source: trunk/src/formats/obj_loader.cc @ 138

// Copyright (C) 2012-2013 ChaosForge / Kornel Kisielewicz
// http://chaosforge.org/
//
// This file is part of NV Libraries.
// For conditions of distribution and use, see copyright notice in nv.hh

#include "nv/formats/obj_loader.hh"
#include "nv/io/std_stream.hh"
#include <sstream>

using namespace nv;

struct obj_reader
{
        std::vector< vec3 > v;
        std::vector< vec3 > n;
        std::vector< vec2 > t;

        std::string line;
        std::string cmd;

        std::size_t size;

        obj_reader();
        bool read_stream( std::istream& stream );

        virtual std::size_t add_face( uint32* vi, uint32* ti, uint32* ni, size_t count ) = 0;
        virtual ~obj_reader(){}
};

obj_reader::obj_reader()
{
        // push in dummy 0-index objects for faster indexing
        v.push_back( vec3() );
        n.push_back( vec3() );
        t.push_back( vec2() );
        size = 0;
}

bool obj_reader::read_stream( std::istream& stream )
{
        f32 x, y, z;

        while ( std::getline( stream, line ) )
        {
                if ( line.length() < 3 || line[0] == '#' )
                {
                        continue;
                }

                std::istringstream ss(line);
                ss >> cmd;

                if ( cmd == "v" )
                {
                        ss >> x >> y >> z;
                        v.push_back( vec3( x, y, z ) );
                        continue;
                }

                if ( cmd == "vn" )
                {
                        ss >> x >> y >> z;
                        n.push_back( vec3( x, y, z ) );
                        continue;
                }

                if ( cmd == "vt" )
                {
                        ss >> x >> y;
                        t.push_back( vec2( x, 1.0f - y ) );
                        continue;
                }

                if ( cmd == "f" )
                {
                        ss >> cmd;

                        uint32 vis[8];
                        uint32 tis[8];
                        uint32 nis[8];
                        bool   normals = false;
                        uint32 count = 0;

                        while ( !ss.fail() )
                        {
                                char ch;

                                std::istringstream ss2( cmd );
                                ss2 >> vis[count] >> ch;
                                ss2 >> tis[count] >> ch;
                                if ( ch == '/')
                                {
                                        normals = true;
                                        ss2 >> nis[count];
                                }

                                ss >> cmd;
                                count++;
                        }

                        size += add_face( vis, tis, normals ? nis : nullptr, count );
                        continue;
                }

                if ( cmd == "g" || cmd == "s" )
                {
                        // ignored
                        continue;
                }

                // unknown command
        }

        return true;
}


struct mesh_obj_reader : public obj_reader
{
        mesh_obj_reader( mesh* m ) : m_mesh( m ), m_position( nullptr ), m_normal( nullptr ), m_tex_coord( nullptr ) {}
        virtual std::size_t add_face( uint32* v, uint32* t, uint32* n, size_t count );

        vertex_attribute< vec3 >* m_position;
        vertex_attribute< vec3 >* m_normal;
        vertex_attribute< vec2 >* m_tex_coord;
        mesh* m_mesh;
};

std::size_t mesh_obj_reader::add_face( uint32* vi, uint32* ti, uint32* ni, size_t count )
{
        if ( count < 3 )
        {
                // TODO : report error?
                return 0;
        }

        if ( m_position == nullptr )
        {
                m_position  = m_mesh->add_attribute< vec3 >( "position" );
        }
        if ( m_tex_coord == nullptr )
        {
                m_tex_coord = m_mesh->add_attribute< vec2 >( "texcoord" );
        }
        if ( m_normal == nullptr && ni != nullptr )
        {
                m_normal = m_mesh->add_attribute< vec3 >( "normal" );
        }

        // TODO : support if normals not present;

        std::vector< vec3 >& vp = m_position->get();
        std::vector< vec2 >& vt = m_tex_coord->get();
        std::vector< vec3 >& vn = m_normal->get();

        std::size_t result = 0;

        // Simple triangulation - obj's shouldn't have more than quads anyway
        for ( size_t i = 2; i < count; ++i )
        {
                result++;
                vp.push_back( v[ vi[ 0 ] ] );   vt.push_back( t[ ti[ 0 ] ] );   vn.push_back( n[ ni[ 0 ] ] );
                vp.push_back( v[ vi[ i-1 ] ] ); vt.push_back( t[ ti[ i-1 ] ] ); vn.push_back( n[ ni[ i-1 ] ] );
                vp.push_back( v[ vi[ i ] ] );   vt.push_back( t[ ti[ i ] ] );   vn.push_back( n[ ni[ i ] ] );
        }

        return result;
}

nv::obj_loader::obj_loader()
        : m_mesh( nullptr )
{

}

nv::obj_loader::~obj_loader()
{
        delete m_mesh;
}

bool nv::obj_loader::load( stream& source )
{
        if ( m_mesh != nullptr )
        {
                delete m_mesh;
        }
        m_mesh = new mesh();
        mesh_obj_reader reader( m_mesh );
        std_stream sstream( &source );
        reader.read_stream( sstream );
        m_size = reader.size;
        return true;
}