editor done

[carveJwlIkooP6JGAAIwe30JlM.git] / player_replay.c

#include "skaterift.h"
#include "player.h"
#include "player_replay.h"
#include "input.h"
#include "gui.h"
#include "freecam.h"

#include "player_walk.h"
#include "player_skate.h"
#include "player_dead.h"
#include "player_glide.h"

struct replay_globals player_replay = 
{
   .active_keyframe = -1,
   .show_ui = 1,
   .editor_mode = 0
};

void replay_clear( replay_buffer *replay )
{
   replay->head = NULL;
   replay->tail = NULL;
   replay->cursor_frame = NULL;
   replay->statehead = NULL;
   replay->cursor = -99999.9;
}

void *replay_frame_data( replay_frame *frame, enum replay_framedata type )
{
   if( frame->data_table[type][1] == 0 )
      return NULL;

   void *baseptr = frame;
   return baseptr + frame->data_table[type][0];
}

static u16 replay_frame_calculate_data_offsets( 
      u16 data_table[k_replay_framedata_rows][2] ){

   u32 total = vg_align8( sizeof(replay_frame) );
   for( u32 i=0; i<k_replay_framedata_rows; i++ ){
      data_table[i][0] = total;
      total += vg_align8(data_table[i][1]);

      if( total > 0xffff )
         vg_fatal_error( "Exceeded frame storage capacity\n" );
   }
   return total;
}

static void replay_tailpop( replay_buffer *replay ){
   if( replay->cursor_frame == replay->tail )
      replay->cursor_frame = NULL;
   if( replay->statehead == replay->tail )
      replay->statehead = NULL;

   replay->tail = replay->tail->r;

   if( replay->tail )
      replay->tail->l = NULL;
   else
      replay->head = NULL;
}

static replay_frame *replay_newframe( replay_buffer *replay, 
                                         u16 animator_size,
                                         u16 gamestate_size,
                                         u16 sfx_count,
                                         bool save_glider ){
   u16 data_table[ k_replay_framedata_rows ][2];
   data_table[ k_replay_framedata_animator ][1]  = animator_size;
   data_table[ k_replay_framedata_gamestate ][1] = gamestate_size;
   data_table[ k_replay_framedata_sfx ][1] = sfx_count*sizeof(struct net_sfx);
   data_table[ k_replay_framedata_internal_gamestate ][1] = 0;
   if( gamestate_size )
   {
      data_table[ k_replay_framedata_internal_gamestate ][1] = 
         sizeof( replay_gamestate );
   }

   data_table[ k_replay_framedata_glider ][1] = 0;
   if( save_glider )
   {
      data_table[ k_replay_framedata_glider ][1] = 
         sizeof(struct replay_glider_data);
   }

   u32 nextsize = replay_frame_calculate_data_offsets( data_table );

   replay_frame *frame = NULL;
   if( replay->head )
   {
      u32 headsize = replay->head->total_size,
          nextpos  = ((void *)replay->head - replay->data) + headsize;

      if( nextpos + nextsize > replay->size )
      {
         nextpos = 0;
         
         /* maintain contiguity */
         while( replay->tail )
         {
            if( (void *)replay->tail - replay->data )
               replay_tailpop( replay );
            else break;
         }
      }

check_again:;
      u32 tailpos = (void *)replay->tail - replay->data;

      if( tailpos >= nextpos )
      {
         if( nextpos + nextsize > tailpos )
         {
            replay_tailpop( replay );

            if( replay->tail )
               goto check_again;
         }
      }

      frame = replay->data + nextpos;

      if( replay->head )
         replay->head->r = frame;
   }
   else
      frame = replay->data;

   for( u32 i=0; i<k_replay_framedata_rows; i++ )
   {
      frame->data_table[i][0] = data_table[i][0];
      frame->data_table[i][1] = data_table[i][1];
   }

   frame->total_size = nextsize;
   frame->l = replay->head;
   frame->r = NULL;
   replay->head = frame;
   if( !replay->tail ) replay->tail = frame;
   if( gamestate_size ) replay->statehead = frame;

   return frame;
}

static void replay_emit_frame_sounds( replay_frame *frame ){
   void *baseptr = frame;
   u16 *inf = frame->data_table[k_replay_framedata_sfx];
   struct net_sfx *buffer = baseptr + inf[0];
   u32 count = inf[1] / sizeof(struct net_sfx);

   for( u32 i=0; i<count; i ++ ){
      net_sfx_play( buffer + i );
   }
}

int replay_seek( replay_buffer *replay, f64 t )
{
   if( !replay->head ) return 0;

   if( t < replay->tail->time ) t = replay->tail->time;
   if( t > replay->head->time ) t = replay->head->time;

   if( !replay->cursor_frame ) {
      replay->cursor = replay->head->time;
      replay->cursor_frame = replay->head;

      if( fabs(replay->head->time-t) > fabs(replay->tail->time-t) ){
         replay->cursor = replay->tail->time;
         replay->cursor_frame = replay->tail;
      }
   }

