quick poll - precalc sin & cos or perform every frame ?

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WolRon
 #1
After comparing apples to apples (your code was doing an extra (unfair) conversion of floating point to integer):
Open in online IDE
Graphics 640,480,32,2

;Lookup Table
Dim Sin2#(360)
Dim Cos2#(360)
For a=0 To 359
	Sin2#(a)=Sin(a)
	Cos2#(a)=Cos(a)
Next

Iterations=71500   ; change

; Calc on the fly
Time1=MilliSecs()
For t=1 To Iterations
    For a=0 To 359
        dx# = Cos(a) 
        dy# = Sin(a)
    Next
Next
Time2=MilliSecs()
TimeTaken1=Time2-Time1


; Now Calc using tables
Time1=MilliSecs()
For t=1 To Iterations
    For a=0 To 359
        dx# = Cos2#(a) 
        dy# = Sin2#(a)
    Next
Next
Time2=MilliSecs()
TimeTaken2=Time2-Time1


Text 10,10,"REPORT"
Text 10,30,"Calc On the fly took "+Str(TimeTaken1)+" millisecs"
Text 10,45,"Look up tables took "+Str(TimeTaken2)+" millisecs"

Flip
WaitKey()
End
this is the results I came up with for
B+ :6693 - 95
B3D:5531 - 122 (approx. 4307 - 95)

Looks like B3D is faster at doing the math than B+ is (35% faster) and slower at looking up the tables.

My machine is a P4-2.53GHz.
I imagine with such small tables (360 elements), it fits entirely in the L2 cache so the processor doesn't have to access the system RAM. With a larger table this may not be true.

I got these results with substantially larger tables which suggest what I was talking about.
B+ :3102 - 103
B3D:2565 - 99
Open in online IDE
Graphics 640,480,32,2

;Lookup Table
Dim Sin2#(36000000)
Dim Cos2#(36000000)
For a=0 To 35999999
	Sin2#(a)=Sin(a)
	Cos2#(a)=Cos(a)
Next

Iterations=1   ; change

; Calc on the fly
Time1=MilliSecs()
For t=1 To Iterations
    For a=0 To 35999999
        dx# = Cos(a) 
        dy# = Sin(a)
    Next
Next
Time2=MilliSecs()
TimeTaken1=Time2-Time1


; Now Calc using tables
Time1=MilliSecs()
For t=1 To Iterations
    For a=0 To 35999999
        dx# = Cos2#(a) 
        dy# = Sin2#(a)
    Next
Next
Time2=MilliSecs()
TimeTaken2=Time2-Time1


Text 10,10,"REPORT"
Text 10,30,"Calc On the fly took "+Str(TimeTaken1)+" millisecs"
Text 10,45,"Look up tables took "+Str(TimeTaken2)+" millisecs"

Flip
WaitKey()
End