source: trunk/src/gfx/mesh_creator.cc @ 481

// Copyright (C) 2012-2015 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

#include "nv/gfx/mesh_creator.hh"

#include "nv/interface/data_channel_access.hh"

#include "nv/core/logging.hh"

struct nv_key_transform { nv::transform tform; };

void nv::mesh_nodes_creator::pre_transform_keys()
{
        if ( m_data->m_flat ) return;
        merge_keys();
        uint16 max_frames = 0;

        nv::vector< sint16 > ids;
        {
                // TODO: simplify this shit!
                // The complexity here is that we cannot pre-transform in any order
                // as the bones depend on previous bones, but ARE NOT IN ORDER
                // 
                // Either rewrite this a lot nicer, or sort the bones on creation
                // by tree-order.

                ids.reserve( m_data->m_data.size() );
                {
                        nv::vector< sint16 > ids_next;
                        ids_next.reserve( m_data->m_data.size() );
                        ids_next.push_back( -1 );
                        while ( !ids_next.empty() )
                        {
                                sint16 pid = ids_next.back();
                                ids_next.pop_back();
                                for ( sint16 i = 0; i < sint16(m_data->m_data.size()); ++i )
                                        if ( m_data->m_data[i]->get_parent_id() == pid )
                                        {
                                                sint16* it = nv::find( ids.begin(), ids.end(), i );
                                                if ( it == ids.end() )
                                                {
                                                        ids.push_back( i );
                                                        ids_next.push_back( i );
                                                }
                                        }
                        }
                }

                if ( ids.size() != m_data->m_data.size() )
                {
                        NV_LOG_WARNING( "Bad skeleton!" );
                }
        }

        NV_LOG_DEBUG( "ID/PID" );
        for ( auto id : ids )
        {
                data_channel_set* keys = m_data->m_data[id];
                sint16 parent_id = keys->get_parent_id();
                NV_LOG_DEBUG( "Id : ", id, " PID", parent_id );
                data_channel_set* pkeys = ( parent_id != -1 ? m_data->m_data[parent_id] : nullptr );
                size_t count     = ( keys ? keys->get_channel_size(0) : 0 );
                size_t pcount    = ( pkeys ? pkeys->get_channel_size(0) : 0 );
                max_frames = nv::max<uint16>( uint16( count ), max_frames );
                if ( pkeys && pkeys->size() > 0 && keys && keys->size() > 0 )
                {
                        data_channel_access< nv_key_transform > channel_creator( keys, 0 );

                        nv_key_transform* channel = channel_creator.data();
                        const nv_key_transform* pchannel = pkeys->get_channel(0)->data_cast< nv_key_transform >();
                        for ( unsigned n = 0; n < count; ++n )
                        {
                                channel[n].tform = pchannel[ nv::min( n, pcount-1 ) ].tform * channel[n].tform;
                        }
                }
        }

        // DAE pre_transform hack
        if ( m_data->m_frame_rate == 1 )
        {
                m_data->m_frame_rate  = 32;
                m_data->m_frame_count = max_frames;
        }

        m_data->m_flat = true;
}


void nv::mesh_nodes_creator::merge_keys()
{
        for ( size_t i = 0; i < m_data->size(); ++i )
        {
                data_channel_set* old_keys = m_data->m_data[i];
                if ( old_keys && old_keys->size() > 0 )
                {
                        size_t chan_count = old_keys->size();
                        if ( chan_count == 1 
                                && old_keys->get_channel(0)->descriptor().size() == 1
                                && old_keys->get_channel(0)->descriptor()[0].etype == TRANSFORM ) continue;

                        size_t max_keys = 0;
                        for ( size_t c = 0; c < chan_count; ++c )
                        {
                                max_keys = nv::max( max_keys, old_keys->get_channel(c)->size() );
                        }

