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       mdl_bone *orig_bone;
  22
  23       u32 collider;
  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 #if 0
  42    m4x3f *final_mtx;
  43 #endif
  44
  45    struct skeleton_ik
  46    {
  47       u32 lower, upper, target, pole;
  48       m3x3f ia, ib;
  49    }
  50    *ik;
  51    u32 ik_count;
  52
  53    u32
  54        collider_count,
  55        bindable_count;
  56 };
  57
  58 static u32 skeleton_bone_id( struct skeleton *skele, const char *name )
  59 {
  60    for( u32 i=1; i<skele->bone_count; i++ ){
  61       if( !strcmp( skele->bones[i].name, name ))
  62          return i;
  63    }
  64
  65    vg_error( "skeleton_bone_id( *, \"%s\" );\n", name );
  66    vg_fatal_error( "Bone does not exist\n" );
  67
  68    return 0;
  69 }
  70
  71 static void keyframe_copy_pose( mdl_keyframe *kfa, mdl_keyframe *kfb,
  72                                    int num )
  73 {
  74    for( int i=0; i<num; i++ )
  75       kfb[i] = kfa[i];
  76 }
  77
  78
  79 /* apply a rotation from the perspective of root */
  80 static void keyframe_rotate_around( mdl_keyframe *kf,
  81                                     v3f origin, v3f offset, v4f q )
  82 {
  83    v3f v0, co;
  84    v3_add( kf->co, offset, co );
  85    v3_sub( co, origin, v0 );
  86    q_mulv( q, v0, v0 );
  87    v3_add( v0, origin, co );
  88    v3_sub( co, offset, kf->co );
  89
  90    q_mul( q, kf->q, kf->q );
  91    q_normalize( kf->q );
  92 }
  93
  94 static void keyframe_lerp( mdl_keyframe *kfa, mdl_keyframe *kfb, f32 t,
  95                            mdl_keyframe *kfd ){
  96    v3_lerp( kfa->co, kfb->co, t, kfd->co );
  97    q_nlerp( kfa->q,  kfb->q,  t, kfd->q );
  98    v3_lerp( kfa->s,  kfb->s,  t, kfd->s );
  99 }
 100
 101 /*
 102  * Lerp between two sets of keyframes and store in dest. Rotations use Nlerp.
 103  */
 104 static void keyframe_lerp_pose( mdl_keyframe *kfa, mdl_keyframe *kfb,
 105                                 float t, mdl_keyframe *kfd, int count ){
 106    if( t <= 0.0001f ){
 107       keyframe_copy_pose( kfa, kfd, count );
 108       return;
 109    }
 110    else if( t >= 0.9999f ){
 111       keyframe_copy_pose( kfb, kfd, count );
 112       return;
 113    }
 114
 115    for( int i=0; i<count; i++ )
 116       keyframe_lerp( kfa+i, kfb+i, t, kfd+i );
 117 }
 118
 119 static
 120 void skeleton_lerp_pose( struct skeleton *skele,
 121                          mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
 122                          mdl_keyframe *kfd )
 123 {
 124    keyframe_lerp_pose( kfa, kfb, t, kfd, skele->bone_count-1 );
 125 }
 126
 127 static void skeleton_copy_pose( struct skeleton *skele,
 128                                    mdl_keyframe *kfa, mdl_keyframe *kfd )
 129 {
 130    keyframe_copy_pose( kfa, kfd, skele->bone_count-1 );
 131 }
 132
 133 /*
 134  * Sample animation between 2 closest frames using time value. Output is a
 135  * keyframe buffer that is allocated with an appropriate size
 136  */
 137 static void skeleton_sample_anim( struct skeleton *skele,
 138                                   struct skeleton_anim *anim,
 139                                   float time,
 140                                   mdl_keyframe *output )
 141 {
 142    f32 animtime  = fmodf( time*anim->rate, anim->length ),
 143        animframe = floorf( animtime ),
 144        t = animtime - animframe;
 145
 146    u32 frame = (u32)animframe % anim->length,
 147        next  = (frame+1) % anim->length;
 148
 149    mdl_keyframe *base  = anim->anim_data + (skele->bone_count-1)*frame,
 150                 *nbase = anim->anim_data + (skele->bone_count-1)*next;
 151
 152    skeleton_lerp_pose( skele, base, nbase, t, output );
 153 }
 154
 155 static int skeleton_sample_anim_clamped( struct skeleton *skele,
 156                                          struct skeleton_anim *anim,
 157                                          float time,