   f64 dir = t - replay->cursor;
   if( dir == 0.0 ) return 0;
   dir = vg_signf( dir );

   
   u32 i=4096;
   while( i --> 0 ){
      if( dir < 0.0 ){
         if( t > replay->cursor_frame->time ) {
            replay->cursor = t;
            return 1;
         }
      }

      replay_frame *next;
      if( dir > 0.0 ) next = replay->cursor_frame->r;
      else            next = replay->cursor_frame->l;

      if( !next ) break;

      if( dir > 0.0 ){
         if( t < next->time ){
            replay->cursor = t;
            return 1;
         }
      }

      replay_emit_frame_sounds( next );

      replay->cursor_frame = next;
      replay->cursor = next->time;

      if( !i ) return 1;
   }

   replay->cursor = t;
   return 0;
}

replay_frame *replay_find_recent_stateframe( replay_buffer *replay )
{
   replay_frame *frame = replay->cursor_frame;
   u32 i=4096;
   while( i --> 0 ){
      if( !frame ) return frame;
      if( frame->data_table[ k_replay_framedata_gamestate ][1] ) return frame;
      frame = frame->l;
   }

   return NULL;
}

f32 replay_subframe_time( replay_buffer *replay )
{
   replay_frame *frame = replay->cursor_frame;
   if( !frame ) return 0.0f;
   replay_frame *next = frame->r;
   if( next )
   {
      f64 l = next->time - frame->time,
          t = (l <= (1.0/128.0))? 0.0: (replay->cursor - frame->time) / l;
      return vg_clampf( t, 0.0f, 1.0f );
   }
   else 
      return 0.0f;
}

void replay_get_frame_camera( replay_frame *frame, vg_camera *cam )
{
   cam->fov = frame->cam.fov;
   v3_copy( frame->cam.pos, cam->pos );
   v3_copy( frame->cam.angles, cam->angles );
}

void replay_get_camera( replay_buffer *replay, vg_camera *cam )
{
   cam->nearz = 0.1f;
   cam->farz = 100.0f;
   if( replay->cursor_frame )
   {
      replay_frame *next = replay->cursor_frame->r;

      if( next )
      {
         vg_camera temp;
         
         replay_get_frame_camera( replay->cursor_frame, cam );
         replay_get_frame_camera( next, &temp );
         vg_camera_lerp( cam, &temp, replay_subframe_time( replay ), cam );
      }
      else 
      {
         replay_get_frame_camera( replay->cursor_frame, cam );
      }
   }
   else 
   {
      v3_zero( cam->pos );
      v3_zero( cam->angles );
      cam->fov = 90.0f;
   }
}

void skaterift_get_replay_cam( vg_camera *cam )
{
   replay_buffer *replay = &player_replay.local;

   if( player_replay.active_keyframe != -1 )
   {
      replay_keyframe *kf = 
         &player_replay.keyframes[player_replay.active_keyframe];

      v3_copy( kf->cam.pos, cam->pos );
      v3_copy( kf->cam.angles, cam->angles );
      cam->fov = kf->cam.fov;
      return;
   }

   if( player_replay.keyframe_count >= 2 )
   {
      for( u32 i=0; i<player_replay.keyframe_count-1; i ++ )
      {
         replay_keyframe *kf = &player_replay.keyframes[i];

         if( (kf[0].time<=replay->cursor) && (kf[1].time>replay->cursor) )
         {
            f64 l = kf[1].time - kf[0].time,
                t = (l <= (1.0/128.0))? 0.0: (replay->cursor-kf[0].time) / l;

            if( player_replay.keyframe_count >= 3 )
            {
               f32 m_start = 0.5f, m_end = 0.5f;

               if( i > 0 )
               {
                  if( (t < 0.5f) || (i==player_replay.keyframe_count-2) )
                  {
                     kf --;
                  }
               }

               u32 last = player_replay.keyframe_count-1;
               if( kf+0 == player_replay.keyframes ) m_start = 1.0f;
               if( kf+2 == player_replay.keyframes+last ) m_end = 1.0f;

               f32 ts = vg_lerpf( kf[0].time, kf[1].time, 1.0f-m_start ),
                   te = vg_lerpf( kf[1].time, kf[2].time, m_end );

               l = te-ts;
               t = (replay->cursor-ts)/l;

               /* 
                * Adjust t, so that its derivative matches at the endpoints.
                * Since t needs to go from 0 to 1, it will naturally change at 
                * different rates between keyframes. So this smooths it out.
                *
                * Newton method, going through standard direct quadratic eq has 
                * precision / other problems. Also we only care about 0>t>1. 
                */
               f32 b = (kf[1].time-ts)/l,
                  x0 = 1.0-t;
               for( u32 i=0; i<4; i ++ )
               {
                  f32 ix0 = 1.0f-x0,
                      fx_x0 = 2.0f*b*x0*ix0 + ix0*ix0 - t,
                      fxd_x0 = 2.0f*(-2.0f*b*x0 + b + x0 - 1.0f);
                   x0 = x0 - (fx_x0/fxd_x0);
               }
               t = 1.0-x0;

               f32 t0 = t*m_start+(1.0f-m_start),
                   t1 = t*m_end;

               v3f ps, pe, as, ae;
               f32 fs, fe;

