model.h

   1 /*
   2  * Copyright (C) 2021-2022 Mt.ZERO Software, Harry Godden - All Rights Reserved
   3  */
   4
   5 #ifndef MODEL_H
   6 #define MODEL_H
   7
   8 #include "common.h"
   9
  10 typedef struct glmesh glmesh;
  11
  12 typedef struct mdl_vert mdl_vert;
  13 typedef struct mdl_submesh mdl_submesh;
  14 typedef struct mdl_material mdl_material;
  15 typedef struct mdl_node mdl_node;
  16 typedef struct mdl_file_header mdl_file_header;
  17 typedef struct mdl_animation mdl_animation;
  18 typedef struct mdl_keyframe mdl_keyframe;
  19 typedef struct mdl_texture mdl_texture;
  20 typedef struct mdl_context mdl_context;
  21
  22 #define MDL_SIZE_MAX          0x1000000
  23 #define MDL_VERT_MAX          1000000
  24 #define MDL_INDICE_MAX        1000000
  25 #define MDL_MATERIAL_MAX      32
  26 #define MDL_NODE_MAX          4000
  27 #define MDL_SUBMESH_MAX       8000
  28 #define MDL_STRING_LENGTH_MAX 64
  29
  30 enum classtype
  31 {
  32    k_classtype_none                 = 000,
  33    k_classtype_bone                 = 001,
  34    k_classtype_skeleton             = 002,
  35    k_classtype_skin                 = 003,
  36    k_classtype_world_light          = 004,
  37
  38    k_classtype_gate                 = 100,
  39    k_classtype_nonlocal_gate        = 101,
  40    k_classtype_spawn                = 200,
  41    k_classtype_water                = 300,
  42    k_classtype_route                = 400,
  43    k_classtype_route_node           = 401,
  44    k_classtype_audio                = 500,
  45    k_classtype_audio_sprite         = 502,
  46    k_classtype_volume_audio         = 600,
  47 };
  48
  49 enum mdl_shader
  50 {
  51    k_shader_standard                = 0,
  52    k_shader_standard_cutout         = 1,
  53    k_shader_terrain_blend           = 2,
  54    k_shader_standard_vertex_blend   = 3,
  55    k_shader_water                   = 4
  56 };
  57
  58 enum mdl_surface_prop
  59 {
  60    k_surface_prop_concrete          = 0,
  61    k_surface_prop_wood              = 1,
  62    k_surface_prop_grass             = 2,
  63    k_surface_prop_tiles             = 3
  64 };
  65
  66 enum material_flag
  67 {
  68    k_material_flag_skate_surface    = 0x1,
  69    k_material_flag_collision        = 0x2,
  70    k_material_flag_grow_grass       = 0x4,
  71    k_material_flag_grind_surface    = 0x8
  72 };
  73
  74 enum bone_flag
  75 {
  76    k_bone_flag_deform               = 0x1,
  77    k_bone_flag_ik                   = 0x2,
  78    k_bone_flag_collider_box         = 0x4,
  79    k_bone_flag_collider_capsule     = 0x8,
  80    k_bone_flag_collider_reserved0   = 0x10,
  81    k_bone_flag_collider_reserved1   = 0x20,
  82    k_bone_flag_collider_reserved2   = 0x40,
  83    k_bone_flag_collider_reserved3   = 0x80,
  84    k_bone_flag_collider_any         = k_bone_flag_collider_box |
  85                                       k_bone_flag_collider_capsule |
  86                                       k_bone_flag_collider_reserved0 |
  87                                       k_bone_flag_collider_reserved1 |
  88                                       k_bone_flag_collider_reserved2 |
  89                                       k_bone_flag_collider_reserved3,
  90    k_bone_flag_cone_constraint      = 0x100,
  91    k_bone_flag_force_u32            = 0xffffffff
  92 };
  93
  94 #pragma pack(push,1)
  95
  96 /* 48 byte */
  97 struct mdl_vert
  98 {
  99    v3f co,        /* 3*32 */
 100        norm;      /* 3*32 */
 101    v2f uv;        /* 2*32 */
 102
 103    u8  colour[4]; /* 4*8 */
 104    u16 weights[4];/* 4*16 */
 105    u8  groups[4]; /* 4*8 */
 106 };
 107
 108 struct mdl_submesh
 109 {
 110    u32 indice_start,
