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 /*
  95  * Lerp between two sets of keyframes and store in dest. Rotations use Nlerp.
  96  */
  97 static void keyframe_lerp_pose( mdl_keyframe *kfa, mdl_keyframe *kfb,
  98                                    float t, mdl_keyframe *kfd, int count )
  99 {
 100    if( t <= 0.0001f ){
 101       keyframe_copy_pose( kfa, kfd, count );
 102       return;
 103    }
 104    else if( t >= 0.9999f ){
 105       keyframe_copy_pose( kfb, kfd, count );
 106       return;
 107    }
 108
 109    for( int i=0; i<count; i++ ){
 110       v3_lerp( kfa[i].co, kfb[i].co, t, kfd[i].co );
 111       q_nlerp( kfa[i].q,  kfb[i].q,  t, kfd[i].q );
 112       v3_lerp( kfa[i].s,  kfb[i].s,  t, kfd[i].s );
 113    }
 114 }
 115
 116 static
 117 void skeleton_lerp_pose( struct skeleton *skele,
 118                          mdl_keyframe *kfa, mdl_keyframe *kfb, float t,
 119                          mdl_keyframe *kfd )
 120 {
 121    keyframe_lerp_pose( kfa, kfb, t, kfd, skele->bone_count-1 );
 122 }
 123
 124 static void skeleton_copy_pose( struct skeleton *skele,
 125                                    mdl_keyframe *kfa, mdl_keyframe *kfd )
 126 {
 127    keyframe_copy_pose( kfa, kfd, skele->bone_count-1 );
 128 }
 129
 130 /*
 131  * Sample animation between 2 closest frames using time value. Output is a
 132  * keyframe buffer that is allocated with an appropriate size
 133  */
 134 static void skeleton_sample_anim( struct skeleton *skele,
 135                                   struct skeleton_anim *anim,
 136                                   float time,
 137                                   mdl_keyframe *output )
 138 {
 139    f32 animtime  = fmodf( time*anim->rate, anim->length ),
 140        animframe = floorf( animtime ),
 141        t = animtime - animframe;
 142
 143    u32 frame = (u32)animframe % anim->length,
 144        next  = (frame+1) % anim->length;
 145
 146    mdl_keyframe *base  = anim->anim_data + (skele->bone_count-1)*frame,
 147                 *nbase = anim->anim_data + (skele->bone_count-1)*next;
 148
 149    skeleton_lerp_pose( skele, base, nbase, t, output );
 150 }
 151
 152 static int skeleton_sample_anim_clamped( struct skeleton *skele,
 153                                          struct skeleton_anim *anim,
 154                                          float time,
 155                                          mdl_keyframe *output )
 156 {
 157    float end = (float)(anim->length-1) / anim->rate;
 158    skeleton_sample_anim( skele, anim, vg_minf( end, time ), output );
 159
 160    if( time > end )
 161       return 0;
 162    else
 163       return 1;
 164 }
 165
 166 typedef enum anim_apply
 167 {
 168    k_anim_apply_always,
 169    k_anim_apply_defer_ik,
 170    k_anim_apply_deffered_only,
 171    k_anim_apply_absolute
 172 }
 173 anim_apply;
 174
 175 static
 176 int should_apply_bone( struct skeleton *skele, u32 id, anim_apply type )
 177 {
 178    struct skeleton_bone *sb = &skele->bones[ id ],
 179                         *sp = &skele->bones[ sb->parent ];
 180
 181    if( type == k_anim_apply_defer_ik ){
