skeleton.h

   1 /*
   2  * Copyright (C) 2021-2022 Mt.ZERO Software, Harry Godden - All Rights Reserved
   3  */
   4
   5 #ifndef SKELETON_H
   6 #define SKELETON_H
   7
   8 #include "model.h"
   9
  10 struct skeleton
  11 {
  12    struct skeleton_bone
  13    {
  14       v3f co, end;
  15       u32 parent;
  16
  17       u32 flags;
  18       int defer;
  19
  20       mdl_keyframe kf;
  21
  22       u32 orig_node;
  23
  24       boxf hitbox;
  25       const char *name;
  26    }
  27    *bones;
  28    u32 bone_count;
  29
  30    struct skeleton_anim
  31    {
  32       const char *name;
  33       u32 length;
  34
  35       float rate;
  36       mdl_keyframe *anim_data;
  37    }
  38    *anims;
  39    u32 anim_count;
  40
  41    m4x3f *final_mtx;
  42
  43    struct skeleton_ik
  44    {
  45       u32 lower, upper, target, pole;
  46       m3x3f ia, ib;
  47    }
  48    *ik;
  49    u32 ik_count;
  50
  51    u32
  52        collider_count,
  53        bindable_count;
  54 };
  55
  56 VG_STATIC u32 skeleton_bone_id( struct skeleton *skele, const char *name )
  57 {
  58    for( u32 i=1; i<skele->bone_count; i++ )
  59    {
  60       if( !strcmp( skele->bones[i].name, name ))
  61          return i;
  62    }
  63
  64    return 0;
  65 }
  66
  67 VG_STATIC void keyframe_copy_pose( mdl_keyframe *kfa, mdl_keyframe *kfb, int num )
  68 {
  69    for( int i=0; i<num; i++ )
  70       kfb[i] = kfa[i];
  71 }
  72
  73 /*
  74  * Lerp between two sets of keyframes and store in dest. Rotations use Nlerp.
  75  */
  76 VG_STATIC void keyframe_lerp_pose( mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
  77                                 mdl_keyframe *kfd, int count )
  78 {
  79    if( t <= 0.01f )
  80    {
  81       keyframe_copy_pose( kfa, kfd, count );
  82       return;
  83    }
  84    else if( t >= 0.99f )
  85    {
  86       keyframe_copy_pose( kfb, kfd, count );
  87       return;
  88    }
  89
  90    for( int i=0; i<count; i++ )
  91    {
  92       v3_lerp( kfa[i].co, kfb[i].co, t, kfd[i].co );
  93       q_nlerp( kfa[i].q,  kfb[i].q,  t, kfd[i].q );
  94       v3_lerp( kfa[i].s,  kfb[i].s,  t, kfd[i].s );
  95    }
  96 }
  97
  98 VG_STATIC void skeleton_lerp_pose( struct skeleton *skele,
  99                                 mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
 100                                 mdl_keyframe *kfd )
 101 {
 102    keyframe_lerp_pose( kfa, kfb, t, kfd, skele->bone_count-1 );
 103 }
 104
 105 /*
 106  * Sample animation between 2 closest frames using time value. Output is a
 107  * keyframe buffer that is allocated with an appropriate size
 108  */
 109 VG_STATIC void skeleton_sample_anim( struct skeleton *skele,
 110                                   struct skeleton_anim *anim,
 111                                   float time,
 112                                   mdl_keyframe *output )
 113 {
 114    float animtime = time*anim->rate;
 115
 116    u32 frame = ((u32)animtime) % anim->length,
 117        next  = (frame+1) % anim->length;
 118
 119    float t = vg_fractf( animtime );
 120
 121    mdl_keyframe *base  = anim->anim_data + (skele->bone_count-1)*frame,
 122                 *nbase = anim->anim_data + (skele->bone_count-1)*next;
 123
 124    skeleton_lerp_pose( skele, base, nbase, t, output );
