source: trunk/src/engine/particle_engine.cc @ 515

// Copyright (C) 2014-2015 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/engine/particle_engine.hh"

#include <nv/interface/device.hh>
#include <nv/core/random.hh>
#include <nv/stl/utility.hh>
#include <nv/lua/lua_math.hh>
#include <nv/core/logging.hh>

static const char *nv_particle_engine_vertex_shader_world =
        "#version 120\n"
        "attribute vec3 nv_position;\n"
        "attribute vec2 nv_texcoord;\n"
        "attribute vec4 nv_color;\n"
        "varying vec4 v_color;\n"
        "varying vec2 v_texcoord;\n"
        "varying vec3 v_position;\n"
        "uniform mat4 nv_m_view;\n"
        "uniform mat4 nv_m_projection;\n"
        "void main(void)\n"
        "{\n"
        "       v_position    = nv_position;\n"
        "       v_texcoord    = nv_texcoord;\n"
        "       v_color       = nv_color;\n"
        "       gl_Position   = nv_m_projection * nv_m_view * vec4 (nv_position, 1.0);\n"
        "}\n";
static const char *nv_particle_engine_vertex_shader_local =
        "#version 120\n"
        "attribute vec3 nv_position;\n"
        "attribute vec2 nv_texcoord;\n"
        "attribute vec4 nv_color;\n"
        "varying vec4 v_color;\n"
        "varying vec2 v_texcoord;\n"
        "varying vec3 v_position;\n"
        "uniform mat4 nv_m_mvp;\n"
        "void main(void)\n"
        "{\n"
        "       v_position    = nv_position;\n"
        "       v_texcoord    = nv_texcoord;\n"
        "       v_color       = nv_color;\n"
        "       gl_Position   = nv_m_mvp * vec4 (nv_position, 1.0);\n"
        "}\n";
static const char *nv_particle_engine_fragment_shader =
        "#version 120\n"
        "uniform sampler2D nv_t_diffuse;\n"
        "varying vec4 v_color;\n"
        "varying vec2 v_texcoord;\n"
        "varying vec3 v_position;\n"
        "void main(void)\n"
        "{\n"
        "       vec4 tex_color = texture2D( nv_t_diffuse, v_texcoord );\n"
        "       float edge = smoothstep( 0.0, 0.1, v_position.y );\n"
        "       gl_FragColor   = v_color * tex_color * edge;\n"
        "}\n";

using namespace nv;

static void nv_particle_emmiter_point( const particle_emmiter_data*, particle* p, uint32 count )
{
        for ( uint32 i = 0; i < count; ++i )
        {
                p[i].position = vec3();
        }

}

static void nv_particle_emmiter_box( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                p[i].position = 
                        r.frange( -pe->hextents[0], pe->hextents[0] ) * pe->cdir +
                        r.frange( 0.0f, pe->extents[1] ) * pe->dir +
                        r.frange( -pe->hextents[2], pe->hextents[2] ) * pe->odir;
        }
}

static void nv_particle_emmiter_cylinder( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec2 rellipse( r.disk_point( pe->precise ) * pe->extents[0] );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        r.frange( 0.0f, pe->extents[1] ) * pe->dir +
                        rellipse.y * pe->odir;
        }
}

static void nv_particle_emmiter_sphere( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec3 rsphere = r.sphere_point( pe->precise ) * pe->extents[0];
                p[i].position = 
                        rsphere.x * pe->cdir +
                        rsphere.y * pe->dir +
                        rsphere.z * pe->odir;
        }
}

static void nv_particle_emmiter_cylindroid( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec2 rellipse = r.ellipse_point( vec2( pe->hextents[0], pe->hextents[2] ), pe->precise );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        r.frange( 0.0f, pe->extents[1] ) * pe->dir +
                        rellipse.y * pe->odir;
        }
}

static void nv_particle_emmiter_ellipsoid( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec3 rsphere = r.ellipsoid_point( pe->hextents, pe->precise );
                p[i].position = 
                        rsphere.x * pe->cdir +
                        rsphere.y * pe->dir +
                        rsphere.z * pe->odir;
        }
}

static void nv_particle_emmiter_hollow_cylinder( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec2 rellipse = r.hollow_disk_point( 
                        pe->ihextents[0],
                        pe->hextents[0],
                        pe->precise );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        r.frange( 0.0f, pe->extents[1] ) * pe->dir +
                        rellipse.y * pe->odir;
        }
}