 182       if( ((sp->flags & k_bone_flag_ik) && !(sb->flags & k_bone_flag_ik))
 183           || sp->defer )
 184       {
 185          sb->defer = 1;
 186          return 0;
 187       }
 188       else{
 189          sb->defer = 0;
 190          return 1;
 191       }
 192    }
 193    else if( type == k_anim_apply_deffered_only ){
 194       if( sb->defer )
 195          return 1;
 196       else
 197          return 0;
 198    }
 199
 200    return 1;
 201 }
 202
 203 /*
 204  * Apply block of keyframes to skeletons final pose
 205  */
 206 static void skeleton_apply_pose( struct skeleton *skele, mdl_keyframe *pose,
 207                                  anim_apply passtype, m4x3f *final_mtx ){
 208    if( passtype == k_anim_apply_absolute ){
 209       for( u32 i=1; i<skele->bone_count; i++ ){
 210          mdl_keyframe *kf = &pose[i-1];
 211
 212          v3f *posemtx = final_mtx[i];
 213
 214          q_m3x3( kf->q, posemtx );
 215          v3_copy( kf->co, posemtx[3] );
 216       }
 217       return;
 218    }
 219
 220    m4x3_identity( final_mtx[0] );
 221    skele->bones[0].defer = 0;
 222    skele->bones[0].flags &= ~k_bone_flag_ik;
 223
 224    for( u32 i=1; i<skele->bone_count; i++ ){
 225       struct skeleton_bone *sb = &skele->bones[i],
 226                            *sp = &skele->bones[sb->parent];
 227
 228       if( !should_apply_bone( skele, i, passtype ) )
 229          continue;
 230
 231       sb->defer = 0;
 232
 233       /* process pose */
 234       m4x3f posemtx;
 235
 236       v3f temp_delta;
 237       v3_sub( skele->bones[i].co, skele->bones[sb->parent].co, temp_delta );
 238
 239       /* pose matrix */
 240       mdl_keyframe *kf = &pose[i-1];
 241       q_m3x3( kf->q, posemtx );
 242       v3_copy( kf->co, posemtx[3] );
 243       v3_add( temp_delta, posemtx[3], posemtx[3] );
 244
 245       /* final matrix */
 246       m4x3_mul( final_mtx[ sb->parent ], posemtx, final_mtx[i] );
 247    }
 248 }
 249
 250 /*
 251  * Take the final matrices and decompose it into an absolute positioned anim
 252  */
 253 static void skeleton_decompose_mtx_absolute( struct skeleton *skele,
 254                                              mdl_keyframe *anim,
 255                                              m4x3f *final_mtx ){
 256    for( u32 i=1; i<skele->bone_count; i++ ){
 257       struct skeleton_bone *sb = &skele->bones[i];
 258       mdl_keyframe *kf = &anim[i-1];
 259       m4x3_decompose( final_mtx[i], kf->co, kf->q, kf->s );
 260    }
 261 }
 262
 263 /*
 264  * creates the reference inverse matrix for an IK bone, as it has an initial
 265  * intrisic rotation based on the direction that the IK is setup..
 266  */
 267 static void skeleton_inverse_for_ik( struct skeleton *skele,
 268                                      v3f ivaxis,
 269                                      u32 id, m3x3f inverse )
 270 {
 271    v3_copy( ivaxis, inverse[0] );
 272    v3_copy( skele->bones[id].end, inverse[1] );
 273    v3_normalize( inverse[1] );
 274    v3_cross( inverse[0], inverse[1], inverse[2] );
 275    m3x3_transpose( inverse, inverse );
 276 }
 277
 278 /*
 279  * Creates inverse rotation matrices which the IK system uses.
