vg_camera.h

   1 #pragma once
   2 #include "vg_m.h"
   3
   4 typedef struct vg_camera vg_camera;
   5 struct vg_camera{
   6    /* Input */
   7    v3f angles;
   8    v3f pos;
   9    f32 fov, nearz, farz;
  10
  11    /* Output */
  12    m4x3f transform,
  13          transform_inverse;
  14
  15    struct vg_camera_mtx{
  16       m4x4f p,
  17             v,
  18             pv;
  19    }
  20    mtx,
  21    mtx_prev;
  22 };
  23
  24 static void vg_camera_lerp_angles( v3f a, v3f b, f32 t, v3f d ){
  25    d[0] = vg_alerpf( a[0], b[0], t );
  26    d[1] = vg_lerpf(  a[1], b[1], t );
  27    d[2] = vg_lerpf(  a[2], b[2], t );
  28 }
  29
  30 /* lerp position, fov, and angles */
  31 static void vg_camera_lerp( vg_camera *a, vg_camera *b, f32 t, vg_camera *d ){
  32    v3_lerp( a->pos, b->pos, t, d->pos );
  33    vg_camera_lerp_angles( a->angles, b->angles, t, d->angles );
  34    d->fov = vg_lerpf( a->fov, b->fov, t );
  35 }
  36
  37 static void vg_camera_copy( vg_camera *a, vg_camera *d ){
  38    v3_copy( a->pos, d->pos );
  39    v3_copy( a->angles, d->angles );
  40    d->fov = a->fov;
  41 }
  42
  43 static void vg_m4x3_transform_camera( m4x3f m, vg_camera *cam ){
  44    m4x3_mulv( m, cam->pos, cam->pos );
  45
  46    v3f v0;
  47    v3_angles_vector( cam->angles, v0 );
  48    m3x3_mulv( m, v0, v0 );
  49    v3_normalize( v0 );
  50    v3_angles( v0, cam->angles );
  51 }
  52
  53 /*
  54  * 1) [angles, pos] -> transform
  55  */
  56 static void vg_camera_update_transform( vg_camera *cam ){
  57    v4f qyaw, qpitch, qcam;
  58    q_axis_angle( qyaw,   (v3f){ 0.0f, 1.0f, 0.0f }, -cam->angles[0] );
  59    q_axis_angle( qpitch, (v3f){ 1.0f, 0.0f, 0.0f }, -cam->angles[1] );
  60
  61    q_mul( qyaw, qpitch, qcam );
  62    q_m3x3( qcam, cam->transform );
  63    v3_copy( cam->pos, cam->transform[3] );
  64 }
  65
  66 /*
  67  * 2) [transform] -> transform_inverse, view matrix
  68  */
  69 static void vg_camera_update_view( vg_camera *cam ){
  70    m4x4_copy( cam->mtx.v,  cam->mtx_prev.v );
  71    m4x3_invert_affine( cam->transform, cam->transform_inverse );
  72    m4x3_expand( cam->transform_inverse, cam->mtx.v );
  73 }
  74
  75 /*
  76  * 3) [fov,nearz,farz] -> projection matrix
  77  */
  78 static void vg_camera_update_projection( vg_camera *cam ){
  79    m4x4_copy( cam->mtx.p,  cam->mtx_prev.p );
  80    m4x4_projection( cam->mtx.p, cam->fov,
  81                     (float)vg.window_x / (float)vg.window_y,
  82                     cam->nearz, cam->farz );
  83 }
  84
  85 /*
  86  * 4) [projection matrix, view matrix] -> previous pv, new pv
  87  */
  88 static void vg_camera_finalize( vg_camera *cam ){
  89    m4x4_copy( cam->mtx.pv, cam->mtx_prev.pv );
  90    m4x4_mul( cam->mtx.p, cam->mtx.v, cam->mtx.pv );
  91 }