PrusaSlicer-NonPlainar/xs/src/libslic3r/Print.cpp

#include "Print.hpp"
#include "BoundingBox.hpp"
#include "ClipperUtils.hpp"
#include "Extruder.hpp"
#include "Flow.hpp"
#include "Geometry.hpp"
#include "SupportMaterial.hpp"
#include <algorithm>

namespace Slic3r {

template class PrintState<PrintStep>;
template class PrintState<PrintObjectStep>;


Print::Print()
:   total_used_filament(0),
    total_extruded_volume(0)
{
}

Print::~Print()
{
    clear_objects();
    clear_regions();
}

void
Print::clear_objects()
{
    for (int i = this->objects.size()-1; i >= 0; --i)
        this->delete_object(i);

    this->clear_regions();
}

PrintObject*
Print::get_object(size_t idx)
{
    return objects.at(idx);
}

void
Print::delete_object(size_t idx)
{
    PrintObjectPtrs::iterator i = this->objects.begin() + idx;
    
    // before deleting object, invalidate all of its steps in order to 
    // invalidate all of the dependent ones in Print
    (*i)->invalidate_all_steps();
    
    // destroy object and remove it from our container
    delete *i;
    this->objects.erase(i);

    // TODO: purge unused regions
}

void
Print::reload_object(size_t idx)
{
    /* TODO: this method should check whether the per-object config and per-material configs
        have changed in such a way that regions need to be rearranged or we can just apply
        the diff and invalidate something.  Same logic as apply_config()
        For now we just re-add all objects since we haven't implemented this incremental logic yet.
        This should also check whether object volumes (parts) have changed. */
    
    // collect all current model objects
    ModelObjectPtrs model_objects;
    FOREACH_OBJECT(this, object) {
        model_objects.push_back((*object)->model_object());
    }
    
    // remove our print objects
    this->clear_objects();
    
    // re-add model objects
    for (ModelObjectPtrs::iterator it = model_objects.begin(); it != model_objects.end(); ++it) {
        this->add_model_object(*it);
    }
}

bool
Print::reload_model_instances()
{
    bool invalidated = false;
    FOREACH_OBJECT(this, object) {
        if ((*object)->reload_model_instances()) invalidated = true;
    }
    return invalidated;
}

void
Print::clear_regions()
{
    for (int i = this->regions.size()-1; i >= 0; --i)
        this->delete_region(i);
}

PrintRegion*
Print::add_region()
{
    PrintRegion *region = new PrintRegion(this);
    regions.push_back(region);
    return region;
}

void
Print::delete_region(size_t idx)
{
    PrintRegionPtrs::iterator i = this->regions.begin() + idx;
    delete *i;
    this->regions.erase(i);
}

bool
Print::invalidate_state_by_config_options(const std::vector<t_config_option_key> &opt_keys)
{
    std::set<PrintStep> steps;
    std::set<PrintObjectStep> osteps;
    