 111        indice_count,
 112        vertex_start,
 113        vertex_count;
 114
 115    boxf bbx;
 116    u32 material_id;
 117 };
 118
 119 struct mdl_texture
 120 {
 121    u32 pstr_name,
 122        pack_offset,
 123        pack_length;
 124 };
 125
 126 struct mdl_material
 127 {
 128    u32 pstr_name,
 129        shader,
 130        flags,
 131        surface_prop;
 132
 133    v4f colour,
 134        colour1;
 135
 136    u32 tex_diffuse,
 137        tex_decal,
 138        tex_normal;
 139 };
 140
 141 struct mdl_node
 142 {
 143    v3f co;
 144    v4f q;
 145    v3f s;
 146
 147    u32 sub_uid,         /* allocated in-file... too bad. */
 148        submesh_start,
 149        submesh_count,
 150        classtype,
 151        offset,
 152        parent,
 153        pstr_name;
 154 };
 155
 156 struct mdl_keyframe
 157 {
 158    v3f co;
 159    v4f q;
 160    v3f s;
 161 };
 162
 163 struct mdl_animation
 164 {
 165    u32 pstr_name,
 166        length;
 167
 168    float rate;
 169
 170    u32 offset;
 171 };
 172
 173 struct mdl_file_header
 174 {
 175    u32 identifier, version, file_length, pad0;
 176
 177    u32
 178        node_count,      node_offset,
 179        submesh_count,   submesh_offset,
 180        material_count,  material_offset,
 181        texture_count,   texture_offset,
 182        anim_count,      anim_offset,
 183        entdata_size,    entdata_offset,
 184        strings_size,    strings_offset,
 185
 186        keyframe_count,  keyframe_offset,
 187
 188        vertex_count,    vertex_offset,
 189        indice_count,    indice_offset,
 190
 191        pack_size,       pack_offset;
 192 };
 193
 194 /*
 195  * Entity data structures
 196  */
 197
 198 struct classtype_bone            /* 001 */
 199 {
 200    u32 flags,
 201        ik_target,
 202        ik_pole;
 203
 204    boxf hitbox;
 205
 206    v3f conevx, conevy, coneva;
 207    float conet;
 208 };
 209
 210 struct classtype_skeleton        /* 002 */
 211 {
 212    u32 channels,
 213        ik_count,
 214        collider_count,
 215        anim_start,
 216        anim_count;
 217 };
 218
 219 struct classtype_skin            /* 003 */
 220 {
 221    u32 skeleton;
 222 };
 223
 224 struct classtype_world_light     /* 004 */
 225 {
 226    enum light_type
 227    {
 228       k_light_type_point,
 229       k_light_type_spot,
 230       k_light_type_point_nighttime_only,
 231       k_light_type_spot_nighttime_only
 232    }
 233    type;
 234
 235    v4f colour; /* RGB, Energy */
 236    float angle, range;
 237 };
 238
 239
 240 struct classtype_gate            /* 100, 101 */
 241 {
 242    u32 target;
 243    v3f dims;
 244 };
 245
 246 struct classtype_spawn           /* 200 */
 247 {
 248    u32 pstr_alias;
 249 };
 250
 251 struct classtype_water           /* 300 */
 252 {
 253    u32 temp;
 254 };
 255
 256 struct classtype_route           /* 400 */
 257 {
 258    u32 id_start;
 259    u32 pstr_name;
 260    v3f colour;
 261 };
 262
 263 struct classtype_route_node      /* 401 */
 264 {
 265    u32 target, target1;
 266 };
 267
 268
 269 struct classtype_audio           /* 500 */
 270 {
 271    u32 pstr_file,
 272        flags;
 273
 274    float volume;
 275 };
 276
 277 struct classtype_audio_sprite    /* 501 */
 278 {
 279    u32 audio,
 280        category;
 281
 282    float probability;
 283 };
 284
 285 struct classtype_volume_audio    /* 600 */
 286 {
 287    u32 category;
 288 };
 289
 290 struct classtype_volume_event    /* 601 */
 291 {
 292    u32 event;
 293 };
 294
 295 #pragma pack(pop)
 296
 297
 298 struct mdl_context
 299 {
 300    FILE *file;
 301    mdl_file_header info;
 302
 303    /* each buffer becomes availible after each _load function is called */