                        data_channel_set* new_keys = data_channel_set_creator::create_set( 1 );
                        data_channel_set_creator nk_access( new_keys );
                        nk_access.set_name( old_keys->get_name() );
                        nk_access.set_parent_id( old_keys->get_parent_id() );
                        nk_access.set_transform( old_keys->get_transform() );
                        data_channel_access< nv_key_transform > kt_channel( nk_access.add_channel<nv_key_transform>( max_keys ) );

                        raw_channel_interpolator interpolator( old_keys );
                        data_descriptor final_key = interpolator.get_interpolation_key();

                        for ( unsigned n = 0; n < max_keys; ++n )
                        {
                                float key[ 16 ];
                                float* pkey = key;

                                for ( uint16 c = 0; c < chan_count; ++c )
                                {
                                        size_t idx = nv::min( old_keys->get_channel_size(c) - 1, n );
                                        pkey += raw_channel_interpolator::get_raw( *old_keys->get_channel(c), idx, pkey );
                                }
                                kt_channel.data()[n].tform = extract_key_raw< nv::transform >( final_key, key );
                        }

                        delete old_keys;
                        m_data->m_data[i] = new_keys;
                }
        }
}

void nv::mesh_nodes_creator::transform( float scale, const mat3& r33 )
{
        mat3 ri33 = math::inverse( r33 );
        mat4 pre_transform ( scale * r33 );
        mat4 post_transform( 1.f/scale * ri33 ); 

        for ( auto node : m_data->m_data )
        {
                node->m_transform = pre_transform * node->m_transform * post_transform;

                for ( size_t c = 0; c < node->size(); ++c )
                {
                        raw_data_channel_access channel( node, c );
                        size_t key_size = channel.element_size();
                        for ( size_t n = 0; n < channel.size(); ++n )
                        {
                                transform_key_raw( node->get_channel( c )->descriptor(), channel.raw_data() + n * key_size, scale, r33, ri33 );
                        }
                }
        }
}

void nv::mesh_data_creator::transform( float scale, const mat3& r33 )
{
        vec3 vertex_offset     = vec3(); 
        mat3 vertex_transform  = scale * r33;
        mat3 normal_transform  = r33;

        for ( uint32 c = 0; c < m_data->size(); ++c )
        {
                raw_data_channel_access channel( m_data, c );
                const data_descriptor&  desc    = channel.descriptor();
                uint8* raw_data = channel.raw_data();
                uint32 vtx_size = desc.element_size();
                int p_offset = -1;
                int n_offset = -1;
                int t_offset = -1;
                for ( const auto& cslot : desc  )
                        switch ( cslot.vslot )
                        {
                                case slot::POSITION : if ( cslot.etype == FLOAT_VECTOR_3 ) p_offset = int( cslot.offset ); break;
                                case slot::NORMAL   : if ( cslot.etype == FLOAT_VECTOR_3 ) n_offset = int( cslot.offset ); break;
                                case slot::TANGENT  : if ( cslot.etype == FLOAT_VECTOR_4 ) t_offset = int( cslot.offset ); break;
                                default             : break;
                        }

                if ( p_offset != -1 )
                        for ( uint32 i = 0; i < channel.size(); i++)
                        {
                                vec3& p = *reinterpret_cast<vec3*>( raw_data + vtx_size*i + p_offset );
                                p = vertex_transform * p + vertex_offset;
                        }

                if ( n_offset != -1 )
                        for ( uint32 i = 0; i < channel.size(); i++)
                        {
                                vec3& n = *reinterpret_cast<vec3*>( raw_data + vtx_size*i + n_offset );
                                n = math::normalize( normal_transform * n );
                        }
                if ( t_offset != -1 )
                        for ( uint32 i = 0; i < channel.size(); i++)
                        {
                                vec4& t = *reinterpret_cast<vec4*>(raw_data + vtx_size*i + t_offset );
                                t = vec4( math::normalize( normal_transform * vec3(t) ), t[3] );
                        }
        }
}

struct vertex_g
{
        nv::vec4 tangent;
};