    // this method only accepts PrintConfig option keys
    for (std::vector<t_config_option_key>::const_iterator opt_key = opt_keys.begin(); opt_key != opt_keys.end(); ++opt_key) {
        if (*opt_key == "skirts"
            || *opt_key == "skirt_height"
            || *opt_key == "skirt_distance"
            || *opt_key == "min_skirt_length"
            || *opt_key == "ooze_prevention") {
            steps.insert(psSkirt);
        } else if (*opt_key == "brim_width") {
            steps.insert(psBrim);
            steps.insert(psSkirt);
        } else if (*opt_key == "nozzle_diameter"
            || *opt_key == "resolution") {
            osteps.insert(posSlice);
        } else if (*opt_key == "avoid_crossing_perimeters"
            || *opt_key == "bed_shape"
            || *opt_key == "bed_temperature"
            || *opt_key == "bridge_acceleration"
            || *opt_key == "bridge_fan_speed"
            || *opt_key == "complete_objects"
            || *opt_key == "cooling"
            || *opt_key == "default_acceleration"
            || *opt_key == "disable_fan_first_layers"
            || *opt_key == "duplicate_distance"
            || *opt_key == "end_gcode"
            || *opt_key == "extruder_clearance_height"
            || *opt_key == "extruder_clearance_radius"
            || *opt_key == "extruder_offset"
            || *opt_key == "extrusion_axis"
            || *opt_key == "extrusion_multiplier"
            || *opt_key == "fan_always_on"
            || *opt_key == "fan_below_layer_time"
            || *opt_key == "filament_diameter"
            || *opt_key == "first_layer_acceleration"
            || *opt_key == "first_layer_bed_temperature"
            || *opt_key == "first_layer_speed"
            || *opt_key == "first_layer_temperature"
            || *opt_key == "gcode_arcs"
            || *opt_key == "gcode_comments"
            || *opt_key == "gcode_flavor"
            || *opt_key == "infill_acceleration"
            || *opt_key == "infill_first"
            || *opt_key == "layer_gcode"
            || *opt_key == "min_fan_speed"
            || *opt_key == "max_fan_speed"
            || *opt_key == "min_print_speed"
            || *opt_key == "notes"
            || *opt_key == "only_retract_when_crossing_perimeters"
            || *opt_key == "output_filename_format"
            || *opt_key == "perimeter_acceleration"
            || *opt_key == "post_process"
            || *opt_key == "pressure_advance"
            || *opt_key == "retract_before_travel"
            || *opt_key == "retract_layer_change"
            || *opt_key == "retract_length"
            || *opt_key == "retract_length_toolchange"
            || *opt_key == "retract_lift"
            || *opt_key == "retract_lift_above"
            || *opt_key == "retract_lift_below"
            || *opt_key == "retract_restart_extra"
            || *opt_key == "retract_restart_extra_toolchange"
            || *opt_key == "retract_speed"
            || *opt_key == "slowdown_below_layer_time"
            || *opt_key == "spiral_vase"
            || *opt_key == "standby_temperature_delta"
            || *opt_key == "start_gcode"
            || *opt_key == "temperature"
            || *opt_key == "threads"
            || *opt_key == "toolchange_gcode"
            || *opt_key == "travel_speed"
            || *opt_key == "use_firmware_retraction"
            || *opt_key == "use_relative_e_distances"
            || *opt_key == "wipe"
            || *opt_key == "z_offset"
            || *opt_key == "max_volumetric_extrusion_rate_slope_negative"
            || *opt_key == "max_volumetric_extrusion_rate_slope_positive") {
            // these options only affect G-code export, so nothing to invalidate
        } else if (*opt_key == "first_layer_extrusion_width") {
            osteps.insert(posPerimeters);
            osteps.insert(posInfill);
            osteps.insert(posSupportMaterial);
            steps.insert(psSkirt);
            steps.insert(psBrim);
        } else {
            // for legacy, if we can't handle this option let's invalidate all steps
            return this->invalidate_all_steps();
        }
    }
    
    bool invalidated = false;
    for (std::set<PrintStep>::const_iterator step = steps.begin(); step != steps.end(); ++step) {
        if (this->invalidate_step(*step)) invalidated = true;
    }
    for (std::set<PrintObjectStep>::const_iterator ostep = osteps.begin(); ostep != osteps.end(); ++ostep) {
        FOREACH_OBJECT(this, object) {
            if ((*object)->invalidate_step(*ostep)) invalidated = true;
        }
    }
    
    return invalidated;
}

bool
Print::invalidate_step(PrintStep step)
{
    bool invalidated = this->state.invalidate(step);
    
    // propagate to dependent steps
    if (step == psSkirt) {
        this->invalidate_step(psBrim);
    }
    
    return invalidated;
}

bool
Print::invalidate_all_steps()
{
    // make a copy because when invalidating steps the iterators are not working anymore
    std::set<PrintStep> steps = this->state.started;
    
    bool invalidated = false;
    for (std::set<PrintStep>::const_iterator step = steps.begin(); step != steps.end(); ++step) {
        if (this->invalidate_step(*step)) invalidated = true;
    }
    return invalidated;
}

// returns true if an object step is done on all objects
// and there's at least one object
bool
Print::step_done(PrintObjectStep step) const
{
    if (this->objects.empty()) return false;
    FOREACH_OBJECT(this, object) {
        if (!(*object)->state.is_done(step))
            return false;
    }
    return true;
}

// returns 0-based indices of used extruders
std::set<size_t>
Print::object_extruders() const
{
    std::set<size_t> extruders;
    
