gzdoom/src/tables.h

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// 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__