CCAutoPolygon.cpp

/****************************************************************************
Copyright (c) 2008-2010 Ricardo Quesada
Copyright (c) 2010-2012 cocos2d-x.org
Copyright (c) 2011      Zynga Inc.
Copyright (c) 2013-2016 Chukong Technologies Inc.
Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.
 
http://www.cocos2d-x.org

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all copies or substantial portions of the Software.

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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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****************************************************************************/

#include "2d/CCAutoPolygon.h"
#include "poly2tri/poly2tri.h"
#include "base/CCDirector.h"
#include "renderer/CCTextureCache.h"
#include "clipper/clipper.hpp"
#include <algorithm>
#include <math.h>

USING_NS_CC;

static unsigned short quadIndices9[]={
    0+4*0,1+4*0,2+4*0, 3+4*0,2+4*0,1+4*0,
    0+4*1,1+4*1,2+4*1, 3+4*1,2+4*1,1+4*1,
    0+4*2,1+4*2,2+4*2, 3+4*2,2+4*2,1+4*2,
    0+4*3,1+4*3,2+4*3, 3+4*3,2+4*3,1+4*3,
    0+4*4,1+4*4,2+4*4, 3+4*4,2+4*4,1+4*4,
    0+4*5,1+4*5,2+4*5, 3+4*5,2+4*5,1+4*5,
    0+4*6,1+4*6,2+4*6, 3+4*6,2+4*6,1+4*6,
    0+4*7,1+4*7,2+4*7, 3+4*7,2+4*7,1+4*7,
    0+4*8,1+4*8,2+4*8, 3+4*8,2+4*8,1+4*8,
};

const static float PRECISION = 10.0f;

PolygonInfo::PolygonInfo()
: _isVertsOwner(true)
, _rect(Rect::ZERO)
, _filename("")
{
    triangles.verts = nullptr;
    triangles.indices = nullptr;
    triangles.vertCount = 0;
    triangles.indexCount = 0;
};

PolygonInfo::PolygonInfo(const PolygonInfo& other)
: triangles()
, _isVertsOwner(true)
, _rect()
{
    _filename = other._filename;
    _isVertsOwner = true;
    _rect = other._rect;
    triangles.verts = new (std::nothrow) V3F_C4B_T2F[other.triangles.vertCount];
    triangles.indices = new (std::nothrow) unsigned short[other.triangles.indexCount];
    CCASSERT(triangles.verts && triangles.indices, "not enough memory");
    triangles.vertCount = other.triangles.vertCount;
    triangles.indexCount = other.triangles.indexCount;
    memcpy(triangles.verts, other.triangles.verts, other.triangles.vertCount * sizeof(other.triangles.verts[0]));
    memcpy(triangles.indices, other.triangles.indices, other.triangles.indexCount * sizeof(other.triangles.indices[0]));
};

PolygonInfo& PolygonInfo::operator= (const PolygonInfo& other)
{
    if(this != &other)
    {
        releaseVertsAndIndices();
        _filename = other._filename;
        _isVertsOwner = true;
        _rect = other._rect;
        triangles.verts = new (std::nothrow) V3F_C4B_T2F[other.triangles.vertCount];
        triangles.indices = new (std::nothrow) unsigned short[other.triangles.indexCount];
        CCASSERT(triangles.verts && triangles.indices, "not enough memory");
        triangles.vertCount = other.triangles.vertCount;
        triangles.indexCount = other.triangles.indexCount;
        memcpy(triangles.verts, other.triangles.verts, other.triangles.vertCount * sizeof(other.triangles.verts[0]));
        memcpy(triangles.indices, other.triangles.indices, other.triangles.indexCount * sizeof(other.triangles.indices[0]));
    }
    return *this;
}

