; + + {*************************************************************************** + LockFPS + Used to lock the frame rate to a set amount. This will block until enough + time has passed to ensure that the fps won't go over the requested amount. + Note that this can only keep the fps from going above the specified level; + it can still drop below it. It is assumed that if used, this function will + be called every frame. The value returned is the instantaneous fps, which + will be less than or equal to the targetFPS. + ***************************************************************************} + procedure LockFPS( targetFPS : Byte ); + end; + +implementation + +{ TSDLTicks } +constructor TSDLTicks.Create; +begin + inherited; + FTicksPerSecond := 1000; +end; + +destructor TSDLTicks.Destroy; +begin + inherited; +end; + +function TSDLTicks.GetElapsedSeconds : Single; +var + currentTime : Cardinal; +begin + currentTime := SDL_GetTicks; + + result := ( currentTime - FElapsedLastTime ) / FTicksPerSecond; + + // reset the timer + FElapsedLastTime := currentTime; +end; + +function TSDLTicks.GetFPS : Single; +var + currentTime, FrameTime : UInt32; + fps : single; +begin + currentTime := SDL_GetTicks; + + FrameTime := ( currentTime - FFPSLastTime ); + + if FrameTime = 0 then + FrameTime := 1; + + fps := FTicksPerSecond / FrameTime; + + // reset the timer + FFPSLastTime := currentTime; + result := fps; +end; + +function TSDLTicks.Init : boolean; +begin + FStartTime := SDL_GetTicks; + FElapsedLastTime := FStartTime; + FFPSLastTime := FStartTime; + FLockFPSLastTime := FStartTime; + result := true; +end; + +procedure TSDLTicks.LockFPS( targetFPS : Byte ); +var + currentTime : UInt32; + targetTime : single; +begin + if ( targetFPS = 0 ) then + targetFPS := 1; + + targetTime := FTicksPerSecond / targetFPS; + + // delay to maintain a constant frame rate + repeat + currentTime := SDL_GetTicks; + until ( ( currentTime - FLockFPSLastTime ) > targetTime ); + + // reset the timer + FLockFPSLastTime := currentTime; +end; + +end. + +
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