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                 = 0,
  33    k_classtype_gate                 = 1,
  34    k_classtype_spawn                = 3,
  35    k_classtype_water                = 4,
  36    k_classtype_route_node           = 8,
  37    k_classtype_route                = 9,
  38    k_classtype_bone                 = 10,
  39    k_classtype_skeleton             = 11,
  40    k_classtype_skin                 = 12,
  41    k_classtype_audio                = 14,
  42    k_classtype_trigger              = 100,
  43    k_classtype_logic_achievement    = 101,
  44    k_classtype_logic_relay          = 102,
  45    k_classtype_world_light          = 200,
  46    k_classtype_nonlocal_gate        = 300
  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_gate
 199 {
 200    u32 target;
 201    v3f dims;
 202 };
 203
 204 struct classtype_spawn
 205 {
 206    u32 pstr_alias;
 207 };
 208
 209 struct classtype_water
 210 {
 211    u32 temp;
 212 };
 213
 214 struct classtype_route_node
 215 {
 216    u32 target, target1;
 217 };
 218
 219 struct classtype_route
 220 {
 221    u32 id_start;
 222    u32 pstr_name;
 223    v3f colour;
 224 };
 225
 226 struct classtype_bone
 227 {
 228    u32 flags,
 229        ik_target,
 230        ik_pole;
 231
 232    boxf hitbox;
 233
 234    v3f conevx, conevy, coneva;
 235    float conet;
 236 };
 237
 238 struct classtype_skeleton
 239 {
 240    u32 channels,
 241        ik_count,
 242        collider_count,
 243        anim_start,
 244        anim_count;
 245 };
 246
 247 struct classtype_skin
 248 {
 249    u32 skeleton;
 250 };
 251
 252 struct classtype_trigger
 253 {
 254    u32 target;
 255 };
 256
 257 struct classtype_logic_relay
 258 {
 259    u32 targets[4];
 260 };
 261
 262 struct classtype_logic_achievement
 263 {
 264    u32 pstr_name;
 265 };
 266
 267 struct classtype_audio
 268 {
 269    u32 pstr_file,
 270        flags;
 271
 272    float volume;
 273 };
 274
 275 struct classtype_world_light
 276 {
 277    enum light_type
 278    {
 279       k_light_type_point,
 280       k_light_type_spot,
 281       k_light_type_point_nighttime_only,
 282       k_light_type_spot_nighttime_only
 283    }
 284    type;
 285
 286    v4f colour; /* RGB, Energy */
 287    float angle, range;
 288 };
 289
 290 #pragma pack(pop)
 291
 292
 293 struct mdl_context
 294 {
 295    FILE *file;
 296    mdl_file_header info;
 297
 298    /* each buffer becomes availible after each _load function is called */
 299    mdl_node       *node_buffer;     /* mdl_load_metadata() */
 300    mdl_submesh    *submesh_buffer;
 301    mdl_material   *material_buffer;
 302    mdl_texture    *texture_buffer;
 303    mdl_animation  *anim_buffer;
 304    void           *entdata_buffer;
 305    const char     *string_buffer;
 306
 307    mdl_keyframe   *keyframe_buffer; /* mdl_load_anim_data() */
 308
 309    mdl_vert       *vertex_buffer;   /* mdl_load_mesh_data() */
 310    u32            *index_buffer;
 311
 312    void           *pack;            /* mdl_load_pack_data() */
 313 };
 314
 315 /*
 316  * Simple mesh interface for OpenGL
 317  */
 318
 319 struct glmesh
 320 {
 321    GLuint vao, vbo, ebo;
 322    u32 indice_count;
 323    u32 loaded;
 324 };
 325
 326 VG_STATIC void mesh_upload( glmesh *mesh,
 327                          mdl_vert *verts, u32 vert_count,
