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    vg_error( "skeleton_bone_id( *, \"%s\" );\n", name );
  65    vg_fatal_exit_loop( "Bone does not exist\n" );
  66
  67    return 0;
  68 }
  69
  70 VG_STATIC void keyframe_copy_pose( mdl_keyframe *kfa, mdl_keyframe *kfb, int num )
  71 {
  72    for( int i=0; i<num; i++ )
  73       kfb[i] = kfa[i];
  74 }
  75
  76 /*
  77  * Lerp between two sets of keyframes and store in dest. Rotations use Nlerp.
  78  */
  79 VG_STATIC void keyframe_lerp_pose( mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
  80                                 mdl_keyframe *kfd, int count )
  81 {
  82    if( t <= 0.01f )
  83    {
  84       keyframe_copy_pose( kfa, kfd, count );
  85       return;
  86    }
  87    else if( t >= 0.99f )
  88    {
  89       keyframe_copy_pose( kfb, kfd, count );
  90       return;
  91    }
  92
  93    for( int i=0; i<count; i++ )
  94    {
  95       v3_lerp( kfa[i].co, kfb[i].co, t, kfd[i].co );
  96       q_nlerp( kfa[i].q,  kfb[i].q,  t, kfd[i].q );
  97       v3_lerp( kfa[i].s,  kfb[i].s,  t, kfd[i].s );
  98    }
  99 }
 100
 101 VG_STATIC void skeleton_lerp_pose( struct skeleton *skele,
 102                                 mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
 103                                 mdl_keyframe *kfd )
 104 {
 105    keyframe_lerp_pose( kfa, kfb, t, kfd, skele->bone_count-1 );
 106 }
 107
 108 /*
 109  * Sample animation between 2 closest frames using time value. Output is a
 110  * keyframe buffer that is allocated with an appropriate size
 111  */
 112 VG_STATIC void skeleton_sample_anim( struct skeleton *skele,
 113                                   struct skeleton_anim *anim,
 114                                   float time,
 115                                   mdl_keyframe *output )
 116 {
 117    float animtime = time*anim->rate;
 118
 119    u32 frame = ((u32)animtime) % anim->length,
 120        next  = (frame+1) % anim->length;
 121
 122    float t = vg_fractf( animtime );
 123
 124    mdl_keyframe *base  = anim->anim_data + (skele->bone_count-1)*frame,
 125                 *nbase = anim->anim_data + (skele->bone_count-1)*next;
 126
 127    skeleton_lerp_pose( skele, base, nbase, t, output );
 128 }
 129
 130 VG_STATIC int skeleton_sample_anim_clamped( struct skeleton *skele,
 131                                          struct skeleton_anim *anim,
 132                                          float time,
 133                                          mdl_keyframe *output )
 134 {
 135    float end = (float)(anim->length-1) / anim->rate;
 136    skeleton_sample_anim( skele, anim, vg_minf( end, time ), output );
 137
 138    if( time > end )
 139       return 0;
 140    else
 141       return 1;
 142 }
 143
 144 typedef enum anim_apply
 145 {
 146    k_anim_apply_always,
 147    k_anim_apply_defer_ik,
 148    k_anim_apply_deffered_only
 149 }
 150 anim_apply;
 151
 152 VG_STATIC int should_apply_bone( struct skeleton *skele, u32 id, anim_apply type )
 153 {
 154    struct skeleton_bone *sb = &skele->bones[ id ],
 155                         *sp = &skele->bones[ sb->parent ];
 156
 157    if( type == k_anim_apply_defer_ik )
 158    {
 159       if( ((sp->flags & k_bone_flag_ik) && !(sb->flags & k_bone_flag_ik))
 160           || sp->defer )
 161       {
 162          sb->defer = 1;
 163          return 0;
 164       }
 165       else
 166       {
 167          sb->defer = 0;
 168          return 1;
 169       }
 170    }
 171    else if( type == k_anim_apply_deffered_only )
 172    {
 173       if( sb->defer )
 174          return 1;
 175       else
 176          return 0;