 304    mdl_node       *node_buffer;     /* mdl_load_metadata() */
 305    mdl_submesh    *submesh_buffer;
 306    mdl_material   *material_buffer;
 307    mdl_texture    *texture_buffer;
 308    mdl_animation  *anim_buffer;
 309    void           *entdata_buffer;
 310    const char     *string_buffer;
 311
 312    mdl_keyframe   *keyframe_buffer; /* mdl_load_anim_data() */
 313
 314    mdl_vert       *vertex_buffer;   /* mdl_load_mesh_data() */
 315    u32            *index_buffer;
 316
 317    void           *pack;            /* mdl_load_pack_data() */
 318 };
 319
 320 /*
 321  * Simple mesh interface for OpenGL
 322  */
 323
 324 struct glmesh
 325 {
 326    GLuint vao, vbo, ebo;
 327    u32 indice_count;
 328    u32 loaded;
 329 };
 330
 331 VG_STATIC void mesh_upload( glmesh *mesh,
 332                          mdl_vert *verts, u32 vert_count,
 333                          u32 *indices, u32 indice_count )
 334 {
 335    //assert( mesh->loaded == 0 );
 336
 337    glGenVertexArrays( 1, &mesh->vao );
 338    glGenBuffers( 1, &mesh->vbo );
 339    glGenBuffers( 1, &mesh->ebo );
 340    glBindVertexArray( mesh->vao );
 341
 342    size_t stride = sizeof(mdl_vert);
 343
 344    glBindBuffer( GL_ARRAY_BUFFER, mesh->vbo );
 345    glBufferData( GL_ARRAY_BUFFER, vert_count*stride, verts, GL_STATIC_DRAW );
 346
 347    glBindVertexArray( mesh->vao );
 348    glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, mesh->ebo );
 349    glBufferData( GL_ELEMENT_ARRAY_BUFFER, indice_count*sizeof(u32),
 350          indices, GL_STATIC_DRAW );
 351
 352    /* 0: coordinates */
 353    glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, stride, (void*)0 );
 354    glEnableVertexAttribArray( 0 );
 355
 356    /* 1: normal */
 357    glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE,
 358          stride, (void *)offsetof(mdl_vert, norm) );
 359    glEnableVertexAttribArray( 1 );
 360
 361    /* 2: uv */
 362    glVertexAttribPointer( 2, 2, GL_FLOAT, GL_FALSE,
 363          stride, (void *)offsetof(mdl_vert, uv) );
 364    glEnableVertexAttribArray( 2 );
 365
 366    /* 3: colour */
 367    glVertexAttribPointer( 3, 4, GL_UNSIGNED_BYTE, GL_TRUE,
 368          stride, (void *)offsetof(mdl_vert, colour) );
 369    glEnableVertexAttribArray( 3 );
 370
 371    /* 4: weights */
 372    glVertexAttribPointer( 4, 4, GL_UNSIGNED_SHORT, GL_TRUE,
 373          stride, (void *)offsetof(mdl_vert, weights) );
 374    glEnableVertexAttribArray( 4 );
 375
 376    /* 5: groups */
 377    glVertexAttribIPointer( 5, 4, GL_UNSIGNED_BYTE,
 378          stride, (void *)offsetof(mdl_vert, groups) );
 379    glEnableVertexAttribArray( 5 );
 380
 381    VG_CHECK_GL_ERR();
 382
 383    mesh->indice_count = indice_count;
 384    mesh->loaded = 1;
 385 }
 386
 387 VG_STATIC void mesh_bind( glmesh *mesh )
 388 {
 389    glBindVertexArray( mesh->vao );
 390 }
 391
 392 VG_STATIC void mesh_drawn( u32 start, u32 count )
 393 {
 394    glDrawElements( GL_TRIANGLES, count, GL_UNSIGNED_INT,
 395          (void *)(start*sizeof(u32)) );
 396 }
 397
 398 VG_STATIC void mesh_draw( glmesh *mesh )
 399 {
 400    mesh_drawn( 0, mesh->indice_count );
 401 }
 402
 403 VG_STATIC void mesh_free( glmesh *mesh )
 404 {
 405    if( mesh->loaded )
 406    {
 407       glDeleteVertexArrays( 1, &mesh->vao );
 408       glDeleteBuffers( 1, &mesh->ebo );
 409       glDeleteBuffers( 1, &mesh->vbo );
 410       mesh->loaded = 0;
 411    }
 412 }
 413
 414 VG_STATIC void mdl_load_fatal_corrupt( mdl_context *mdl )
 415 {
 416    fclose( mdl->file );
 417    vg_file_print_invalid( mdl->file );
 418    vg_fatal_exit_loop( "Corrupt model" );
 419 }
 420
 421 /*
 422  * Model implementation
 423  *
 424  * TODO.