 125 }
 126
 127 VG_STATIC int skeleton_sample_anim_clamped( struct skeleton *skele,
 128                                          struct skeleton_anim *anim,
 129                                          float time,
 130                                          mdl_keyframe *output )
 131 {
 132    float end = (float)(anim->length-1) / anim->rate;
 133    skeleton_sample_anim( skele, anim, vg_minf( end, time ), output );
 134
 135    if( time > end )
 136       return 0;
 137    else
 138       return 1;
 139 }
 140
 141 typedef enum anim_apply
 142 {
 143    k_anim_apply_always,
 144    k_anim_apply_defer_ik,
 145    k_anim_apply_deffered_only
 146 }
 147 anim_apply;
 148
 149 VG_STATIC int should_apply_bone( struct skeleton *skele, u32 id, anim_apply type )
 150 {
 151    struct skeleton_bone *sb = &skele->bones[ id ],
 152                         *sp = &skele->bones[ sb->parent ];
 153
 154    if( type == k_anim_apply_defer_ik )
 155    {
 156       if( ((sp->flags & k_bone_flag_ik) && !(sb->flags & k_bone_flag_ik))
 157           || sp->defer )
 158       {
 159          sb->defer = 1;
 160          return 0;
 161       }
 162       else
 163       {
 164          sb->defer = 0;
 165          return 1;
 166       }
 167    }
 168    else if( type == k_anim_apply_deffered_only )
 169    {
 170       if( sb->defer )
 171          return 1;
 172       else
 173          return 0;
 174    }
 175
 176    return 1;
 177 }
 178
 179 /*
 180  * Apply block of keyframes to skeletons final pose
 181  */
 182 VG_STATIC void skeleton_apply_pose( struct skeleton *skele, mdl_keyframe *pose,
 183                                  anim_apply passtype )
 184 {
 185    m4x3_identity( skele->final_mtx[0] );
 186    skele->bones[0].defer = 0;
 187    skele->bones[0].flags &= ~k_bone_flag_ik;
 188
 189    for( int i=1; i<skele->bone_count; i++ )
 190    {
 191       struct skeleton_bone *sb = &skele->bones[i],
 192                            *sp = &skele->bones[ sb->parent ];
 193
 194       if( !should_apply_bone( skele, i, passtype ) )
 195          continue;
 196
 197       sb->defer = 0;
 198
 199       /* process pose */
 200       m4x3f posemtx;
 201
 202       v3f temp_delta;
 203       v3_sub( skele->bones[i].co, skele->bones[sb->parent].co, temp_delta );
 204
 205       /* pose matrix */
 206       mdl_keyframe *kf = &pose[i-1];
 207       q_m3x3( kf->q, posemtx );
 208       v3_copy( kf->co, posemtx[3] );
 209       v3_add( temp_delta, posemtx[3], posemtx[3] );
 210
 211       /* final matrix */
 212       m4x3_mul( skele->final_mtx[ sb->parent ], posemtx, skele->final_mtx[i] );
 213    }
 214 }
 215
 216 /*
 217  * creates the reference inverse matrix for an IK bone, as it has an initial
 218  * intrisic rotation based on the direction that the IK is setup..
 219  */
 220 VG_STATIC void skeleton_inverse_for_ik( struct skeleton *skele,
 221                                      v3f ivaxis,
 222                                      u32 id, m3x3f inverse )
 223 {
 224    v3_copy( ivaxis, inverse[0] );
 225    v3_copy( skele->bones[id].end, inverse[1] );
 226    v3_normalize( inverse[1] );
 227    v3_cross( inverse[0], inverse[1], inverse[2] );
 228    m3x3_transpose( inverse, inverse );
 229 }
 230
 231 /*
 232  * Creates inverse rotation matrices which the IK system uses.