    FOREACH_REGION(this, region) {
        // these checks reflect the same logic used in the GUI for enabling/disabling
        // extruder selection fields
        if ((*region)->config.perimeters.value > 0 || this->config.brim_width.value > 0)
            extruders.insert((*region)->config.perimeter_extruder - 1);
        
        if ((*region)->config.fill_density.value > 0)
            extruders.insert((*region)->config.infill_extruder - 1);
        
        if ((*region)->config.top_solid_layers.value > 0 || (*region)->config.bottom_solid_layers.value > 0)
            extruders.insert((*region)->config.solid_infill_extruder - 1);
    }
    
    return extruders;
}

// returns 0-based indices of used extruders
std::set<size_t>
Print::support_material_extruders() const
{
    std::set<size_t> extruders;
    bool support_uses_current_extruder = false;

    FOREACH_OBJECT(this, object) {
        if ((*object)->has_support_material()) {
            if ((*object)->config.support_material_extruder == 0)
                support_uses_current_extruder = true;
            else
                extruders.insert((*object)->config.support_material_extruder - 1);
            if ((*object)->config.support_material_interface_extruder == 0)
                support_uses_current_extruder = true;
            else
                extruders.insert((*object)->config.support_material_interface_extruder - 1);
        }
    }

    if (support_uses_current_extruder) {
        // Add all object extruders to the support extruders as it is not know which one will be used to print supports.
        std::set<size_t> object_extruders = this->object_extruders();
        extruders.insert(object_extruders.begin(), object_extruders.end());
    }
    
    return extruders;
}

// returns 0-based indices of used extruders
std::set<size_t>
Print::extruders() const
{
    std::set<size_t> extruders = this->object_extruders();
    
    std::set<size_t> s_extruders = this->support_material_extruders();
    extruders.insert(s_extruders.begin(), s_extruders.end());
    
    return extruders;
}

void
Print::_simplify_slices(double distance)
{
    FOREACH_OBJECT(this, object) {
        FOREACH_LAYER(*object, layer) {
            (*layer)->slices.simplify(distance);
            FOREACH_LAYERREGION(*layer, layerm) {
                (*layerm)->slices.simplify(distance);
            }
        }
    }
}

double
Print::max_allowed_layer_height() const
{
    std::vector<double> nozzle_diameter;
    
    std::set<size_t> extruders = this->extruders();
    for (std::set<size_t>::const_iterator e = extruders.begin(); e != extruders.end(); ++e) {
        nozzle_diameter.push_back(this->config.nozzle_diameter.get_at(*e));
    }
    
    return *std::max_element(nozzle_diameter.begin(), nozzle_diameter.end());
}

/*  Caller is responsible for supplying models whose objects don't collide
    and have explicit instance positions */
void
Print::add_model_object(ModelObject* model_object, int idx)
{
    DynamicPrintConfig object_config = model_object->config;  // clone
    object_config.normalize();

    // initialize print object and store it at the given position
    PrintObject* o;
    {
        BoundingBoxf3 bb = model_object->raw_bounding_box();
        if (idx != -1) {
            // replacing existing object
            PrintObjectPtrs::iterator old_it = this->objects.begin() + idx;
            // before deleting object, invalidate all of its steps in order to 
            // invalidate all of the dependent ones in Print
            (*old_it)->invalidate_all_steps();
            delete *old_it;
            
            this->objects[idx] = o = new PrintObject(this, model_object, bb);
        } else {
            o = new PrintObject(this, model_object, bb);
            this->objects.push_back(o);
    
            // invalidate steps
            this->invalidate_step(psSkirt);
            this->invalidate_step(psBrim);
        }
    }

    for (ModelVolumePtrs::const_iterator v_i = model_object->volumes.begin(); v_i != model_object->volumes.end(); ++v_i) {
        size_t volume_id = v_i - model_object->volumes.begin();
        ModelVolume* volume = *v_i;
        
        // get the config applied to this volume
        PrintRegionConfig config = this->_region_config_from_model_volume(*volume);
        
        // find an existing print region with the same config
        int region_id = -1;
        for (PrintRegionPtrs::const_iterator region = this->regions.begin(); region != this->regions.end(); ++region) {
            if (config.equals((*region)->config)) {
                region_id = region - this->regions.begin();
                break;
            }
        }
        
        // if no region exists with the same config, create a new one
        if (region_id == -1) {
            PrintRegion* r = this->add_region();
            r->config.apply(config);
            region_id = this->regions.size() - 1;
        }
        