 425  *
 426  * you have two api options for loading a model, first, the easy way:
 427  *       mdl_load ...
 428  *    will put the entire model straight into the linear_alloc
 429  *
 430  * or, to target different allocators:
 431  *
 432  *       mdl_open
 433  *       mdl_load_metadata
 434  *       mdl_load_vertex_data
 435  *       mdl_load_indice_data
 436  *       mdl_close
 437  *
 438  * these should ideally be called in quick succession to limit stalls.
 439  */
 440
 441 /*
 442  * if calling mdl_open, and the file does not exist, the game will fatal quit
 443  */
 444 VG_STATIC void mdl_open( mdl_context *mdl, const char *path )
 445 {
 446    memset( mdl, 0, sizeof( mdl_context ) );
 447    mdl->file = fopen( path, "rb" );
 448
 449    if( !mdl->file )
 450    {
 451       vg_error( "mdl_open('%s'): %s\n", path, strerror(errno) );
 452       vg_fatal_exit_loop( "see above for details" );
 453    }
 454
 455    u64 l = fread( &mdl->info, sizeof(mdl_file_header), 1, mdl->file );
 456    if( l != 1 )
 457       mdl_load_fatal_corrupt( mdl );
 458 }
 459
 460 /*
 461  * Load all metadata (everything up until the large buffers). Probs at most 50k
 462  */
 463 VG_STATIC void mdl_load_metadata( mdl_context *mdl, void *lin_alloc )
 464 {
 465    assert( mdl->file );
 466
 467    u64 lheader  = sizeof(mdl_file_header),
 468        ldata    = mdl->info.keyframe_offset - lheader;
 469
 470    void *all_data = vg_linear_alloc( lin_alloc, ldata );
 471
 472    fseek( mdl->file, lheader, SEEK_SET );
 473    u64 l = fread( all_data, ldata, 1, mdl->file );
 474
 475    if( l != 1 )
 476    {
 477       vg_file_print_invalid( mdl->file );
 478       vg_fatal_exit_loop( "Corrupt model" );
 479    }
 480
 481    mdl->node_buffer     = all_data + (mdl->info.node_offset     - lheader);
 482    mdl->submesh_buffer  = all_data + (mdl->info.submesh_offset  - lheader);
 483    mdl->material_buffer = all_data + (mdl->info.material_offset - lheader);
 484    mdl->texture_buffer  = all_data + (mdl->info.texture_offset  - lheader);
 485    mdl->anim_buffer     = all_data + (mdl->info.anim_offset     - lheader);
 486    mdl->entdata_buffer  = all_data + (mdl->info.entdata_offset  - lheader);
 487    mdl->string_buffer   = all_data + (mdl->info.strings_offset  - lheader);
 488 }
 489
 490 /*
 491  * Load just the mesh data
 492  */
 493 VG_STATIC void mdl_load_mesh_data( mdl_context *mdl, void *lin_alloc )
 494 {
 495    assert( mdl->file );
 496
 497    u64 size_verts = vg_align8( mdl->info.vertex_count * sizeof(mdl_vert) ),
 498        size_index = vg_align8( mdl->info.indice_count * sizeof(u32) );
 499
 500    mdl->vertex_buffer = vg_linear_alloc( lin_alloc, size_verts );
 501    mdl->index_buffer  = vg_linear_alloc( lin_alloc, size_index );
 502
 503    {
 504       fseek( mdl->file, mdl->info.vertex_offset, SEEK_SET );
 505       u64 l = fread( mdl->vertex_buffer, size_verts, 1, mdl->file );
 506       if( l != 1 )
 507          mdl_load_fatal_corrupt( mdl );
 508    }
 509    {
 510       fseek( mdl->file, mdl->info.indice_offset, SEEK_SET );
 511       u64 l = fread( mdl->index_buffer, size_index, 1, mdl->file );
 512       if( l != 1 )
 513          mdl_load_fatal_corrupt( mdl );
 514    }
 515 }
 516
 517 /*
 518  * Load animation data
 519  */
 520 VG_STATIC void mdl_load_anim_data( mdl_context *mdl, void *lin_alloc )