void nv::mesh_data_creator::flip_normals()
{
        if ( m_nrm_channel == nullptr ) return;
        NV_ASSERT( m_nrm_type == FLOAT_VECTOR_3, "Unknown normal vector type!" );
        raw_data_channel_access channel( m_nrm_channel );
        for ( uint32 i = 0; i < channel.size(); ++i )
        {
                vec3& normal = *reinterpret_cast<vec3*>( channel.raw_data() + channel.element_size() * i + m_nrm_offset );
                normal = -normal;
        }
}


void nv::mesh_data_creator::scale_texture( vec2 min, vec2 max )
{
        if ( m_tex_channel == nullptr ) return;
        NV_ASSERT( m_tex_type == FLOAT_VECTOR_2, "Unknown texcoord vector type!" );
        raw_data_channel_access channel( m_tex_channel );
        vec2 scale = max - min;
        for ( uint32 i = 0; i < channel.size(); ++i )
        {
                vec2& tc = *reinterpret_cast<vec2*>( channel.raw_data() + channel.element_size() * i + m_tex_offset );
                tc = min + tc * scale;
        }
}

void nv::mesh_data_creator::generate_tangents()
{
        if ( m_tan_channel != nullptr ) return;
        if ( !m_pos_channel || !m_nrm_channel || !m_tex_channel ) return;

        if ( m_pos_channel->size() != m_nrm_channel->size()
                || m_pos_channel->size() % m_tex_channel->size() != 0
                || ( m_idx_type != UINT && m_idx_type != USHORT && m_idx_type != NONE ) )
        {
                return;
        }

        NV_ASSERT( m_pos_type == FLOAT_VECTOR_3, "Unsupported position vector type!" );
        NV_ASSERT( m_nrm_type == FLOAT_VECTOR_3, "Unsupported normal vector type!" );
        NV_ASSERT( m_tex_type == FLOAT_VECTOR_2, "Unknown texcoord vector type!" );

        raw_data_channel g_channel  = data_channel_creator::create< vertex_g >( m_pos_channel->size() );
        vec4* tangents              = &( data_channel_access< vertex_g >( &g_channel ).data()[0].tangent );
        fill_n( tangents, m_pos_channel->size(), vec4() );
        vec3* tangents2             = new vec3[ m_pos_channel->size() ];
        uint32 tri_count = m_idx_channel ? m_idx_channel->size() / 3 : m_tex_channel->size() / 3;
        uint32 vtx_count = m_pos_channel->size();
        uint32 sets      = m_pos_channel->size() / m_tex_channel->size();

        for ( unsigned int i = 0; i < tri_count; ++i )
        {
                uint32 ti0 = 0;
                uint32 ti1 = 0;
                uint32 ti2 = 0;
                if ( m_idx_type == UINT )
                {
                        const uint32* idata = reinterpret_cast<const uint32*>( m_idx_channel->raw_data() );
                        ti0 = idata[ i * 3 ];
                        ti1 = idata[ i * 3 + 1 ];
                        ti2 = idata[ i * 3 + 2 ];
                }
                else if ( m_idx_type == USHORT )
                {
                        const uint16* idata = reinterpret_cast<const uint16*>( m_idx_channel->raw_data() );
                        ti0 = idata[ i * 3 ];
                        ti1 = idata[ i * 3 + 1 ];
                        ti2 = idata[ i * 3 + 2 ];
                }
                else // if ( m_idx_type == NONE )
                {
                        ti0 = i * 3;
                        ti1 = i * 3 + 1;
                        ti2 = i * 3 + 2;
                }

                vec2 w1 = *reinterpret_cast<const vec2*>( m_tex_channel->raw_data() + m_tex_channel->element_size()*ti0 + m_tex_offset );
                vec2 w2 = *reinterpret_cast<const vec2*>( m_tex_channel->raw_data() + m_tex_channel->element_size()*ti1 + m_tex_offset );
                vec2 w3 = *reinterpret_cast<const vec2*>( m_tex_channel->raw_data() + m_tex_channel->element_size()*ti2 + m_tex_offset );
                vec2 st1 = w3 - w1;
                vec2 st2 = w2 - w1;
                float stst = (st1.x * st2.y - st2.x * st1.y);
                float coef = ( stst != 0.0f ? 1.0f / stst : 0.0f );