 280  */
 281 static void skeleton_create_inverses( struct skeleton *skele )
 282 {
 283    /* IK: inverse 'plane-bone space' axis '(^axis,^bone,...)[base] */
 284    for( u32 i=0; i<skele->ik_count; i++ ){
 285       struct skeleton_ik *ik = &skele->ik[i];
 286
 287       m4x3f inverse;
 288       v3f iv0, iv1, ivaxis;
 289       v3_sub( skele->bones[ik->target].co, skele->bones[ik->lower].co, iv0 );
 290       v3_sub( skele->bones[ik->pole].co,   skele->bones[ik->lower].co, iv1 );
 291       v3_cross( iv0, iv1, ivaxis );
 292       v3_normalize( ivaxis );
 293
 294       skeleton_inverse_for_ik( skele, ivaxis, ik->lower, ik->ia );
 295       skeleton_inverse_for_ik( skele, ivaxis, ik->upper, ik->ib );
 296    }
 297 }
 298
 299 /*
 300  * Apply a model matrix to all bones, should be done last
 301  */
 302 static
 303 void skeleton_apply_transform( struct skeleton *skele, m4x3f transform,
 304                                m4x3f *final_mtx )
 305 {
 306    for( u32 i=0; i<skele->bone_count; i++ ){
 307       struct skeleton_bone *sb = &skele->bones[i];
 308       m4x3_mul( transform, final_mtx[i], final_mtx[i] );
 309    }
 310 }
 311
 312 /*
 313  * Apply an inverse matrix to all bones which maps vertices from bind space into
 314  * bone relative positions
 315  */
 316 static void skeleton_apply_inverses( struct skeleton *skele, m4x3f *final_mtx ){
 317    for( u32 i=0; i<skele->bone_count; i++ ){
 318       struct skeleton_bone *sb = &skele->bones[i];
 319       m4x3f inverse;
 320       m3x3_identity( inverse );
 321       v3_negate( sb->co, inverse[3] );
 322
 323       m4x3_mul( final_mtx[i], inverse, final_mtx[i] );
 324    }
 325 }
 326
 327 /*
 328  * Apply all IK modifiers (2 bone ik reference from blender is supported)
 329  */
 330 static void skeleton_apply_ik_pass( struct skeleton *skele, m4x3f *final_mtx ){
 331    for( u32 i=0; i<skele->ik_count; i++ ){
 332       struct skeleton_ik *ik = &skele->ik[i];
 333
 334       v3f v0, /* base -> target */
 335           v1, /* base -> pole */
 336           vaxis;
 337
 338       v3f co_base,
 339           co_target,
 340           co_pole;
 341
 342       v3_copy( final_mtx[ik->lower][3], co_base );
 343       v3_copy( final_mtx[ik->target][3], co_target );
 344       v3_copy( final_mtx[ik->pole][3], co_pole );
 345
 346       v3_sub( co_target, co_base, v0 );
 347       v3_sub( co_pole, co_base, v1 );
 348       v3_cross( v0, v1, vaxis );
 349       v3_normalize( vaxis );
 350       v3_normalize( v0 );
 351       v3_cross( vaxis, v0, v1 );
 352
 353       /* localize problem into [x:v0,y:v1] 2d plane */
 354       v2f base = { v3_dot( v0, co_base   ), v3_dot( v1, co_base   ) },
 355           end  = { v3_dot( v0, co_target ), v3_dot( v1, co_target ) },
 356           knee;
 357
 358       /* Compute angles (basic trig)*/
 359       v2f delta;
 360       v2_sub( end, base, delta );
 361
 362       float
 363          l1 = v3_length( skele->bones[ik->lower].end ),
 364          l2 = v3_length( skele->bones[ik->upper].end ),
 365          d = vg_clampf( v2_length(delta), fabsf(l1 - l2), l1+l2-0.00001f ),
 366          c = acosf( (l1*l1 + d*d - l2*l2) / (2.0f*l1*d) ),
 367          rot = atan2f( delta[1], delta[0] ) + c - VG_PIf/2.0f;
 368
 369       knee[0] = sinf(-rot) * l1;
 370       knee[1] = cosf(-rot) * l1;
 371
 372       m4x3_identity( final_mtx[ik->lower] );
 373       m4x3_identity( final_mtx[ik->upper] );
 374
 375       /* create rotation matrix */
 376       v3f co_knee;
 377       v3_muladds( co_base, v0, knee[0], co_knee );
 378       v3_muladds( co_knee, v1, knee[1], co_knee );
 379       vg_line( co_base, co_knee, 0xff00ff00 );
 380
 381       m4x3f transform;
 382       v3_copy( vaxis, transform[0] );
 383       v3_muls( v0, knee[0], transform[1] );