 158                                          mdl_keyframe *output )
 159 {
 160    float end = (float)(anim->length-1) / anim->rate;
 161    skeleton_sample_anim( skele, anim, vg_minf( end, time ), output );
 162
 163    if( time > end )
 164       return 0;
 165    else
 166       return 1;
 167 }
 168
 169 typedef enum anim_apply
 170 {
 171    k_anim_apply_always,
 172    k_anim_apply_defer_ik,
 173    k_anim_apply_deffered_only,
 174    k_anim_apply_absolute
 175 }
 176 anim_apply;
 177
 178 static
 179 int should_apply_bone( struct skeleton *skele, u32 id, anim_apply type )
 180 {
 181    struct skeleton_bone *sb = &skele->bones[ id ],
 182                         *sp = &skele->bones[ sb->parent ];
 183
 184    if( type == k_anim_apply_defer_ik ){
 185       if( ((sp->flags & k_bone_flag_ik) && !(sb->flags & k_bone_flag_ik))
 186           || sp->defer )
 187       {
 188          sb->defer = 1;
 189          return 0;
 190       }
 191       else{
 192          sb->defer = 0;
 193          return 1;
 194       }
 195    }
 196    else if( type == k_anim_apply_deffered_only ){
 197       if( sb->defer )
 198          return 1;
 199       else
 200          return 0;
 201    }
 202
 203    return 1;
 204 }
 205
 206 /*
 207  * Apply block of keyframes to skeletons final pose
 208  */
 209 static void skeleton_apply_pose( struct skeleton *skele, mdl_keyframe *pose,
 210                                  anim_apply passtype, m4x3f *final_mtx ){
 211    if( passtype == k_anim_apply_absolute ){
 212       for( u32 i=1; i<skele->bone_count; i++ ){
 213          mdl_keyframe *kf = &pose[i-1];
 214
 215          v3f *posemtx = final_mtx[i];
 216
 217          q_m3x3( kf->q, posemtx );
 218          m3x3_scale( posemtx, kf->s );
 219          v3_copy( kf->co, posemtx[3] );
 220       }
 221       return;
 222    }
 223
 224    m4x3_identity( final_mtx[0] );
 225    skele->bones[0].defer = 0;
 226    skele->bones[0].flags &= ~k_bone_flag_ik;
 227
 228    for( u32 i=1; i<skele->bone_count; i++ ){
 229       struct skeleton_bone *sb = &skele->bones[i],
 230                            *sp = &skele->bones[sb->parent];
 231
 232       if( !should_apply_bone( skele, i, passtype ) )
 233          continue;
 234
 235       sb->defer = 0;
 236
 237       /* process pose */
 238       m4x3f posemtx;
 239
 240       v3f temp_delta;
 241       v3_sub( skele->bones[i].co, skele->bones[sb->parent].co, temp_delta );
 242
 243       /* pose matrix */
 244       mdl_keyframe *kf = &pose[i-1];
 245       q_m3x3( kf->q, posemtx );
 246       m3x3_scale( posemtx, kf->s );
 247       v3_copy( kf->co, posemtx[3] );
 248       v3_add( temp_delta, posemtx[3], posemtx[3] );
 249
 250       /* final matrix */
 251       m4x3_mul( final_mtx[ sb->parent ], posemtx, final_mtx[i] );
 252    }
 253 }
 254
 255 /*
 256  * Take the final matrices and decompose it into an absolute positioned anim
 257  */
 258 static void skeleton_decompose_mtx_absolute( struct skeleton *skele,
 259                                              mdl_keyframe *anim,
 260                                              m4x3f *final_mtx ){
 261    for( u32 i=1; i<skele->bone_count; i++ ){
 262       struct skeleton_bone *sb = &skele->bones[i];
 263       mdl_keyframe *kf = &anim[i-1];
 264       m4x3_decompose( final_mtx[i], kf->co, kf->q, kf->s );
 265    }
 266 }
 267
 268 /*
 269  * creates the reference inverse matrix for an IK bone, as it has an initial
 270  * intrisic rotation based on the direction that the IK is setup..
 271  */
 272 static void skeleton_inverse_for_ik( struct skeleton *skele,
 273                                      v3f ivaxis,
 274                                      u32 id, m3x3f inverse )
 275 {
 276    v3_copy( ivaxis, inverse[0] );
 277    v3_copy( skele->bones[id].end, inverse[1] );
 278    v3_normalize( inverse[1] );
 279    v3_cross( inverse[0], inverse[1], inverse[2] );
 280    m3x3_transpose( inverse, inverse );
 281 }
 282
 283 /*
 284  * Creates inverse rotation matrices which the IK system uses.