 521 {
 522    assert( mdl->file );
 523
 524    if( mdl->info.keyframe_count == 0 )
 525       return;
 526
 527    u64 size_kf = vg_align8( mdl->info.keyframe_count * sizeof(mdl_keyframe) );
 528    mdl->keyframe_buffer = vg_linear_alloc( lin_alloc, size_kf );
 529
 530    fseek( mdl->file, mdl->info.keyframe_offset, SEEK_SET );
 531    u64 l = fread( mdl->keyframe_buffer, size_kf, 1, mdl->file );
 532    if( l != 1 )
 533       mdl_load_fatal_corrupt( mdl );
 534 }
 535
 536 /*
 537  * Load pack contents
 538  *
 539  * TODO request specific files (low)
 540  */
 541 VG_STATIC void mdl_load_pack_data( mdl_context *mdl, void *lin_alloc )
 542 {
 543    assert( mdl->file );
 544
 545    if( mdl->info.pack_size == 0 )
 546       return;
 547
 548    mdl->pack = vg_linear_alloc( lin_alloc, vg_align8( mdl->info.pack_size ) );
 549    fseek( mdl->file, mdl->info.pack_offset, SEEK_SET );
 550
 551    u64 l = fread( mdl->pack, mdl->info.pack_size, 1, mdl->file );
 552    if( l != 1 )
 553       mdl_load_fatal_corrupt( mdl );
 554 }
 555
 556 /*
 557  * close file handle
 558  */
 559 VG_STATIC void mdl_close( mdl_context *mdl )
 560 {
 561    fclose( mdl->file );
 562    mdl->file = NULL;
 563 }
 564
 565 /* open a model. TODO: make this flags ( ANIM_DATA|MESH_DATA ... ) */
 566 VG_STATIC mdl_context *mdl_load_full( void *lin_alloc, const char *path )
 567 {
 568    /* Inspect the header by opening it, give us the size needed */
 569    mdl_context temp_ctx;
 570    mdl_open( &temp_ctx, path );
 571
 572    /* create allocator */
 573    u32 tot_size = temp_ctx.info.file_length + sizeof( mdl_context ) + 64;
 574    void *data = vg_create_linear_allocator( lin_alloc, tot_size,
 575                                             VG_MEMORY_SYSTEM );
 576
 577    /* copy context and load all other data */
 578    mdl_context *ctx = vg_linear_alloc( data, sizeof(mdl_context) );
 579    memcpy( ctx, &temp_ctx, sizeof(mdl_context) );
 580
 581    mdl_load_metadata( ctx, data );
 582    mdl_load_anim_data( ctx, data );
 583    mdl_load_mesh_data( ctx, data );
 584    mdl_load_pack_data( ctx, data );
 585    mdl_close( ctx );
 586
 587    return ctx;
 588 }
 589
 590 /*
 591  * Item getters
 592  * ----------------------------------------------------------------------------
 593  * TODO: Clamp access and oob errors
 594  */
 595 VG_STATIC const char *mdl_pstr( mdl_context *mdl, u32 pstr )
 596 {
 597    return mdl->string_buffer + pstr;
 598 }
 599
 600 VG_STATIC mdl_node *mdl_node_from_id( mdl_context *mdl, u32 id )
 601 {
 602    return &mdl->node_buffer[id];
 603 }
 604
 605 VG_STATIC mdl_node *mdl_node_from_name( mdl_context *mdl, const char *name )
 606 {
 607    for( int i=0; i < mdl->info.node_count; i++ )
 608    {
 609       mdl_node *pnode = mdl_node_from_id( mdl, i );
 610
 611       if( !strcmp( name, mdl_pstr( mdl, pnode->pstr_name )) )
 612          return pnode;
 613    }
 614
 615    return NULL;
 616 }
 617
 618 VG_STATIC mdl_submesh *mdl_node_submesh( mdl_context *mdl,
 619                                          mdl_node *node, u32 i )
 620 {
 621    return &mdl->submesh_buffer[ node->submesh_start+i ];
 622 }
 623
 624 VG_STATIC u32 *mdl_submesh_indices( mdl_context *mdl, mdl_submesh *sm )
 625 {
 626    return &mdl->index_buffer[ sm->indice_start ];
