camera.h

   1 #ifndef CAMERA_H
   2 #define CAMERA_H
   3
   4 #include "skaterift.h"
   5
   6 typedef struct camera camera;
   7 struct camera{
   8    /* Input */
   9    v3f angles;
  10    v3f pos;
  11    float fov, nearz, farz;
  12
  13    /* Output */
  14    m4x3f transform,
  15          transform_inverse;
  16
  17    struct camera_mtx{
  18       m4x4f p,
  19             v,
  20             pv;
  21    }
  22    mtx,
  23    mtx_prev;
  24 };
  25
  26 VG_STATIC void camera_lerp_angles( v3f a, v3f b, float t, v3f d )
  27 {
  28    d[0] = vg_alerpf( a[0], b[0], t );
  29    d[1] = vg_lerpf(  a[1], b[1], t );
  30    d[2] = vg_lerpf(  a[2], b[2], t );
  31 }
  32
  33 VG_STATIC void camera_lerp( camera *a, camera *b, float t, camera *d )
  34 {
  35    v3_lerp( a->pos, b->pos, t, d->pos );
  36    d->angles[0] = vg_alerpf( a->angles[0], b->angles[0], t );
  37    d->angles[1] = vg_lerpf( a->angles[1], b->angles[1], t );
  38    d->angles[2] = vg_lerpf( a->angles[2], b->angles[2], t );
  39    d->fov = vg_lerpf( a->fov, b->fov, t );
  40 }
  41
  42 /*
  43  * 1) [angles, pos] -> transform
  44  */
  45 VG_STATIC void camera_update_transform( camera *cam )
  46 {
  47    v4f qyaw, qpitch, qcam;
  48    q_axis_angle( qyaw,   (v3f){ 0.0f, 1.0f, 0.0f }, -cam->angles[0] );
  49    q_axis_angle( qpitch, (v3f){ 1.0f, 0.0f, 0.0f }, -cam->angles[1] );
  50
  51    q_mul( qyaw, qpitch, qcam );
  52    q_m3x3( qcam, cam->transform );
  53    v3_copy( cam->pos, cam->transform[3] );
  54 }
  55
  56 /*
  57  * 2) [transform] -> transform_inverse, view matrix
  58  */
  59 VG_STATIC void camera_update_view( camera *cam )
  60 {
  61    m4x4_copy( cam->mtx.v,  cam->mtx_prev.v );
  62    m4x3_invert_affine( cam->transform, cam->transform_inverse );
  63    m4x3_expand( cam->transform_inverse, cam->mtx.v );
  64 }
  65
  66 /*
  67  * 3) [fov,nearz,farz] -> projection matrix
  68  */
  69 VG_STATIC void camera_update_projection( camera *cam )
  70 {
  71    m4x4_copy( cam->mtx.p,  cam->mtx_prev.p );
  72    m4x4_projection( cam->mtx.p, cam->fov,
  73                     (float)vg.window_x / (float)vg.window_y,
  74                     cam->nearz, cam->farz );
  75 }
  76
  77 /*
  78  * 4) [projection matrix, view matrix] -> previous pv, new pv
  79  */
  80 VG_STATIC void camera_finalize( camera *cam )
  81 {
  82    m4x4_copy( cam->mtx.pv, cam->mtx_prev.pv );
  83    m4x4_mul( cam->mtx.p, cam->mtx.v, cam->mtx.pv );
  84 }
  85
  86 /*
  87  * http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
  88  */
  89 VG_STATIC void m4x4_clip_projection( m4x4f mat, v4f plane )
  90 {
  91    v4f c =
  92    {
  93       (vg_signf(plane[0]) + mat[2][0]) / mat[0][0],
  94       (vg_signf(plane[1]) + mat[2][1]) / mat[1][1],
  95       -1.0f,
  96       (1.0f + mat[2][2]) / mat[3][2]
  97    };
  98
  99    v4_muls( plane, 2.0f / v4_dot(plane,c), c );
 100
 101    mat[0][2] = c[0];
 102    mat[1][2] = c[1];
 103    mat[2][2] = c[2] + 1.0f;
 104    mat[3][2] = c[3];
 105 }
 106
 107 /*
 108  * Undoes the above operation
 109  */
 110 VG_STATIC void m4x4_reset_clipping( m4x4f mat, float ffar, float fnear )
 111 {
 112    mat[0][2] = 0.0f;
 113    mat[1][2] = 0.0f;
 114    mat[2][2] = -(ffar + fnear) / (ffar - fnear);
 115    mat[3][2] = -2.0f * ffar * fnear / (ffar - fnear);
 116 }
 117
 118 #endif /* CAMERA_H */