 285  */
 286 static void skeleton_create_inverses( struct skeleton *skele )
 287 {
 288    /* IK: inverse 'plane-bone space' axis '(^axis,^bone,...)[base] */
 289    for( u32 i=0; i<skele->ik_count; i++ ){
 290       struct skeleton_ik *ik = &skele->ik[i];
 291
 292       m4x3f inverse;
 293       v3f iv0, iv1, ivaxis;
 294       v3_sub( skele->bones[ik->target].co, skele->bones[ik->lower].co, iv0 );
 295       v3_sub( skele->bones[ik->pole].co,   skele->bones[ik->lower].co, iv1 );
 296       v3_cross( iv0, iv1, ivaxis );
 297       v3_normalize( ivaxis );
 298
 299       skeleton_inverse_for_ik( skele, ivaxis, ik->lower, ik->ia );
 300       skeleton_inverse_for_ik( skele, ivaxis, ik->upper, ik->ib );
 301    }
 302 }
 303
 304 /*
 305  * Apply a model matrix to all bones, should be done last
 306  */
 307 static
 308 void skeleton_apply_transform( struct skeleton *skele, m4x3f transform,
 309                                m4x3f *final_mtx )
 310 {
 311    for( u32 i=0; i<skele->bone_count; i++ ){
 312       struct skeleton_bone *sb = &skele->bones[i];
 313       m4x3_mul( transform, final_mtx[i], final_mtx[i] );
 314    }
 315 }
 316
 317 /*
 318  * Apply an inverse matrix to all bones which maps vertices from bind space into
 319  * bone relative positions
 320  */
 321 static void skeleton_apply_inverses( struct skeleton *skele, m4x3f *final_mtx ){
 322    for( u32 i=0; i<skele->bone_count; i++ ){
 323       struct skeleton_bone *sb = &skele->bones[i];
 324       m4x3f inverse;
 325       m3x3_identity( inverse );
 326       v3_negate( sb->co, inverse[3] );
 327
 328       m4x3_mul( final_mtx[i], inverse, final_mtx[i] );
 329    }
 330 }
 331
 332 /*
 333  * Apply all IK modifiers (2 bone ik reference from blender is supported)
 334  */
 335 static void skeleton_apply_ik_pass( struct skeleton *skele, m4x3f *final_mtx ){
 336    for( u32 i=0; i<skele->ik_count; i++ ){
 337       struct skeleton_ik *ik = &skele->ik[i];
 338
 339       v3f v0, /* base -> target */
 340           v1, /* base -> pole */
 341           vaxis;
 342
 343       v3f co_base,
 344           co_target,
 345           co_pole;
 346
 347       v3_copy( final_mtx[ik->lower][3], co_base );
 348       v3_copy( final_mtx[ik->target][3], co_target );
 349       v3_copy( final_mtx[ik->pole][3], co_pole );
 350
 351       v3_sub( co_target, co_base, v0 );
 352       v3_sub( co_pole, co_base, v1 );
 353       v3_cross( v0, v1, vaxis );
 354       v3_normalize( vaxis );
 355       v3_normalize( v0 );
 356       v3_cross( vaxis, v0, v1 );
 357
 358       /* localize problem into [x:v0,y:v1] 2d plane */
 359       v2f base = { v3_dot( v0, co_base   ), v3_dot( v1, co_base   ) },
 360           end  = { v3_dot( v0, co_target ), v3_dot( v1, co_target ) },
 361           knee;
 362
 363       /* Compute angles (basic trig)*/
 364       v2f delta;
 365       v2_sub( end, base, delta );
 366
 367       float
 368          l1 = v3_length( skele->bones[ik->lower].end ),
 369          l2 = v3_length( skele->bones[ik->upper].end ),
 370          d = vg_clampf( v2_length(delta), fabsf(l1 - l2), l1+l2-0.00001f ),
 371          c = acosf( (l1*l1 + d*d - l2*l2) / (2.0f*l1*d) ),
 372          rot = atan2f( delta[1], delta[0] ) + c - VG_PIf/2.0f;
 373
 374       knee[0] = sinf(-rot) * l1;
 375       knee[1] = cosf(-rot) * l1;
 376
 377       m4x3_identity( final_mtx[ik->lower] );
 378       m4x3_identity( final_mtx[ik->upper] );
 379
 380       /* create rotation matrix */
 381       v3f co_knee;
 382       v3_muladds( co_base, v0, knee[0], co_knee );
 383       v3_muladds( co_knee, v1, knee[1], co_knee );
 384       vg_line( co_base, co_knee, 0xff00ff00 );
 385
 386       m4x3f transform;
 387       v3_copy( vaxis, transform[0] );