static void nv_particle_emmiter_hollow_sphere( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec3 rellipse = r.hollow_sphere_point( pe->ihextents[0], pe->hextents[0], pe->precise );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        rellipse.y * pe->dir +
                        rellipse.z * pe->odir;
        }
}

static void nv_particle_emmiter_hollow_cylindroid( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec2 rellipse = r.hollow_ellipse_point( 
                        vec2( pe->ihextents[0], pe->ihextents[2] ), 
                        vec2( pe->hextents[0], pe->hextents[2] ), 
                        pe->precise );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        r.frange( 0.0f, pe->extents[1] ) * pe->dir +
                        rellipse.y * pe->odir;
        }
}

static void nv_particle_emmiter_hollow_ellipsoid( const particle_emmiter_data* pe, particle* p, uint32 count )
{
        random& r = random::get();
        for ( uint32 i = 0; i < count; ++i )
        {
                vec3 rellipse = r.hollow_ellipsoid_point( pe->ihextents, pe->hextents, pe->precise );
                p[i].position = 
                        rellipse.x * pe->cdir +
                        rellipse.y * pe->dir +
                        rellipse.z * pe->odir;
        }
}

struct nvpe_linear_force_data
{
        nv::vec3 force_vector;
        bool     average;
};

static bool nv_particle_affector_linear_force_init( lua::table_guard* table, particle_affector_data* data )
{
        nvpe_linear_force_data* datap = reinterpret_cast<nvpe_linear_force_data*>( data->paramters );
        datap->force_vector = table->get<vec3>("force_vector", vec3() );
        datap->average      = table->get<bool>("average", false );
        return true;
}

static void nv_particle_affector_linear_force( const particle_affector_data* data, particle* p, float factor, uint32 count )
{
        const nvpe_linear_force_data* datap = reinterpret_cast<const nvpe_linear_force_data*>( data->paramters );
        if ( datap->average )
        {
                float norm_factor = nv::min( factor, 1.0f, p->lifetime );
                for ( uint32 i = 0; i < count; ++i ) 
                        p[i].velocity = datap->force_vector * norm_factor + p[i].velocity * ( 1.0f - norm_factor );
        }
        else
        {
                vec3 scvector = datap->force_vector * nv::min( factor, p->lifetime );
                for ( uint32 i = 0; i < count; ++i ) p[i].velocity += scvector;
        }
}

struct nvpe_deflector_plane_data
{
        nv::vec3 plane_point;
        nv::vec3 plane_normal;
        float    bounce;
        float    distance;
};

static bool nv_particle_affector_deflector_plane_init( lua::table_guard* table, particle_affector_data* data )
{
        nvpe_deflector_plane_data* datap = reinterpret_cast<nvpe_deflector_plane_data*>( data->paramters );
        datap->plane_point  = table->get<vec3>("plane_point",  vec3() );
        datap->plane_normal = table->get<vec3>("plane_normal", vec3(0.0f,1.0f,0.0f) );
        datap->plane_normal = normalize_safe( datap->plane_normal, vec3(0.0f,1.0f,0.0f) );
        datap->bounce       = table->get<float>("bounce", 0.0f );
        datap->distance     = -math::dot( datap->plane_normal, datap->plane_point ) / sqrt( math::dot( datap->plane_normal, datap->plane_normal ) );
        return true;
}

static void nv_particle_affector_deflector_plane( const particle_affector_data* data, particle* p, float factor, uint32 count )
{
        const nvpe_deflector_plane_data* datap = reinterpret_cast<const nvpe_deflector_plane_data*>( data->paramters );
        for ( uint32 i = 0; i < count; ++i )
        {
                particle& pt = p[i];
                vec3 direction  = pt.velocity * nv::min( factor, p->lifetime );
                if ( math::dot( datap->plane_normal, pt.position + direction ) + datap->distance <= 0.0f )
                {
                        float val = math::dot( datap->plane_normal, pt.position ) + datap->distance;
                        if ( val > 0.0f )
                        {
                                vec3 part_dir = direction * ( -val / math::dot( datap->plane_normal, direction ) );
                                pt.position = pt.position + part_dir + ( part_dir - direction ) * datap->bounce;
                                pt.velocity = math::reflect( pt.velocity, datap->plane_normal ) * datap->bounce;
                        }
                }
        }
}

struct nvpe_color_fader_data
{
        nv::vec4 adjustment;
};

static bool nv_particle_affector_color_fader_init( lua::table_guard* table, particle_affector_data* data )
{
        nvpe_color_fader_data* datap = reinterpret_cast<nvpe_color_fader_data*>( data->paramters );
        datap->adjustment = table->get<vec4>("adjustment",  vec4() );
        return true;
}

