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https://github.com/bulletphysics/bullet3
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140 lines
4.9 KiB
Markdown
140 lines
4.9 KiB
Markdown
tinyobjloader
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=============
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http://syoyo.github.io/tinyobjloader/
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Tiny but poweful single file wavefront obj loader written in C++. No dependency except for C++ STL. It can parse 10M over polygons with moderate memory and time.
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Good for embedding .obj loader to your (global illumination) renderer ;-)
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Example
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-------
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tinyobjloader can successfully load 6M triangles Rungholt scene.
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http://graphics.cs.williams.edu/data/meshes.xml
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Features
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--------
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* Group
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* Vertex
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* Texcoord
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* Normal
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* Material
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* Unknown material attributes are treated as key-value.
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Notes
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-----
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Polygon is converted into triangle.
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License
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-------
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Licensed under 2 clause BSD.
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Usage
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-----
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Data format
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attrib_t contains single and linear array of vertex data(position, normal and texcoord).
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attrib_t::vertices => 3 floats per vertex
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v[0] v[1] v[2] v[3] v[n-1]
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+-----------+-----------+-----------+-----------+ +-----------+
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| x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
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+-----------+-----------+-----------+-----------+ +-----------+
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attrib_t::normals => 3 floats per vertex
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n[0] n[1] n[2] n[3] n[n-1]
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+-----------+-----------+-----------+-----------+ +-----------+
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| x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
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+-----------+-----------+-----------+-----------+ +-----------+
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attrib_t::texcoords => 2 floats per vertex
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t[0] t[1] t[2] t[3] t[n-1]
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+-----------+-----------+-----------+-----------+ +-----------+
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| u | v | u | v | u | v | u | v | .... | u | v |
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+-----------+-----------+-----------+-----------+ +-----------+
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attrib_t::colors => 3 floats per vertex(vertex color. optional)
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c[0] c[1] c[2] c[3] c[n-1]
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+-----------+-----------+-----------+-----------+ +-----------+
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| x | y | z | x | y | z | x | y | z | x | y | z | .... | x | y | z |
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+-----------+-----------+-----------+-----------+ +-----------+
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Each shape_t::mesh_t does not contain vertex data but contains array index to attrib_t. See loader_example.cc for more details.
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mesh_t::indices => array of vertex indices.
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+----+----+----+----+----+----+----+----+----+----+ +--------+
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| i0 | i1 | i2 | i3 | i4 | i5 | i6 | i7 | i8 | i9 | ... | i(n-1) |
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+----+----+----+----+----+----+----+----+----+----+ +--------+
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Each index has an array index to attrib_t::vertices, attrib_t::normals and attrib_t::texcoords.
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mesh_t::num_face_vertices => array of the number of vertices per face(e.g. 3 = triangle, 4 = quad , 5 or more = N-gons).
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+---+---+---+ +---+
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| 3 | 4 | 3 | ...... | 3 |
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+---+---+---+ +---+
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| | | |
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| | | +-----------------------------------------+
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| | | |
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| | +------------------------------+ |
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| | | |
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| +------------------+ | |
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| | | |
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|/ |/ |/ |/
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mesh_t::indices
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| face[0] | face[1] | face[2] | | face[n-1] |
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+----+----+----+----+----+----+----+----+----+----+ +--------+--------+--------+
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| i0 | i1 | i2 | i3 | i4 | i5 | i6 | i7 | i8 | i9 | ... | i(n-3) | i(n-2) | i(n-1) |
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+----+----+----+----+----+----+----+----+----+----+ +--------+--------+--------+
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```c++
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#define TINYOBJLOADER_IMPLEMENTATION // define this in only *one* .cc
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#include "tiny_obj_loader.h"
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std::string inputfile = "cornell_box.obj";
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tinyobj::attrib_t attrib;
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std::vector<tinyobj::shape_t> shapes;
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LoadObj(attrib, shapes, inputfile.c_str());
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// Loop over shapes
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for (size_t s = 0; s < shapes.size(); s++) {
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// Loop over faces(polygon)
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size_t index_offset = 0;
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for (size_t f = 0; f < shapes[s].mesh.indices.size(); f++) {
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int fv = 3;
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// Loop over vertices in the face.
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for (size_t v = 0; v < fv; v++) {
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// access to vertex
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tinyobj::index_t idx = shapes[s].mesh.indices[index_offset + v];
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tinyobj::real_t vx = attrib.vertices[3*idx.vertex_index+0];
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tinyobj::real_t vy = attrib.vertices[3*idx.vertex_index+1];
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tinyobj::real_t vz = attrib.vertices[3*idx.vertex_index+2];
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tinyobj::real_t nx = attrib.normals[3*idx.normal_index+0];
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tinyobj::real_t ny = attrib.normals[3*idx.normal_index+1];
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tinyobj::real_t nz = attrib.normals[3*idx.normal_index+2];
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tinyobj::real_t tx = attrib.texcoords[2*idx.texcoord_index+0];
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tinyobj::real_t ty = attrib.texcoords[2*idx.texcoord_index+1];
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}
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index_offset += fv;
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}
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}
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```
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