vlc_viewpoint.h

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/*****************************************************************************
 * vlc_viewpoint.h: viewpoint struct and helpers
 *****************************************************************************
 * Copyright (C) 2017 VLC authors and VideoLAN
 *
 * 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.
 *
 * This program 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifndef VLC_VIEWPOINT_H_
#define VLC_VIEWPOINT_H_ 1

#include <vlc_common.h>

#include <math.h>

/**
 * \file
 * Video and audio viewpoint struct and helpers
 */

#define FIELD_OF_VIEW_DEGREES_DEFAULT  80.f
#define FIELD_OF_VIEW_DEGREES_MAX 150.f
#define FIELD_OF_VIEW_DEGREES_MIN 20.f

/**
 * Viewpoints
 */
struct vlc_viewpoint_t {
    float yaw;   /* yaw in degrees */
    float pitch; /* pitch in degrees */
    float roll;  /* roll in degrees */
    float fov;   /* field of view in degrees */
};

static inline void vlc_viewpoint_init( vlc_viewpoint_t *p_vp )
{
    p_vp->yaw = p_vp->pitch = p_vp->roll = 0.0f;
    p_vp->fov = FIELD_OF_VIEW_DEGREES_DEFAULT;
}

static inline void vlc_viewpoint_clip( vlc_viewpoint_t *p_vp )
{
    p_vp->yaw = fmodf( p_vp->yaw, 360.f );
    p_vp->pitch = fmodf( p_vp->pitch, 360.f );
    p_vp->roll = fmodf( p_vp->roll, 360.f );
    p_vp->fov = VLC_CLIP( p_vp->fov, FIELD_OF_VIEW_DEGREES_MIN,
                          FIELD_OF_VIEW_DEGREES_MAX );
}

/**
 * Reverse the viewpoint rotation.
 *
 * It can be used to convert a camera view into a world transformation.
 * It will also copy non-rotation related data from \p src to \p dst.
 *
 * \param dst the viewpoint with the final reversed rotation
 * \param src the viewpoint for which the rotation need to be reversed
 */
static inline void vlc_viewpoint_reverse( vlc_viewpoint_t *dst,
                                          const vlc_viewpoint_t *src )
{
    dst->yaw   = -src->yaw;
    dst->pitch = -src->pitch;
    dst->roll  = -src->roll;

    dst->fov   = src->fov;
}

/**
 * Generate the 4x4 transform matrix corresponding to a viewpoint
 *
 * Convert a vlc_viewpoint_t into a 4x4 transform matrix with a column-major
 * layout.
 * The transformation is applied as-is. you have to reverse the viewpoint with
 * \ref vlc_viewpoint_reverse first if you want to transform the world.
 *
 * \param vp a valid viewpoint object
 * \param matrix a 4x4-sized array which will contain the matrix data
 */
VLC_API
void vlc_viewpoint_to_4x4( const vlc_viewpoint_t *vp, float *matrix );

#endif /* VLC_VIEWPOINT_H_ */