static void nv_particle_affector_color_fader( const particle_affector_data* data, particle* p, float factor, uint32 count )
{
        const nvpe_color_fader_data* datap = reinterpret_cast<const nvpe_color_fader_data*>( data->paramters );
        vec4 adjustment = datap->adjustment * nv::min( factor, p->lifetime );
        for ( uint32 i = 0; i < count; ++i )
        {
                p[i].color = math::clamp( p[i].color + adjustment, 0.0f, 1.0f );
        }
}

struct nvpe_scaler_data
{
        nv::vec2 adjustment;
};

static bool nv_particle_affector_scaler_init( lua::table_guard* table, particle_affector_data* data )
{
        nvpe_scaler_data* datap = reinterpret_cast<nvpe_scaler_data*>( data->paramters );
        float rate        = table->get<float>("rate", 0.0f );
        datap->adjustment = table->get<vec2>("adjustment",  vec2(rate,rate) );
        return true;
}

static void nv_particle_affector_scaler( const particle_affector_data* data, particle* p, float factor, uint32 count )
{
        const nvpe_scaler_data* datap = reinterpret_cast<const nvpe_scaler_data*>( data->paramters );
        vec2 adjustment = datap->adjustment * nv::min( factor, p->lifetime );
        for ( uint32 i = 0; i < count; ++i )
        {
                p[i].size = math::max( p[i].size + adjustment, vec2() );
        }
}

void nv::particle_engine::load( lua::table_guard& table )
{
        shash64 id = table.get_string_hash_64( "id" );
        if ( !id )
        {
                NV_LOG_ERROR( "Bad table passed to particle_engine!" )
        }
        // TODO : overwrite check
        m_names[ id ] = m_data.size();

        m_data.emplace_back();
        auto& data = m_data.back();

        data.quota   = table.get<uint32>("quota", 1024 );
//      data.local   = table.get<bool>("local_space", false );
        data.accurate_facing = table.get<bool>("accurate_facing", false );
        data.emmiter_count   = 0;
        data.affector_count  = 0;

        const_string orientation = table.get_string( "orientation", "point" );
        if ( orientation == "point" )                     { data.orientation = particle_orientation::POINT; }
        else if ( orientation == "oriented" )             { data.orientation = particle_orientation::ORIENTED; }
        else if ( orientation == "oriented_common" )      { data.orientation = particle_orientation::ORIENTED_COMMON; }
        else if ( orientation == "perpendicular" )        { data.orientation = particle_orientation::PERPENDICULAR; }
        else if ( orientation == "perpendicular_common" ) { data.orientation = particle_orientation::PERPENDICULAR_COMMON; }
        else 
        {
                NV_LOG_ERROR( "Unknown orientation type! (", orientation, ")!" );
                data.orientation = particle_orientation::POINT;
        }

        const_string origin = table.get_string( "origin", "center" );
        if      ( origin == "center" )        { data.origin = particle_origin::CENTER; }
        else if ( origin == "top_left" )      { data.origin = particle_origin::TOP_LEFT; }
        else if ( origin == "top_center" )    { data.origin = particle_origin::TOP_CENTER; }
        else if ( origin == "top_right" )     { data.origin = particle_origin::TOP_RIGHT; }
        else if ( origin == "center_left" )   { data.origin = particle_origin::CENTER_LEFT; }
        else if ( origin == "center_right" )  { data.origin = particle_origin::CENTER_RIGHT; }
        else if ( origin == "bottom_left" )   { data.origin = particle_origin::BOTTOM_LEFT; }
        else if ( origin == "bottom_center" ) { data.origin = particle_origin::BOTTOM_CENTER; }
        else if ( origin == "bottom_right" )  { data.origin = particle_origin::BOTTOM_RIGHT; }
        else 
        {
                NV_LOG_ERROR( "Unknown particle origin! (", origin, ")!" );
                data.origin = particle_origin::CENTER;
        }

        data.common_up  = math::normalize( table.get<vec3>("common_up",  vec3(1,0,0) ) );
        data.common_dir = math::normalize( table.get<vec3>("common_dir", vec3(0,1,0) ) );

        vec2 def_size        = table.get<vec2>("size", vec2(0.1,0.1) );
        uint32 elements = table.get_size();
        for ( uint32 i = 0; i < elements; ++i )
        {
                lua::table_guard element( table, i+1 );
                const_string type     = element.get_string( "type" );
                const_string sub_type = element.get_string( "sub_type" );
                if ( type == "emmiter" )
                {
                        if ( data.emmiter_count < MAX_PARTICLE_EMMITERS )
                        {
                                particle_emmiter_data& edata = data.emmiters[ data.emmiter_count ];
                                auto emmiter_iter = m_emmiters.find( sub_type );
                                if ( emmiter_iter != m_emmiters.end() )
                                {
                                        edata.emmiter_func = emmiter_iter->second;
                                }
                                else
                                {
                                        edata.emmiter_func = nv_particle_emmiter_point;
                                        NV_LOG_WARNING( "Unknown emmiter type in particle system! (", sub_type, ")" );
                                }

