I keep forgetting the fact that PB is retarded when it comes to the modulo operator and floating point values!.

It’s time to write our own fmod() equivalent; lucky for us the Intel guys were kind enough as to implement quite a useful instruction called FPREM a few eons ago, which pretty much means “Partial REMinder” and what it does is rather simple: it computes the partial remainder of st(0)/st(1).

Procedure.f fmod( x.f, y.f )
  EnableASM
	  FLD DWORD[p.v_y]
	  FLD DWORD[p.v_x]
	  !NOT_READY:
		  FPREM
		  FSTSW AX
		  TEST AH, 100b
	  !JNZ NOT_READY
	  FSTP ST1
  DisableASM
  ProcedureReturn
EndProcedure

Of course with great instructions comes great limitations: in this case we cannot produce the final reminder if the difference between X and Y is bigger than 63. We can solve this by implementing a loop and checking for the C2 bit of the status word to be cleared. This is all explained in the IA32 manuals.

It’s not pretty but until fpu modulo operations are officially supported in the language, this might well be your only sane choice.

Same link as before: VEC3_MACRO.PBI

Or you can download the package: VEC3_MACRO.ZIP

New functionality as seen on the change-log:

24/01/2009: Added min, max. Fixed Lerp.

18/01/2009: Fixed structure, made FMOD compliant with VEC3_TYPE. Refactored FastSine() and PIWRAP().

12/01/2009: Optimized/Fixed the PIWRAP macro with FMOD. Added resolution switch For the quadratic curve.

11/01/2009: Added wrap, clamp, lerp, string. Fixed some bugs. Refactored the vec3 structure. Added approximation method for sine and cosine functions.

10/01/2009: Library created.

I think I got carried away a little, but it proves to be a useful library for quick prototyping (at least that’s what I use it for). I’ll write a few examples with a small drawing framework perhaps by next week if I have time for it. Some of the things that are left to do include angle and coordinate helpers, which also means isometric transformation for 3d points, projections, etc.

As it stands right now, you could prototype almost any type of game/application without having to code most of the trivial stuff (such as, the vector code, provided by the library!).

Cheers.