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+---- Thread: Function to calculate FPS with another FPS (/showthread.php?tid=1118)
Function to calculate FPS with another FPS - TerryRitchie - 11-14-2022
In another post I asked for help in how to determine slower frame rates within a master frame rate for a Pac-Man clone I'm working on. DSMan decoded some of the original Ms. Pac-Man assembly code to reveal how it was being accomplished.
I took that idea and created a function that will determine any frame rate within a master frame rate up to 60 FPS. The function and demo code created to show the function in action are below. With this function you can change the frame rate of a game at any time and still maintain any object's desired slower frame rate.
There is an anomaly in the slope that you'll see as it is drawn. I'm not really sure what to make of this? Any ideas?
Code: (Select All)
' Getting slower frame rates within a master frame rate
DIM F(60) AS INTEGER ' frame counters
DIM FramesPerSecond AS INTEGER ' game's frames per second
DIM Dummy AS INTEGER ' used to set intital data
DIM Frame AS INTEGER ' frame counter
DIM Wipe AS INTEGER ' trigger a clearing of frame counters
DIM x AS INTEGER ' cycle through 1 to FramesPerSecond
'+--------------+
'+ Example code |
'+--------------+
Frame = 0 ' reset frame counter
FramesPerSecond = 60 ' set game FPS
SCREEN _NEWIMAGE(640, 480, 32) ' create graphics screen
DO ' begin various FPS loop
Dummy = FPS(-1, FramesPerSecond) ' create frame data set
DO ' begin demo loop
_LIMIT FramesPerSecond ' limit loop to game's frame rate
CLS ' clear the screen
LOCATE 2, 2: PRINT "Counting down from 60 FPS to 1 FPS" ' inform user of progress
LOCATE 3, 2: PRINT "Frames per second ="; FramesPerSecond
LOCATE 4, 1: PRINT INT(Frame / FramesPerSecond) + 1; "of 5 seconds elapsed"
Frame = Frame + 1 ' increment game frame counter
Wipe = 0 ' reset frame counter wipe trigger
IF Frame = FramesPerSecond * 5 THEN Frame = 0: Wipe = -1 ' when 5 seconds has elapsed reset frame counter and trigger a wipe
FOR x = 1 TO FramesPerSecond ' cycle through all available frame rates
IF Wipe THEN F(x) = 0 ' clear frame counter if wipe triggered
IF FPS(x, Frame) THEN F(x) = F(x) + 1 ' is this frame rate's frame active during this frame in the game?
LINE (10, 200 - x * 2)-(10 + F(x), 200 - x * 2) ' yes, draw a line showing progress of frames counted
NEXT x
_DISPLAY ' update the screen with changes
LOOP UNTIL Wipe OR _KEYDOWN(27) ' leave when user presses the ESC key or a wipe triggered
FramesPerSecond = FramesPerSecond - 1 ' decrease the game's frames per second
IF FramesPerSecond < 1 THEN FramesPerSecond = 60 ' reset the game's frame rate when needed
LOOP UNTIL _KEYDOWN(27) ' leave when user presses the ESC key
SYSTEM ' return to the operating system
'--------------------------------------------------------------------------------------------------------------------------------------------+-----+
FUNCTION FPS (TargetFPS AS INTEGER, Frame AS INTEGER) STATIC ' | FPS |
'+---------------------------------------------------------------------------------------------------------------------------------------+-----+
'| Returns frame rates embedded in a master frame rate |
'| |
'| Usage: dummy = FPS(-1, 60) When the target FPS is less than 1 a new data set is created for the requested frame rate |
'| MoveNow = FPS(24, InputFrame) Will return -1 (TRUE) if input frame is on during the target frame rate |
'| |
'| Example: IF FPS(Object.FPS, GameFrame) then Move(Object) Move the object if the object's frame is on within the game's current frame count |
'+---------------------------------------------------------------------------------------------------------------------------------------------+
DIM f AS INTEGER ' frame counter/value
DIM b AS SINGLE ' bit counter/step rate
DIM FramesCreated AS INTEGER ' numer of frames calculated
IF TargetFPS < 1 THEN ' calculate frame counters?
REDIM FPSnum(Frame) AS _UNSIGNED _INTEGER64 ' yes, resize 64bit value array
REDIM Bit(Frame) AS _UNSIGNED _INTEGER64 ' resize bit value array
FOR b = 1 TO Frame ' cycle through bit values
Bit(b) = 2 ^ (b - 1) ' calculate value of each bit
NEXT b
FOR f = 1 TO Frame ' cycle through requested frames
FOR b = 1 TO Frame STEP (Frame / f) ' cycle through bits at current frames per second
FPSnum(f) = FPSnum(f) + Bit(b) ' calculate which bits are turned on
NEXT b
NEXT f
FramesCreated = Frame ' remember number of frames created
EXIT FUNCTION ' leave function
END IF
IF FramesCreated = 0 THEN EXIT FUNCTION ' no data created yet, leave
f = Frame ' don't modify input value
IF f < 1 THEN EXIT FUNCTION ' invalid frame number requested, leave
IF f > FramesCreated THEN f = f MOD FramesCreated ' keep frame number within range
IF FPSnum(TargetFPS) AND Bit(f) THEN FPS = -1 ' report if bit is on for current frame in requested FPS
END FUNCTION
'---------------------------------------------------------------------------------------------------------------------------------------------------