 233  */
 234 VG_STATIC void skeleton_create_inverses( struct skeleton *skele )
 235 {
 236    /* IK: inverse 'plane-bone space' axis '(^axis,^bone,...)[base] */
 237    for( int i=0; i<skele->ik_count; i++ )
 238    {
 239       struct skeleton_ik *ik = &skele->ik[i];
 240
 241       m4x3f inverse;
 242       v3f iv0, iv1, ivaxis;
 243       v3_sub( skele->bones[ik->target].co, skele->bones[ik->lower].co, iv0 );
 244       v3_sub( skele->bones[ik->pole].co,   skele->bones[ik->lower].co, iv1 );
 245       v3_cross( iv0, iv1, ivaxis );
 246       v3_normalize( ivaxis );
 247
 248       skeleton_inverse_for_ik( skele, ivaxis, ik->lower, ik->ia );
 249       skeleton_inverse_for_ik( skele, ivaxis, ik->upper, ik->ib );
 250    }
 251 }
 252
 253 /*
 254  * Apply a model matrix to all bones, should be done last
 255  */
 256 VG_STATIC void skeleton_apply_transform( struct skeleton *skele, m4x3f transform )
 257 {
 258    for( int i=0; i<skele->bone_count; i++ )
 259    {
 260       struct skeleton_bone *sb = &skele->bones[i];
 261       m4x3_mul( transform, skele->final_mtx[i], skele->final_mtx[i] );
 262    }
 263 }
 264
 265 /*
 266  * Apply an inverse matrix to all bones which maps vertices from bind space into
 267  * bone relative positions
 268  */
 269 VG_STATIC void skeleton_apply_inverses( struct skeleton *skele )
 270 {
 271    for( int i=0; i<skele->bone_count; i++ )
 272    {
 273       struct skeleton_bone *sb = &skele->bones[i];
 274       m4x3f inverse;
 275       m3x3_identity( inverse );
 276       v3_negate( sb->co, inverse[3] );
 277
 278       m4x3_mul( skele->final_mtx[i], inverse, skele->final_mtx[i] );
 279    }
 280 }
 281
 282 /*
 283  * Apply all IK modifiers (2 bone ik reference from blender is supported)
 284  */
 285 VG_STATIC void skeleton_apply_ik_pass( struct skeleton *skele )
 286 {
 287    for( int i=0; i<skele->ik_count; i++ )
 288    {
 289       struct skeleton_ik *ik = &skele->ik[i];
 290
 291       v3f v0, /* base -> target */
 292           v1, /* base -> pole */
 293           vaxis;
 294
 295       v3f co_base,
 296           co_target,
 297           co_pole;
 298
 299       v3_copy( skele->final_mtx[ik->lower][3], co_base );
 300       v3_copy( skele->final_mtx[ik->target][3], co_target );
 301       v3_copy( skele->final_mtx[ik->pole][3], co_pole );
 302
 303       v3_sub( co_target, co_base, v0 );
 304       v3_sub( co_pole, co_base, v1 );
 305       v3_cross( v0, v1, vaxis );
 306       v3_normalize( vaxis );
 307       v3_normalize( v0 );
 308       v3_cross( vaxis, v0, v1 );
 309
 310       /* localize problem into [x:v0,y:v1] 2d plane */
 311       v2f base = { v3_dot( v0, co_base   ), v3_dot( v1, co_base   ) },
 312           end  = { v3_dot( v0, co_target ), v3_dot( v1, co_target ) },
 313           knee;
 314
 315       /* Compute angles (basic trig)*/
 316       v2f delta;
 317       v2_sub( end, base, delta );
 318
 319       float
 320          l1 = v3_length( skele->bones[ik->lower].end ),
 321          l2 = v3_length( skele->bones[ik->upper].end ),
 322          d = vg_clampf( v2_length(delta), fabsf(l1 - l2), l1+l2-0.00001f ),
 323          c = acosf( (l1*l1 + d*d - l2*l2) / (2.0f*l1*d) ),
 324          rot = atan2f( delta[1], delta[0] ) + c - VG_PIf/2.0f;
 325
 326       knee[0] = sinf(-rot) * l1;
 327       knee[1] = cosf(-rot) * l1;
 328
 329       m4x3_identity( skele->final_mtx[ik->lower] );
 330       m4x3_identity( skele->final_mtx[ik->upper] );
 331
 332       /* create rotation matrix */
 333       v3f co_knee;
 334       v3_muladds( co_base, v0, knee[0], co_knee );
 335       v3_muladds( co_knee, v1, knee[1], co_knee );
 336       vg_line( co_base, co_knee, 0xff00ff00 );
 337
 338       m4x3f transform;
 339       v3_copy( vaxis, transform[0] );
 340       v3_muls( v0, knee[0], transform[1] );
 341       v3_muladds( transform[1], v1, knee[1], transform[1] );
 342       v3_normalize( transform[1] );
 343       v3_cross( transform[0], transform[1], transform[2] );
 344       v3_copy( co_base, transform[3] );
 345
 346       m3x3_mul( transform, ik->ia, transform );
 347       m4x3_copy( transform, skele->final_mtx[ik->lower] );
 348
 349       /* upper/knee bone */