                                edata.position     = element.get<vec3>("position", vec3() );
                                edata.extents      = element.get<vec3>("extents", vec3(1,1,1) );
                                edata.extents[0]   = element.get<float>("width",  edata.extents[0] );
                                edata.extents[1]   = element.get<float>("depth",  edata.extents[1] );
                                edata.extents[2]   = element.get<float>("height", edata.extents[2] );
                                edata.extents[0]   = element.get<float>("radius",  edata.extents[0] );
                                edata.iextents     = element.get<vec3>("inner_extents", vec3() );
                                edata.iextents[0]  = element.get<float>("inner_width",  edata.iextents[0] );
                                edata.iextents[1]  = element.get<float>("inner_depth",  edata.iextents[1] );
                                edata.iextents[2]  = element.get<float>("inner_height", edata.iextents[2] );
                                edata.iextents[0]  = element.get<float>("inner_radius",  edata.iextents[0] );
                                edata.hextents     = 0.5f * edata.extents;
                                edata.ihextents    = 0.5f * edata.iextents;
                                edata.precise      = element.get<bool>("precise", false );
                                edata.square       = element.get<bool>("square", true );
                                vec4 color         = element.get<vec4>("color", vec4(1,1,1,1) );
                                edata.color_min    = element.get<vec4>("color_min", color );
                                edata.color_max    = element.get<vec4>("color_max", color );
                                vec2 size          = element.get<vec2>("size", def_size );
                                edata.size_min     = element.get<vec2>("size_min", size );
                                edata.size_max     = element.get<vec2>("size_max", size );
                                edata.angle        = element.get<float>("angle", 0.0f );
                                float velocity     = element.get<float>("velocity", 0.0f );
                                edata.velocity_min = element.get<float>("velocity_min", velocity );
                                edata.velocity_max = element.get<float>("velocity_max", velocity );
                                float lifetime     = element.get<float>("lifetime", 1.0f );
                                edata.lifetime_min = element.get<float>("lifetime_min", lifetime );
                                edata.lifetime_max = element.get<float>("lifetime_max", lifetime );
                                float duration     = element.get<float>("duration", 0.0f );
                                edata.duration_min = element.get<float>("duration_min", duration );
                                edata.duration_max = element.get<float>("duration_max", duration );
                                float repeat       = element.get<float>("repeat_delay", 0.0f );
                                edata.repeat_min   = element.get<float>("repeat_delay_min", repeat );
                                edata.repeat_max   = element.get<float>("repeat_delay_max", repeat );

                                edata.rate         = element.get<float>("rate", 1.0f );
                                edata.dir          = math::normalize( element.get<vec3>("direction", vec3(0,1,0) ) );
                                
                                edata.odir = vec3( 0, 0, 1 );
                                if ( edata.dir != vec3( 0, 1, 0 ) && edata.dir != vec3( 0, -1, 0 ) )
                                        edata.odir = math::normalize( math::cross( edata.dir, vec3( 0, 1, 0 ) ) );
                                edata.cdir = math::cross( edata.dir, edata.odir );

                                data.emmiter_count++;
                        }
                        else
                        {
                                NV_LOG_ERROR( "Too many emmiters (", MAX_PARTICLE_EMMITERS, " is MAX)!" );
                        }
                }
                else if ( type == "affector" )
                {
                        if ( data.affector_count < MAX_PARTICLE_AFFECTORS )
                        {
                                particle_affector_data& adata = data.affectors[ data.affector_count ];
                                data.affector_count++;
                                auto affector_iter = m_affectors.find( sub_type );
                                if ( affector_iter != m_affectors.end() )
                                {
                                        adata.process = affector_iter->second.process;
                                        if ( !affector_iter->second.init( &element, &adata ) )
                                        {
                                                data.affector_count--;
                                                NV_LOG_WARNING( "Bad data passed to ", sub_type, " affector in particle system!" );
                                        }
                                }
                                else
                                {
                                        data.affector_count--;
                                        NV_LOG_WARNING( "Unknown affector type in particle system! (", sub_type, ")" );
                                }
                        }
                        else
                        {
                                NV_LOG_ERROR( "Too many affectors (", MAX_PARTICLE_AFFECTORS, " is MAX)!" );
                        }
                }
                else 
                {
                        NV_LOG_WARNING( "Unknown element in particle system! (", type, ")" );
                }
        }

