//-----------------------------------------------------------------------------
// File: D3DMath.h
//
// Desc: Math functions and shortcuts for Direct3D programming.
//
// Copyright (c) 1997-1999 Microsoft Corporation. All rights reserved
//-----------------------------------------------------------------------------
#ifndef D3DMATH_H
#define D3DMATH_H
#include <ddraw.h>
#include <d3d.h>


//-----------------------------------------------------------------------------
// Useful Math constants
//-----------------------------------------------------------------------------
const FLOAT g_PI       =  3.14159265358979323846f; // Pi
const FLOAT g_2_PI     =  6.28318530717958623200f; // 2 * Pi
const FLOAT g_PI_DIV_2 =  1.57079632679489655800f; // Pi / 2
const FLOAT g_PI_DIV_4 =  0.78539816339744827900f; // Pi / 4
const FLOAT g_INV_PI   =  0.31830988618379069122f; // 1 / Pi
const FLOAT g_DEGTORAD =  0.01745329251994329547f; // Degrees to Radians
const FLOAT g_RADTODEG = 57.29577951308232286465f; // Radians to Degrees
const FLOAT g_HUGE     =  1.0e+38f;                // Huge number for FLOAT
const FLOAT g_EPSILON  =  1.0e-5f;                 // Tolerance for FLOATs




//-----------------------------------------------------------------------------
// Fuzzy compares (within tolerance)
//-----------------------------------------------------------------------------
inline BOOL D3DMath_IsZero(FLOAT a, FLOAT fTol = g_EPSILON)
{ return (a <= 0.0f) ? (a >= -fTol) : (a <= fTol); }




//-----------------------------------------------------------------------------
// Matrix functions
//-----------------------------------------------------------------------------
VOID    D3DMath_MatrixMultiply(D3DMATRIX& q, D3DMATRIX& a, D3DMATRIX& b);
HRESULT D3DMath_MatrixInvert(D3DMATRIX& q, D3DMATRIX& a);




//-----------------------------------------------------------------------------
// Vector functions
//-----------------------------------------------------------------------------
HRESULT D3DMath_VectorMatrixMultiply(D3DVECTOR& vDest, D3DVECTOR& vSrc,
                                      D3DMATRIX& mat);
HRESULT D3DMath_VertexMatrixMultiply(D3DVERTEX& vDest, D3DVERTEX& vSrc,
                                      D3DMATRIX& mat);




//-----------------------------------------------------------------------------
// Quaternion functions
//-----------------------------------------------------------------------------
VOID D3DMath_QuaternionFromRotation(FLOAT& x, FLOAT& y, FLOAT& z, FLOAT& w,
                                     D3DVECTOR& v, FLOAT fTheta);
VOID D3DMath_RotationFromQuaternion(D3DVECTOR& v, FLOAT& fTheta,
                                     FLOAT x, FLOAT y, FLOAT z, FLOAT w);
VOID D3DMath_QuaternionFromAngles(FLOAT& x, FLOAT& y, FLOAT& z, FLOAT& w,
                                   FLOAT fYaw, FLOAT fPitch, FLOAT fRoll);
VOID D3DMath_MatrixFromQuaternion(D3DMATRIX& mat, FLOAT x, FLOAT y, FLOAT z,
                                   FLOAT w);
VOID D3DMath_QuaternionFromMatrix(FLOAT &x, FLOAT &y, FLOAT &z, FLOAT &w,
                                   D3DMATRIX& mat);
VOID D3DMath_QuaternionMultiply(FLOAT& Qx, FLOAT& Qy, FLOAT& Qz, FLOAT& Qw,
                                 FLOAT Ax, FLOAT Ay, FLOAT Az, FLOAT Aw,
                                 FLOAT Bx, FLOAT By, FLOAT Bz, FLOAT Bw);
VOID D3DMath_QuaternionSlerp(FLOAT& Qx, FLOAT& Qy, FLOAT& Qz, FLOAT& Qw,
                              FLOAT Ax, FLOAT Ay, FLOAT Az, FLOAT Aw,
                              FLOAT Bx, FLOAT By, FLOAT Bz, FLOAT Bw,
                              FLOAT fAlpha);


#endif // D3DMATH_H