// FILE: transfm.c

#include <windows.h>
#include <math.h>
#include "3d\compatib.h"
#include "3d\gdi3d.h"
#include "3d\intern.h"
#include "3d\globals.h"
#include "3d\helpers.h"


/*
     PROJECT:        GDI3D DLL
     PROGRAMMER(S):  Pasi Paavola
     COMPILER:       Microsoft C/C++ 7.0
     ENVIRONMENT:    Windows 3.1 running on 386/33/SuperVGA/no 80x87;
                     386 enhanced mode
     ROUTINES:       Routines related to 3D transformations
*/



////////////////////////////////////////////////////////////////////////////
/*

G3RemoveTransformations() restores the transformation system to its original
state (identity matrix, I).

Parameter           Description

Comments


*/
////////////////////////////////////////////////////////////////////////////

VOID WINAPI_LIB G3RemoveTransformations()

{

GpParams->M11 = 1.0;
GpParams->M22 = 1.0;
GpParams->M33 = 1.0;

GpParams->M12 = 0.0;
GpParams->M13 = 0.0;
GpParams->M14 = 0.0;

GpParams->M21 = 0.0;
GpParams->M23 = 0.0;
GpParams->M24 = 0.0;

GpParams->M31 = 0.0;
GpParams->M32 = 0.0;
GpParams->M34 = 0.0;

GpParams->iTrFlag = 0;

}



////////////////////////////////////////////////////////////////////////////
/*

G3SetTranslation() multiplies the current transformation matrix from
the left by the translation matrix defined by the parameters. (Of course
full matrix multiplication is not performed, only needed modifications
to the transformation matrix.)

Parameter           Description

x, y, z             Translation shifts in the directions of x, y and z axes
                    respectively

Comments


*/
////////////////////////////////////////////////////////////////////////////

VOID WINAPI_LIB G3SetTranslation(double x, double y, double z)
{

GpParams->M14 += x;
GpParams->M24 += y;
GpParams->M34 += z;

GpParams->iTrFlag |= TM_TRANS;

}



////////////////////////////////////////////////////////////////////////////
/*

G3SetScale() multiplies the current transformation matrix from
the left by the scaling matrix defined by the parameters. (Of course
full matrix multiplication is not performed, only needed modifications
to the transformation matrix.)

Parameter           Description

Scx, Scy, Scz       Scaling factors for x, y and z directions.
                    If all values are the same, the transformation is
                    normal overall scaling.

Comments


*/
////////////////////////////////////////////////////////////////////////////

VOID WINAPI_LIB G3SetScale(double Scx, double Scy, double Scz)

{

GpParams->M11 *= Scx;
GpParams->M12 *= Scx;
GpParams->M13 *= Scx;
GpParams->M14 *= Scx;

GpParams->M21 *= Scy;
GpParams->M22 *= Scy;
GpParams->M23 *= Scy;
GpParams->M24 *= Scy;

GpParams->M31 *= Scz;
GpParams->M32 *= Scz;
GpParams->M33 *= Scz;
GpParams->M34 *= Scz;

GpParams->iTrFlag |= TM_SCALE;

}

////////////////////////////////////////////////////////////////////////////
/*

G3SetRotate() multiplies the current transformation matrix from
left by the rotation matrix defined by the parameters. (Of course
full matrix multiplication is not performed, only needed modifications
to the transformation matrix.)


Parameter           Description

lpRotAxis           Rotation axis. The rotation is performed about the
                    axis defined by vector having coordinates lpRotAxis->x
                    lpRotAxis->y and lpRotAxis->z.

theta               Rotation angle in radians

Returns

Comments


*/
////////////////////////////////////////////////////////////////////////////

VOID WINAPI_LIB G3SetRotate(LPG3VECTOR lpRotAxis, double theta)
{

double txy, txz, tyz, s, c, sz, sy, sx, t;          // Temporaries
double R11, R12, R13, R21, R22, R23, R31, R32, R33; // Rotation matrix elements
double m11, m12, m13, m14, m21, m22, m23, m24,      // Old tr. matrix values
       m31, m32, m33, m34;
G3VECTOR Normalized;


Normalized.x = lpRotAxis->x;
Normalized.y = lpRotAxis->y;
Normalized.z = lpRotAxis->z;

G3Normalize(&Normalized);

// Formulae taken from Graphics Gems, p. 466

s = sin(theta);
c = cos(theta);
t = 1 - c;

txy = t * Normalized.x * Normalized.y;
txz = t * Normalized.x * Normalized.z;
tyz = t * Normalized.y * Normalized.z;

sz = s*Normalized.z; sy = s*Normalized.y; sx = s*Normalized.x;

// Calculate coefficient matrix elements

R11 = t * Normalized.x * Normalized.x + c;
R22 = t * Normalized.y * Normalized.y + c;
R33 = t * Normalized.z * Normalized.z + c;

R12 = txy - sz;
R13 = txz + sy;
R21 = txy + sz;
R23 = tyz - sx;
R31 = txz - sy;
R32 = tyz + sx;


// Save the old transformation matrix values

m11 = GpParams->M11;
m12 = GpParams->M12;
m13 = GpParams->M13;
m14 = GpParams->M14;

m21 = GpParams->M21;
m22 = GpParams->M22;
m23 = GpParams->M23;
m24 = GpParams->M24;

m31 = GpParams->M31;
m32 = GpParams->M32;
m33 = GpParams->M33;
m34 = GpParams->M34;

// Modify current transformation matrix

GpParams->M11 = R11*m11 + R12*m21 + R13*m31;
GpParams->M12 = R11*m12 + R12*m22 + R13*m32;
GpParams->M13 = R11*m13 + R12*m23 + R13*m33;
GpParams->M14 = R11*m14 + R12*m24 + R13*m34;

GpParams->M21 = R21*m11 + R22*m21 + R23*m31;
GpParams->M22 = R21*m12 + R22*m22 + R23*m32;
GpParams->M23 = R21*m13 + R22*m23 + R23*m33;
GpParams->M24 = R21*m14 + R22*m24 + R23*m34;

GpParams->M31 = R31*m11 + R32*m21 + R33*m31;
GpParams->M32 = R31*m12 + R32*m22 + R33*m32;
GpParams->M33 = R31*m13 + R32*m23 + R33*m33;
GpParams->M34 = R31*m14 + R32*m24 + R33*m34;

GpParams->iTrFlag |= TM_SCALE | TM_ROTATE;

}