PolygonInfo::~PolygonInfo()
{
    releaseVertsAndIndices();
}

void PolygonInfo::setQuad(V3F_C4B_T2F_Quad *quad)
{
    releaseVertsAndIndices();
    _isVertsOwner = false;
    triangles.indices = quadIndices9;
    triangles.vertCount = 4;
    triangles.indexCount = 6;
    triangles.verts = (V3F_C4B_T2F*)quad;
}

void PolygonInfo::setQuads(V3F_C4B_T2F_Quad *quad, int numberOfQuads)
{
    CCASSERT(numberOfQuads >= 1 && numberOfQuads <= 9, "Invalid number of Quads");

    releaseVertsAndIndices();
    _isVertsOwner = false;
    triangles.indices = quadIndices9;
    triangles.vertCount = 4 * numberOfQuads;
    triangles.indexCount = 6 * numberOfQuads;
    triangles.verts = (V3F_C4B_T2F*)quad;
}

void PolygonInfo::setTriangles(const TrianglesCommand::Triangles& other)
{
    this->releaseVertsAndIndices();
    _isVertsOwner = false;
    
    this->triangles.vertCount = other.vertCount;
    this->triangles.indexCount = other.indexCount;
    this->triangles.verts = other.verts;
    this->triangles.indices = other.indices;
}

void PolygonInfo::releaseVertsAndIndices()
{
    if(_isVertsOwner)
    {
        if(nullptr != triangles.verts)
        {
            CC_SAFE_DELETE_ARRAY(triangles.verts);
        }
        
        if(nullptr != triangles.indices)
        {
            CC_SAFE_DELETE_ARRAY(triangles.indices);
        }
    }
}

unsigned int PolygonInfo::getVertCount() const
{
    return (unsigned int)triangles.vertCount;
}

unsigned int PolygonInfo::getTrianglesCount() const
{
    return (unsigned int)triangles.indexCount/3;
}

float PolygonInfo::getArea() const
{
    float area = 0;
    V3F_C4B_T2F *verts = triangles.verts;
    unsigned short *indices = triangles.indices;
    for(unsigned int i = 0; i < triangles.indexCount; i+=3)
    {
        auto A = verts[indices[i]].vertices;
        auto B = verts[indices[i+1]].vertices;
        auto C = verts[indices[i+2]].vertices;
        area += (A.x*(B.y-C.y) + B.x*(C.y-A.y) + C.x*(A.y - B.y))/2;
    }
    return area;
}

AutoPolygon::AutoPolygon(const std::string &filename)
:_image(nullptr)
,_data(nullptr)
,_filename("")
,_width(0)
,_height(0)
,_scaleFactor(0)
{
    _filename = filename;
    _image = new (std::nothrow) Image();
    _image->initWithImageFile(filename);
    CCASSERT(_image->getPixelFormat()==backend::PixelFormat::RGBA8888, "unsupported format, currently only supports rgba8888");
    _data = _image->getData();
    _width = _image->getWidth();
    _height = _image->getHeight();
    _scaleFactor = Director::getInstance()->getContentScaleFactor();
}

AutoPolygon::~AutoPolygon()
{
    CC_SAFE_DELETE(_image);
}

std::vector<Vec2> AutoPolygon::trace(const Rect& rect, float threshold)
{
    Vec2 first = findFirstNoneTransparentPixel(rect, threshold);
    return marchSquare(rect, first, threshold);
}

Vec2 AutoPolygon::findFirstNoneTransparentPixel(const Rect& rect, float threshold)
{
	bool found = false;
    Vec2 i;
    for(i.y = rect.origin.y; i.y < rect.origin.y+rect.size.height; i.y++)
    {
        if(found)break;
        for(i.x = rect.origin.x; i.x < rect.origin.x+rect.size.width; i.x++)
        {
            auto alpha = getAlphaByPos(i);
            if(alpha>threshold)
            {
                found = true;
                break;
            }
        }
    }
    CCASSERT(found, "image is all transparent!");
    return i;
}

unsigned char AutoPolygon::getAlphaByIndex(unsigned int i)
{
    return *(_data+i*4+3);
}
unsigned char AutoPolygon::getAlphaByPos(const Vec2& pos)
{
    return *(_data+((int)pos.y*_width+(int)pos.x)*4+3);
}

unsigned int AutoPolygon::getSquareValue(unsigned int x, unsigned int y, const Rect& rect, float threshold)
{
    /*
     checking the 2x2 pixel grid, assigning these values to each pixel, if not transparent
     +---+---+
     | 1 | 2 |
     +---+---+
     | 4 | 8 | <- current pixel (curx,cury)
     +---+---+
     */
    unsigned int sv = 0;
    //NOTE: due to the way we pick points from texture, rect needs to be smaller, otherwise it goes outside 1 pixel
    auto fixedRect = Rect(rect.origin, rect.size-Size(2,2));
    