        // assign volume to region
        o->add_region_volume(region_id, volume_id);
    }

    // apply config to print object
    o->config.apply(this->default_object_config);
    o->config.apply(object_config, true);
}

bool
Print::apply_config(DynamicPrintConfig config)
{
    // we get a copy of the config object so we can modify it safely
    config.normalize();
    
    // apply variables to placeholder parser
    this->placeholder_parser.apply_config(config);
    
    bool invalidated = false;
    
    // handle changes to print config
    t_config_option_keys print_diff = this->config.diff(config);
    if (!print_diff.empty()) {
        this->config.apply(config, true);
        
        if (this->invalidate_state_by_config_options(print_diff))
            invalidated = true;
    }
    
    // handle changes to object config defaults
    this->default_object_config.apply(config, true);
    FOREACH_OBJECT(this, obj_ptr) {
        // we don't assume that config contains a full ObjectConfig,
        // so we base it on the current print-wise default
        PrintObjectConfig new_config = this->default_object_config;
        new_config.apply(config, true);
        
        // we override the new config with object-specific options
        {
            DynamicPrintConfig model_object_config = (*obj_ptr)->model_object()->config;
            model_object_config.normalize();
            new_config.apply(model_object_config, true);
        }
        
        // check whether the new config is different from the current one
        t_config_option_keys diff = (*obj_ptr)->config.diff(new_config);
        if (!diff.empty()) {
            (*obj_ptr)->config.apply(new_config, true);
            
            if ((*obj_ptr)->invalidate_state_by_config_options(diff))
                invalidated = true;
        }
    }
    
    // handle changes to regions config defaults
    this->default_region_config.apply(config, true);
    
    // All regions now have distinct settings.
    // Check whether applying the new region config defaults we'd get different regions.
    bool rearrange_regions = false;
    std::vector<PrintRegionConfig> other_region_configs;
    FOREACH_REGION(this, it_r) {
        size_t region_id = it_r - this->regions.begin();
        PrintRegion* region = *it_r;
        
        std::vector<PrintRegionConfig> this_region_configs;
        FOREACH_OBJECT(this, it_o) {
            PrintObject* object = *it_o;
            
            std::vector<int> &region_volumes = object->region_volumes[region_id];
            for (std::vector<int>::const_iterator volume_id = region_volumes.begin(); volume_id != region_volumes.end(); ++volume_id) {
                ModelVolume* volume = object->model_object()->volumes.at(*volume_id);
                
                PrintRegionConfig new_config = this->_region_config_from_model_volume(*volume);
                
                for (std::vector<PrintRegionConfig>::iterator it = this_region_configs.begin(); it != this_region_configs.end(); ++it) {
                    // if the new config for this volume differs from the other
                    // volume configs currently associated to this region, it means
                    // the region subdivision does not make sense anymore
                    if (!it->equals(new_config)) {
                        rearrange_regions = true;
                        goto NEXT_REGION;
                    }
                }
                this_region_configs.push_back(new_config);
                
                for (std::vector<PrintRegionConfig>::iterator it = other_region_configs.begin(); it != other_region_configs.end(); ++it) {
                    // if the new config for this volume equals any of the other
                    // volume configs that are not currently associated to this
                    // region, it means the region subdivision does not make
                    // sense anymore
                    if (it->equals(new_config)) {
                        rearrange_regions = true;
                        goto NEXT_REGION;
                    }
                }
                
                // if we're here and the new region config is different from the old
                // one, we need to apply the new config and invalidate all objects
                // (possible optimization: only invalidate objects using this region)
                t_config_option_keys region_config_diff = region->config.diff(new_config);
                if (!region_config_diff.empty()) {
                    region->config.apply(new_config);
                    FOREACH_OBJECT(this, o) {
                        if ((*o)->invalidate_state_by_config_options(region_config_diff))
                            invalidated = true;
                    }
                }
            }
        }
        other_region_configs.insert(other_region_configs.end(), this_region_configs.begin(), this_region_configs.end());
        