 350       v3_copy( vaxis, transform[0] );
 351       v3_sub( co_target, co_knee, transform[1] );
 352       v3_normalize( transform[1] );
 353       v3_cross( transform[0], transform[1], transform[2] );
 354       v3_copy( co_knee, transform[3] );
 355
 356       m3x3_mul( transform, ik->ib, transform );
 357       m4x3_copy( transform, skele->final_mtx[ik->upper] );
 358    }
 359 }
 360
 361 /*
 362  * Applies the typical operations that you want for an IK rig:
 363  *    Pose, IK, Pose(deferred), Inverses, Transform
 364  */
 365 VG_STATIC void skeleton_apply_standard( struct skeleton *skele, mdl_keyframe *pose,
 366                                      m4x3f transform )
 367 {
 368    skeleton_apply_pose( skele, pose, k_anim_apply_defer_ik );
 369    skeleton_apply_ik_pass( skele );
 370    skeleton_apply_pose( skele, pose, k_anim_apply_deffered_only );
 371    skeleton_apply_inverses( skele );
 372    skeleton_apply_transform( skele, transform );
 373 }
 374
 375 /*
 376  * Get an animation by name
 377  */
 378 VG_STATIC struct skeleton_anim *skeleton_get_anim( struct skeleton *skele,
 379                                                 const char *name )
 380 {
 381    for( int i=0; i<skele->anim_count; i++ )
 382    {
 383       struct skeleton_anim *anim = &skele->anims[i];
 384
 385       if( !strcmp( anim->name, name ) )
 386          return anim;
 387    }
 388
 389    return NULL;
 390 }
 391
 392 VG_STATIC void skeleton_alloc_from( struct skeleton *skele,
 393                                  void *lin_alloc,
 394                                  struct classtype_skeleton *inf )
 395 {
 396    skele->bone_count     = inf->channels;
 397    skele->ik_count       = inf->ik_count;
 398    skele->collider_count = inf->collider_count;
 399    skele->anim_count     = inf->anim_count;
 400
 401    u32 bone_size = sizeof(struct skeleton_bone) * skele->bone_count,
 402        ik_size   = sizeof(struct skeleton_ik)   * skele->ik_count,
 403        mtx_size  = sizeof(m4x3f)                * skele->bone_count,
 404        anim_size = sizeof(struct skeleton_anim) * skele->anim_count;
 405
 406    skele->bones      = vg_linear_alloc( lin_alloc, bone_size );
 407    skele->ik         = vg_linear_alloc( lin_alloc, ik_size );
 408    skele->final_mtx  = vg_linear_alloc( lin_alloc, mtx_size );
 409    skele->anims      = vg_linear_alloc( lin_alloc, anim_size );
 410 }
 411
 412 VG_STATIC void skeleton_fatal_err(void)
 413 {
 414    vg_fatal_exit_loop( "Skeleton setup failed" );
 415 }
 416
 417 /* Setup an animated skeleton from model. mdl's metadata should stick around */
 418 VG_STATIC void skeleton_setup( struct skeleton *skele,
 419                                void *lin_alloc, mdl_context *mdl )
 420 {
 421    u32 bone_count = 1, skeleton_root = 0, ik_count = 0, collider_count = 0;
 422    skele->bone_count = 0;
 423    skele->bones = NULL;
 424    skele->final_mtx = NULL;
 425    skele->anims = NULL;
 426
 427    struct classtype_skeleton *inf = NULL;
 428
 429    for( u32 i=0; i<mdl->info.node_count; i++ )
 430    {
 431       mdl_node *pnode = mdl_node_from_id( mdl, i );
 432
 433       if( pnode->classtype == k_classtype_skeleton )
 434       {
 435          inf = mdl_get_entdata( mdl, pnode );
 436          skeleton_alloc_from( skele, lin_alloc, inf );
 437          skeleton_root = i;
 438       }
 439       else if( skele->bone_count )
 440       {
 441          int is_bone = pnode->classtype == k_classtype_bone;
 442
 443          if( is_bone )
 444          {
 445             if( bone_count == skele->bone_count )
 446             {
 447                vg_error( "too many bones (%u/%u) @%s!\n",
 448                            bone_count, skele->bone_count,
 449                            mdl_pstr( mdl, pnode->pstr_name ));
 450
 451                skeleton_fatal_err();
 452             }
 453
 454             struct skeleton_bone *sb = &skele->bones[bone_count];
 455             struct classtype_bone *bone_inf = mdl_get_entdata( mdl, pnode );
 456
 457             v3_copy( pnode->co, sb->co );
 458             v3_copy( pnode->s, sb->end );
 459             sb->parent = pnode->parent-skeleton_root;