 388       v3_muls( v0, knee[0], transform[1] );
 389       v3_muladds( transform[1], v1, knee[1], transform[1] );
 390       v3_normalize( transform[1] );
 391       v3_cross( transform[0], transform[1], transform[2] );
 392       v3_copy( co_base, transform[3] );
 393
 394       m3x3_mul( transform, ik->ia, transform );
 395       m4x3_copy( transform, final_mtx[ik->lower] );
 396
 397       /* upper/knee bone */
 398       v3_copy( vaxis, transform[0] );
 399       v3_sub( co_target, co_knee, transform[1] );
 400       v3_normalize( transform[1] );
 401       v3_cross( transform[0], transform[1], transform[2] );
 402       v3_copy( co_knee, transform[3] );
 403
 404       m3x3_mul( transform, ik->ib, transform );
 405       m4x3_copy( transform, final_mtx[ik->upper] );
 406    }
 407 }
 408
 409 /*
 410  * Applies the typical operations that you want for an IK rig:
 411  *    Pose, IK, Pose(deferred), Inverses, Transform
 412  */
 413 static void skeleton_apply_standard( struct skeleton *skele, mdl_keyframe *pose,
 414                                      m4x3f transform, m4x3f *final_mtx ){
 415    skeleton_apply_pose( skele, pose, k_anim_apply_defer_ik, final_mtx );
 416    skeleton_apply_ik_pass( skele, final_mtx );
 417    skeleton_apply_pose( skele, pose, k_anim_apply_deffered_only, final_mtx );
 418    skeleton_apply_inverses( skele, final_mtx );
 419    skeleton_apply_transform( skele, transform, final_mtx );
 420 }
 421
 422 /*
 423  * Get an animation by name
 424  */
 425 static struct skeleton_anim *skeleton_get_anim( struct skeleton *skele,
 426                                                    const char *name ){
 427    for( u32 i=0; i<skele->anim_count; i++ ){
 428       struct skeleton_anim *anim = &skele->anims[i];
 429
 430       if( !strcmp( anim->name, name ) )
 431          return anim;
 432    }
 433
 434    vg_error( "skeleton_get_anim( *, \"%s\" )\n", name );
 435    vg_fatal_error( "Invalid animation name\n" );
 436
 437    return NULL;
 438 }
 439
 440 static void skeleton_alloc_from( struct skeleton *skele,
 441                                     void *lin_alloc,
 442                                     mdl_context *mdl,
 443                                     mdl_armature *armature ){
 444    skele->bone_count     = armature->bone_count+1;
 445    skele->anim_count     = armature->anim_count;
 446    skele->ik_count       = 0;
 447    skele->collider_count = 0;
 448
 449    for( u32 i=0; i<armature->bone_count; i++ ){
 450       mdl_bone *bone = mdl_arritm( &mdl->bones, armature->bone_start+i );
 451
 452       if( bone->flags & k_bone_flag_ik )
 453          skele->ik_count ++;
 454
 455       if( bone->collider )
 456          skele->collider_count ++;
 457    }
 458
 459    u32 bone_size = sizeof(struct skeleton_bone) * skele->bone_count,
 460        ik_size   = sizeof(struct skeleton_ik)   * skele->ik_count,
 461        mtx_size  = sizeof(m4x3f)                * skele->bone_count,
 462        anim_size = sizeof(struct skeleton_anim) * skele->anim_count;
 463
 464    skele->bones      = vg_linear_alloc( lin_alloc, bone_size );
 465    skele->ik         = vg_linear_alloc( lin_alloc, ik_size );
 466    //skele->final_mtx  = vg_linear_alloc( lin_alloc, mtx_size );
 467    skele->anims      = vg_linear_alloc( lin_alloc, anim_size );
 468
 469    memset( skele->bones, 0, bone_size );
 470    memset( skele->ik, 0, ik_size );
 471    //memset( skele->final_mtx, 0, mtx_size );
 472    memset( skele->anims, 0, anim_size );
 473 }
 474
 475 static void skeleton_fatal_err(void){
 476    vg_fatal_error( "Skeleton setup failed" );
 477 }
 478
 479 /* Setup an animated skeleton from model. mdl's metadata should stick around */