}

nv::particle_engine::particle_engine( context* a_context )
{
        m_context       = a_context;
        m_program_local = m_context->create_program( nv_particle_engine_vertex_shader_local, nv_particle_engine_fragment_shader );
        m_program_world = m_context->create_program( nv_particle_engine_vertex_shader_world, nv_particle_engine_fragment_shader );

        register_standard_emmiters();
        register_standard_affectors();
}

nv::particle_system nv::particle_engine::create_system( const string_view& id, particle_system_group group )
{
        particle_system_group_info* ginfo = m_groups.get( group );
        if ( !ginfo ) return nv::particle_system();

        auto it = m_names.find( id );
        if ( it == m_names.end() )
        {
                return particle_system();
        }
        const particle_system_data* data = &(m_data[it->second]);
        particle_system result = m_systems.create();
        particle_system_info* info = m_systems.get( result );
        info->group = group;
        info->data     = data;
        uint32 ecount = data->emmiter_count;
        for ( uint32 i = 0; i < ecount; ++i )
        {
                info->emmiters[i].active      = true;
                if ( data->emmiters[i].duration_max == 0.0f )
                        info->emmiters[i].pause = 0;
                else
                        info->emmiters[i].pause = random::get().frange( data->emmiters[i].duration_min, data->emmiters[i].duration_max );

        }

        info->count = 0;
        info->particles = new particle[ data->quota ];
        ginfo->ref_counter++;

        return result;
}

void nv::particle_engine::prepare( particle_system_group group )
{
        particle_system_group_info* info = m_groups.get( group );
        if ( info )
        {
                info->count = 0;
        }
}

void nv::particle_engine::draw( particle_system_group group, const render_state& rs, const scene_state& ss )
{
        particle_system_group_info* info = m_groups.get( group );
        if ( info )
        {
                m_context->draw( nv::TRIANGLES, rs, ss, info->local ? m_program_local : m_program_world, info->vtx_array, info->count * 6, 0 );
        }
}

nv::particle_system_group nv::particle_engine::create_group( uint32 max_particles )
{
        particle_system_group result     = m_groups.create();
        particle_system_group_info* info = m_groups.get( result );
        info->local = false;
        info->count = 0;
        info->quota = max_particles;
        info->vtx_buffer = m_context->create_buffer( VERTEX_BUFFER, STREAM_DRAW, info->quota * sizeof( particle_quad )/*, info->quads_[0].data*/ );
        vertex_array_desc desc;
        desc.add_vertex_buffers< particle_vtx >( info->vtx_buffer, true );
        info->vtx_array = m_context->create_vertex_array( desc );
        info->quads     = new particle_quad[info->quota];
        info->ref_counter = 0;
        return result;
}

nv::particle_engine::~particle_engine()
{
        clear();
        m_context->release( m_program_world );
        m_context->release( m_program_local );
}

void nv::particle_engine::reset()
{
        clear();
        register_standard_emmiters();
        register_standard_affectors();
}

bool nv::particle_engine::loaded( const string_view& system_id )
{
        return m_names.find( system_id ) != m_names.end();
}

void nv::particle_engine::clear()
{
        while ( m_systems.size() > 0 )
                release( m_systems.get_handle( 0 ) );
        while ( m_groups.size() > 0 )
                release( m_groups.get_handle( 0 ) );
        m_emmiters.clear();
        m_affectors.clear();
        m_names.clear();
        m_data.clear();
}


void nv::particle_engine::release( particle_system system )
{
        particle_system_info* info = m_systems.get( system );
        if ( info )
        {
                particle_system_group_info* ginfo = m_groups.get( info->group );
                if ( ginfo ) ginfo->ref_counter--;
                                delete[] info->particles;
                m_systems.destroy( system );
        }
}

void nv::particle_engine::release( particle_system_group group )
{
        particle_system_group_info* info = m_groups.get( group );
        if ( info )
        {
                delete[] info->quads;
                m_context->release( info->vtx_array );
                m_groups.destroy( group );
        }
}

void nv::particle_engine::render( particle_system system, const scene_state& s )
{
        particle_system_info* info = m_systems.get( system );
        if ( info )
        {
                generate_data( info, s );
        }
}

void nv::particle_engine::update( particle_system system, transform model, float dtime  )
{
        particle_system_info* info = m_systems.get( system );
        if ( info )
        {
//              while ( dtime > 0.2 )
//              {
//                      update_emmiters( info, 0.2 );
//                      destroy_particles( info, 0.2 );
//                      create_particles( info, 0.2 );
//                      update_particles( info, 0.2 );
//                      dtime -= 0.2;
//              }

                update_emmiters( info, dtime );
                destroy_particles( info, dtime );
                create_particles( info, model, dtime );
                update_particles( info, dtime );