                for ( uint32 set = 0; set < sets; ++set )
                {
                        uint32 nti0 = m_tex_channel->size() * set + ti0;
                        uint32 nti1 = m_tex_channel->size() * set + ti1;
                        uint32 nti2 = m_tex_channel->size() * set + ti2;
                        const vec3& v1 = *reinterpret_cast<const vec3*>( m_pos_channel->raw_data() + m_pos_channel->element_size()*nti0 + m_pos_offset );
                        const vec3& v2 = *reinterpret_cast<const vec3*>( m_pos_channel->raw_data() + m_pos_channel->element_size()*nti1 + m_pos_offset );
                        const vec3& v3 = *reinterpret_cast<const vec3*>( m_pos_channel->raw_data() + m_pos_channel->element_size()*nti2 + m_pos_offset );
                        vec3 xyz1 = v3 - v1;
                        vec3 xyz2 = v2 - v1;

                        //vec3 normal = math::cross( xyz1, xyz2 );
                        //
                        //vtcs[ ti0 ].normal += normal;
                        //vtcs[ ti1 ].normal += normal;
                        //vtcs[ ti2 ].normal += normal;
                        vec3 tangent  = (( xyz1 * st2.y ) - ( xyz2 * st1.y )) * coef;
                        vec3 tangent2 = (( xyz2 * st1.x ) - ( xyz1 * st2.x )) * coef;

                        tangents[nti0] = vec4( vec3( tangents[nti0] ) + tangent, 0 );
                        tangents[nti1] = vec4( vec3( tangents[nti1] ) + tangent, 0 );
                        tangents[nti2] = vec4( vec3( tangents[nti2] ) + tangent, 0 );

                        tangents2[nti0] += tangent2;
                        tangents2[nti1] += tangent2;
                        tangents2[nti2] += tangent2;
                }
        }

        for ( unsigned int i = 0; i < vtx_count; ++i )
        {
                const vec3 n = *reinterpret_cast<const vec3*>( m_nrm_channel->raw_data() + m_nrm_channel->element_size()*i + m_nrm_offset );
                const vec3 t = vec3(tangents[i]);
                if ( ! ( t.x == 0.0f && t.y == 0.0f && t.z == 0.0f ) )
                {
                        tangents[i]    = vec4( math::normalize(t - n * math::dot( n, t )), 0.0f );
                        tangents[i][3] = ( math::dot( math::cross(n, t), tangents2[i]) < 0.0f) ? -1.0f : 1.0f;
                }
        }
        delete[] tangents2;

        uint32 n_channel_index = m_data->get_channel_index( slot::NORMAL );
        data_channel_set_creator( m_data ).set_channel( n_channel_index, merge_channels( *m_nrm_channel, g_channel ) );
        initialize();
}

void nv::mesh_data_creator::rotate_quadrant( uint8 rotation )
{
        if ( rotation % 4 == 0 ) return;
        NV_ASSERT( m_pos_type == FLOAT_VECTOR_3, "Unsupported position vector type!" );
        NV_ASSERT( m_nrm_type == FLOAT_VECTOR_3, "Unsupported normal vector type!" );
        NV_ASSERT( m_tan_type == FLOAT_VECTOR_4, "Unsupported tangent vector type!" );

        float r11 = 0.f;
        float r12 = 0.f;
        float r21 = 0.f;
        float r22 = 0.f;

        switch ( rotation % 4 )
        {
        case 1: r12 = -1.f; r21 =  1.f; break;
        case 2: r11 = -1.f; r22 = -1.f; break;
        case 3: r12 =  1.f; r21 = -1.f; break;
        default:
                break;
        }