               /* first order */
               v3_lerp( kf[0].cam.pos, kf[1].cam.pos, t0, ps );
               vg_camera_lerp_angles( kf[0].cam.angles, kf[1].cam.angles, 
                                      t0, as );
               fs = vg_lerpf( kf[0].cam.fov, kf[1].cam.fov, t0 );

               v3_lerp( kf[1].cam.pos, kf[2].cam.pos, t1, pe );
               vg_camera_lerp_angles( kf[1].cam.angles, kf[2].cam.angles, 
                                      t1, ae );
               fe = vg_lerpf( kf[1].cam.fov, kf[2].cam.fov, t1 );

               /* second order */
               v3_lerp( ps, pe, t, cam->pos );
               vg_camera_lerp_angles( as, ae, t, cam->angles );
               cam->fov = vg_lerpf( fs, fe, t );
            }
            else 
            {
               v3_lerp( kf[0].cam.pos,  kf[1].cam.pos, t, cam->pos );
               vg_camera_lerp_angles( kf[0].cam.angles, kf[1].cam.angles, 
                                      t, cam->angles );
               cam->fov = vg_lerpf( kf[0].cam.fov, kf[1].cam.fov, t );
            }
            return;
         }
      }
   }

   replay_get_camera( replay, cam );
}

struct replay_rb
{
   v3f co, v, w;
   v4f q;
};

void skaterift_record_frame( replay_buffer *replay, int force_gamestate )
{
   f64 delta      = 9999999.9,
       statedelta = 9999999.9;

   if( replay->head )
      delta = vg.time - replay->head->time;

   if( replay->statehead )
      statedelta = vg.time - replay->statehead->time;

   const f64 k_replay_rate = 1.0/30.0,
             k_gamestate_rate = 0.5;

   int save_frame = 0,
       save_state = 0,
       save_glider = 0;

   if( force_gamestate ) save_state = 1;
   if( statedelta > k_gamestate_rate ) save_state = 1;
   if( delta > k_replay_rate ) save_frame = 1;
   if( save_state ) save_frame = 1;

   if( localplayer.have_glider || localplayer.glider_orphan ||
       localplayer.subsystem == k_player_subsystem_glide ){
      save_glider = 1;
   }

   if( !save_frame ) return;

   u16 gamestate_size = 0;
   if( save_state ){
      /* TODO: have as part of system struct */
      gamestate_size = (u32 []){ 
         [k_player_subsystem_walk ] = sizeof(struct player_walk_state),
         [k_player_subsystem_drive] = 0,
         [k_player_subsystem_skate] = sizeof(struct player_skate_state),
         [k_player_subsystem_dead ] = localplayer.ragdoll.part_count * 
                                       sizeof(struct replay_rb),
         [k_player_subsystem_glide] = sizeof(struct replay_rb),
      }[ localplayer.subsystem ];
   }

   u16 animator_size = player_subsystems[localplayer.subsystem]->animator_size;
   
   replay_frame *frame = replay_newframe( replay,
                                          animator_size, gamestate_size, 
                                          localplayer.local_sfx_buffer_count,
                                          save_glider );
   frame->system = localplayer.subsystem;

   if( save_state ){
      replay_gamestate *gs = 
         replay_frame_data( frame, k_replay_framedata_internal_gamestate );

      gs->current_run_version = world_static.current_run_version;

      /* permanent block */
      memcpy( &gs->rb, &localplayer.rb, sizeof(rigidbody) );
      memcpy( &gs->glider_rb, &player_glide.rb, sizeof(rigidbody) );
      memcpy( &gs->cam_control, &localplayer.cam_control, 
               sizeof(struct player_cam_controller) );
      v3_copy( localplayer.angles, gs->angles );

      void *dst = replay_frame_data( frame, k_replay_framedata_gamestate );

      /* subsytem/dynamic block */
      if( localplayer.subsystem == k_player_subsystem_walk )
         memcpy( dst, &player_walk.state, gamestate_size );
      else if( localplayer.subsystem == k_player_subsystem_skate )
         memcpy( dst, &player_skate.state, gamestate_size );
      else if( localplayer.subsystem == k_player_subsystem_dead ){
         struct replay_rb *arr = dst;
         for( u32 i=0; i<localplayer.ragdoll.part_count; i ++ ){
            rigidbody *rb = &localplayer.ragdoll.parts[i].rb;
            v3_copy( rb->co, arr[i].co );
            v3_copy( rb->w, arr[i].w );
            v3_copy( rb->v, arr[i].v );
            v4_copy( rb->q, arr[i].q );
         }
      }
      else if( localplayer.subsystem == k_player_subsystem_glide ){
         struct replay_rb *arr = dst;
         rigidbody *rb = &player_glide.rb;
         v3_copy( rb->co, arr[0].co );
         v3_copy( rb->w, arr[0].w );
         v3_copy( rb->v, arr[0].v );
         v4_copy( rb->q, arr[0].q );
      }
   }

   if( save_glider ){
      struct replay_glider_data *inf = 
         replay_frame_data( frame, k_replay_framedata_glider );

      inf->have_glider   = localplayer.have_glider;
      inf->glider_orphan = localplayer.glider_orphan;
      inf->t             = player_glide.t;
      v3_copy( player_glide.rb.co, inf->co );
      v4_copy( player_glide.rb.q,  inf->q );
   }

   replay->cursor = vg.time;
   replay->cursor_frame = frame;
   frame->time = vg.time;