 480 static void skeleton_setup( struct skeleton *skele,
 481                             void *lin_alloc, mdl_context *mdl ){
 482    u32 ik_count = 0, collider_count = 0;
 483    skele->bone_count = 0;
 484    skele->bones = NULL;
 485    //skele->final_mtx = NULL;
 486    skele->anims = NULL;
 487
 488    if( !mdl->armatures.count ){
 489       vg_error( "No skeleton in model\n" );
 490       skeleton_fatal_err();
 491    }
 492
 493    mdl_armature *armature = mdl_arritm( &mdl->armatures, 0 );
 494    skeleton_alloc_from( skele, lin_alloc, mdl, armature );
 495
 496    for( u32 i=0; i<armature->bone_count; i++ ){
 497       mdl_bone *bone = mdl_arritm( &mdl->bones, armature->bone_start+i );
 498       struct skeleton_bone *sb = &skele->bones[i+1];
 499
 500       v3_copy( bone->co, sb->co );
 501       v3_copy( bone->end, sb->end );
 502
 503       sb->parent = bone->parent;
 504       sb->name   = mdl_pstr( mdl, bone->pstr_name );
 505       sb->flags  = bone->flags;
 506       sb->collider = bone->collider;
 507       sb->orig_bone = bone;
 508
 509       if( sb->flags & k_bone_flag_ik ){
 510          skele->bones[ sb->parent ].flags |= k_bone_flag_ik;
 511
 512          if( ik_count == skele->ik_count ){
 513             vg_error( "Too many ik bones, corrupt model file\n" );
 514             skeleton_fatal_err();
 515          }
 516
 517          struct skeleton_ik *ik = &skele->ik[ ik_count ++ ];
 518          ik->upper = i+1;
 519          ik->lower = bone->parent;
 520          ik->target = bone->ik_target;
 521          ik->pole = bone->ik_pole;
 522       }
 523
 524       box_copy( bone->hitbox, sb->hitbox );
 525
 526       if( bone->collider ){
 527          if( collider_count == skele->collider_count ){
 528             vg_error( "Too many collider bones\n" );
 529             skeleton_fatal_err();
 530          }
 531
 532          collider_count ++;
 533       }
 534    }
 535
 536    /* fill in implicit root bone */
 537    v3_zero( skele->bones[0].co );
 538    v3_copy( (v3f){0.0f,1.0f,0.0f}, skele->bones[0].end );
 539    skele->bones[0].parent = 0xffffffff;
 540    skele->bones[0].flags = 0;
 541    skele->bones[0].name = "[root]";
 542
 543    /* process animation quick refs */
 544    for( u32 i=0; i<skele->anim_count; i++ ){
 545       mdl_animation *anim =
 546          mdl_arritm( &mdl->animations, armature->anim_start+i );
 547
 548       skele->anims[i].rate       = anim->rate;
 549       skele->anims[i].length     = anim->length;
 550       skele->anims[i].name       = mdl_pstr(mdl, anim->pstr_name);
 551       skele->anims[i].anim_data  =
 552          mdl_arritm( &mdl->keyframes, anim->offset );
 553
 554       vg_info( "animation[ %f, %u ] '%s'\n", anim->rate,
 555                                              anim->length,
 556                                              skele->anims[i].name );
 557    }
 558
 559    skeleton_create_inverses( skele );
 560    vg_success( "Loaded skeleton with %u bones\n", skele->bone_count );
 561    vg_success( "                     %u colliders\n", skele->collider_count );
 562 }
 563
 564 static void skeleton_debug( struct skeleton *skele, m4x3f *final_mtx ){
 565    for( u32 i=1; i<skele->bone_count; i ++ ){
 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
 572       m4x3_mulv( final_mtx[i], p0, p0 );
 573       m4x3_mulv( final_mtx[i], p1, p1 );
 574
 575       if( sb->flags & k_bone_flag_deform ){
 576          if( sb->flags & k_bone_flag_ik ){
 577             vg_line( p0, p1, 0xff0000ff );
 578          }
 579          else{
 580             vg_line( p0, p1, 0xffcccccc );
 581          }
 582       }
 583       else
 584          vg_line( p0, p1, 0xff00ffff );
 585    }
 586 }
 587
 588 #endif /* SKELETON_H */