    Vec2 tl = Vec2(x-1.0f, y-1.0f);
    sv += (fixedRect.containsPoint(tl) && getAlphaByPos(tl) > threshold)? 1 : 0;
    Vec2 tr = Vec2(x-0.0f, y-1.0f);
    sv += (fixedRect.containsPoint(tr) && getAlphaByPos(tr) > threshold)? 2 : 0;
    Vec2 bl = Vec2(x-1.0f, y-0.0f);
    sv += (fixedRect.containsPoint(bl) && getAlphaByPos(bl) > threshold)? 4 : 0;
    Vec2 br = Vec2(x-0.0f, y-0.0f);
    sv += (fixedRect.containsPoint(br) && getAlphaByPos(br) > threshold)? 8 : 0;
    CCASSERT(sv != 0 && sv != 15, "square value should not be 0, or 15");
    return sv;
}

std::vector<cocos2d::Vec2> AutoPolygon::marchSquare(const Rect& rect, const Vec2& start, float threshold)
{
    int stepx = 0;
    int stepy = 0;
    int prevx = 0;
    int prevy = 0;
    int startx = (int)start.x;
    int starty = (int)start.y;
    int curx = startx;
    int cury = starty;
    unsigned int count = 0;
    std::vector<int> case9s;
    std::vector<int> case6s;
    int i;
    std::vector<int>::iterator it;
    std::vector<cocos2d::Vec2> _points;
    do{
        int sv = getSquareValue(curx, cury, rect, threshold);
        switch(sv){

            case 1:
            case 5:
            case 13:
                /* going UP with these cases:
                 1          5           13
                 +---+---+  +---+---+  +---+---+ 
                 | 1 |   |  | 1 |   |  | 1 |   | 
                 +---+---+  +---+---+  +---+---+ 
                 |   |   |  | 4 |   |  | 4 | 8 | 
                 +---+---+  +---+---+  +---+---+
                 */
                stepx = 0;
                stepy = -1;
                break;

                
            case 8:
            case 10:
            case 11:
                /* going DOWN with these cases:
                 8          10          11
                 +---+---+  +---+---+   +---+---+
                 |   |   |  |   | 2 |   | 1 | 2 |
                 +---+---+  +---+---+   +---+---+
                 |   | 8 |  |   | 8 |   |   | 8 |
                 +---+---+  +---+---+  	+---+---+
                 */
                stepx = 0;
                stepy = 1;
                break;

                
            case 4:
            case 12:
            case 14:
                /* going LEFT with these cases:
                 4          12          14
                 +---+---+  +---+---+   +---+---+
                 |   |   |  |   |   |   |   | 2 |
                 +---+---+  +---+---+   +---+---+
                 | 4 |   |  | 4 | 8 |   | 4 | 8 |
                 +---+---+  +---+---+  	+---+---+
                 */
                stepx = -1;
                stepy = 0;
                break;
                
                
            case 2 :
            case 3 :
            case 7 :
                /* going RIGHT with these cases:
                 2          3           7        
                 +---+---+  +---+---+   +---+---+
                 |   | 2 |  | 1 | 2 |   | 1 | 2 |
                 +---+---+  +---+---+   +---+---+
                 |   |   |  |   |   |   | 4 |   |
                 +---+---+  +---+---+  	+---+---+
                 */
                stepx=1;
                stepy=0;
                break;
            case 9 :
                /*
                 +---+---+
                 | 1 |   |
                 +---+---+
                 |   | 8 |
                 +---+---+
                 this should normally go UP, but if we already been here, we go down
                */
                //find index from xy;
                i = getIndexFromPos(curx, cury);
                it = find (case9s.begin(), case9s.end(), i);
                if (it != case9s.end())
                {
                    //found, so we go down, and delete from case9s;
                    stepx = 0;
                    stepy = 1;
                    case9s.erase(it);
                }
                else
                {
                    //not found, we go up, and add to case9s;
                    stepx = 0;
                    stepy = -1;
                    case9s.push_back(i);
                }
                break;
            case 6 :
                /*
                 6
                 +---+---+
                 |   | 2 |
                 +---+---+
                 | 4 |   |
                 +---+---+
                 this normally go RIGHT, but if its coming from UP, it should go LEFT
                 */
                i = getIndexFromPos(curx, cury);
                it = find (case6s.begin(), case6s.end(), i);
                if (it != case6s.end())
                {
                    //found, so we go down, and delete from case9s;
                    stepx = -1;
                    stepy = 0;
                    case6s.erase(it);
                }
                else{
                    //not found, we go up, and add to case9s;
                    stepx = 1;
                    stepy = 0;
                    case6s.push_back(i);
                }
                break;
            default:
                CCLOG("this shouldn't happen.");
        }
        //little optimization
        // if previous direction is same as current direction,
        // then we should modify the last vec to current
        curx += stepx;
        cury += stepy;
        if(stepx == prevx && stepy == prevy)
        {
            _points.back().x = (float)(curx-rect.origin.x) / _scaleFactor;
            _points.back().y = (float)(rect.size.height - cury + rect.origin.y) / _scaleFactor;
        }
        else
        {
            _points.push_back(Vec2((float)(curx - rect.origin.x) / _scaleFactor, (float)(rect.size.height - cury + rect.origin.y) / _scaleFactor));
        }