 384       v3_muladds( transform[1], v1, knee[1], transform[1] );
 385       v3_normalize( transform[1] );
 386       v3_cross( transform[0], transform[1], transform[2] );
 387       v3_copy( co_base, transform[3] );
 388
 389       m3x3_mul( transform, ik->ia, transform );
 390       m4x3_copy( transform, final_mtx[ik->lower] );
 391
 392       /* upper/knee bone */
 393       v3_copy( vaxis, transform[0] );
 394       v3_sub( co_target, co_knee, transform[1] );
 395       v3_normalize( transform[1] );
 396       v3_cross( transform[0], transform[1], transform[2] );
 397       v3_copy( co_knee, transform[3] );
 398
 399       m3x3_mul( transform, ik->ib, transform );
 400       m4x3_copy( transform, final_mtx[ik->upper] );
 401    }
 402 }
 403
 404 /*
 405  * Applies the typical operations that you want for an IK rig:
 406  *    Pose, IK, Pose(deferred), Inverses, Transform
 407  */
 408 static void skeleton_apply_standard( struct skeleton *skele, mdl_keyframe *pose,
 409                                      m4x3f transform, m4x3f *final_mtx ){
 410    skeleton_apply_pose( skele, pose, k_anim_apply_defer_ik, final_mtx );
 411    skeleton_apply_ik_pass( skele, final_mtx );
 412    skeleton_apply_pose( skele, pose, k_anim_apply_deffered_only, final_mtx );
 413    skeleton_apply_inverses( skele, final_mtx );
 414    skeleton_apply_transform( skele, transform, final_mtx );
 415 }
 416
 417 /*
 418  * Get an animation by name
 419  */
 420 static struct skeleton_anim *skeleton_get_anim( struct skeleton *skele,
 421                                                    const char *name ){
 422    for( u32 i=0; i<skele->anim_count; i++ ){
 423       struct skeleton_anim *anim = &skele->anims[i];
 424
 425       if( !strcmp( anim->name, name ) )
 426          return anim;
 427    }
 428
 429    vg_error( "skeleton_get_anim( *, \"%s\" )\n", name );
 430    vg_fatal_error( "Invalid animation name\n" );
 431
 432    return NULL;
 433 }
 434
 435 static void skeleton_alloc_from( struct skeleton *skele,
 436                                     void *lin_alloc,
 437                                     mdl_context *mdl,
 438                                     mdl_armature *armature ){
 439    skele->bone_count     = armature->bone_count+1;
 440    skele->anim_count     = armature->anim_count;
 441    skele->ik_count       = 0;
 442    skele->collider_count = 0;
 443
 444    for( u32 i=0; i<armature->bone_count; i++ ){
 445       mdl_bone *bone = mdl_arritm( &mdl->bones, armature->bone_start+i );
 446
 447       if( bone->flags & k_bone_flag_ik )
 448          skele->ik_count ++;
 449
 450       if( bone->collider )
 451          skele->collider_count ++;
 452    }
 453
 454    u32 bone_size = sizeof(struct skeleton_bone) * skele->bone_count,
 455        ik_size   = sizeof(struct skeleton_ik)   * skele->ik_count,
 456        mtx_size  = sizeof(m4x3f)                * skele->bone_count,
 457        anim_size = sizeof(struct skeleton_anim) * skele->anim_count;
 458
 459    skele->bones      = vg_linear_alloc( lin_alloc, bone_size );
 460    skele->ik         = vg_linear_alloc( lin_alloc, ik_size );
 461    //skele->final_mtx  = vg_linear_alloc( lin_alloc, mtx_size );
 462    skele->anims      = vg_linear_alloc( lin_alloc, anim_size );
 463
 464    memset( skele->bones, 0, bone_size );
 465    memset( skele->ik, 0, ik_size );
 466    //memset( skele->final_mtx, 0, mtx_size );
 467    memset( skele->anims, 0, anim_size );
 468 }
 469
 470 static void skeleton_fatal_err(void){
 471    vg_fatal_error( "Skeleton setup failed" );
 472 }
 473
 474 /* Setup an animated skeleton from model. mdl's metadata should stick around */
 475 static void skeleton_setup( struct skeleton *skele,