   /* camera */
   v3_copy( localplayer.cam.pos, frame->cam.pos );
   if( localplayer.gate_waiting ){
      m4x3_mulv( localplayer.gate_waiting->transport, 
                  frame->cam.pos, frame->cam.pos );

      v3f v0;
      v3_angles_vector( localplayer.cam.angles, v0 );
      m3x3_mulv( localplayer.gate_waiting->transport, v0, v0 );
      v3_angles( v0, frame->cam.angles );
   }
   else 
      v3_copy( localplayer.cam.angles, frame->cam.angles );

   frame->cam.fov = localplayer.cam.fov;

   /* animator */
   void *dst = replay_frame_data( frame, k_replay_framedata_animator ),
        *src = player_subsystems[localplayer.subsystem]->animator_data;
   memcpy( dst, src, animator_size );

   /* sound effects */
   memcpy( replay_frame_data( frame, k_replay_framedata_sfx ),
           localplayer.local_sfx_buffer,
           sizeof(struct net_sfx)*localplayer.local_sfx_buffer_count );

   localplayer.local_sfx_buffer_count = 0;
}

static
void skaterift_restore_frame( replay_frame *frame ){
   replay_gamestate *gs = 
      replay_frame_data( frame, k_replay_framedata_internal_gamestate );
   void *src = replay_frame_data( frame, k_replay_framedata_gamestate );
   u16 src_size = frame->data_table[ k_replay_framedata_gamestate ][1];
   world_static.current_run_version = gs->current_run_version;

   if(frame->system == k_player_subsystem_walk ){
      memcpy( &player_walk.state, src, src_size );
   }
   else if( frame->system == k_player_subsystem_skate ){
      memcpy( &player_skate.state, src, src_size );
   }
   else if( frame->system == k_player_subsystem_dead ){
      player__dead_transition(0);
      struct replay_rb *arr = src;

      for( u32 i=0; i<localplayer.ragdoll.part_count; i ++ ){
         struct ragdoll_part *part = &localplayer.ragdoll.parts[i];
         rigidbody *rb = &part->rb;

         v3_copy( arr[i].co, rb->co );
         v3_copy( arr[i].w, rb->w );
         v3_copy( arr[i].v, rb->v );
         v4_copy( arr[i].q, rb->q );

         v3_copy( arr[i].co, part->prev_co );
         v4_copy( arr[i].q, part->prev_q );
         rb_update_matrices( rb );
      }
   }
   else if( frame->system == k_player_subsystem_glide ){
      struct replay_rb *arr = src;
      rigidbody *rb = &player_glide.rb;
      v3_copy( arr[0].co, rb->co );
      v3_copy( arr[0].w, rb->w );
      v3_copy( arr[0].v, rb->v );
      v4_copy( arr[0].q, rb->q );
      rb_update_matrices( rb );
   }

   localplayer.subsystem = frame->system;

   /* restore the seperated glider data if we have it */
   if( frame->data_table[ k_replay_framedata_glider ][1] ){
      struct replay_glider_data *inf = 
         replay_frame_data( frame, k_replay_framedata_glider );

      localplayer.have_glider   = inf->have_glider;
      localplayer.glider_orphan = inf->glider_orphan;
      player_glide.t            = inf->t;
   }
   else {
      localplayer.have_glider = 0;
      localplayer.glider_orphan = 0;
      player_glide.t = 0.0f;
   }

   memcpy( &localplayer.rb, &gs->rb, sizeof(rigidbody) );
   memcpy( &player_glide.rb, &gs->glider_rb, sizeof(rigidbody) );
   v3_copy( gs->angles, localplayer.angles );

   v3_copy( frame->cam.pos, localplayer.cam.pos );
   v3_copy( frame->cam.angles, localplayer.cam.angles );
   localplayer.cam.fov = frame->cam.fov;

   memcpy( &localplayer.cam_control, &gs->cam_control, 
            sizeof(struct player_cam_controller) );

