lib3ds_matrix.c

/*
    Copyright (C) 1996-2008 by Jan Eric Kyprianidis <www.kyprianidis.com>
    All rights reserved.
    
    This program is free  software: you can redistribute it and/or modify 
    it under the terms of the GNU Lesser General Public License as published 
    by the Free Software Foundation, either version 2.1 of the License, or 
    (at your option) any later version.

    Thisprogram  is  distributed in the hope that it will be useful, 
    but WITHOUT ANY WARRANTY; without even the implied warranty of 
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
    GNU Lesser General Public License for more details.
    
    You should  have received a copy of the GNU Lesser General Public License
    along with  this program; If not, see <http://www.gnu.org/licenses/>. 
*/

#include "lib3ds_impl.h"


void
lib3ds_matrix_zero(float m[4][4]) {
    int i, j;

    for (i = 0; i < 4; i++) {
        for (j = 0; j < 4; j++) m[i][j] = 0.0f;
    }
}


void
lib3ds_matrix_identity(float m[4][4]) {
    int i, j;

    for (i = 0; i < 4; i++) {
        for (j = 0; j < 4; j++) m[i][j] = 0.0;
    }
    for (i = 0; i < 4; i++) m[i][i] = 1.0;
}


void
lib3ds_matrix_copy(float dest[4][4], float src[4][4]) {
    memcpy(dest, src, 16 * sizeof(float));
}


void
lib3ds_matrix_neg(float m[4][4]) {
    int i, j;

    for (j = 0; j < 4; j++) {
        for (i = 0; i < 4; i++) {
            m[j][i] = -m[j][i];
        }
    }
}


void
lib3ds_matrix_transpose(float m[4][4]) {
    int i, j;
    float swp;

    for (j = 0; j < 4; j++) {
        for (i = j + 1; i < 4; i++) {
            swp = m[j][i];
            m[j][i] = m[i][j];
            m[i][j] = swp;
        }
    }
}


void
lib3ds_matrix_add(float m[4][4], float a[4][4], float b[4][4]) {
    int i, j;

    for (j = 0; j < 4; j++) {
        for (i = 0; i < 4; i++) {
            m[j][i] = a[j][i] + b[j][i];
        }
    }
}


void
lib3ds_matrix_sub(float m[4][4], float a[4][4], float b[4][4]) {
    int i, j;

    for (j = 0; j < 4; j++) {
        for (i = 0; i < 4; i++) {
            m[j][i] = a[j][i] - b[j][i];
        }
    }
}


void
lib3ds_matrix_mult(float m[4][4], float a[4][4], float b[4][4]) {
    float tmp[4][4];
    int i, j, k;
    float ab;

    memcpy(tmp, a, 16 * sizeof(float));
    for (j = 0; j < 4; j++) {
        for (i = 0; i < 4; i++) {
            ab = 0.0f;
            for (k = 0; k < 4; k++) ab += tmp[k][i] * b[j][k];
            m[j][i] = ab;
        }
    }
}


void
lib3ds_matrix_scalar(float m[4][4], float k) {
    int i, j;

    for (j = 0; j < 4; j++) {
        for (i = 0; i < 4; i++) {
            m[j][i] *= k;
        }
    }
}


static float
det2x2(
    float a, float b,
    float c, float d) {
    return((a)*(d) - (b)*(c));
}


static float
det3x3(
    float a1, float a2, float a3,
    float b1, float b2, float b3,
    float c1, float c2, float c3) {
    return(
              a1*det2x2(b2, b3, c2, c3) -
              b1*det2x2(a2, a3, c2, c3) +
              c1*det2x2(a2, a3, b2, b3)
          );
}


float
lib3ds_matrix_det(float m[4][4]) {
    float a1, a2, a3, a4, b1, b2, b3, b4, c1, c2, c3, c4, d1, d2, d3, d4;

    a1 = m[0][0];
    b1 = m[1][0];
    c1 = m[2][0];
    d1 = m[3][0];
    a2 = m[0][1];
    b2 = m[1][1];
    c2 = m[2][1];
    d2 = m[3][1];
    a3 = m[0][2];
    b3 = m[1][2];
    c3 = m[2][2];
    d3 = m[3][2];
    a4 = m[0][3];
    b4 = m[1][3];
    c4 = m[2][3];
    d4 = m[3][3];
    return(
              a1 * det3x3(b2, b3, b4, c2, c3, c4, d2, d3, d4) -
              b1 * det3x3(a2, a3, a4, c2, c3, c4, d2, d3, d4) +
              c1 * det3x3(a2, a3, a4, b2, b3, b4, d2, d3, d4) -
              d1 * det3x3(a2, a3, a4, b2, b3, b4, c2, c3, c4)
          );
}


int
lib3ds_matrix_inv(float m[4][4]) {
    int i, j, k;
    int pvt_i[4], pvt_j[4];            /* Locations of pivot elements */
    float pvt_val;               /* Value of current pivot element */
    float hold;                  /* Temporary storage */
    float determinat;

    determinat = 1.0f;
    for (k = 0; k < 4; k++)  {
        /* Locate k'th pivot element */
        pvt_val = m[k][k];          /* Initialize for search */
        pvt_i[k] = k;
        pvt_j[k] = k;
        for (i = k; i < 4; i++) {
            for (j = k; j < 4; j++) {
                if (fabs(m[i][j]) > fabs(pvt_val)) {
                    pvt_i[k] = i;
                    pvt_j[k] = j;
                    pvt_val = m[i][j];
                }
            }
        }

        /* Product of pivots, gives determinant when finished */
        determinat *= pvt_val;
        if (fabs(determinat) < LIB3DS_EPSILON) {
            return(FALSE);  /* Matrix is singular (zero determinant) */
        }

