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tinyobjloader

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https://github.com/syoyo/tinyobjloader

Tiny but powerful single file wavefront obj loader written in C++. No dependency except for C++ STL. It can parse over 10M polygons with moderate memory and time.

tinyobjloader is good for embedding .obj loader to your (global illumination) renderer ;-)

If you are looking for C89 version, please see https://github.com/syoyo/tinyobjloader-c .

Notice!

We have released new version v1.0.0 on 20 Aug, 2016. Old version is available v0.9.x branch https://github.com/syoyo/tinyobjloader/tree/v0.9.x

What's new

  • 20 Aug, 2016 : Bump version v1.0.0. New data structure and API!

Old version

Previous old version is avaiable in v0.9.x branch.

Example

Rungholt

tinyobjloader can successfully load 6M triangles Rungholt scene. http://casual-effects.com/data/index.html

Use case

TinyObjLoader is successfully used in ...

New version(v1.0.x)

  • Double precision support through TINYOBJLOADER_USE_DOUBLE thanks to noma
  • Loading models in Vulkan Tutorial https://vulkan-tutorial.com/Loading_models
  • .obj viewer with Metal https://github.com/middlefeng/NuoModelViewer/tree/master
  • Vulkan Cookbook https://github.com/PacktPublishing/Vulkan-Cookbook
  • cudabox: CUDA Solid Voxelizer Engine https://github.com/gaspardzoss/cudavox
  • Drake: A planning, control, and analysis toolbox for nonlinear dynamical systems https://github.com/RobotLocomotion/drake
  • VFPR - a Vulkan Forward Plus Renderer : https://github.com/WindyDarian/Vulkan-Forward-Plus-Renderer
  • Your project here! (Letting us know via github issue is welcome!)

Old version(v0.9.x)

  • bullet3 https://github.com/erwincoumans/bullet3
  • pbrt-v2 https://github.com/mmp/pbrt-v2
  • OpenGL game engine development http://swarminglogic.com/jotting/2013_10_gamedev01
  • mallie https://lighttransport.github.io/mallie
  • IBLBaker (Image Based Lighting Baker). http://www.derkreature.com/iblbaker/
  • Stanford CS148 http://web.stanford.edu/class/cs148/assignments/assignment3.pdf
  • Awesome Bump http://awesomebump.besaba.com/about/
  • sdlgl3-wavefront OpenGL .obj viewer https://github.com/chrisliebert/sdlgl3-wavefront
  • pbrt-v3 https://github.com/mmp/pbrt-v3
  • cocos2d-x https://github.com/cocos2d/cocos2d-x/
  • Android Vulkan demo https://github.com/SaschaWillems/Vulkan
  • voxelizer https://github.com/karimnaaji/voxelizer
  • Probulator https://github.com/kayru/Probulator
  • OptiX Prime baking https://github.com/nvpro-samples/optix_prime_baking
  • FireRays SDK https://github.com/GPUOpen-LibrariesAndSDKs/FireRays_SDK
  • parg, tiny C library of various graphics utilities and GL demos https://github.com/prideout/parg
  • Opengl unit of ChronoEngine https://github.com/projectchrono/chrono-opengl
  • Point Based Global Illumination on modern GPU https://pbgi.wordpress.com/code-source/
  • Fast OBJ file importing and parsing in CUDA http://researchonline.jcu.edu.au/42515/1/2015.CVM.OBJCUDA.pdf
  • Sorted Shading for Uni-Directional Pathtracing by Joshua Bainbridge https://nccastaff.bournemouth.ac.uk/jmacey/MastersProjects/MSc15/02Josh/joshua_bainbridge_thesis.pdf
  • GeeXLab http://www.geeks3d.com/hacklab/20160531/geexlab-0-12-0-0-released-for-windows/

Features

  • Group(parse multiple group name)
  • Vertex
  • Vertex color(as an extension: https://blender.stackexchange.com/questions/31997/how-can-i-get-vertex-painted-obj-files-to-import-into-blender)
  • Texcoord
  • Normal
  • Material
  • Unknown material attributes are returned as key-value(value is string) map.
  • Crease tag('t'). This is OpenSubdiv specific(not in wavefront .obj specification)
  • PBR material extension for .MTL. Its proposed here: http://exocortex.com/blog/extending_wavefront_mtl_to_support_pbr
  • Callback API for custom loading.
  • Double precision support(for HPC application).

TODO

  • [ ] Fix obj_sticker example.
  • [ ] More unit test codes.
  • [x] Texture options
  • [ ] Normal vector generation
  • [ ] Support smoothing groups

License

Licensed under MIT license.