        NEXT_REGION:
            continue;
    }
    
    if (rearrange_regions) {
        // the current subdivision of regions does not make sense anymore.
        // we need to remove all objects and re-add them
        ModelObjectPtrs model_objects;
        FOREACH_OBJECT(this, o) {
            model_objects.push_back((*o)->model_object());
        }
        this->clear_objects();
        for (ModelObjectPtrs::iterator it = model_objects.begin(); it != model_objects.end(); ++it) {
            this->add_model_object(*it);
            // Update layer_height_profile from the main thread as it may pull the data from the associated ModelObject.
            this->objects.back()->update_layer_height_profile();
        }
        invalidated = true;
    } else {
        // Check validity of the layer height profiles.
        FOREACH_OBJECT(this, o) {
            if (! (*o)->layer_height_profile_valid) {
                // The layer_height_profile is not valid for some reason (updated by the user or invalidated due to some option change).
                // Start slicing of this object from scratch.
                (*o)->invalidate_all_steps();
                // Following line sets the layer_height_profile_valid flag.
                (*o)->update_layer_height_profile();
                invalidated = true;
            } else if (! step_done(posSlice)) {
                // Update layer_height_profile from the main thread as it may pull the data from the associated ModelObject.
                // Only update if the slicing was not finished yet.
                (*o)->update_layer_height_profile();
            }
        }
    }
    
    return invalidated;
}

bool Print::has_infinite_skirt() const
{
    return (this->config.skirt_height == -1 && this->config.skirts > 0)
        || (this->config.ooze_prevention && this->extruders().size() > 1);
}

bool Print::has_skirt() const
{
    return (this->config.skirt_height > 0 && this->config.skirts > 0)
        || this->has_infinite_skirt();
}

std::string
Print::validate() const
{
    if (this->config.complete_objects) {
        // check horizontal clearance
        {
            Polygons a;
            FOREACH_OBJECT(this, i_object) {
                PrintObject* object = *i_object;
                
                /*  get convex hull of all meshes assigned to this print object
                    (this is the same as model_object()->raw_mesh.convex_hull()
                    but probably more efficient */
                Polygon convex_hull;
                {
                    Polygons mesh_convex_hulls;
                    for (size_t i = 0; i < this->regions.size(); ++i) {
                        for (std::vector<int>::const_iterator it = object->region_volumes[i].begin(); it != object->region_volumes[i].end(); ++it) {
                            Polygon hull = object->model_object()->volumes[*it]->mesh.convex_hull();
                            mesh_convex_hulls.push_back(hull);
                        }
                    }
                
                    // make a single convex hull for all of them
                    convex_hull = Slic3r::Geometry::convex_hull(mesh_convex_hulls);
                }
                
                // apply the same transformations we apply to the actual meshes when slicing them
                object->model_object()->instances.front()->transform_polygon(&convex_hull);
                
                // grow convex hull with the clearance margin
                convex_hull = offset(convex_hull, scale_(this->config.extruder_clearance_radius.value)/2, jtRound, scale_(0.1)).front();
                
                // now we check that no instance of convex_hull intersects any of the previously checked object instances
                for (Points::const_iterator copy = object->_shifted_copies.begin(); copy != object->_shifted_copies.end(); ++copy) {
                    Polygon p = convex_hull;
                    p.translate(*copy);
                    if (! intersection(a, p).empty())
                        return "Some objects are too close; your extruder will collide with them.";
                    polygons_append(a, p);
                }
            }
        }
        
        // check vertical clearance
        {
            std::vector<coord_t> object_height;
            FOREACH_OBJECT(this, i_object) {
                PrintObject* object = *i_object;
                object_height.insert(object_height.end(), object->copies().size(), object->size.z);
            }
            std::sort(object_height.begin(), object_height.end());
            // ignore the tallest *copy* (this is why we repeat height for all of them):
            // it will be printed as last one so its height doesn't matter
            object_height.pop_back();
            if (!object_height.empty() && object_height.back() > scale_(this->config.extruder_clearance_height.value))
                return "Some objects are too tall and cannot be printed without extruder collisions.";
        }
    } // end if (this->config.complete_objects)
    
    if (this->config.spiral_vase) {
        size_t total_copies_count = 0;
        FOREACH_OBJECT(this, i_object) total_copies_count += (*i_object)->copies().size();
        if (total_copies_count > 1)
            return "The Spiral Vase option can only be used when printing a single object.";
        if (this->regions.size() > 1)
            return "The Spiral Vase option can only be used when printing single material objects.";
    }
    