 328                          u32 *indices, u32 indice_count )
 329 {
 330    //assert( mesh->loaded == 0 );
 331
 332    glGenVertexArrays( 1, &mesh->vao );
 333    glGenBuffers( 1, &mesh->vbo );
 334    glGenBuffers( 1, &mesh->ebo );
 335    glBindVertexArray( mesh->vao );
 336
 337    size_t stride = sizeof(mdl_vert);
 338
 339    glBindBuffer( GL_ARRAY_BUFFER, mesh->vbo );
 340    glBufferData( GL_ARRAY_BUFFER, vert_count*stride, verts, GL_STATIC_DRAW );
 341
 342    glBindVertexArray( mesh->vao );
 343    glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, mesh->ebo );
 344    glBufferData( GL_ELEMENT_ARRAY_BUFFER, indice_count*sizeof(u32),
 345          indices, GL_STATIC_DRAW );
 346
 347    /* 0: coordinates */
 348    glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, stride, (void*)0 );
 349    glEnableVertexAttribArray( 0 );
 350
 351    /* 1: normal */
 352    glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE,
 353          stride, (void *)offsetof(mdl_vert, norm) );
 354    glEnableVertexAttribArray( 1 );
 355
 356    /* 2: uv */
 357    glVertexAttribPointer( 2, 2, GL_FLOAT, GL_FALSE,
 358          stride, (void *)offsetof(mdl_vert, uv) );
 359    glEnableVertexAttribArray( 2 );
 360
 361    /* 3: colour */
 362    glVertexAttribPointer( 3, 4, GL_UNSIGNED_BYTE, GL_TRUE,
 363          stride, (void *)offsetof(mdl_vert, colour) );
 364    glEnableVertexAttribArray( 3 );
 365
 366    /* 4: weights */
 367    glVertexAttribPointer( 4, 4, GL_UNSIGNED_SHORT, GL_TRUE,
 368          stride, (void *)offsetof(mdl_vert, weights) );
 369    glEnableVertexAttribArray( 4 );
 370
 371    /* 5: groups */
 372    glVertexAttribIPointer( 5, 4, GL_UNSIGNED_BYTE,
 373          stride, (void *)offsetof(mdl_vert, groups) );
 374    glEnableVertexAttribArray( 5 );
 375
 376    VG_CHECK_GL_ERR();
 377
 378    mesh->indice_count = indice_count;
 379    mesh->loaded = 1;
 380 }
 381
 382 VG_STATIC void mesh_bind( glmesh *mesh )
 383 {
 384    glBindVertexArray( mesh->vao );
 385 }
 386
 387 VG_STATIC void mesh_drawn( u32 start, u32 count )
 388 {
 389    glDrawElements( GL_TRIANGLES, count, GL_UNSIGNED_INT,
 390          (void *)(start*sizeof(u32)) );
 391 }
 392
 393 VG_STATIC void mesh_draw( glmesh *mesh )
 394 {
 395    mesh_drawn( 0, mesh->indice_count );
 396 }
 397
 398 VG_STATIC void mesh_free( glmesh *mesh )
 399 {
 400    if( mesh->loaded )
 401    {
 402       glDeleteVertexArrays( 1, &mesh->vao );
 403       glDeleteBuffers( 1, &mesh->ebo );
 404       glDeleteBuffers( 1, &mesh->vbo );
 405       mesh->loaded = 0;
 406    }
 407 }
 408
 409 VG_STATIC void mdl_load_fatal_corrupt( mdl_context *mdl )
 410 {
 411    fclose( mdl->file );
 412    vg_file_print_invalid( mdl->file );
 413    vg_fatal_exit_loop( "Corrupt model" );
 414 }
 415
 416 /*
 417  * Model implementation
 418  *
 419  * TODO.
 420  *
 421  * you have two api options for loading a model, first, the easy way:
 422  *       mdl_load ...
 423  *    will put the entire model straight into the linear_alloc
 424  *
 425  * or, to target different allocators:
 426  *
 427  *       mdl_open
 428  *       mdl_load_metadata
 429  *       mdl_load_vertex_data
 430  *       mdl_load_indice_data
 431  *       mdl_close
 432  *
 433  * these should ideally be called in quick succession to limit stalls.