//              generate_data( info );
        }
}

void nv::particle_engine::set_texcoords( particle_system system, vec2 a, vec2 b )
{

        particle_system_info* info = m_systems.get( system );
        if ( info )
        {
                info->texcoords[0] = a;
                info->texcoords[1] = b;
        }
}

void nv::particle_engine::generate_data( particle_system_info* info, const scene_state& s )
{
//      void* rawptr = m_context->map_buffer( info->vtx_buffer, nv::WRITE_UNSYNCHRONIZED, offset, info->count*sizeof( particle_quad ) );
//      particle_quad* quads = reinterpret_cast<particle_quad*>( rawptr );

        particle_system_group_info* group = m_groups.get( info->group );
        if ( !info )
        {
                return;
        }

        vec2 lb     = vec2( -0.5f, -0.5f );
        vec2 rt     = vec2( 0.5f, 0.5f );

        switch ( info->data->origin )
        {
        case particle_origin::CENTER        : break;
        case particle_origin::TOP_LEFT      : lb = vec2(0.f,-1.f); rt = vec2(1.f,0.f);  break;
        case particle_origin::TOP_CENTER    : lb.y = -1.f; rt.y = 0.f; break;
        case particle_origin::TOP_RIGHT     : lb = vec2(-1.f,-1.f); rt = vec2(); break;
        case particle_origin::CENTER_LEFT   : lb.x = 0.f; rt.x = 1.f; break;
        case particle_origin::CENTER_RIGHT  : lb.x = -1.f; rt.x = 0.f; break;
        case particle_origin::BOTTOM_LEFT   : lb = vec2(); rt = vec2(1.f,1.f); break;
        case particle_origin::BOTTOM_CENTER : lb.y = 0.f; rt.y = 1.f; break; 
        case particle_origin::BOTTOM_RIGHT  : lb = vec2(-1.f,0.f); rt = vec2(.0f,1.f); break;
        }

        const vec3 sm[4] = 
        { 
                vec3( lb.x, lb.y, 0.0f ),
                vec3( rt.x, lb.y, 0.0f ),
                vec3( lb.x, rt.y, 0.0f ),
                vec3( rt.x, rt.y, 0.0f ),
        };
        vec3 z( 0.0f, 0.0f ,1.0f );

        particle_orientation orientation = info->data->orientation;
        vec3 common_up ( info->data->common_up );
        vec3 common_dir( info->data->common_dir );
        bool accurate_facing = info->data->accurate_facing;
        mat3 rot_mat;
        vec3 right;
        vec3 pdir( 0.0f, 1.0f, 0.0f );

        vec3 camera_pos   = s.get_camera().get_position();
        vec3 inv_view_dir = math::normalize( -s.get_camera().get_direction() );

        for ( uint32 i = 0; i < info->count; ++i )
        {
                const particle& pdata = info->particles[i];
//              particle_quad& rdata  = quads[i];
                particle_quad& rdata  = group->quads[i + group->count];

                vec3 view_dir( inv_view_dir );
                if ( accurate_facing ) view_dir = math::normalize( camera_pos - pdata.position );

                switch ( orientation )
                {
                case particle_orientation::POINT :
                        right   = math::normalize( math::cross( view_dir, vec3( 0, 1, 0 ) ) );
                        right   = math::rotate( right, pdata.rotation, view_dir );
                        rot_mat = mat3( right, math::cross( right, -view_dir ), -view_dir );
                        break;
                case particle_orientation::ORIENTED :
                        pdir    = normalize_safe( pdata.velocity, pdir );
                        right   = math::normalize( math::cross( pdir, view_dir ) );
                        rot_mat = mat3( right, pdir, math::cross( pdir, right ) );
                        break;
                case particle_orientation::ORIENTED_COMMON :
                        right   = math::normalize( math::cross( common_dir, view_dir ) );
                        rot_mat = mat3( right, common_dir, math::cross( common_dir, right ) );
                        break;
                case particle_orientation::PERPENDICULAR :
                        pdir    = normalize_safe( pdata.velocity, pdir );
                        right   = math::normalize( math::cross( common_up, pdir ) );
                        rot_mat = mat3( right, common_up, math::cross( common_up, right ) );
                        break;
                case particle_orientation::PERPENDICULAR_COMMON :
                        right   = math::normalize( math::cross( common_up, common_dir ) );
                        rot_mat = mat3( right, common_up, math::cross( common_up, right ) );
                        break;
                }