        unsigned vtx_count = m_pos_channel->size();
        uint8* pos_data = raw_data_channel_access( m_pos_channel ).raw_data();
        uint8* nrm_data = raw_data_channel_access( m_nrm_channel ).raw_data();
        uint8* tan_data = raw_data_channel_access( m_tan_channel ).raw_data();
        for ( unsigned int i = 0; i < vtx_count; ++i )
        {
                vec3& pos = *reinterpret_cast<vec3*>( pos_data + m_pos_channel->element_size() * i + m_pos_offset );
                vec3& nrm = *reinterpret_cast<vec3*>( nrm_data + m_nrm_channel->element_size() * i + m_nrm_offset );
                vec4& tan = *reinterpret_cast<vec4*>( tan_data + m_tan_channel->element_size() * i + m_tan_offset );

                pos = vec3(
                        pos.x * r11 + pos.z * r12,
                        pos.y,
                        pos.x * r21 + pos.z * r22
                        );
                nrm = vec3(
                        nrm.x * r11 + nrm.z * r12,
                        nrm.y,
                        nrm.x * r21 + nrm.z * r22
                        );
                tan = vec4(
                        tan.x * r11 + tan.z * r12,
                        tan.y,
                        tan.x * r21 + tan.z * r22,
                        tan.w // make sure this is proper
                        );
        }


}

void nv::mesh_data_creator::mirror( bool x, bool z )
{
        if ( !x && !z ) return;
        NV_ASSERT( m_pos_type == FLOAT_VECTOR_3, "Unsupported position vector type!" );
        NV_ASSERT( m_nrm_type == FLOAT_VECTOR_3, "Unsupported normal vector type!" );
        NV_ASSERT( m_tan_type == FLOAT_VECTOR_4, "Unsupported tangent vector type!" );

        float kx = x ? -1.0f : 1.0f;
        float kz = z ? -1.0f : 1.0f;

        unsigned vtx_count = m_pos_channel->size();
        uint8* pos_data = raw_data_channel_access( m_pos_channel ).raw_data();
        uint8* nrm_data = raw_data_channel_access( m_nrm_channel ).raw_data();
        uint8* tan_data = raw_data_channel_access( m_tan_channel ).raw_data();
        for ( unsigned int i = 0; i < vtx_count; ++i )
        {
                vec3& pos = *reinterpret_cast<vec3*>( pos_data + m_pos_channel->element_size() * i + m_pos_offset );
                vec3& nrm = *reinterpret_cast<vec3*>( nrm_data + m_nrm_channel->element_size() * i + m_nrm_offset );
                vec4& tan = *reinterpret_cast<vec4*>( tan_data + m_tan_channel->element_size() * i + m_tan_offset );

                pos = vec3(
                        pos.x * kx,
                        pos.y,
                        pos.z * kz
                        );
                nrm = vec3(
                        nrm.x * kx,
                        nrm.y,
                        nrm.z * kz
                        );
                tan = vec4(
                        tan.x * kx,
                        tan.y,
                        tan.z * kz,
                        tan.w * kx * kz// make sure this is proper
                        );
        }

        if ( !( x && z ) ) 
                swap_culling();
}

template < typename T >
static inline void swap_culling_impl( nv::raw_data_channel* index_channel )
{
        nv::raw_data_channel_access ichannel( index_channel );
        T* indices = reinterpret_cast<T*>( ichannel.raw_data() );
        nv::uint32 count = index_channel->size() / 3;
        for ( nv::uint32 i = 0; i < count; ++i )
        {
                nv::swap( indices[i * 3], indices[i * 3 + 1] );
        }
}

void nv::mesh_data_creator::swap_culling()
{
        NV_ASSERT( m_idx_channel, "Swap culling unsupported on non-indexed meshes!" );
        NV_ASSERT( m_idx_channel->descriptor().size() == 1, "Malformed index channel!" );
        NV_ASSERT( m_idx_channel->size() % 3 == 0, "Malformed index channel - not per GL_TRIANGLE LAYOUT?" );