 434  */
 435
 436 /*
 437  * if calling mdl_open, and the file does not exist, the game will fatal quit
 438  */
 439 VG_STATIC void mdl_open( mdl_context *mdl, const char *path )
 440 {
 441    memset( mdl, 0, sizeof( mdl_context ) );
 442    mdl->file = fopen( path, "rb" );
 443
 444    if( !mdl->file )
 445    {
 446       vg_error( "mdl_open('%s'): %s\n", path, strerror(errno) );
 447       vg_fatal_exit_loop( "see above for details" );
 448    }
 449
 450    u64 l = fread( &mdl->info, sizeof(mdl_file_header), 1, mdl->file );
 451    if( l != 1 )
 452       mdl_load_fatal_corrupt( mdl );
 453 }
 454
 455 /*
 456  * Load all metadata (everything up until the large buffers). Probs at most 50k
 457  */
 458 VG_STATIC void mdl_load_metadata( mdl_context *mdl, void *lin_alloc )
 459 {
 460    assert( mdl->file );
 461
 462    u64 lheader  = sizeof(mdl_file_header),
 463        ldata    = mdl->info.keyframe_offset - lheader;
 464
 465    void *all_data = vg_linear_alloc( lin_alloc, ldata );
 466
 467    fseek( mdl->file, lheader, SEEK_SET );
 468    u64 l = fread( all_data, ldata, 1, mdl->file );
 469
 470    if( l != 1 )
 471    {
 472       vg_file_print_invalid( mdl->file );
 473       vg_fatal_exit_loop( "Corrupt model" );
 474    }
 475
 476    mdl->node_buffer     = all_data + (mdl->info.node_offset     - lheader);
 477    mdl->submesh_buffer  = all_data + (mdl->info.submesh_offset  - lheader);
 478    mdl->material_buffer = all_data + (mdl->info.material_offset - lheader);
 479    mdl->texture_buffer  = all_data + (mdl->info.texture_offset  - lheader);
 480    mdl->anim_buffer     = all_data + (mdl->info.anim_offset     - lheader);
 481    mdl->entdata_buffer  = all_data + (mdl->info.entdata_offset  - lheader);
 482    mdl->string_buffer   = all_data + (mdl->info.strings_offset  - lheader);
 483 }
 484
 485 /*
 486  * Load just the mesh data
 487  */
 488 VG_STATIC void mdl_load_mesh_data( mdl_context *mdl, void *lin_alloc )
 489 {
 490    assert( mdl->file );
 491
 492    u64 size_verts = vg_align8( mdl->info.vertex_count * sizeof(mdl_vert) ),
 493        size_index = vg_align8( mdl->info.indice_count * sizeof(u32) );
 494
 495    mdl->vertex_buffer = vg_linear_alloc( lin_alloc, size_verts );
 496    mdl->index_buffer  = vg_linear_alloc( lin_alloc, size_index );
 497
 498    {
 499       fseek( mdl->file, mdl->info.vertex_offset, SEEK_SET );
 500       u64 l = fread( mdl->vertex_buffer, size_verts, 1, mdl->file );
 501       if( l != 1 )
 502          mdl_load_fatal_corrupt( mdl );
 503    }
 504    {
 505       fseek( mdl->file, mdl->info.indice_offset, SEEK_SET );
 506       u64 l = fread( mdl->index_buffer, size_index, 1, mdl->file );
 507       if( l != 1 )
 508          mdl_load_fatal_corrupt( mdl );
 509    }
 510 }
 511
 512 /*
 513  * Load animation data
 514  */
 515 VG_STATIC void mdl_load_anim_data( mdl_context *mdl, void *lin_alloc )
 516 {
 517    assert( mdl->file );
 518
 519    if( mdl->info.keyframe_count == 0 )
 520       return;
 521
 522    u64 size_kf = vg_align8( mdl->info.keyframe_count * sizeof(mdl_keyframe) );
 523    mdl->keyframe_buffer = vg_linear_alloc( lin_alloc, size_kf );
 524
