camera.h

   1 #ifndef CAMERA_H
   2 #define CAMERA_H
   3
   4 #include "common.h"
   5
   6 typedef struct camera camera;
   7
   8 struct camera
   9 {
  10    /* Input */
  11    v3f angles;
  12    v3f pos;
  13    float fov, nearz, farz;
  14
  15    /* Output */
  16    m4x3f transform,
  17          transform_inverse;
  18
  19    struct camera_mtx{
  20       m4x4f p,
  21             v,
  22             pv;
  23    }
  24    mtx,
  25    mtx_prev;
  26 }
  27 static main_camera, gate_camera;
  28
  29 VG_STATIC void camera_lerp_angles( v3f a, v3f b, float t, v3f d )
  30 {
  31    d[0] = vg_alerpf( a[0], b[0], t );
  32    d[1] = vg_lerpf(  a[1], b[1], t );
  33    d[2] = vg_lerpf(  a[2], b[2], t );
  34 }
  35
  36 VG_STATIC void camera_lerp( camera *a, camera *b, float t, camera *d )
  37 {
  38    v3_lerp( a->pos, b->pos, t, d->pos );
  39    d->angles[0] = vg_alerpf( a->angles[0], b->angles[0], t );
  40    d->angles[1] = vg_lerpf( a->angles[1], b->angles[1], t );
  41    d->angles[2] = vg_lerpf( a->angles[2], b->angles[2], t );
  42    d->fov = vg_lerpf( a->fov, b->fov, t );
  43 }
  44
  45 /*
  46  * 1) [angles, pos] -> transform
  47  */
  48 VG_STATIC void camera_update_transform( camera *cam )
  49 {
  50    v4f qyaw, qpitch, qcam;
  51    q_axis_angle( qyaw,   (v3f){ 0.0f, 1.0f, 0.0f }, -cam->angles[0] );
  52    q_axis_angle( qpitch, (v3f){ 1.0f, 0.0f, 0.0f }, -cam->angles[1] );
  53
  54    q_mul( qyaw, qpitch, qcam );
  55    q_m3x3( qcam, cam->transform );
  56    v3_copy( cam->pos, cam->transform[3] );
  57 }
  58
  59 /*
  60  * 2) [transform] -> transform_inverse, view matrix
  61  */
  62 VG_STATIC void camera_update_view( camera *cam )
  63 {
  64    m4x4_copy( cam->mtx.v,  cam->mtx_prev.v );
  65    m4x3_invert_affine( cam->transform, cam->transform_inverse );
  66    m4x3_expand( cam->transform_inverse, cam->mtx.v );
  67 }
  68
  69 /*
  70  * 3) [fov,nearz,farz] -> projection matrix
  71  */
  72 VG_STATIC void camera_update_projection( camera *cam )
  73 {
  74    m4x4_copy( cam->mtx.p,  cam->mtx_prev.p );
  75    m4x4_projection( cam->mtx.p, cam->fov,
  76                     (float)vg.window_x / (float)vg.window_y,
  77                     cam->nearz, cam->farz );
  78 }
  79
  80 /*
  81  * 4) [projection matrix, view matrix] -> previous pv, new pv
  82  */
  83 VG_STATIC void camera_finalize( camera *cam )
  84 {
  85    m4x4_copy( cam->mtx.pv, cam->mtx_prev.pv );
  86    m4x4_mul( cam->mtx.p, cam->mtx.v, cam->mtx.pv );
  87 }
  88
  89 /*
  90  * http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
  91  */
  92 VG_STATIC void m4x4_clip_projection( m4x4f mat, v4f plane )
  93 {
  94    v4f c =
  95    {
  96       (vg_signf(plane[0]) + mat[2][0]) / mat[0][0],
  97       (vg_signf(plane[1]) + mat[2][1]) / mat[1][1],
  98       -1.0f,
  99       (1.0f + mat[2][2]) / mat[3][2]
 100    };
 101
 102    v4_muls( plane, 2.0f / v4_dot(plane,c), c );
 103
 104    mat[0][2] = c[0];
 105    mat[1][2] = c[1];
 106    mat[2][2] = c[2] + 1.0f;
 107    mat[3][2] = c[3];
 108 }
 109
 110 /*
 111  * Undoes the above operation
 112  */
 113 VG_STATIC void m4x4_reset_clipping( m4x4f mat, float ffar, float fnear )
 114 {
 115    mat[0][2] = 0.0f;
 116    mat[1][2] = 0.0f;
 117    mat[2][2] = -(ffar + fnear) / (ffar - fnear);
 118    mat[3][2] = -2.0f * ffar * fnear / (ffar - fnear);
 119 }
 120
 121 #endif /* CAMERA_H */