 627 }
 628
 629 VG_STATIC mdl_vert *mdl_submesh_vertices( mdl_context *mdl, mdl_submesh *sm )
 630 {
 631    return &mdl->vertex_buffer[ sm->vertex_start ];
 632 }
 633
 634 VG_STATIC void mdl_node_transform( mdl_node *pnode, m4x3f transform )
 635 {
 636    q_m3x3( pnode->q, transform );
 637    v3_muls( transform[0], pnode->s[0], transform[0] );
 638    v3_muls( transform[1], pnode->s[1], transform[1] );
 639    v3_muls( transform[2], pnode->s[2], transform[2] );
 640    v3_copy( pnode->co, transform[3] );
 641 }
 642
 643 /* upload a mesh based on file submesh */
 644 VG_STATIC void mdl_unpack_submesh( mdl_context *mdl, glmesh *mesh,
 645                                 mdl_submesh *sm )
 646 {
 647    mesh_upload( mesh, mdl_submesh_vertices( mdl, sm ), sm->vertex_count,
 648                       mdl_submesh_indices( mdl, sm ), sm->indice_count );
 649 }
 650
 651 /* upload entire mesh from model */
 652 VG_STATIC void mdl_unpack_glmesh( mdl_context *mdl, glmesh *mesh )
 653 {
 654    u32 offset = mdl->submesh_buffer[0].vertex_count;
 655
 656    for( int i=1; i< mdl->info.submesh_count; i++ )
 657    {
 658       mdl_submesh *sm = &mdl->submesh_buffer[i];
 659       u32 *indices    =  mdl_submesh_indices( mdl, sm );
 660
 661       for( u32 j=0; j<sm->indice_count; j++ )
 662          indices[j] += offset;
 663
 664       offset += sm->vertex_count;
 665    }
 666
 667    mesh_upload( mesh, mdl->vertex_buffer, mdl->info.vertex_count,
 668                       mdl->index_buffer,  mdl->info.indice_count );
 669 }
 670
 671 VG_STATIC void mdl_draw_submesh( mdl_submesh *sm )
 672 {
 673    mesh_drawn( sm->indice_start, sm->indice_count );
 674 }
 675
 676 VG_STATIC void *mdl_get_entdata( mdl_context *mdl, mdl_node *pnode )
 677 {
 678    return mdl->entdata_buffer + pnode->offset;
 679 }
 680
 681 VG_STATIC mdl_keyframe *mdl_get_animdata( mdl_context *mdl, mdl_animation *anim )
 682 {
 683    return mdl->keyframe_buffer + anim->offset;
 684 }
 685
 686 VG_STATIC void mdl_link_materials( mdl_context *root, mdl_context *child )
 687 {
 688    u32 lookup[MDL_MATERIAL_MAX];
 689
 690    for( int i=0; i<child->info.material_count; i++ )
 691    {
 692       mdl_material *mi = &child->material_buffer[i];
 693       const char *si = mdl_pstr( child, mi->pstr_name );
 694
 695       lookup[i] = 0;
 696
 697       for( int j=0; j<root->info.material_count; j++ )
 698       {
 699          mdl_material *mj = &root->material_buffer[j];
 700          const char *sj = mdl_pstr( root, mj->pstr_name );
 701
 702          if( !strcmp( si, sj ) )
 703          {
 704             lookup[i] = j;
 705             break;
 706          }
 707       }
 708
 709       if( lookup[i] == 0 && i != 0 )
 710       {
 711          vg_warn( "Could not link material '%s' (not present in root model)\n",
 712                    si );
 713       }
 714    }
 715
 716    for( int i=0; i<child->info.submesh_count; i++ )
 717    {
 718       mdl_submesh *sm = &child->submesh_buffer[i];
 719       sm->material_id =  lookup[sm->material_id];
 720    }
 721 }
 722
 723 VG_STATIC void mdl_invert_uv_coordinates( mdl_context *mdl )
 724 {
 725    for( int i=0; i<mdl->info.vertex_count; i++ )
 726    {
 727       mdl_vert *vert = &mdl->vertex_buffer[i];
 728       vert->uv[1] = 1.0f-vert->uv[1];
 729    }
 730 }
 731
 732 #endif