 525    fseek( mdl->file, mdl->info.keyframe_offset, SEEK_SET );
 526    u64 l = fread( mdl->keyframe_buffer, size_kf, 1, mdl->file );
 527    if( l != 1 )
 528       mdl_load_fatal_corrupt( mdl );
 529 }
 530
 531 /*
 532  * Load pack contents
 533  *
 534  * TODO request specific files (low)
 535  */
 536 VG_STATIC void mdl_load_pack_data( mdl_context *mdl, void *lin_alloc )
 537 {
 538    assert( mdl->file );
 539
 540    if( mdl->info.pack_size == 0 )
 541       return;
 542
 543    mdl->pack = vg_linear_alloc( lin_alloc, vg_align8( mdl->info.pack_size ) );
 544    fseek( mdl->file, mdl->info.pack_offset, SEEK_SET );
 545
 546    u64 l = fread( mdl->pack, mdl->info.pack_size, 1, mdl->file );
 547    if( l != 1 )
 548       mdl_load_fatal_corrupt( mdl );
 549 }
 550
 551 /*
 552  * close file handle
 553  */
 554 VG_STATIC void mdl_close( mdl_context *mdl )
 555 {
 556    fclose( mdl->file );
 557    mdl->file = NULL;
 558 }
 559
 560 /* open a model. TODO: make this flags ( ANIM_DATA|MESH_DATA ... ) */
 561 VG_STATIC mdl_context *mdl_load_full( void *lin_alloc, const char *path )
 562 {
 563    /* Inspect the header by opening it, give us the size needed */
 564    mdl_context temp_ctx;
 565    mdl_open( &temp_ctx, path );
 566
 567    /* create allocator */
 568    u32 tot_size = temp_ctx.info.file_length + sizeof( mdl_context ) + 64;
 569    void *data = vg_create_linear_allocator( lin_alloc, tot_size,
 570                                             VG_MEMORY_SYSTEM );
 571
 572    /* copy context and load all other data */
 573    mdl_context *ctx = vg_linear_alloc( data, sizeof(mdl_context) );
 574    memcpy( ctx, &temp_ctx, sizeof(mdl_context) );
 575
 576    mdl_load_metadata( ctx, data );
 577    mdl_load_anim_data( ctx, data );
 578    mdl_load_mesh_data( ctx, data );
 579    mdl_load_pack_data( ctx, data );
 580    mdl_close( ctx );
 581
 582    return ctx;
 583 }
 584
 585 /*
 586  * Item getters
 587  * ----------------------------------------------------------------------------
 588  * TODO: Clamp access and oob errors
 589  */
 590 VG_STATIC const char *mdl_pstr( mdl_context *mdl, u32 pstr )
 591 {
 592    return mdl->string_buffer + pstr;
 593 }
 594
 595 VG_STATIC mdl_node *mdl_node_from_id( mdl_context *mdl, u32 id )
 596 {
 597    return &mdl->node_buffer[id];
 598 }
 599
 600 VG_STATIC mdl_node *mdl_node_from_name( mdl_context *mdl, const char *name )
 601 {
 602    for( int i=0; i < mdl->info.node_count; i++ )
 603    {
 604       mdl_node *pnode = mdl_node_from_id( mdl, i );
 605
 606       if( !strcmp( name, mdl_pstr( mdl, pnode->pstr_name )) )
 607          return pnode;
 608    }
 609
 610    return NULL;
 611 }
 612
 613 VG_STATIC mdl_submesh *mdl_node_submesh( mdl_context *mdl,
 614                                          mdl_node *node, u32 i )
 615 {
 616    return &mdl->submesh_buffer[ node->submesh_start+i ];
 617 }
 618
 619 VG_STATIC u32 *mdl_submesh_indices( mdl_context *mdl, mdl_submesh *sm )
 620 {
 621    return &mdl->index_buffer[ sm->indice_start ];
 622 }
 623
 624 VG_STATIC mdl_vert *mdl_submesh_vertices( mdl_context *mdl, mdl_submesh *sm )
 625 {
 626    return &mdl->vertex_buffer[ sm->vertex_start ];