 177    }
 178
 179    return 1;
 180 }
 181
 182 /*
 183  * Apply block of keyframes to skeletons final pose
 184  */
 185 VG_STATIC void skeleton_apply_pose( struct skeleton *skele, mdl_keyframe *pose,
 186                                  anim_apply passtype )
 187 {
 188    m4x3_identity( skele->final_mtx[0] );
 189    skele->bones[0].defer = 0;
 190    skele->bones[0].flags &= ~k_bone_flag_ik;
 191
 192    for( int i=1; i<skele->bone_count; i++ )
 193    {
 194       struct skeleton_bone *sb = &skele->bones[i],
 195                            *sp = &skele->bones[ sb->parent ];
 196
 197       if( !should_apply_bone( skele, i, passtype ) )
 198          continue;
 199
 200       sb->defer = 0;
 201
 202       /* process pose */
 203       m4x3f posemtx;
 204
 205       v3f temp_delta;
 206       v3_sub( skele->bones[i].co, skele->bones[sb->parent].co, temp_delta );
 207
 208       /* pose matrix */
 209       mdl_keyframe *kf = &pose[i-1];
 210       q_m3x3( kf->q, posemtx );
 211       v3_copy( kf->co, posemtx[3] );
 212       v3_add( temp_delta, posemtx[3], posemtx[3] );
 213
 214       /* final matrix */
 215       m4x3_mul( skele->final_mtx[ sb->parent ], posemtx, skele->final_mtx[i] );
 216    }
 217 }
 218
 219 /*
 220  * creates the reference inverse matrix for an IK bone, as it has an initial
 221  * intrisic rotation based on the direction that the IK is setup..
 222  */
 223 VG_STATIC void skeleton_inverse_for_ik( struct skeleton *skele,
 224                                      v3f ivaxis,
 225                                      u32 id, m3x3f inverse )
 226 {
 227    v3_copy( ivaxis, inverse[0] );
 228    v3_copy( skele->bones[id].end, inverse[1] );
 229    v3_normalize( inverse[1] );
 230    v3_cross( inverse[0], inverse[1], inverse[2] );
 231    m3x3_transpose( inverse, inverse );
 232 }
 233
 234 /*
 235  * Creates inverse rotation matrices which the IK system uses.
 236  */
 237 VG_STATIC void skeleton_create_inverses( struct skeleton *skele )
 238 {
 239    /* IK: inverse 'plane-bone space' axis '(^axis,^bone,...)[base] */
 240    for( int i=0; i<skele->ik_count; i++ )
 241    {
 242       struct skeleton_ik *ik = &skele->ik[i];
 243
 244       m4x3f inverse;
 245       v3f iv0, iv1, ivaxis;
 246       v3_sub( skele->bones[ik->target].co, skele->bones[ik->lower].co, iv0 );
 247       v3_sub( skele->bones[ik->pole].co,   skele->bones[ik->lower].co, iv1 );
 248       v3_cross( iv0, iv1, ivaxis );
 249       v3_normalize( ivaxis );
 250
 251       skeleton_inverse_for_ik( skele, ivaxis, ik->lower, ik->ia );
 252       skeleton_inverse_for_ik( skele, ivaxis, ik->upper, ik->ib );
 253    }
 254 }
 255
 256 /*
 257  * Apply a model matrix to all bones, should be done last
 258  */
 259 VG_STATIC void skeleton_apply_transform( struct skeleton *skele, m4x3f transform )
 260 {
 261    for( int i=0; i<skele->bone_count; i++ )
 262    {
 263       struct skeleton_bone *sb = &skele->bones[i];
 264       m4x3_mul( transform, skele->final_mtx[i], skele->final_mtx[i] );
 265    }
 266 }
 267
 268 /*
 269  * Apply an inverse matrix to all bones which maps vertices from bind space into
 270  * bone relative positions
 271  */
 272 VG_STATIC void skeleton_apply_inverses( struct skeleton *skele )
 273 {
 274    for( int i=0; i<skele->bone_count; i++ )
 275    {
 276       struct skeleton_bone *sb = &skele->bones[i];
 277       m4x3f inverse;
 278       m3x3_identity( inverse );
 279       v3_negate( sb->co, inverse[3] );
 280
 281       m4x3_mul( skele->final_mtx[i], inverse, skele->final_mtx[i] );
 282    }
 283 }
 284
 285 /*
 286  * Apply all IK modifiers (2 bone ik reference from blender is supported)