   /* chop end off replay */
   frame->r = NULL;
   player_replay.local.statehead = frame;
   player_replay.local.head = frame;
   player_replay.local.cursor_frame = frame;
   player_replay.local.cursor = frame->time;
   player_replay.replay_control = k_replay_control_scrub;
   skaterift.activity = k_skaterift_default;
   vg.time = frame->time;
}

static void skaterift_replay_resume(void){
   replay_frame *prev = replay_find_recent_stateframe(&player_replay.local);

   if( prev ){
      player_replay.replay_control = k_replay_control_resume;
      player_replay.resume_target = prev;
      player_replay.resume_begin = player_replay.local.cursor;
      player_replay.resume_transition = 0.0f;
   }

   gui_helper_clear();
}

static void skaterift_replay_update_helpers(void);

void skaterift_replay_pre_update(void)
{
   if( skaterift.activity != k_skaterift_replay ) return;

   bool input = player_replay.editor_mode^0x1;

   if( player_replay.replay_control == k_replay_control_resume )
   {
      if( player_replay.local.cursor_frame == player_replay.resume_target ||
          player_replay.local.cursor_frame == NULL )
      {
         skaterift_restore_frame( player_replay.resume_target );
      }
      else 
      {
         vg_slewf( &player_replay.resume_transition, 1.0f, 
                   vg.time_frame_delta * (1.0f/1.0f) );

         if( player_replay.resume_transition >= 1.0f )
            skaterift_restore_frame( player_replay.resume_target );
         else {
            f64 target = vg_lerp( player_replay.resume_begin, 
                           player_replay.resume_target->time, 
                           vg_smoothstepf( player_replay.resume_transition ) );
            if( replay_seek( &player_replay.local, target ) )
               player_replay.track_velocity = 1.0f;
            else
               player_replay.track_velocity = 0.0f;
         }
      }
   }
   else 
   {
      if( input && button_down( k_srbind_replay_play ) )
         player_replay.replay_control = k_replay_control_play;
      if( input && button_down( k_srbind_replay_freecam ) )
      {
         player_replay.use_freecam ^= 0x1;

         if( player_replay.use_freecam )
         {
            replay_get_camera( &player_replay.local, 
                               &player_replay.replay_freecam );
         }
         skaterift_replay_update_helpers();
      }

      f32 target_speed = 0.0f;
      if( input )
         target_speed = axis_state( k_sraxis_replay_h ) * 5.0;

      if( input && button_press( k_srbind_reset ) )
         target_speed += -2.0;

      if( fabsf(target_speed) > 0.01f )
         player_replay.replay_control = k_replay_control_scrub;

      if( player_replay.replay_control == k_replay_control_play )
         target_speed = 1.0;

      vg_slewf( &player_replay.track_velocity, target_speed, 
                18.0f*vg.time_frame_delta );

      if( fabsf( player_replay.track_velocity ) > 0.0001f )
      {
         f64 target = player_replay.local.cursor;
         target += player_replay.track_velocity * vg.time_frame_delta;

         if( !replay_seek( &player_replay.local, target ) )
            player_replay.track_velocity = 0.0f;
      }

      if( input && button_down( k_srbind_mback ) )
      {
         if( player_replay.local.statehead )
            skaterift_restore_frame( player_replay.local.statehead );
         else
            skaterift.activity = k_skaterift_default;
         srinput.state = k_input_state_resume;
         gui_helper_clear();
      }

      if( input )
      {
         if( player_replay.use_freecam )
         {
            freecam_preupdate();
         }
         else 
         {
            if( button_down( k_srbind_replay_resume ) )
            {
               skaterift_replay_resume();
            }
         }
      }
   }
}

static void skaterift_replay_update_helpers(void)
{
   player_replay.helper_resume->greyed = player_replay.use_freecam;

   vg_str freecam_text;
   vg_strnull( &freecam_text, player_replay.helper_freecam->text, 
               GUI_HELPER_TEXT_LENGTH );
   vg_strcat( &freecam_text, 
               player_replay.use_freecam? "exit freecam": "freecam" );
}

static void replay_show_helpers(void)
{
   gui_helper_clear();
   vg_str text;

   if( gui_new_helper( input_axis_list[k_sraxis_replay_h], &text ) )
      vg_strcat( &text, "scrub" );

   if( (player_replay.helper_resume = gui_new_helper( 
               input_button_list[k_srbind_replay_resume], &text )) )
      vg_strcat( &text, "resume" );
   
   if( gui_new_helper( input_button_list[k_srbind_replay_play], &text ))
      vg_strcat( &text, "playback" );

   player_replay.helper_freecam = gui_new_helper(
         input_button_list[k_srbind_replay_freecam], &text );

   skaterift_replay_update_helpers();
}

void skaterift_replay_post_render(void)
{
#ifndef SR_ALLOW_REWIND_HUB
   if( world_static.active_instance != k_world_purpose_client )
      return;
#endif

