CCmpFootprint.cpp

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/* Copyright (C) 2013 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "precompiled.h"

#include "simulation2/system/Component.h"
#include "ICmpFootprint.h"

#include "simulation2/components/ICmpObstruction.h"
#include "simulation2/components/ICmpObstructionManager.h"
#include "simulation2/components/ICmpPathfinder.h"
#include "simulation2/components/ICmpPosition.h"
#include "simulation2/components/ICmpUnitMotion.h"
#include "simulation2/MessageTypes.h"
#include "graphics/Terrain.h"   // For TERRAIN_TILE_SIZE
#include "maths/FixedVector2D.h"

class CCmpFootprint : public ICmpFootprint
{
public:
    static void ClassInit(CComponentManager& UNUSED(componentManager))
    {
    }

    DEFAULT_COMPONENT_ALLOCATOR(Footprint)

    EShape m_Shape;
    entity_pos_t m_Size0; // width/radius
    entity_pos_t m_Size1; // height/radius
    entity_pos_t m_Height;

    static std::string GetSchema()
    {
        return
            "<a:help>Approximation of the entity's shape, for collision detection and outline rendering. "
            "Shapes are flat horizontal squares or circles, extended vertically to a given height.</a:help>"
            "<a:example>"
                "<Square width='3.0' height='3.0'/>"
                "<Height>0.0</Height>"
            "</a:example>"
            "<a:example>"
                "<Circle radius='0.5'/>"
                "<Height>0.0</Height>"
            "</a:example>"
            "<choice>"
                "<element name='Square' a:help='Set the footprint to a square of the given size'>"
                    "<attribute name='width' a:help='Size of the footprint along the left/right direction (in metres)'>"
                        "<ref name='positiveDecimal'/>"
                    "</attribute>"
                    "<attribute name='depth' a:help='Size of the footprint along the front/back direction (in metres)'>"
                        "<ref name='positiveDecimal'/>"
                    "</attribute>"
                "</element>"
                "<element name='Circle' a:help='Set the footprint to a circle of the given size'>"
                    "<attribute name='radius' a:help='Radius of the footprint (in metres)'>"
                        "<ref name='positiveDecimal'/>"
                    "</attribute>"
                "</element>"
            "</choice>"
            "<element name='Height' a:help='Vertical extent of the footprint (in metres)'>"
                "<ref name='nonNegativeDecimal'/>"
            "</element>";
    }

    virtual void Init(const CParamNode& paramNode)
    {
        if (paramNode.GetChild("Square").IsOk())
        {
            m_Shape = SQUARE;
            m_Size0 = paramNode.GetChild("Square").GetChild("@width").ToFixed();
            m_Size1 = paramNode.GetChild("Square").GetChild("@depth").ToFixed();
        }
        else if (paramNode.GetChild("Circle").IsOk())
        {
            m_Shape = CIRCLE;
            m_Size0 = m_Size1 = paramNode.GetChild("Circle").GetChild("@radius").ToFixed();
        }
        else
        {
            // Error - pick some default
            m_Shape = CIRCLE;
            m_Size0 = m_Size1 = entity_pos_t::FromInt(1);
        }

        m_Height = paramNode.GetChild("Height").ToFixed();
    }

    virtual void Deinit()
    {
    }

    virtual void Serialize(ISerializer& UNUSED(serialize))
    {
        // No dynamic state to serialize
    }

    virtual void Deserialize(const CParamNode& paramNode, IDeserializer& UNUSED(deserialize))
    {
        Init(paramNode);
    }

    virtual void GetShape(EShape& shape, entity_pos_t& size0, entity_pos_t& size1, entity_pos_t& height)
    {
        shape = m_Shape;
        size0 = m_Size0;
        size1 = m_Size1;
        height = m_Height;
    }

    virtual CFixedVector3D PickSpawnPoint(entity_id_t spawned)
    {
        // Try to find a free space around the building's footprint.
        // (Note that we use the footprint, not the obstruction shape - this might be a bit dodgy
        // because the footprint might be inside the obstruction, but it hopefully gives us a nicer
        // shape.)

        const CFixedVector3D error(fixed::FromInt(-1), fixed::FromInt(-1), fixed::FromInt(-1));

        CmpPtr<ICmpPosition> cmpPosition(GetEntityHandle());
        if (!cmpPosition || !cmpPosition->IsInWorld())
            return error;

        CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSystemEntity());
        if (!cmpObstructionManager)
            return error;

        entity_pos_t spawnedRadius;
        ICmpObstructionManager::tag_t spawnedTag;

        CmpPtr<ICmpObstruction> cmpSpawnedObstruction(GetSimContext(), spawned);
        if (cmpSpawnedObstruction)
        {
            spawnedRadius = cmpSpawnedObstruction->GetUnitRadius();
            spawnedTag = cmpSpawnedObstruction->GetObstruction();
        }
        // else use zero radius

        // Get passability class from UnitMotion
        CmpPtr<ICmpUnitMotion> cmpUnitMotion(GetSimContext(), spawned);
        if (!cmpUnitMotion)
            return error;

        ICmpPathfinder::pass_class_t spawnedPass = cmpUnitMotion->GetPassabilityClass();
        CmpPtr<ICmpPathfinder> cmpPathfinder(GetSystemEntity());
        if (!cmpPathfinder)
            return error;
        
        CFixedVector2D initialPos = cmpPosition->GetPosition2D();
        entity_angle_t initialAngle = cmpPosition->GetRotation().Y;

        // Max spawning distance in tiles
        const i32 maxSpawningDistance = 4;

        if (m_Shape == CIRCLE)
        {
            // Expand outwards from foundation
            for (i32 dist = 0; dist <= maxSpawningDistance; ++dist)
            {
                // The spawn point should be far enough from this footprint to fit the unit, plus a little gap
                entity_pos_t clearance = spawnedRadius + entity_pos_t::FromInt(2 + (int)TERRAIN_TILE_SIZE*dist);
                entity_pos_t radius = m_Size0 + clearance;

                // Try equally-spaced points around the circle in alternating directions, starting from the front
                const i32 numPoints = 31 + 2*dist;
                for (i32 i = 0; i < (numPoints+1)/2; i = (i > 0 ? -i : 1-i)) // [0, +1, -1, +2, -2, ... (np-1)/2, -(np-1)/2]
                {
                    entity_angle_t angle = initialAngle + (entity_angle_t::Pi()*2).Multiply(entity_angle_t::FromInt(i)/(int)numPoints);

                    fixed s, c;
                    sincos_approx(angle, s, c);

                    CFixedVector3D pos (initialPos.X + s.Multiply(radius), fixed::Zero(), initialPos.Y + c.Multiply(radius));

                    SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
                    if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Z, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
                        return pos; // this position is okay, so return it
                }
            }
        }
        else
        {
            fixed s, c;
            sincos_approx(initialAngle, s, c);

            // Expand outwards from foundation
            for (i32 dist = 0; dist <= maxSpawningDistance; ++dist)
            {
                // The spawn point should be far enough from this footprint to fit the unit, plus a little gap
                entity_pos_t clearance = spawnedRadius + entity_pos_t::FromInt(2 + (int)TERRAIN_TILE_SIZE*dist);

                for (i32 edge = 0; edge < 4; ++edge)
                {
                    // Try equally-spaced points along the edge in alternating directions, starting from the middle
                    const i32 numPoints = 9 + 2*dist;

                    // Compute the direction and length of the current edge
                    CFixedVector2D dir;
                    fixed sx, sy;
                    switch (edge)
                    {
                    case 0:
                        dir = CFixedVector2D(c, -s);
                        sx = m_Size0;
                        sy = m_Size1;
                        break;
                    case 1:
                        dir = CFixedVector2D(-s, -c);
                        sx = m_Size1;
                        sy = m_Size0;
                        break;
                    case 2:
                        dir = CFixedVector2D(s, c);
                        sx = m_Size1;
                        sy = m_Size0;
                        break;
                    case 3:
                        dir = CFixedVector2D(-c, s);
                        sx = m_Size0;
                        sy = m_Size1;
                        break;
                    }
                    CFixedVector2D center = initialPos - dir.Perpendicular().Multiply(sy/2 + clearance);
                    dir = dir.Multiply((sx + clearance*2) / (int)(numPoints-1));

                    for (i32 i = 0; i < (numPoints+1)/2; i = (i > 0 ? -i : 1-i)) // [0, +1, -1, +2, -2, ... (np-1)/2, -(np-1)/2]
                    {
                        CFixedVector2D pos (center + dir*i);

                        SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
                        if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Y, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
                            return CFixedVector3D(pos.X, fixed::Zero(), pos.Y); // this position is okay, so return it
                    }
                }
            }
        }

        return error;
    }
};

REGISTER_COMPONENT_TYPE(Footprint)