        /* "Interchange" rows (with sign change stuff) */
        i = pvt_i[k];
        if (i != k) {             /* If rows are different */
            for (j = 0; j < 4; j++) {
                hold = -m[k][j];
                m[k][j] = m[i][j];
                m[i][j] = hold;
            }
        }

        /* "Interchange" columns */
        j = pvt_j[k];
        if (j != k) {            /* If columns are different */
            for (i = 0; i < 4; i++) {
                hold = -m[i][k];
                m[i][k] = m[i][j];
                m[i][j] = hold;
            }
        }

        /* Divide column by minus pivot value */
        for (i = 0; i < 4; i++) {
            if (i != k) m[i][k] /= (-pvt_val) ;
        }

        /* Reduce the matrix */
        for (i = 0; i < 4; i++) {
            hold = m[i][k];
            for (j = 0; j < 4; j++) {
                if (i != k && j != k) m[i][j] += hold * m[k][j];
            }
        }

        /* Divide row by pivot */
        for (j = 0; j < 4; j++) {
            if (j != k) m[k][j] /= pvt_val;
        }

        /* Replace pivot by reciprocal (at last we can touch it). */
        m[k][k] = 1.0f / pvt_val;
    }

    /* That was most of the work, one final pass of row/column interchange */
    /* to finish */
    for (k = 4 - 2; k >= 0; k--) { /* Don't need to work with 1 by 1 corner*/
        i = pvt_j[k];          /* Rows to swap correspond to pivot COLUMN */
        if (i != k) {          /* If rows are different */
            for (j = 0; j < 4; j++) {
                hold = m[k][j];
                m[k][j] = -m[i][j];
                m[i][j] = hold;
            }
        }

        j = pvt_i[k];         /* Columns to swap correspond to pivot ROW */
        if (j != k)           /* If columns are different */
            for (i = 0; i < 4; i++) {
                hold = m[i][k];
                m[i][k] = -m[i][j];
                m[i][j] = hold;
            }
    }
    return(TRUE);
}


void
lib3ds_matrix_translate(float m[4][4], float x, float y, float z) {
    int i;

    for (i = 0; i < 3; i++) {
        m[3][i] += m[0][i] * x + m[1][i] * y + m[2][i] * z;
    }
}


void
lib3ds_matrix_scale(float m[4][4], float x, float y, float z) {
    int i;

    for (i = 0; i < 4; i++) {
        m[0][i] *= x;
        m[1][i] *= y;
        m[2][i] *= z;
    }
}


void
lib3ds_matrix_rotate_quat(float m[4][4], float q[4]) {
    float s, xs, ys, zs, wx, wy, wz, xx, xy, xz, yy, yz, zz, l;
    float R[4][4];

    l = q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3];
    if (fabs(l) < LIB3DS_EPSILON) {
        s = 1.0f;
    } else {
        s = 2.0f / l;
    }

    xs = q[0] * s;
    ys = q[1] * s;
    zs = q[2] * s;
    wx = q[3] * xs;
    wy = q[3] * ys;
    wz = q[3] * zs;
    xx = q[0] * xs;
    xy = q[0] * ys;
    xz = q[0] * zs;
    yy = q[1] * ys;
    yz = q[1] * zs;
    zz = q[2] * zs;

    R[0][0] = 1.0f - (yy + zz);
    R[1][0] = xy - wz;
    R[2][0] = xz + wy;
    R[0][1] = xy + wz;
    R[1][1] = 1.0f - (xx + zz);
    R[2][1] = yz - wx;
    R[0][2] = xz - wy;
    R[1][2] = yz + wx;
    R[2][2] = 1.0f - (xx + yy);
    R[3][0] = R[3][1] = R[3][2] = R[0][3] = R[1][3] = R[2][3] = 0.0f;
    R[3][3] = 1.0f;

    lib3ds_matrix_mult(m, m, R);
}


void
lib3ds_matrix_rotate(float m[4][4], float angle, float ax, float ay, float az) {
    float q[4];
    float axis[3];

    lib3ds_vector_make(axis, ax, ay, az);
    lib3ds_quat_axis_angle(q, axis, angle);
    lib3ds_matrix_rotate_quat(m, q);
}


void
lib3ds_matrix_camera(float matrix[4][4], float pos[3], float tgt[3], float roll) {
    float M[4][4];
    float x[3], y[3], z[3];

    lib3ds_vector_sub(y, tgt, pos);
    lib3ds_vector_normalize(y);

    if (y[0] != 0. || y[1] != 0) {
        z[0] = 0;
        z[1] = 0;
        z[2] = 1.0;
    } else { /* Special case:  looking straight up or down z axis */
        z[0] = -1.0;
        z[1] = 0;
        z[2] = 0;
    }

    lib3ds_vector_cross(x, y, z);
    lib3ds_vector_cross(z, x, y);
    lib3ds_vector_normalize(x);
    lib3ds_vector_normalize(z);

    lib3ds_matrix_identity(M);
    M[0][0] = x[0];
    M[1][0] = x[1];
    M[2][0] = x[2];
    M[0][1] = y[0];
    M[1][1] = y[1];
    M[2][1] = y[2];
    M[0][2] = z[0];
    M[1][2] = z[1];
    M[2][2] = z[2];

    lib3ds_matrix_identity(matrix);
    lib3ds_matrix_rotate(matrix, roll, 0, 1, 0);
    lib3ds_matrix_mult(matrix, matrix, M);
    lib3ds_matrix_translate(matrix, -pos[0], -pos[1], -pos[2]);
}

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