        if ( m_idx_channel->size() == 0 ) return;
        switch ( m_idx_type )
        {
        case USHORT: swap_culling_impl< uint16 >( m_idx_channel ); break;
        case UINT: swap_culling_impl< uint16 >( m_idx_channel ); break;
        default: NV_ASSERT( false, "Swap culling supports only unsigned and unsigned short indices!" ); break;
        }
}

void nv::mesh_data_creator::translate( vec3 offset )
{
        if ( m_pos_channel == nullptr ) return;
        NV_ASSERT( m_pos_type == FLOAT_VECTOR_3, "Unsupported poosition vector type!" );
        raw_data_channel_access channel( m_pos_channel );
        for ( uint32 i = 0; i < channel.size(); ++i )
        {
                vec3& p = *reinterpret_cast<vec3*>( channel.raw_data() + channel.element_size() * i + m_pos_offset );
                p = p + offset;
        }

}

void nv::mesh_data_creator::initialize()
{
        NV_ASSERT( m_data, "bad parameter!" );
        m_pos_channel = nullptr;
        m_nrm_channel = nullptr;
        m_tan_channel = nullptr;
        m_tex_channel = nullptr;
        m_idx_channel = nullptr;

        m_pos_offset = -1;
        m_nrm_offset = -1;
        m_tan_offset = -1;
        m_tex_offset = -1;
        m_idx_offset = -1;

        m_pos_type = NONE;
        m_nrm_type = NONE;
        m_tan_type = NONE;
        m_tex_type = NONE;
        m_idx_type = NONE;

        for ( uint32 c = 0; c < m_data->size(); ++c )
        {
                raw_data_channel* channel = data_channel_set_creator( m_data )[c];

                for ( const auto& cslot : channel->descriptor() )
                        switch ( cslot.vslot )
                        {
                        case slot::POSITION:
                                m_pos_type = cslot.etype;
                                m_pos_offset = int( cslot.offset );
                                m_pos_channel = channel;
                                break;
                        case slot::NORMAL:
                                m_nrm_type = cslot.etype;
                                m_nrm_offset = int( cslot.offset );
                                m_nrm_channel = channel;
                                break;
                        case slot::TANGENT:
                                m_tan_type = cslot.etype;
                                m_tan_offset = int( cslot.offset );
                                m_tan_channel = channel;
                                break;
                        case slot::TEXCOORD:
                                m_tex_type = cslot.etype;
                                m_tex_offset = int( cslot.offset );
                                m_tex_channel = channel;
                                break;
                        case slot::INDEX:
                                m_idx_type = cslot.etype;
                                m_idx_offset = int( cslot.offset );
                                m_idx_channel = channel;
                                break;
                        default: break;
                        }
        }
}

nv::raw_data_channel nv::mesh_data_creator::merge_channels( const raw_data_channel& a, const raw_data_channel& b )
{
        NV_ASSERT( a.size() == b.size(), "merge_channel - bad channels!" );
        data_descriptor desc  = a.descriptor();
        desc.append( b.descriptor() );

        raw_data_channel result = data_channel_creator::create( desc, a.size() );
        for ( uint32 i = 0; i < a.size(); ++i )
        {
                raw_copy_n( a.raw_data() + i * a.element_size(), a.element_size(), raw_data_channel_access( &result ).raw_data() + i*desc.element_size() );
                raw_copy_n( b.raw_data() + i * b.element_size(), b.element_size(), raw_data_channel_access( &result ).raw_data() + i*desc.element_size() + a.element_size() );
        }
        initialize();
        return result;
}

nv::raw_data_channel nv::mesh_data_creator::append_channels( const raw_data_channel& a, const raw_data_channel& b, uint32 frame_count )
{
        NV_ASSERT( a.descriptor() == b.descriptor(), "Merge - append not compatible format!" );
        NV_ASSERT( a.size() % frame_count == 0, "Merge - append first mesh empty!" );
        NV_ASSERT( b.size() % frame_count == 0, "Merge - append second mesh empty!" );
        size_t vtx_size = a.element_size();