                vec2 texcoords[4] =
                {
                        pdata.tcoord_a,
                        vec2( pdata.tcoord_b.x, pdata.tcoord_a.y ),
                        vec2( pdata.tcoord_a.x, pdata.tcoord_b.y ),
                        pdata.tcoord_b
                };

                vec3 size( pdata.size.x, pdata.size.y, 0.0f );
                vec3 s0 = rot_mat * ( ( size * sm[0] ) );
                vec3 s1 = rot_mat * ( ( size * sm[1] ) );
                vec3 s2 = rot_mat * ( ( size * sm[2] ) );
                vec3 s3 = rot_mat * ( ( size * sm[3] ) );

                rdata.data[0].position = pdata.position + s0;
                rdata.data[0].color    = pdata.color;
                rdata.data[0].texcoord = texcoords[0];

                rdata.data[1].position = pdata.position + s1;
                rdata.data[1].color    = pdata.color;
                rdata.data[1].texcoord = texcoords[1];

                rdata.data[2].position = pdata.position + s2;
                rdata.data[2].color    = pdata.color;
                rdata.data[2].texcoord = texcoords[2];

                rdata.data[3].position = pdata.position + s3;
                rdata.data[3].color    = pdata.color;
                rdata.data[3].texcoord = texcoords[3];

                rdata.data[4] = rdata.data[2];
                rdata.data[5] = rdata.data[1];
        }
//      m_context->unmap_buffer( info->vtx_buffer );

        m_context->update( group->vtx_buffer, group->quads, group->count*sizeof(particle_quad), info->count*sizeof( particle_quad ) );
        group->count += info->count;
}

void nv::particle_engine::destroy_particles( particle_system_info* info, float dtime )
{
        if ( info->count > 0 )
                for ( sint32 i = sint32( info->count ) - 1; i >= 0; --i )
                {
                        particle& pinfo = info->particles[i];
                        pinfo.lifetime += dtime;
                        if ( pinfo.lifetime >= pinfo.death )
                        {
                                info->count--;
                                swap( info->particles[i], info->particles[info->count] );
                        }
                }
}

void nv::particle_engine::create_particles( particle_system_info* info, transform model, float dtime )
{
        uint32 ecount = info->data->emmiter_count;
        if ( ecount == 0 ) return;

        random& r = random::get();
        bool local = model.is_identity();
//      if ( !local ) 
//      {
//              source = vec3( m_model_matrix[3] );
//              orient = mat3( m_model_matrix );
//      }

        for ( uint32 i = 0; i < ecount; ++i )
        {
                const auto& edata = info->data->emmiters[i];
                auto& einfo = info->emmiters[i];
                if ( einfo.active )
                {
                        einfo.next -= dtime;
                        float fperiod = 1.0f / edata.rate;
                        while ( einfo.next < 0.0f )
                        {
                                if ( info->count < info->data->quota-1 )
                                {
                                        particle& pinfo = info->particles[info->count];
                                        edata.emmiter_func( &(info->data->emmiters[i]), &pinfo, 1 );
                                        pinfo.position = vec3();
                                        pinfo.position+= edata.position;
                                        if ( !local )
                                                pinfo.position = pinfo.position * model;
                                        pinfo.color    = edata.color_min == edata.color_max ?
                                                edata.color_min : r.range( edata.color_min, edata.color_max );
                                        pinfo.size     = edata.size_min == edata.size_max ?
                                                edata.size_min : r.range( edata.size_min, edata.size_max );
                                        if ( edata.square ) pinfo.size.y = pinfo.size.x;
                                        float velocity = edata.velocity_min == edata.velocity_max ?
                                                edata.velocity_min : r.frange( edata.velocity_min, edata.velocity_max );
                                        pinfo.lifetime = dtime + einfo.next;
                                        pinfo.death = ( edata.lifetime_min == edata.lifetime_max ?
                                                edata.lifetime_min : r.frange( edata.lifetime_min, edata.lifetime_max ) );
                                        pinfo.rotation = r.frand( 2* math::pi<float>() );
                                        pinfo.tcoord_a = info->texcoords[0];
                                        pinfo.tcoord_b = info->texcoords[1];