 287  */
 288 VG_STATIC void skeleton_apply_ik_pass( struct skeleton *skele )
 289 {
 290    for( int i=0; i<skele->ik_count; i++ )
 291    {
 292       struct skeleton_ik *ik = &skele->ik[i];
 293
 294       v3f v0, /* base -> target */
 295           v1, /* base -> pole */
 296           vaxis;
 297
 298       v3f co_base,
 299           co_target,
 300           co_pole;
 301
 302       v3_copy( skele->final_mtx[ik->lower][3], co_base );
 303       v3_copy( skele->final_mtx[ik->target][3], co_target );
 304       v3_copy( skele->final_mtx[ik->pole][3], co_pole );
 305
 306       v3_sub( co_target, co_base, v0 );
 307       v3_sub( co_pole, co_base, v1 );
 308       v3_cross( v0, v1, vaxis );
 309       v3_normalize( vaxis );
 310       v3_normalize( v0 );
 311       v3_cross( vaxis, v0, v1 );
 312
 313       /* localize problem into [x:v0,y:v1] 2d plane */
 314       v2f base = { v3_dot( v0, co_base   ), v3_dot( v1, co_base   ) },
 315           end  = { v3_dot( v0, co_target ), v3_dot( v1, co_target ) },
 316           knee;
 317
 318       /* Compute angles (basic trig)*/
 319       v2f delta;
 320       v2_sub( end, base, delta );
 321
 322       float
 323          l1 = v3_length( skele->bones[ik->lower].end ),
 324          l2 = v3_length( skele->bones[ik->upper].end ),
 325          d = vg_clampf( v2_length(delta), fabsf(l1 - l2), l1+l2-0.00001f ),
 326          c = acosf( (l1*l1 + d*d - l2*l2) / (2.0f*l1*d) ),
 327          rot = atan2f( delta[1], delta[0] ) + c - VG_PIf/2.0f;
 328
 329       knee[0] = sinf(-rot) * l1;
 330       knee[1] = cosf(-rot) * l1;
 331
 332       m4x3_identity( skele->final_mtx[ik->lower] );
 333       m4x3_identity( skele->final_mtx[ik->upper] );
 334
 335       /* create rotation matrix */
 336       v3f co_knee;
 337       v3_muladds( co_base, v0, knee[0], co_knee );
 338       v3_muladds( co_knee, v1, knee[1], co_knee );
 339       vg_line( co_base, co_knee, 0xff00ff00 );
 340
 341       m4x3f transform;
 342       v3_copy( vaxis, transform[0] );
 343       v3_muls( v0, knee[0], transform[1] );
 344       v3_muladds( transform[1], v1, knee[1], transform[1] );
 345       v3_normalize( transform[1] );
 346       v3_cross( transform[0], transform[1], transform[2] );
 347       v3_copy( co_base, transform[3] );
 348
 349       m3x3_mul( transform, ik->ia, transform );
 350       m4x3_copy( transform, skele->final_mtx[ik->lower] );
 351
 352       /* upper/knee bone */
 353       v3_copy( vaxis, transform[0] );
 354       v3_sub( co_target, co_knee, transform[1] );
 355       v3_normalize( transform[1] );
 356       v3_cross( transform[0], transform[1], transform[2] );
 357       v3_copy( co_knee, transform[3] );
 358
 359       m3x3_mul( transform, ik->ib, transform );
 360       m4x3_copy( transform, skele->final_mtx[ik->upper] );
 361    }
 362 }
 363
 364 /*
 365  * Applies the typical operations that you want for an IK rig:
 366  *    Pose, IK, Pose(deferred), Inverses, Transform
 367  */
 368 VG_STATIC void skeleton_apply_standard( struct skeleton *skele, mdl_keyframe *pose,
 369                                      m4x3f transform )
 370 {
 371    skeleton_apply_pose( skele, pose, k_anim_apply_defer_ik );
 372    skeleton_apply_ik_pass( skele );
 373    skeleton_apply_pose( skele, pose, k_anim_apply_deffered_only );
 374    skeleton_apply_inverses( skele );
 375    skeleton_apply_transform( skele, transform );
 376 }
 377
 378 /*
 379  * Get an animation by name
 380  */
 381 VG_STATIC struct skeleton_anim *skeleton_get_anim( struct skeleton *skele,
 382                                                    const char *name )
 383 {