        raw_data_channel result = data_channel_creator::create( a.descriptor(), a.size() + b.size() );
        uint8* rdata = raw_data_channel_access( &result ).raw_data();

        if ( frame_count == 1 )
        {
                size_t a_size = vtx_size * a.size();
                raw_copy_n( a.raw_data(), a_size, rdata );
                raw_copy_n( b.raw_data(), vtx_size * b.size(), rdata + a_size );
        }
        else
        {
                size_t frame_size_a = ( a.size() / frame_count ) * vtx_size;
                size_t frame_size_b = ( b.size() / frame_count ) * vtx_size;
                size_t pos_a = 0;
                size_t pos_b = 0;
                size_t pos   = 0;
                for ( size_t i = 0; i < frame_count; ++i )
                {
                        raw_copy_n( a.raw_data() + pos_a, frame_size_a, rdata + pos );
                        raw_copy_n( b.raw_data() + pos_b, frame_size_b, rdata + pos + frame_size_a );                           pos_a += frame_size_a;
                        pos_b += frame_size_b; 
                        pos   += frame_size_a + frame_size_b;
                }
        }

        initialize();
        return result;
}



bool nv::mesh_data_creator::is_same_format( const data_channel_set* other )
{
        if ( m_data->size() != other->size() ) return false;
        for ( uint32 c = 0; c < m_data->size(); ++c )
        {
                if ( m_data->get_channel(c)->descriptor() != other->get_channel(c)->descriptor() )
                        return false;
        }
        return true;
}

void nv::mesh_data_creator::merge( const data_channel_set* other )
{
        if ( !is_same_format( other ) ) return;
        int ch_pi  = m_data->get_channel_index( slot::POSITION );
        int ch_ti  = m_data->get_channel_index( slot::TEXCOORD );
        int och_pi = other->get_channel_index( slot::POSITION );
        int och_ti = other->get_channel_index( slot::TEXCOORD );
        if ( ch_pi == -1 || ch_ti == -1 ) return;
        size_t size   = m_data->get_channel_size( unsigned(ch_ti) );
        size_t osize  =  other->get_channel_size( unsigned(och_ti) );
        size_t count  = m_data->get_channel_size( unsigned(ch_pi) );
        size_t ocount =  other->get_channel_size( unsigned(och_pi) );
        if ( count % size != 0 || ocount % osize != 0 ) return;
        if ( count / size != ocount / osize ) return;
        
        data_channel_set_creator data( m_data );

        for ( uint32 c = 0; c < m_data->size(); ++c )
        {
                const raw_data_channel* old = m_data->get_channel( c );
                uint32 old_size = old->size();
                data_descriptor old_desc = old->descriptor();
                bool old_is_index = old_size > 0 && old_desc[0].vslot == slot::INDEX;
                size_t frame_count = ( old_is_index ? 1 : old_size / size );
                data.set_channel( c, append_channels( *old, *other->get_channel(c), frame_count ) );
                if ( old_is_index )
                {
                        switch ( old_desc[0].etype )
                        {
                        case USHORT : 
                                {
                                        NV_ASSERT( size + osize < uint16(-1), "Index out of range!" );
                                        raw_data_channel_access ic( data[c] );
                                        uint16* indexes = reinterpret_cast<uint16*>( ic.raw_data() );
                                        for ( uint16 i = uint16( old_size ); i < ic.size(); ++i )
                                                indexes[i] += uint16( size );

                                }
                                break;
                        case UINT   : 
                                {
                                        raw_data_channel_access ic( data[c] );
                                        uint32* indexes = reinterpret_cast<uint32*>( ic.raw_data() );
                                        for ( uint32 i = old_size; i < ic.size(); ++i )
                                                indexes[i] += size;
                                }
                                break;
                        default : NV_ASSERT( false, "Unsupported index type!" ); break;
                        }
                }
        }
        initialize();
}