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