   /* capture the current resume frame at the very last point */
   if( button_down( k_srbind_reset ) )
   {
      if( skaterift.activity == k_skaterift_default )
      {
         localplayer.rewinded_since_last_gate = 1;
         skaterift.activity = k_skaterift_replay;
         skaterift_record_frame( &player_replay.local, 1 );
         if( player_replay.local.head )
         {
            player_replay.local.cursor = player_replay.local.head->time;
            player_replay.local.cursor_frame = player_replay.local.head;
         }
         player_replay.replay_control = k_replay_control_scrub;
         replay_show_helpers();
      }
   }
}

void skaterift_replay_init(void)
{
   u32 bytes = 1024*1024*10;
   player_replay.local.data = vg_linear_alloc( vg_mem.rtmemory, bytes );
   player_replay.local.size = bytes;
   replay_clear( &player_replay.local );
}

void skaterift_replay_debug_info(void)
{
   player__debugtext( 2, "replay info" );
   replay_buffer *replay = &player_replay.local;

   u32 head = 0,
       tail = 0;
   if( replay->tail ) tail = (void *)replay->tail - replay->data;
   if( replay->head ) head = (void *)replay->head - replay->data;

   player__debugtext( 1, "head @%u | tail @%u\n", head, tail );

   if( replay->statehead ){
      for( u32 i=0; i<k_replay_framedata_rows; i++ ){
         player__debugtext( 1, "[%u]: [%hu, %hu]\n", i,
              replay->statehead->data_table[i][0],
              replay->statehead->data_table[i][1] );
      }
      u32 state = (void *)replay->statehead - replay->data;
      player__debugtext( 1, "gs @%u\n", state );
      player__debugtext( 1, "gamestate_size: %hu\n", 
           replay->statehead->data_table[k_replay_framedata_gamestate][1] );
   }
   else
      player__debugtext( 1, "gs @NULL\n" );

   f64 start = replay->cursor,
       end   = replay->cursor;
   if( replay->tail ) start = replay->tail->time;
   if( replay->head ) end = replay->head->time;

   f64 cur = replay->cursor - start,
       len = end - start;

   player__debugtext( 1, "cursor: %.2fs / %.2fs\n", cur, len );
}

static int _keyframe_cmp( const void *p1, const void *p2 )
{
   const replay_keyframe *kf1 = p1, *kf2 = p2;
   return kf1->time > kf2->time;
}

static void replay_keyframe_sort(void)
{
   qsort( player_replay.keyframes, player_replay.keyframe_count,
          sizeof(replay_keyframe), _keyframe_cmp );
}

static void replay_fly_edit_keyframe( replay_keyframe *kf )
{
   if( ui_click_down( UI_MOUSE_LEFT ) )
   {
      /* init freecam */
      v3_copy( kf->cam.pos, player_replay.replay_freecam.pos );
      v3_copy( kf->cam.angles, player_replay.replay_freecam.angles );
      v3_zero( player_replay.freecam_v );
      v3_zero( player_replay.freecam_w );
      player_replay.replay_freecam.fov = kf->cam.fov;
   }

   /* move freecam */
   vg_ui.wants_mouse = 0;
   freecam_preupdate();

   if( vg_getkey(SDLK_q) )
      player_replay.freecam_v[1] -= vg.time_frame_delta*6.0f*20.0f;
   if( vg_getkey(SDLK_e) )
      player_replay.freecam_v[1] += vg.time_frame_delta*6.0f*20.0f;

   v3_copy( player_replay.replay_freecam.pos, skaterift.cam.pos );
   v3_copy( player_replay.replay_freecam.angles, skaterift.cam.angles);
   skaterift.cam.fov = player_replay.replay_freecam.fov;

   v3_copy( skaterift.cam.pos, kf->cam.pos );
   v3_copy( skaterift.cam.angles, kf->cam.angles );
   kf->cam.fov = skaterift.cam.fov;
}

void skaterift_replay_imgui(void)
{
   if( skaterift.activity != k_skaterift_replay ) return;

   /* extra keys for entering editor */
   static u8 f1_key = 0;
   u8 f1_now = vg_getkey(SDLK_F1);
   if( f1_now && !f1_key && player_replay.show_ui )
   {
      player_replay.editor_mode ^= 0x1;

      if( player_replay.editor_mode )
         gui_helper_clear();
      else
         replay_show_helpers();
   }
   f1_key = f1_now;

   static u8 f2_key = 0;
   u8 f2_now = vg_getkey(SDLK_F2);
   if( f2_now && !f2_key )
   {
      player_replay.show_ui ^= 0x1;
   }
   f2_key = f2_now;

   if( player_replay.editor_mode )
   {
      static u8 space_key = 0;
      u8 space_now = vg_getkey(SDLK_SPACE);
      if( space_now & !space_key )
      {
         player_replay.replay_control ^= k_replay_control_play;
      }
      space_key = space_now;
   }

   if( !player_replay.show_ui ) return;

   if( player_replay.editor_mode )
   {
      u32 colour = ui_opacity( ui_colour(k_ui_fg), 0.3333f );
      ui_rect cx = { vg.window_x/2, 0, 1, vg.window_y },
              cy = { 0, vg.window_y/2, vg.window_x, 1 };
      ui_fill( cx, colour );
      ui_fill( cy, colour );
   }

   replay_buffer *replay = &player_replay.local;
   f64 start = replay->cursor,
       end   = replay->cursor;
   if( replay->tail ) start = replay->tail->time;
   if( replay->head ) end = replay->head->time;
   f64 len = end - start,
       cur = (replay->cursor - start) / len;

   char buffer[ 128 ];

