gzdoom/src/tables.h

// Emacs style mode select	 -*- C++ -*- 
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// DESCRIPTION:
//		Lookup tables.
//		Do not try to look them up :-).
//		In the order of appearance: 
//
//		int finetangent[4096]	- Tangens LUT.
//		 Should work with BAM fairly well (12 of 16bit,
//		effectively, by shifting).
//
//		int finesine[10240] 			- Sine lookup.
//		 Guess what, serves as cosine, too.
//		 Remarkable thing is, how to use BAMs with this? 
//
//		int tantoangle[2049]	- ArcTan LUT,
//		  maps tan(angle) to angle fast. Gotta search.	
//	  
//-----------------------------------------------------------------------------


#ifndef __TABLES_H__
#define __TABLES_H__

#include <math.h>

#ifndef PI
#define PI				3.14159265358979323846		// matches value in gcc v2 math.h
#endif


#include "m_fixed.h"
		
#define FINEANGLES		8192
#define FINEMASK		(FINEANGLES-1)


// 0x100000000 to 0x2000
#define ANGLETOFINESHIFT		19

// Effective size is 10240.
extern	fixed_t 		finesine[5*FINEANGLES/4];

// Re-use data, is just PI/2 phase shift.
// [RH] Instead of using a pointer, use some inline code
// (encapsulated in a struct so that we can still use array accesses).
struct cosine_inline
{
	fixed_t operator[] (unsigned int x)
	{
		return finesine[x+FINEANGLES/4];
	}
};
extern cosine_inline finecosine;

// Effective size is 4096.
extern fixed_t			finetangent[FINEANGLES/2];

// Binary Angle Measument, BAM.
#define ANG45			(0x20000000)
#define ANG90			(0x40000000)
#define ANG180			(0x80000000)
#define ANG270			(0xc0000000)

#define ANGLE_45		(0x20000000)
#define ANGLE_90		(0x40000000)
#define ANGLE_180		(0x80000000)
#define ANGLE_270		(0xc0000000)
#define ANGLE_MAX		(0xffffffff)
#define ANGLE_1			(ANGLE_45/45)
#define ANGLE_60		(ANGLE_180/3)


#define SLOPERANGE		2048
#define SLOPEBITS		11
#define DBITS			(FRACBITS-SLOPEBITS)

typedef uint32			angle_t;

// Avoid "ambiguous call to overloaded function" errors
// Only to be used when you have subtracted two angles.
#ifndef __GNUC__
inline angle_t abs (angle_t ang)
{
	return (angle_t)abs((SDWORD)ang);
}
#endif

// Effective size is 2049;
// The +1 size is to handle the case when x==y
//	without additional checking.
extern angle_t			tantoangle[SLOPERANGE+1];


// Utility function,
//	called by R_PointToAngle.
inline int SlopeDiv (unsigned int num, unsigned den)
{
	unsigned int ans;

	if (den < 512)
		return SLOPERANGE;

	ans = (num << 3) / (den >> 8);

	return ans <= SLOPERANGE ? ans : SLOPERANGE;
}

#endif // __TABLES_H__