 460             sb->name   = mdl_pstr( mdl, pnode->pstr_name );
 461             sb->flags  = bone_inf->flags;
 462
 463             if( sb->flags & k_bone_flag_ik )
 464             {
 465                skele->bones[ sb->parent ].flags |= k_bone_flag_ik;
 466
 467                if( ik_count == skele->ik_count )
 468                {
 469                   vg_error( "Too many ik bones, corrupt model file\n" );
 470                   skeleton_fatal_err();
 471                }
 472
 473                struct skeleton_ik *ik = &skele->ik[ ik_count ++ ];
 474                ik->upper = bone_count;
 475                ik->lower = sb->parent;
 476                ik->target = bone_inf->ik_target;
 477                ik->pole = bone_inf->ik_pole;
 478             }
 479
 480             sb->orig_node = i;
 481             box_copy( bone_inf->hitbox, sb->hitbox );
 482
 483             if( bone_inf->flags & k_bone_flag_collider_any )
 484             {
 485                if( collider_count == skele->collider_count )
 486                {
 487                   vg_error( "Too many collider bones\n" );
 488                   skeleton_fatal_err();
 489                }
 490
 491                collider_count ++;
 492             }
 493
 494             bone_count ++;
 495          }
 496          else
 497          {
 498             break;
 499          }
 500       }
 501    }
 502
 503    if( !inf )
 504    {
 505       vg_error( "No skeleton in model\n" );
 506       skeleton_fatal_err();
 507    }
 508
 509    if( collider_count != skele->collider_count )
 510    {
 511       vg_error( "Loaded %u colliders out of %u\n", collider_count,
 512                                                    skele->collider_count );
 513       skeleton_fatal_err();
 514    }
 515
 516    if( bone_count != skele->bone_count )
 517    {
 518       vg_error( "Loaded %u bones out of %u\n", bone_count, skele->bone_count );
 519       vg_fatal_exit_loop( "Skeleton setup failed" );
 520       skeleton_fatal_err();
 521    }
 522
 523    if( ik_count != skele->ik_count )
 524    {
 525       vg_error( "Loaded %u ik bones out of %u\n", ik_count, skele->ik_count );
 526       skeleton_fatal_err();
 527    }
 528
 529    /* fill in implicit root bone */
 530    v3_zero( skele->bones[0].co );
 531    v3_copy( (v3f){0.0f,1.0f,0.0f}, skele->bones[0].end );
 532    skele->bones[0].parent = 0xffffffff;
 533    skele->bones[0].flags = 0;
 534    skele->bones[0].name = "[root]";
 535
 536    /* process animation quick refs */
 537    for( int i=0; i<skele->anim_count; i++ )
 538    {
 539       mdl_animation *anim = &mdl->anim_buffer[ inf->anim_start + i ];
 540
 541       skele->anims[i].rate       = anim->rate;
 542       skele->anims[i].length     = anim->length;
 543       skele->anims[i].name       = mdl_pstr(mdl, anim->pstr_name);
 544       skele->anims[i].anim_data  = &mdl->keyframe_buffer[ anim->offset ];
 545
 546       vg_info( "animation[ %f, %u ] '%s'\n", anim->rate,
 547                                              anim->length,
 548                                              skele->anims[i].name );
 549    }
 550
 551    skeleton_create_inverses( skele );
 552    vg_success( "Loaded skeleton with %u bones\n", skele->bone_count );
 553    vg_success( "                     %u colliders\n", skele->collider_count );
 554 }
 555
 556 VG_STATIC void skeleton_debug( struct skeleton *skele )
 557 {
 558    for( int i=0; i<skele->bone_count; i ++ )
 559    {
 560       struct skeleton_bone *sb = &skele->bones[i];
 561
 562       v3f p0, p1;
 563       v3_copy( sb->co, p0 );
 564       v3_add( p0, sb->end, p1 );
 565       //vg_line( p0, p1, 0xffffffff );
 566
 567       m4x3_mulv( skele->final_mtx[i], p0, p0 );
 568       m4x3_mulv( skele->final_mtx[i], p1, p1 );
 569
 570       if( sb->flags & k_bone_flag_deform )
 571       {
 572          if( sb->flags & k_bone_flag_ik )
 573          {
 574             vg_line( p0, p1, 0xff0000ff );
 575          }
 576          else
 577          {
 578             vg_line( p0, p1, 0xffcccccc );
 579          }
 580       }
 581       else
 582          vg_line( p0, p1, 0xff00ffff );
 583    }
 584 }
 585
 586 #endif /* SKELETON_H */