        count++;
        prevx = stepx;
        prevy = stepy;

#if defined(COCOS2D_DEBUG) && (COCOS2D_DEBUG > 0)
        const auto totalPixel = _width * _height;
        CCASSERT(count <= totalPixel, "oh no, marching square cannot find starting position");
#endif
    } while(curx != startx || cury != starty);
    return _points;
}

float AutoPolygon::perpendicularDistance(const cocos2d::Vec2& i, const cocos2d::Vec2& start, const cocos2d::Vec2& end)
{
    float res;
    float slope;
    float intercept;
    
    if(start.x == end.x)
    {
        res = fabsf(i.x- end.x);
    }
    else if (start.y == end.y)
    {
        res = fabsf(i.y - end.y);
    }
    else{
        slope = (end.y - start.y) / (end.x - start.x);
        intercept = start.y - (slope*start.x);
        res = fabsf(slope * i.x - i.y + intercept) / sqrtf(powf(slope, 2)+1);
    }
    return res;
}
std::vector<cocos2d::Vec2> AutoPolygon::rdp(const std::vector<cocos2d::Vec2>& v, float optimization)
{
    if(v.size() < 3)
        return v;
    
    int index = -1;
    float dist = 0;
    //not looping first and last point
    for(size_t i = 1, size = v.size(); i < size-1; ++i)
    {
        float cdist = perpendicularDistance(v[i], v.front(), v.back());
        if(cdist > dist)
        {
            dist = cdist;
            index = static_cast<int>(i);
        }
    }
    if (dist>optimization)
    {
        std::vector<Vec2>::const_iterator begin = v.begin();
        std::vector<Vec2>::const_iterator end   = v.end();
        std::vector<Vec2> l1(begin, begin+index+1);
        std::vector<Vec2> l2(begin+index, end);
        
        std::vector<Vec2> r1 = rdp(l1, optimization);
        std::vector<Vec2> r2 = rdp(l2, optimization);
        
        r1.insert(r1.end(), r2.begin()+1, r2.end());
        return r1;
    }
    else {
        std::vector<Vec2> ret;
        ret.push_back(v.front());
        ret.push_back(v.back());
        return ret;
    }
}
std::vector<Vec2> AutoPolygon::reduce(const std::vector<Vec2>& points, const Rect& rect, float epsilon)
{
    auto size = points.size();
    // if there are less than 3 points, then we have nothing
    if(size<3)
    {
        log("AUTOPOLYGON: cannot reduce points for %s that has less than 3 points in input, e: %f", _filename.c_str(), epsilon);
        return std::vector<Vec2>();
    }
    // if there are less than 9 points (but more than 3), then we don't need to reduce it
    else if (size < 9)
    {
        log("AUTOPOLYGON: cannot reduce points for %s e: %f",_filename.c_str(), epsilon);
        return points;
    }
    float maxEp = MIN(rect.size.width, rect.size.height);
    float ep = clampf(epsilon, 0.0, maxEp/_scaleFactor/2);
    std::vector<Vec2> result = rdp(points, ep);
    
    auto last = result.back();
    if (last.y > result.front().y && last.getDistance(result.front()) < ep * 0.5f)
    {
        result.front().y = last.y;
        result.pop_back();
    }
    return result;
}

