source: trunk/src/formats/obj_loader.cc @ 239

// 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_vertex_vt
{
        vec3 position;
        vec2 texcoord;

        obj_vertex_vt( vec3 a_position, vec2 a_texcoord ) 
                : position( a_position ), texcoord( a_texcoord ) {}
};

struct obj_vertex_vtn
{
        vec3 position;
        vec2 texcoord;
        vec3 normal;

        obj_vertex_vtn( vec3 a_position, vec2 a_texcoord, vec3 a_normal ) 
                : position( a_position ), texcoord( a_texcoord ), normal( a_normal ) {}
};


struct obj_vertex_vtnt
{
        vec3 position;
        vec2 texcoord;
        vec3 normal;
        vec4 tangent;

        obj_vertex_vtnt( vec3 a_position, vec2 a_texcoord, vec3 a_normal ) 
                : position( a_position ), texcoord( a_texcoord ), normal( a_normal ) {}
};

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 size_t add_face( uint32* vi, uint32* ti, uint32* ni, size_t count ) = 0;
        virtual size_t raw_size() const = 0;
        virtual const uint8* raw_pointer() const = 0;
        virtual void calculate_tangents() {}

        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_data_reader_vt : public obj_reader
{
        mesh_data_reader_vt()  {}
        virtual std::size_t add_face( uint32* vi, uint32* ti, uint32*, size_t count )
        {
                if ( count < 3 ) return 0; // TODO : report error?
                // TODO : support if normals not present;
                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++;
                        m_data.emplace_back( v[ vi[ 0 ]   ], t[ ti[ 0   ] ] );
                        m_data.emplace_back( v[ vi[ i-1 ] ], t[ ti[ i-1 ] ] );
                        m_data.emplace_back( v[ vi[ i ]   ], t[ ti[ i   ] ] );
                }
                return result;
        }
        std::vector< obj_vertex_vt > m_data;
        virtual size_t raw_size() const { return m_data.size() * sizeof( obj_vertex_vt ); }
        virtual const uint8* raw_pointer() const { return (const uint8*)m_data.data(); }
};

struct mesh_data_reader_vtn : public obj_reader
{
        mesh_data_reader_vtn()  {}
        virtual std::size_t add_face( uint32* vi, uint32* ti, uint32* ni, size_t count )
        {
                if ( count < 3 ) return 0; // TODO : report error?
                // TODO : support if normals not present;
                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++;
                        m_data.emplace_back( v[ vi[ 0 ]   ], t[ ti[ 0   ] ], n[ ni[ 0   ] ] );
                        m_data.emplace_back( v[ vi[ i-1 ] ], t[ ti[ i-1 ] ], n[ ni[ i-1 ] ] );
                        m_data.emplace_back( v[ vi[ i ]   ], t[ ti[ i   ] ], n[ ni[ i   ] ] );
                }
                return result;
        }
        std::vector< obj_vertex_vtn > m_data;
        virtual size_t raw_size() const { return m_data.size() * sizeof( obj_vertex_vtn ); }
        virtual const uint8* raw_pointer() const { return (const uint8*)m_data.data(); }
};

struct mesh_data_reader_vtnt : public obj_reader
{
        mesh_data_reader_vtnt()  {}
        virtual std::size_t add_face( uint32* vi, uint32* ti, uint32* ni, size_t count )
        {
                if ( count < 3 ) return 0; // TODO : report error?
                // TODO : support if normals not present;
                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++;
                        m_data.emplace_back( v[ vi[ 0 ]   ], t[ ti[ 0   ] ], n[ ni[ 0   ] ] );
                        m_data.emplace_back( v[ vi[ i-1 ] ], t[ ti[ i-1 ] ], n[ ni[ i-1 ] ] );
                        m_data.emplace_back( v[ vi[ i ]   ], t[ ti[ i   ] ], n[ ni[ i   ] ] );
                }
                return result;
        }
        std::vector< obj_vertex_vtnt > m_data;
        virtual size_t raw_size() const { return m_data.size() * sizeof( obj_vertex_vtnt ); }
        virtual const uint8* raw_pointer() const { return (const uint8*)m_data.data(); }