 384    for( int i=0; i<skele->anim_count; i++ )
 385    {
 386       struct skeleton_anim *anim = &skele->anims[i];
 387
 388       if( !strcmp( anim->name, name ) )
 389          return anim;
 390    }
 391
 392    vg_error( "skeleton_get_anim( *, \"%s\" )\n", name );
 393    vg_fatal_exit_loop( "Invalid animation name\n" );
 394
 395    return NULL;
 396 }
 397
 398 VG_STATIC void skeleton_alloc_from( struct skeleton *skele,
 399                                  void *lin_alloc,
 400                                  struct classtype_skeleton *inf )
 401 {
 402    skele->bone_count     = inf->channels;
 403    skele->ik_count       = inf->ik_count;
 404    skele->collider_count = inf->collider_count;
 405    skele->anim_count     = inf->anim_count;
 406
 407    u32 bone_size = sizeof(struct skeleton_bone) * skele->bone_count,
 408        ik_size   = sizeof(struct skeleton_ik)   * skele->ik_count,
 409        mtx_size  = sizeof(m4x3f)                * skele->bone_count,
 410        anim_size = sizeof(struct skeleton_anim) * skele->anim_count;
 411
 412    skele->bones      = vg_linear_alloc( lin_alloc, bone_size );
 413    skele->ik         = vg_linear_alloc( lin_alloc, ik_size );
 414    skele->final_mtx  = vg_linear_alloc( lin_alloc, mtx_size );
 415    skele->anims      = vg_linear_alloc( lin_alloc, anim_size );
 416 }
 417
 418 VG_STATIC void skeleton_fatal_err(void)
 419 {
 420    vg_fatal_exit_loop( "Skeleton setup failed" );
 421 }
 422
 423 /* Setup an animated skeleton from model. mdl's metadata should stick around */
 424 VG_STATIC void skeleton_setup( struct skeleton *skele,
 425                                void *lin_alloc, mdl_context *mdl )
 426 {
 427    u32 bone_count = 1, skeleton_root = 0, ik_count = 0, collider_count = 0;
 428    skele->bone_count = 0;
 429    skele->bones = NULL;
 430    skele->final_mtx = NULL;
 431    skele->anims = NULL;
 432
 433    struct classtype_skeleton *inf = NULL;
 434
 435    for( u32 i=0; i<mdl->info.node_count; i++ )
 436    {
 437       mdl_node *pnode = mdl_node_from_id( mdl, i );
 438
 439       if( pnode->classtype == k_classtype_skeleton )
 440       {
 441          inf = mdl_get_entdata( mdl, pnode );
 442          skeleton_alloc_from( skele, lin_alloc, inf );
 443          skeleton_root = i;
 444       }
 445       else if( skele->bone_count )
 446       {
 447          int is_bone = pnode->classtype == k_classtype_bone;
 448
 449          if( is_bone )
 450          {
 451             if( bone_count == skele->bone_count )
 452             {
 453                vg_error( "too many bones (%u/%u) @%s!\n",
 454                            bone_count, skele->bone_count,
 455                            mdl_pstr( mdl, pnode->pstr_name ));
 456
 457                skeleton_fatal_err();
 458             }
 459
 460             struct skeleton_bone *sb = &skele->bones[bone_count];
 461             struct classtype_bone *bone_inf = mdl_get_entdata( mdl, pnode );
 462
 463             v3_copy( pnode->co, sb->co );
 464             v3_copy( pnode->s, sb->end );
 465             sb->parent = pnode->parent-skeleton_root;
 466             sb->name   = mdl_pstr( mdl, pnode->pstr_name );
 467             sb->flags  = bone_inf->flags;
 468
 469             if( sb->flags & k_bone_flag_ik )
 470             {
 471                skele->bones[ sb->parent ].flags |= k_bone_flag_ik;
 472
 473                if( ik_count == skele->ik_count )
 474                {
 475                   vg_error( "Too many ik bones, corrupt model file\n" );
 476                   skeleton_fatal_err();
 477                }
 478
 479                struct skeleton_ik *ik = &skele->ik[ ik_count ++ ];