    {
        // find the smallest nozzle diameter
        std::set<size_t> extruders = this->extruders();
        if (extruders.empty())
            return "The supplied settings will cause an empty print.";
        
        std::set<double> nozzle_diameters;
        for (std::set<size_t>::iterator it = extruders.begin(); it != extruders.end(); ++it)
            nozzle_diameters.insert(this->config.nozzle_diameter.get_at(*it));
        double min_nozzle_diameter = *std::min_element(nozzle_diameters.begin(), nozzle_diameters.end());
        
        FOREACH_OBJECT(this, i_object) {
            PrintObject* object = *i_object;

            if ((object->config.support_material_extruder == -1 || object->config.support_material_interface_extruder == -1) &&
                (object->config.raft_layers > 0 || object->config.support_material.value)) {
                // The object has some form of support and either support_material_extruder or support_material_interface_extruder
                // will be printed with the current tool without a forced tool change. Play safe, assert that all object nozzles
                // are of the same diameter.
                if (nozzle_diameters.size() > 1)
                    return "Printing with multiple extruders of differing nozzle diameters. "
                           "If support is to be printed with the current extruder (support_material_extruder == 0 or support_material_interface_extruder == 0), "
                           "all nozzles have to be of the same diameter.";
            }
            
            // validate first_layer_height
            double first_layer_height = object->config.get_abs_value("first_layer_height");
            double first_layer_min_nozzle_diameter;
            if (object->config.raft_layers > 0) {
                // if we have raft layers, only support material extruder is used on first layer
                size_t first_layer_extruder = object->config.raft_layers == 1
                    ? object->config.support_material_interface_extruder-1
                    : object->config.support_material_extruder-1;
                first_layer_min_nozzle_diameter = (first_layer_extruder == size_t(-1)) ? 
                    min_nozzle_diameter : 
                    this->config.nozzle_diameter.get_at(first_layer_extruder);
            } else {
                // if we don't have raft layers, any nozzle diameter is potentially used in first layer
                first_layer_min_nozzle_diameter = min_nozzle_diameter;
            }
            if (first_layer_height > first_layer_min_nozzle_diameter)
                return "First layer height can't be greater than nozzle diameter";
            
            // validate layer_height
            if (object->config.layer_height.value > min_nozzle_diameter)
                return "Layer height can't be greater than nozzle diameter";
        }
    }

    return std::string();
}

// the bounding box of objects placed in copies position
// (without taking skirt/brim/support material into account)
BoundingBox
Print::bounding_box() const
{
    BoundingBox bb;
    FOREACH_OBJECT(this, object) {
        for (Points::const_iterator copy = (*object)->_shifted_copies.begin(); copy != (*object)->_shifted_copies.end(); ++copy) {
            bb.merge(*copy);
            
            Point p = *copy;
            p.translate((*object)->size);
            bb.merge(p);
        }
    }
    return bb;
}

// the total bounding box of extrusions, including skirt/brim/support material
// this methods needs to be called even when no steps were processed, so it should
// only use configuration values
BoundingBox
Print::total_bounding_box() const
{
    // get objects bounding box
    BoundingBox bb = this->bounding_box();
    
    // we need to offset the objects bounding box by at least half the perimeters extrusion width
    Flow perimeter_flow = this->objects.front()->get_layer(0)->get_region(0)->flow(frPerimeter);
    double extra = perimeter_flow.width/2;
    
    // consider support material
    if (this->has_support_material()) {
        extra = std::max(extra, SUPPORT_MATERIAL_MARGIN);
    }
    
    // consider brim and skirt
    if (this->config.brim_width.value > 0) {
        Flow brim_flow = this->brim_flow();
        extra = std::max(extra, this->config.brim_width.value + brim_flow.width/2);
    }
    if (this->has_skirt()) {
        int skirts = this->config.skirts.value;
        if (skirts == 0 && this->has_infinite_skirt()) skirts = 1;
        Flow skirt_flow = this->skirt_flow();
        extra = std::max(
            extra,
            this->config.brim_width.value
                + this->config.skirt_distance.value
                + skirts * skirt_flow.spacing()
                + skirt_flow.width/2
        );
    }
    
    if (extra > 0)
        bb.offset(scale_(extra));
    
    return bb;
}

double
Print::skirt_first_layer_height() const
{
    if (this->objects.empty()) CONFESS("skirt_first_layer_height() can't be called without PrintObjects");
    return this->objects.front()->config.get_abs_value("first_layer_height");
}

