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