   /* mainbar */
   ui_px height = 32,
         cwidth = 2;
   ui_rect timeline = { 0, 0, vg.window_x, height };
   ui_fill( timeline, ui_colour( k_ui_bg ) );

   /* cursor frame block */
   if( replay->cursor_frame )
   {
      if( replay->cursor_frame->r )
      {
         f64 l = (replay->cursor_frame->r->time-replay->cursor_frame->time)/len,
             s = (replay->cursor_frame->time - start) / len;
         ui_rect box = { s*(f64)vg.window_x, 0, 
                         VG_MAX(4,(ui_px)(l*vg.window_x)), timeline[3]+2 };
         ui_fill( box, ui_colour( k_ui_bg+4 ) );
      }
   }

   /* cursor */
   ui_rect cusor = { cur * (f64)vg.window_x - (cwidth/2), 0, 
                     cwidth, (player_replay.editor_mode? 0: 16) + timeline[3] };
   ui_fill( cusor, ui_colour( k_ui_bg+7 ) );

   /* latest state marker */
   if( replay->statehead )
   {
      f64 t = (replay->statehead->time - start) / len;
      ui_rect tag = { t*(f64)vg.window_x, 0, 2, timeline[3]+8 };
      ui_fill( tag, ui_colour( k_ui_green+k_ui_brighter ) );
   }

   /* previous state marker */
   replay_frame *prev = replay_find_recent_stateframe( replay );
   if( prev )
   {
      f64 t = (prev->time - start) / len;
      ui_rect tag = { t*(f64)vg.window_x, 0, 2, timeline[3]+8 };
      ui_fill( tag, ui_colour( k_ui_yellow+k_ui_brighter ) );
   }

   snprintf( buffer, 128, "-%.2fs (F1: Edit replay)", (end-replay->cursor) );
   ui_text( timeline, buffer, 1, k_ui_align_middle_left, 0 );
   ui_text( timeline, "0s", 1, k_ui_align_middle_right, 0 );

   if( !player_replay.editor_mode ) return;
   vg_ui.wants_mouse = 1;

   ui_rect panel = { 0, timeline[3] + 20, 200, 400 };
   ui_fill( panel, ui_opacity( ui_colour(k_ui_bg), 0.5f ) );
   ui_rect_pad( panel, (ui_px[2]){4,4} );

   if( ui_button( panel, 
            (player_replay.replay_control == k_replay_control_play)? 
               "Pause (space)": "Play (space)" ) == k_ui_button_click )
   {
      player_replay.replay_control ^= k_replay_control_play;
   }

   /* script bar */
   ui_rect script = { 0, height + 2, vg.window_x, 16 };
   ui_fill( script, ui_colour( k_ui_bg ) );

   f64 mouse_t = start + ((f64)vg_ui.mouse[0] / (f64)vg.window_x)*len;

   /* keyframe draw and select */
   bool absorb_by_keyframe = 0;
   ui_px lx = 0;
   for( u32 i=0; i<player_replay.keyframe_count; i ++ )
   {
      replay_keyframe *kf = &player_replay.keyframes[i];
      f64 t = (kf->time-start)/len;

      ui_px x = t*(f64)vg.window_x-8;

      /* draw connections between keyframes */
      if( i )
      {
         ui_rect con = { lx, script[1]+7, x-lx, 1 };
         ui_fill( con, ui_colour(k_ui_blue) );
         vg_line( kf->cam.pos, player_replay.keyframes[i-1].cam.pos, VG__BLUE );
      }

      /* keyframe selection */
      ui_rect tag = { x, script[1], 16, 16 };

      if( ui_inside_rect( tag, vg_ui.mouse ) )
      {
         absorb_by_keyframe = 1;

         if( ui_click_down( UI_MOUSE_LEFT ) )
         {
            if( player_replay.active_keyframe != i )
            {
               player_replay.active_keyframe = i;
               replay_seek( &player_replay.local, kf->time );
            }
         }
         else
         {
            ui_outline( tag, 1, ui_colour(k_ui_fg), 0 );
         }
      }

      /* edit controls */
      u32 drag_colour = ui_opacity( ui_colour(k_ui_bg+2), 0.5f );
      if( i == player_replay.active_keyframe )
      {
         ui_outline( tag, 2, ui_colour(k_ui_fg), 0 );

         ui_rect tray = { tag[0]+8-32, tag[1]+16+2, 64, 16 };
         ui_rect dragbar = { tray[0]+16, tray[1], 32, 16 };

         bool pos_correct = 0;

         if( ui_inside_rect( dragbar, vg_ui.mouse_click ) )
         {
            if( ui_clicking( UI_MOUSE_LEFT ) )
            {
               drag_colour = ui_opacity( ui_colour(k_ui_fg), 0.5f );
               pos_correct = 1;
               replay_seek( &player_replay.local, mouse_t );
            }
            else if( ui_click_up( UI_MOUSE_LEFT ) )
            {
               pos_correct = 1;
               kf->time = mouse_t;
               replay_keyframe_sort();