 627 }
 628
 629 VG_STATIC void mdl_node_transform( mdl_node *pnode, m4x3f transform )
 630 {
 631    q_m3x3( pnode->q, transform );
 632    v3_muls( transform[0], pnode->s[0], transform[0] );
 633    v3_muls( transform[1], pnode->s[1], transform[1] );
 634    v3_muls( transform[2], pnode->s[2], transform[2] );
 635    v3_copy( pnode->co, transform[3] );
 636 }
 637
 638 /* upload a mesh based on file submesh */
 639 VG_STATIC void mdl_unpack_submesh( mdl_context *mdl, glmesh *mesh,
 640                                 mdl_submesh *sm )
 641 {
 642    mesh_upload( mesh, mdl_submesh_vertices( mdl, sm ), sm->vertex_count,
 643                       mdl_submesh_indices( mdl, sm ), sm->indice_count );
 644 }
 645
 646 /* upload entire mesh from model */
 647 VG_STATIC void mdl_unpack_glmesh( mdl_context *mdl, glmesh *mesh )
 648 {
 649    u32 offset = mdl->submesh_buffer[0].vertex_count;
 650
 651    for( int i=1; i< mdl->info.submesh_count; i++ )
 652    {
 653       mdl_submesh *sm = &mdl->submesh_buffer[i];
 654       u32 *indices    =  mdl_submesh_indices( mdl, sm );
 655
 656       for( u32 j=0; j<sm->indice_count; j++ )
 657          indices[j] += offset;
 658
 659       offset += sm->vertex_count;
 660    }
 661
 662    mesh_upload( mesh, mdl->vertex_buffer, mdl->info.vertex_count,
 663                       mdl->index_buffer,  mdl->info.indice_count );
 664 }
 665
 666 VG_STATIC void mdl_draw_submesh( mdl_submesh *sm )
 667 {
 668    mesh_drawn( sm->indice_start, sm->indice_count );
 669 }
 670
 671 VG_STATIC void *mdl_get_entdata( mdl_context *mdl, mdl_node *pnode )
 672 {
 673    return mdl->entdata_buffer + pnode->offset;
 674 }
 675
 676 VG_STATIC mdl_keyframe *mdl_get_animdata( mdl_context *mdl, mdl_animation *anim )
 677 {
 678    return mdl->keyframe_buffer + anim->offset;
 679 }
 680
 681 VG_STATIC void mdl_link_materials( mdl_context *root, mdl_context *child )
 682 {
 683    u32 lookup[MDL_MATERIAL_MAX];
 684
 685    for( int i=0; i<child->info.material_count; i++ )
 686    {
 687       mdl_material *mi = &child->material_buffer[i];
 688       const char *si = mdl_pstr( child, mi->pstr_name );
 689
 690       lookup[i] = 0;
 691
 692       for( int j=0; j<root->info.material_count; j++ )
 693       {
 694          mdl_material *mj = &root->material_buffer[j];
 695          const char *sj = mdl_pstr( root, mj->pstr_name );
 696
 697          if( !strcmp( si, sj ) )
 698          {
 699             lookup[i] = j;
 700             break;
 701          }
 702       }
 703
 704       if( lookup[i] == 0 && i != 0 )
 705       {
 706          vg_warn( "Could not link material '%s' (not present in root model)\n",
 707                    si );
 708       }
 709    }
 710
 711    for( int i=0; i<child->info.submesh_count; i++ )
 712    {
 713       mdl_submesh *sm = &child->submesh_buffer[i];
 714       sm->material_id =  lookup[sm->material_id];
 715    }
 716 }
 717
 718 VG_STATIC void mdl_invert_uv_coordinates( mdl_context *mdl )
 719 {
 720    for( int i=0; i<mdl->info.vertex_count; i++ )
 721    {
 722       mdl_vert *vert = &mdl->vertex_buffer[i];
 723       vert->uv[1] = 1.0f-vert->uv[1];
 724    }
 725 }
 726
 727 #endif