 476                             void *lin_alloc, mdl_context *mdl ){
 477    u32 ik_count = 0, collider_count = 0;
 478    skele->bone_count = 0;
 479    skele->bones = NULL;
 480    //skele->final_mtx = NULL;
 481    skele->anims = NULL;
 482
 483    if( !mdl->armatures.count ){
 484       vg_error( "No skeleton in model\n" );
 485       skeleton_fatal_err();
 486    }
 487
 488    mdl_armature *armature = mdl_arritm( &mdl->armatures, 0 );
 489    skeleton_alloc_from( skele, lin_alloc, mdl, armature );
 490
 491    for( u32 i=0; i<armature->bone_count; i++ ){
 492       mdl_bone *bone = mdl_arritm( &mdl->bones, armature->bone_start+i );
 493       struct skeleton_bone *sb = &skele->bones[i+1];
 494
 495       v3_copy( bone->co, sb->co );
 496       v3_copy( bone->end, sb->end );
 497
 498       sb->parent = bone->parent;
 499       sb->name   = mdl_pstr( mdl, bone->pstr_name );
 500       sb->flags  = bone->flags;
 501       sb->collider = bone->collider;
 502       sb->orig_bone = bone;
 503
 504       if( sb->flags & k_bone_flag_ik ){
 505          skele->bones[ sb->parent ].flags |= k_bone_flag_ik;
 506
 507          if( ik_count == skele->ik_count ){
 508             vg_error( "Too many ik bones, corrupt model file\n" );
 509             skeleton_fatal_err();
 510          }
 511
 512          struct skeleton_ik *ik = &skele->ik[ ik_count ++ ];
 513          ik->upper = i+1;
 514          ik->lower = bone->parent;
 515          ik->target = bone->ik_target;
 516          ik->pole = bone->ik_pole;
 517       }
 518
 519       box_copy( bone->hitbox, sb->hitbox );
 520
 521       if( bone->collider ){
 522          if( collider_count == skele->collider_count ){
 523             vg_error( "Too many collider bones\n" );
 524             skeleton_fatal_err();
 525          }
 526
 527          collider_count ++;
 528       }
 529    }
 530
 531    /* fill in implicit root bone */
 532    v3_zero( skele->bones[0].co );
 533    v3_copy( (v3f){0.0f,1.0f,0.0f}, skele->bones[0].end );
 534    skele->bones[0].parent = 0xffffffff;
 535    skele->bones[0].flags = 0;
 536    skele->bones[0].name = "[root]";
 537
 538    /* process animation quick refs */
 539    for( u32 i=0; i<skele->anim_count; i++ ){
 540       mdl_animation *anim =
 541          mdl_arritm( &mdl->animations, armature->anim_start+i );
 542
 543       skele->anims[i].rate       = anim->rate;
 544       skele->anims[i].length     = anim->length;
 545       skele->anims[i].name       = mdl_pstr(mdl, anim->pstr_name);
 546       skele->anims[i].anim_data  =
 547          mdl_arritm( &mdl->keyframes, anim->offset );
 548
 549       vg_info( "animation[ %f, %u ] '%s'\n", anim->rate,
 550                                              anim->length,
 551                                              skele->anims[i].name );
 552    }
 553
 554    skeleton_create_inverses( skele );
 555    vg_success( "Loaded skeleton with %u bones\n", skele->bone_count );
 556    vg_success( "                     %u colliders\n", skele->collider_count );
 557 }
 558
 559 static void skeleton_debug( struct skeleton *skele, m4x3f *final_mtx ){
 560    for( u32 i=1; i<skele->bone_count; i ++ ){
 561       struct skeleton_bone *sb = &skele->bones[i];
 562
 563       v3f p0, p1;
 564       v3_copy( sb->co, p0 );
 565       v3_add( p0, sb->end, p1 );
 566
 567       m4x3_mulv( final_mtx[i], p0, p0 );
 568       m4x3_mulv( final_mtx[i], p1, p1 );
 569
 570       if( sb->flags & k_bone_flag_deform ){
 571          if( sb->flags & k_bone_flag_ik ){
 572             vg_line( p0, p1, 0xff0000ff );
 573          }
 574          else{
 575             vg_line( p0, p1, 0xffcccccc );
 576          }
 577       }
 578       else
 579          vg_line( p0, p1, 0xff00ffff );
 580    }
 581 }
 582
 583 #endif /* SKELETON_H */