Flow
Print::brim_flow() const
{
    ConfigOptionFloatOrPercent width = this->config.first_layer_extrusion_width;
    if (width.value == 0) width = this->regions.front()->config.perimeter_extrusion_width;
    
    /* We currently use a random region's perimeter extruder.
       While this works for most cases, we should probably consider all of the perimeter
       extruders and take the one with, say, the smallest index.
       The same logic should be applied to the code that selects the extruder during G-code
       generation as well. */
    return Flow::new_from_config_width(
        frPerimeter,
        width, 
        this->config.nozzle_diameter.get_at(this->regions.front()->config.perimeter_extruder-1),
        this->skirt_first_layer_height(),
        0
    );
}

Flow
Print::skirt_flow() const
{
    ConfigOptionFloatOrPercent width = this->config.first_layer_extrusion_width;
    if (width.value == 0) width = this->regions.front()->config.perimeter_extrusion_width;
    
    /* We currently use a random object's support material extruder.
       While this works for most cases, we should probably consider all of the support material
       extruders and take the one with, say, the smallest index;
       The same logic should be applied to the code that selects the extruder during G-code
       generation as well. */
    return Flow::new_from_config_width(
        frPerimeter,
        width, 
        this->config.nozzle_diameter.get_at(this->objects.front()->config.support_material_extruder-1),
        this->skirt_first_layer_height(),
        0
    );
}


PrintRegionConfig
Print::_region_config_from_model_volume(const ModelVolume &volume)
{
    PrintRegionConfig config = this->default_region_config;
    {
        DynamicPrintConfig other_config = volume.get_object()->config;
        other_config.normalize();
        config.apply(other_config, true);
    }
    {
        DynamicPrintConfig other_config = volume.config;
        other_config.normalize();
        config.apply(other_config, true);
    }
    if (!volume.material_id().empty()) {
        DynamicPrintConfig material_config = volume.material()->config;
        material_config.normalize();
        config.apply(material_config, true);
    }
    return config;
}

bool
Print::has_support_material() const
{
    FOREACH_OBJECT(this, object) {
        if ((*object)->has_support_material()) return true;
    }
    return false;
}

/*  This method assigns extruders to the volumes having a material
    but not having extruders set in the volume config. */
void
Print::auto_assign_extruders(ModelObject* model_object) const
{
    // only assign extruders if object has more than one volume
    if (model_object->volumes.size() < 2) return;
    
    size_t extruders = this->config.nozzle_diameter.values.size();
    for (ModelVolumePtrs::const_iterator v = model_object->volumes.begin(); v != model_object->volumes.end(); ++v) {
        if (!(*v)->material_id().empty()) {
            //FIXME Vojtech: This assigns an extruder ID even to a modifier volume, if it has a material assigned.
            size_t extruder_id = (v - model_object->volumes.begin()) + 1;
            if (!(*v)->config.has("extruder"))
                (*v)->config.opt<ConfigOptionInt>("extruder", true)->value = int(extruder_id);
        }
    }
}


void Print::_make_skirt()
{
    // First off we need to decide how tall the skirt must be.
    // The skirt_height option from config is expressed in layers, but our
    // object might have different layer heights, so we need to find the print_z
    // of the highest layer involved.
    // Note that unless has_infinite_skirt() == true
    // the actual skirt might not reach this $skirt_height_z value since the print
    // order of objects on each layer is not guaranteed and will not generally
    // include the thickest object first. It is just guaranteed that a skirt is
    // prepended to the first 'n' layers (with 'n' = skirt_height).
    // $skirt_height_z in this case is the highest possible skirt height for safety.
    coordf_t skirt_height_z = 0.;
    for (const PrintObject *object : this->objects) {
        size_t skirt_layers = this->has_infinite_skirt() ? 
            object->layer_count() : 
            std::min(size_t(this->config.skirt_height.value), object->layer_count());
        skirt_height_z = std::max(skirt_height_z, object->layers[skirt_layers-1]->print_z);
    }
    
