src/misc/viewpoint.c

   1 /*****************************************************************************
   2  * viewpoint.c: viewpoint helpers for conversions and transformations
   3  *****************************************************************************
   4  * Copyright (C) 2019 VLC authors and VideoLAN
   5  *
   6  * Authors: Alexandre Janniaux <ajanni@videolabs.io>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include "config.h"
  25 #endif
  26
  27 #include <vlc_viewpoint.h>
  28
  29 void vlc_viewpoint_to_4x4( const vlc_viewpoint_t *vp, float *m )
  30 {
  31     float yaw   = vp->yaw   * (float)M_PI / 180.f + (float)M_PI_2;
  32     float pitch = vp->pitch * (float)M_PI / 180.f;
  33     float roll  = vp->roll  * (float)M_PI / 180.f;
  34
  35     float s, c;
  36
  37     s = sinf(pitch);
  38     c = cosf(pitch);
  39     const float x_rot[4][4] = {
  40         { 1.f,    0.f,    0.f,    0.f },
  41         { 0.f,    c,      -s,      0.f },
  42         { 0.f,    s,      c,      0.f },
  43         { 0.f,    0.f,    0.f,    1.f } };
  44
  45     s = sinf(yaw);
  46     c = cosf(yaw);
  47     const float y_rot[4][4] = {
  48         { c,      0.f,    s,     0.f },
  49         { 0.f,    1.f,    0.f,    0.f },
  50         { -s,      0.f,    c,      0.f },
  51         { 0.f,    0.f,    0.f,    1.f } };
  52
  53     s = sinf(roll);
  54     c = cosf(roll);
  55     const float z_rot[4][4] = {
  56         { c,      s,      0.f,    0.f },
  57         { -s,     c,      0.f,    0.f },
  58         { 0.f,    0.f,    1.f,    0.f },
  59         { 0.f,    0.f,    0.f,    1.f } };
  60
  61     /**
  62      * Column-major matrix multiplication mathematically equal to
  63      * z_rot * x_rot * y_rot
  64      */
  65     memset(m, 0, 16 * sizeof(float));
  66     for (int i=0; i<4; ++i)
  67         for (int j=0; j<4; ++j)
  68             for (int k=0; k<4; ++k)
  69                 for (int l=0; l<4; ++l)
  70                     m[4*i+l] += y_rot[i][j] * x_rot[j][k] * z_rot[k][l];
  71 }