        // based on http://www.terathon.com/code/tangent.html
        void calculate_tangents()
        {
                //              const std::vector< vec3 >& vp = m_mesh->get_positions();
                //              const std::vector< vec2 >& vt = m_mesh->get_texcoords();
                //              const std::vector< vec3 >& vn = m_mesh->get_normals();
                //              std::vector< vec3 >& tg = m_mesh->get_tangents();

                size_t count  = m_data.size();
                size_t tcount = count / 3;

                std::vector< vec3 > tan1( count );
                std::vector< vec3 > tan2( count );

                for (size_t a = 0; a < tcount; ++a )
                {
                        size_t i1 = a * 3;
                        size_t i2 = a * 3 + 1;
                        size_t i3 = a * 3 + 2;
                        obj_vertex_vtnt& vtx1 = m_data[ i1 ];
                        obj_vertex_vtnt& vtx2 = m_data[ i2 ];
                        obj_vertex_vtnt& vtx3 = m_data[ i3 ];

                        // TODO: simplify
                        vec3 xyz1 = vtx2.position - vtx1.position;
                        vec3 xyz2 = vtx3.position - vtx1.position;
                        //vec2 st1  = w2 - w1;
                        //vec2 st2  = w3 - w1;

                        float s1 = vtx2.texcoord.x - vtx1.texcoord.x;
                        float t1 = vtx2.texcoord.y - vtx1.texcoord.y;
                        float s2 = vtx3.texcoord.x - vtx1.texcoord.x;
                        float t2 = vtx3.texcoord.y - vtx1.texcoord.y;

                        float stst = s1 * t2 - s2 * t1;
                        float r = 0.0f;
                        if (stst > 0.0f || stst < 0.0f) r = 1.0f / stst;

                        vec3 sdir = ( t2 * xyz1 - t1 * xyz2 ) * r;
                        vec3 tdir = ( s1 * xyz2 - s2 * xyz1 ) * r;

                        // the += below obviously doesn't make sense in this case, but I'll
                        // leave it here for when I move to indices
                        tan1[i1] += sdir;
                        tan1[i2] += sdir;
                        tan1[i3] += sdir;

                        // tan2 not needed anymore??
                        tan2[i1] += tdir;
                        tan2[i2] += tdir;
                        tan2[i3] += tdir;
                }

                for (std::size_t a = 0; a < count; ++a )
                {
                        const vec3& n = m_data[a].normal;
                        const vec3& t = tan1[a];
                        if ( ! (t.x == 0.0f && t.y == 0.0f && t.z == 0.0f) )
                        {
                                m_data[a].tangent    = vec4( glm::normalize(t - n * glm::dot( n, t )), 0.0f ); 
                                m_data[a].tangent[3] = (glm::dot(glm::cross(n, t), tan2[a]) < 0.0f) ? -1.0f : 1.0f;
                        }
                }

        }


};

nv::obj_loader::obj_loader( bool normals /*= true*/, bool tangents /*= false */ )
        : m_normals( normals ), m_tangents( tangents ), m_mesh( nullptr )
{
        if ( normals )
        {
                if ( tangents )
                        m_descriptor.initialize<obj_vertex_vtnt>();
                else
                        m_descriptor.initialize<obj_vertex_vtn>();
        }
        else
                m_descriptor.initialize<obj_vertex_vt>();
}

bool nv::obj_loader::load( stream& source )
{
        if ( m_mesh ) delete m_mesh;
        
        obj_reader* reader = nullptr;
        if ( m_normals )
        {
                if ( m_tangents )
                        reader = new mesh_data_reader_vtnt();
                else
                        reader = new mesh_data_reader_vtn();
        }
        else
                reader = new mesh_data_reader_vt();
        std_stream sstream( &source );
        reader->read_stream( sstream );

        if ( m_tangents )
        {
                reader->calculate_tangents();
        }
        

        mesh_raw_channel* channel = new mesh_raw_channel();
        nv::uint8* data = nullptr;

        if ( reader->raw_size() > 0 ) 
        {
                data = new uint8[ reader->raw_size() ];
                std::copy_n( reader->raw_pointer(), reader->raw_size(), data );
        }
        channel->data  = data;
        channel->desc  = m_descriptor;
        channel->count = reader->size * 3;
        channel->size  = reader->raw_size();
        delete reader;

        m_mesh = new mesh_data();
        m_mesh->add_channel( channel );
        return true;

}

mesh_data* nv::obj_loader::release_mesh_data()
{
        mesh_data* result = m_mesh;
        m_mesh = nullptr;
        return result;
}

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