 480                ik->upper = bone_count;
 481                ik->lower = sb->parent;
 482                ik->target = bone_inf->ik_target;
 483                ik->pole = bone_inf->ik_pole;
 484             }
 485
 486             sb->orig_node = i;
 487             box_copy( bone_inf->hitbox, sb->hitbox );
 488
 489             if( bone_inf->flags & k_bone_flag_collider_any )
 490             {
 491                if( collider_count == skele->collider_count )
 492                {
 493                   vg_error( "Too many collider bones\n" );
 494                   skeleton_fatal_err();
 495                }
 496
 497                collider_count ++;
 498             }
 499
 500             bone_count ++;
 501          }
 502          else
 503          {
 504             break;
 505          }
 506       }
 507    }
 508
 509    if( !inf )
 510    {
 511       vg_error( "No skeleton in model\n" );
 512       skeleton_fatal_err();
 513    }
 514
 515    if( collider_count != skele->collider_count )
 516    {
 517       vg_error( "Loaded %u colliders out of %u\n", collider_count,
 518                                                    skele->collider_count );
 519       skeleton_fatal_err();
 520    }
 521
 522    if( bone_count != skele->bone_count )
 523    {
 524       vg_error( "Loaded %u bones out of %u\n", bone_count, skele->bone_count );
 525       vg_fatal_exit_loop( "Skeleton setup failed" );
 526       skeleton_fatal_err();
 527    }
 528
 529    if( ik_count != skele->ik_count )
 530    {
 531       vg_error( "Loaded %u ik bones out of %u\n", ik_count, skele->ik_count );
 532       skeleton_fatal_err();
 533    }
 534
 535    /* fill in implicit root bone */
 536    v3_zero( skele->bones[0].co );
 537    v3_copy( (v3f){0.0f,1.0f,0.0f}, skele->bones[0].end );
 538    skele->bones[0].parent = 0xffffffff;
 539    skele->bones[0].flags = 0;
 540    skele->bones[0].name = "[root]";
 541
 542    /* process animation quick refs */
 543    for( int i=0; i<skele->anim_count; i++ )
 544    {
 545       mdl_animation *anim = &mdl->anim_buffer[ inf->anim_start + i ];
 546
 547       skele->anims[i].rate       = anim->rate;
 548       skele->anims[i].length     = anim->length;
 549       skele->anims[i].name       = mdl_pstr(mdl, anim->pstr_name);
 550       skele->anims[i].anim_data  = &mdl->keyframe_buffer[ anim->offset ];
 551
 552       vg_info( "animation[ %f, %u ] '%s'\n", anim->rate,
 553                                              anim->length,
 554                                              skele->anims[i].name );
 555    }
 556
 557    skeleton_create_inverses( skele );
 558    vg_success( "Loaded skeleton with %u bones\n", skele->bone_count );
 559    vg_success( "                     %u colliders\n", skele->collider_count );
 560 }
 561
 562 VG_STATIC void skeleton_debug( struct skeleton *skele )
 563 {
 564    for( int i=0; i<skele->bone_count; i ++ )
 565    {
 566       struct skeleton_bone *sb = &skele->bones[i];
 567
 568       v3f p0, p1;
 569       v3_copy( sb->co, p0 );
 570       v3_add( p0, sb->end, p1 );
 571       //vg_line( p0, p1, 0xffffffff );
 572
 573       m4x3_mulv( skele->final_mtx[i], p0, p0 );
 574       m4x3_mulv( skele->final_mtx[i], p1, p1 );
 575
 576       if( sb->flags & k_bone_flag_deform )
 577       {
 578          if( sb->flags & k_bone_flag_ik )
 579          {
 580             vg_line( p0, p1, 0xff0000ff );
 581          }
 582          else
 583          {
 584             vg_line( p0, p1, 0xffcccccc );
 585          }
 586       }
 587       else
 588          vg_line( p0, p1, 0xff00ffff );
 589    }
 590 }
 591
 592 #endif /* SKELETON_H */