               for( u32 j=0; j<player_replay.keyframe_count; j ++ )
               {
                  if( player_replay.keyframes[j].time == mouse_t )
                  {
                     player_replay.active_keyframe = j;
                     break;
                  }
               }
            }

            if( pos_correct )
            {
               tag[0] = vg_ui.mouse[0]-8;
               tray[0] = tag[0]+8-32;
               dragbar[0] = tray[0]+16;
            }
         }

         if( ui_inside_rect( dragbar, vg_ui.mouse ) )
         {
            vg_ui.cursor = k_ui_cursor_hand;
         }

         if( !pos_correct )
            ui_fill( tray, ui_opacity( ui_colour(k_ui_bg+2), 0.5f ) );

         ui_fill( dragbar, drag_colour );
         ui_text( dragbar, ":::", 1, k_ui_align_middle_center, 0 );

         if( !pos_correct )
         {
            ui_rect btn = { tray[0], tray[1], 16, 16 };
            if( ui_button_text( btn, "X", 1 ) == k_ui_button_click )
            {
               for( u32 j=i; j<player_replay.keyframe_count-1; j ++ )
                  player_replay.keyframes[j] = player_replay.keyframes[j+1];

               player_replay.keyframe_count --;
               player_replay.active_keyframe = -1;
            }

            ui_rect btn1 = { tray[0]+48, tray[1], 16, 16 };

            enum ui_button_state mask_using = 
                  k_ui_button_holding_inside |
                  k_ui_button_holding_outside |
                  k_ui_button_click;

            if( ui_button_text( btn1, "E", 1 ) & mask_using )
            {
               replay_fly_edit_keyframe( kf );
               ui_set_mouse_pos( btn1[0]+8, btn1[1]+8 );
            }
         }
      }

      ui_fill( tag, ui_colour(k_ui_blue) );
      lx = x;
   }

   /* adding keyframes */
   if( ui_inside_rect( script, vg_ui.mouse ) )
   {
      vg_ui.cursor = k_ui_cursor_hand;

      ui_rect cursor = { vg_ui.mouse[0], script[1], 4, 16 };
      ui_fill( cursor, ui_colour( k_ui_fg ) );

      if( !absorb_by_keyframe && ui_click_down( UI_MOUSE_LEFT ) )
      {
         u32 max = vg_list_size( player_replay.keyframes );
         if( player_replay.keyframe_count == max )
         {
            ui_start_modal( "Maximum keyframes reached", UI_MODAL_BAD );
         }
         else 
         {
            replay_keyframe *kf = 
               &player_replay.keyframes[player_replay.keyframe_count++];

            kf->time = mouse_t;
            v3_copy( skaterift.cam.pos, kf->cam.pos );
            v3_copy( skaterift.cam.angles, kf->cam.angles );
            kf->cam.fov = skaterift.cam.fov;

            replay_keyframe_sort();
         }
      }
   }

   /* timeline scrub */
   bool start_in_timeline = 
      ui_clicking(UI_MOUSE_LEFT) && 
      ui_inside_rect(timeline, vg_ui.mouse_click);
   if( (ui_inside_rect( timeline, vg_ui.mouse )) || start_in_timeline )
   {
      ui_rect cursor = { vg_ui.mouse[0], timeline[1], 4, timeline[3] };
      ui_fill( cursor, ui_colour( k_ui_fg ) );
      vg_ui.cursor = k_ui_cursor_ibeam;

      if( ui_clicking( UI_MOUSE_LEFT ) && start_in_timeline )
      {
         replay_seek( &player_replay.local, mouse_t );
         player_replay.active_keyframe = -1;
      }
   }

   if( ui_button( panel, "Clear keyframes" ) == k_ui_button_click )
   {
      player_replay.keyframe_count = 0;
   }

   if( (ui_button( panel, "Hide UI (F2)" ) == k_ui_button_click) )
   {
      player_replay.show_ui ^= 0x1;
   }

   if( player_replay.active_keyframe != -1 )
   {
      replay_keyframe *kf = 
         &player_replay.keyframes[ player_replay.active_keyframe ];

      enum ui_button_state mask_using = 
            k_ui_button_holding_inside |
            k_ui_button_holding_outside |
            k_ui_button_click;

      if( ui_button( panel, "Edit cam" ) & mask_using )
      {
         replay_fly_edit_keyframe( kf );
      }
   }

   ui_info( panel, "World settings" );
   f32 new_time = world_current_instance()->time;
   if( ui_slider( panel, "Time of day", 0, 1, &new_time, NULL ) )
   {
      world_current_instance()->time = new_time;
   }

   ui_info( panel, "" );
   if( ui_button( panel, "Exit editor (F1)" ) == k_ui_button_click )
   {
      player_replay.editor_mode = 0;
      replay_show_helpers();
   }
}