                                        pinfo.velocity = edata.dir;
                                        if ( edata.angle > 0.0f )
                                        {
                                                float emission_angle = math::radians( edata.angle );
                                                float cos_theta = r.frange( cos( emission_angle ), 1.0f );
                                                float sin_theta = sqrt(1.0f - cos_theta * cos_theta );
                                                float phi       = r.frange( 0.0f, 2* math::pi<float>() );
                                                pinfo.velocity  = model.get_orientation() * 
                                                        ( edata.odir * ( cos(phi) * sin_theta ) +
                                                        edata.cdir * ( sin(phi)*sin_theta ) +
                                                        edata.dir  * cos_theta );
                                        }

                                        pinfo.velocity *= velocity;

                                        info->count++;
                                }
                                einfo.next += fperiod;
                        }

                }
        }
}

void nv::particle_engine::update_particles( particle_system_info* info, float dtime )
{
        if ( dtime <= 0.0f ) return;

        uint32 acount = info->data->affector_count;
        for ( uint32 i = 0; i < acount; ++i )
        {
                const particle_affector_data* padata = &(info->data->affectors[i]);
                padata->process( padata, info->particles, dtime, info->count );
        }


        for ( uint32 i = 0; i < info->count; ++i )
        {
                particle& pdata = info->particles[i];
                float factor = min( dtime, pdata.lifetime );
                pdata.position += pdata.velocity * factor;
        }
}

void nv::particle_engine::update_emmiters( particle_system_info* info, float dtime )
{
        uint32 ecount = info->data->emmiter_count;
        if ( ecount == 0 ) return;
        random& r = random::get();

        for ( uint32 i = 0; i < ecount; ++i )
        {
                const auto& edata = info->data->emmiters[i];
                auto& einfo = info->emmiters[i];

                if ( einfo.pause > 0.0f )
                {
                        einfo.pause -= dtime;
                        if ( einfo.pause == 0.0f ) einfo.pause = -0.001f;
                }

                if ( einfo.pause < 0.0f )
                {
                        if ( einfo.active )
                        {
                                einfo.active = false;
                                if ( edata.repeat_min > 0.0f )
                                        einfo.pause += r.frange( edata.repeat_min, edata.repeat_max );
                                else
                                        einfo.pause = 0.0f;
                        }
                        else
                        {
                                einfo.active = true;
                                einfo.pause += r.frange( edata.duration_min, edata.duration_max );
                        }
                }
        }

}

void nv::particle_engine::register_emmiter_type( const string_view& name, particle_emmiter_func func )
{
        m_emmiters[ name ] = func;
}

void nv::particle_engine::register_standard_emmiters()
{
        register_emmiter_type( "point",             nv_particle_emmiter_point );
        register_emmiter_type( "box",               nv_particle_emmiter_box );
        register_emmiter_type( "cylinder",          nv_particle_emmiter_cylinder );
        register_emmiter_type( "sphere",            nv_particle_emmiter_sphere );
        register_emmiter_type( "cylindroid",        nv_particle_emmiter_cylindroid );
        register_emmiter_type( "ellipsoid",         nv_particle_emmiter_ellipsoid );
        register_emmiter_type( "hollow_cylinder",   nv_particle_emmiter_hollow_cylinder );
        register_emmiter_type( "hollow_sphere",     nv_particle_emmiter_hollow_sphere );
        register_emmiter_type( "hollow_cylindroid", nv_particle_emmiter_hollow_cylindroid );
        register_emmiter_type( "hollow_ellipsoid",  nv_particle_emmiter_hollow_ellipsoid );
}

void nv::particle_engine::register_affector_type( const string_view& name, particle_affector_init_func init, particle_affector_func process )
{
        m_affectors[ name ].init    = init;
        m_affectors[ name ].process = process;
}

nv::particle_render_data nv::particle_engine::get_render_data( particle_system_group group )
{
        const particle_system_group_info* info = m_groups.get( group );
        if ( info )
        {
                return{ info->count, info->vtx_array };
        }
        return { 0, nv::vertex_array() };
}

void nv::particle_engine::register_standard_affectors()
{
        register_affector_type( "linear_force",    nv_particle_affector_linear_force_init, nv_particle_affector_linear_force );
        register_affector_type( "deflector_plane", nv_particle_affector_deflector_plane_init, nv_particle_affector_deflector_plane );
        register_affector_type( "color_fader",     nv_particle_affector_color_fader_init, nv_particle_affector_color_fader );
        register_affector_type( "scaler",          nv_particle_affector_scaler_init, nv_particle_affector_scaler );
}