    // Collect points from all layers contained in skirt height.
    Points points;
    for (const PrintObject *object : this->objects) {
        Points object_points;
        // Get object layers up to skirt_height_z.
        for (const Layer *layer : object->layers) {
            if (layer->print_z > skirt_height_z)
                break;
            for (const ExPolygon &expoly : layer->slices.expolygons)
                // Collect the outer contour points only, ignore holes for the calculation of the convex hull.
                append(object_points, expoly.contour.points);
        }
        // Get support layers up to skirt_height_z.
        for (const SupportLayer *layer : object->support_layers) {
            if (layer->print_z > skirt_height_z)
                break;
            for (const ExtrusionEntity *extrusion_entity : layer->support_fills.entities)
                append(object_points, extrusion_entity->as_polyline().points);
            for (const ExtrusionEntity *extrusion_entity : layer->support_interface_fills.entities)
                append(object_points, extrusion_entity->as_polyline().points);
        }
        // Repeat points for each object copy.
        for (const Point &shift : object->_shifted_copies) {
            Points copy_points = object_points;
            for (Point &pt : copy_points)
                pt.translate(shift);
            append(points, copy_points);
        }
    }

    if (points.size() < 3)
        // At least three points required for a convex hull.
        return;
    
    Polygon convex_hull = Slic3r::Geometry::convex_hull(points);
    
    // Skirt may be printed on several layers, having distinct layer heights,
    // but loops must be aligned so can't vary width/spacing
    // TODO: use each extruder's own flow
    double first_layer_height = this->skirt_first_layer_height();
    Flow   flow = this->skirt_flow();
    float  spacing = flow.spacing();
    double mm3_per_mm = flow.mm3_per_mm();
    
    std::vector<size_t> extruders;
    std::vector<double> extruders_e_per_mm;
    {
        auto set_extruders = this->extruders();
        extruders.reserve(set_extruders.size());
        extruders_e_per_mm.reserve(set_extruders.size());
        for (auto &extruder_id : set_extruders) {
            extruders.push_back(extruder_id);
            GCodeConfig config;
            config.apply(this->config, true);
            extruders_e_per_mm.push_back(Extruder((unsigned int)extruder_id, &config).e_per_mm(mm3_per_mm));
        }
    }

    // Number of skirt loops per skirt layer.
    int n_skirts = this->config.skirts.value;
    if (this->has_infinite_skirt() && n_skirts == 0)
        n_skirts = 1;

    // Initial offset of the brim inner edge from the object (possible with a support & raft).
    // The skirt will touch the brim if the brim is extruded.
    coord_t distance = scale_(std::max(this->config.skirt_distance.value, this->config.brim_width.value));
    // Draw outlines from outside to inside.
    // Loop while we have less skirts than required or any extruder hasn't reached the min length if any.
    std::vector<coordf_t> extruded_length(extruders.size(), 0.);
    for (int i = n_skirts, extruder_idx = 0; i > 0; -- i) {
        // Offset the skirt outside.
        distance += coord_t(scale_(spacing));
        // Generate the skirt centerline.
        Polygon loop = offset(convex_hull, distance, ClipperLib::jtRound, scale_(0.1)).front();
        // Extrude the skirt loop.
        ExtrusionLoop eloop(elrSkirt);
        eloop.paths.emplace_back(ExtrusionPath(
            ExtrusionPath(
                erSkirt,
                mm3_per_mm,         // this will be overridden at G-code export time
                flow.width,
                first_layer_height  // this will be overridden at G-code export time
            )));
        eloop.paths.back().polyline = loop.split_at_first_point();
        this->skirt.append(eloop);
        if (this->config.min_skirt_length.value > 0) {
            // The skirt length is limited. Sum the total amount of filament length extruded, in mm.
            extruded_length[extruder_idx] += unscale(loop.length()) * extruders_e_per_mm[extruder_idx];
            if (extruded_length[extruder_idx] < this->config.min_skirt_length.value) {
                // Not extruded enough yet with the current extruder. Add another loop.
                if (i == 1)
                    ++ i;
            } else {
                assert(extruded_length[extruder_idx] >= this->config.min_skirt_length.value);
                // Enough extruded with the current extruder. Extrude with the next one,
                // until the prescribed number of skirt loops is extruded.
                if (extruder_idx + 1 < extruders.size())
                    ++ extruder_idx;
            }
        } else {
            // The skirt lenght is not limited, extrude the skirt with the 1st extruder only.
        }
    }
    // Brims were generated inside out, reverse to print the outmost contour first.
    this->skirt.reverse();
}

}