Usage

Data format

attrib_t contains single and linear array of vertex data(position, normal and texcoord).

attrib_t::vertices => 3 floats per vertex

       v[0]        v[1]        v[2]        v[3]               v[n-1]
  +-----------+-----------+-----------+-----------+      +-----------+
  | x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
  +-----------+-----------+-----------+-----------+      +-----------+

attrib_t::normals => 3 floats per vertex

       n[0]        n[1]        n[2]        n[3]               n[n-1]
  +-----------+-----------+-----------+-----------+      +-----------+
  | x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
  +-----------+-----------+-----------+-----------+      +-----------+

attrib_t::texcoords => 2 floats per vertex

       t[0]        t[1]        t[2]        t[3]               t[n-1]
  +-----------+-----------+-----------+-----------+      +-----------+
  |  u  |  v  |  u  |  v  |  u  |  v  |  u  |  v  | .... |  u  |  v  |
  +-----------+-----------+-----------+-----------+      +-----------+

attrib_t::colors => 3 floats per vertex(vertex color. optional)

       c[0]        c[1]        c[2]        c[3]               c[n-1]
  +-----------+-----------+-----------+-----------+      +-----------+
  | x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
  +-----------+-----------+-----------+-----------+      +-----------+

Each shape_t::mesh_t does not contain vertex data but contains array index to attrib_t. See loader_example.cc for more details.

mesh_t::indices => array of vertex indices.

  +----+----+----+----+----+----+----+----+----+----+     +--------+
  | i0 | i1 | i2 | i3 | i4 | i5 | i6 | i7 | i8 | i9 | ... | i(n-1) |
  +----+----+----+----+----+----+----+----+----+----+     +--------+

Each index has an array index to attrib_t::vertices, attrib_t::normals and attrib_t::texcoords.

mesh_t::num_face_vertices => array of the number of vertices per face(e.g. 3 = triangle, 4 = quad , 5 or more = N-gons).


  +---+---+---+        +---+
  | 3 | 4 | 3 | ...... | 3 |
  +---+---+---+        +---+
    |   |   |            |
    |   |   |            +-----------------------------------------+
    |   |   |                                                      |
    |   |   +------------------------------+                       |
    |   |                                  |                       |
    |   +------------------+               |                       |
    |                      |               |                       |
    |/                     |/              |/                      |/

 mesh_t::indices

  |    face[0]   |       face[1]     |    face[2]   |     |      face[n-1]           |
  +----+----+----+----+----+----+----+----+----+----+     +--------+--------+--------+
  | i0 | i1 | i2 | i3 | i4 | i5 | i6 | i7 | i8 | i9 | ... | i(n-3) | i(n-2) | i(n-1) | 
  +----+----+----+----+----+----+----+----+----+----+     +--------+--------+--------+

Note that when triangulate flas is true in tinyobj::LoadObj() argument, num_face_vertices are all filled with 3(triangle).

float data type

TinyObjLoader now use real_t for floating point data type. Default is float(32bit). You can enable double(64bit) precision by using TINYOBJLOADER_USE_DOUBLE define.

Example code

#define TINYOBJLOADER_IMPLEMENTATION // define this in only *one* .cc
#include "tiny_obj_loader.h"

std::string inputfile = "cornell_box.obj";
tinyobj::attrib_t attrib;
std::vector<tinyobj::shape_t> shapes;
std::vector<tinyobj::material_t> materials;

std::string err;
bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, inputfile.c_str());

if (!err.empty()) { // `err` may contain warning message.
  std::cerr << err << std::endl;
}

if (!ret) {
  exit(1);
}

// Loop over shapes
for (size_t s = 0; s < shapes.size(); s++) {
  // Loop over faces(polygon)
  size_t index_offset = 0;
  for (size_t f = 0; f < shapes[s].mesh.num_face_vertices.size(); f++) {
    int fv = shapes[s].mesh.num_face_vertices[f];

    // Loop over vertices in the face.
    for (size_t v = 0; v < fv; v++) {
      // access to vertex
      tinyobj::index_t idx = shapes[s].mesh.indices[index_offset + v];
      tinyobj::real_t vx = attrib.vertices[3*idx.vertex_index+0];
      tinyobj::real_t vy = attrib.vertices[3*idx.vertex_index+1];
      tinyobj::real_t vz = attrib.vertices[3*idx.vertex_index+2];
      tinyobj::real_t nx = attrib.normals[3*idx.normal_index+0];
      tinyobj::real_t ny = attrib.normals[3*idx.normal_index+1];
      tinyobj::real_t nz = attrib.normals[3*idx.normal_index+2];
      tinyobj::real_t tx = attrib.texcoords[2*idx.texcoord_index+0];
      tinyobj::real_t ty = attrib.texcoords[2*idx.texcoord_index+1];
      // Optional: vertex colors
      // tinyobj::real_t red = attrib.colors[3*idx.vertex_index+0];
      // tinyobj::real_t green = attrib.colors[3*idx.vertex_index+1];
      // tinyobj::real_t blue = attrib.colors[3*idx.vertex_index+2];
    }
    index_offset += fv;

    // per-face material
    shapes[s].mesh.material_ids[f];
  }
}

Optimized loader

Optimized multi-threaded .obj loader is available at experimental/ directory. If you want absolute performance to load .obj data, this optimized loader will fit your purpose. Note that the optimized loader uses C++11 thread and it does less error checks but may work most .obj data.

Here is some benchmark result. Time are measured on MacBook 12(Early 2016, Core m5 1.2GHz).

  • Rungholt scene(6M triangles)
  • old version(v0.9.x): 15500 msecs.
  • baseline(v1.0.x): 6800 msecs(2.3x faster than old version)
  • optimised: 1500 msecs(10x faster than old version, 4.5x faster than baseline)

Tests

Unit tests are provided in tests directory. See tests/README.md for details.

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