std::vector<Vec2> AutoPolygon::expand(const std::vector<Vec2>& points, const cocos2d::Rect &rect, float epsilon)
{
    auto size = points.size();
    // if there are less than 3 points, then we have nothing
    if(size<3)
    {
        log("AUTOPOLYGON: cannot expand points for %s with less than 3 points, e: %f", _filename.c_str(), epsilon);
        return std::vector<Vec2>();
    }
    ClipperLib::Path subj;
    ClipperLib::PolyTree solution;
    ClipperLib::PolyTree out;
    for(const auto& pt : points)
    {
        subj << ClipperLib::IntPoint(static_cast<ClipperLib::cInt>(pt.x* PRECISION), static_cast<ClipperLib::cInt>(pt.y * PRECISION));
    }
    ClipperLib::ClipperOffset co;
    co.AddPath(subj, ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
    co.Execute(solution, epsilon * PRECISION);
    
    ClipperLib::PolyNode* p = solution.GetFirst();
    if(!p)
    {
        log("AUTOPOLYGON: Clipper failed to expand the points");
        return points;
    }
    while(p->IsHole()){
        p = p->GetNext();
    }

    //turn the result into simply polygon (AKA, fix overlap)
    
    //clamp into the specified rect
    ClipperLib::Clipper cl;
    cl.StrictlySimple(true);
    cl.AddPath(p->Contour, ClipperLib::ptSubject, true);
    //create the clipping rect
    ClipperLib::Path clamp;
    clamp.push_back(ClipperLib::IntPoint(0, 0));
    clamp.push_back(ClipperLib::IntPoint(static_cast<ClipperLib::cInt>(rect.size.width/_scaleFactor * PRECISION), 0));
    clamp.push_back(ClipperLib::IntPoint(static_cast<ClipperLib::cInt>(rect.size.width/_scaleFactor * PRECISION), 
                                         static_cast<ClipperLib::cInt>(rect.size.height/_scaleFactor * PRECISION)));
    clamp.push_back(ClipperLib::IntPoint(0, static_cast<ClipperLib::cInt>(rect.size.height/_scaleFactor * PRECISION)));
    cl.AddPath(clamp, ClipperLib::ptClip, true);
    cl.Execute(ClipperLib::ctIntersection, out);
    
    std::vector<Vec2> outPoints;
    ClipperLib::PolyNode* p2 = out.GetFirst();
    while(p2->IsHole()){
        p2 = p2->GetNext();
    }
    for(const auto& pt : p2->Contour)
    {
        outPoints.push_back(Vec2(pt.X/PRECISION, pt.Y/PRECISION));
    }
    return outPoints;
}

TrianglesCommand::Triangles AutoPolygon::triangulate(const std::vector<Vec2>& points)
{
    // if there are less than 3 points, then we can't triangulate
    if(points.size()<3)
    {
        log("AUTOPOLYGON: cannot triangulate %s with less than 3 points", _filename.c_str());
        return TrianglesCommand::Triangles();
    }
    std::vector<p2t::Point*> p2points;
    for(const auto& pt : points)
    {
        p2t::Point * p = new (std::nothrow) p2t::Point(pt.x, pt.y);
        p2points.push_back(p);
    }
    p2t::CDT cdt(p2points);
    cdt.Triangulate();
    std::vector<p2t::Triangle*> tris = cdt.GetTriangles();
    
    // we won't know the size of verts and indices until we process all of the triangles!
    std::vector<V3F_C4B_T2F> verts;
    std::vector<unsigned short> indices;

    unsigned short idx = 0;
    unsigned short vdx = 0;

    for(const auto& ite : tris)
    {
        for(int i = 0; i < 3; ++i)
        {
            auto p = ite->GetPoint(i);
            auto v3 = Vec3((float)p->x, (float)p->y, 0);
            bool found = false;
            unsigned short j;
            auto length = vdx;
            for(j = 0; j < length; j++)
            {
                if(verts[j].vertices == v3)
                {
                    found = true;
                    break;
                }
            }
            if(found)
            {
                //if we found the same vertex, don't add to verts, but use the same vertex with indices
                indices.push_back(j);
                idx++;
            }
            else
            {
                //vert does not exist yet, so we need to create a new one,
                auto c4b = Color4B::WHITE;
                auto t2f = Tex2F(0,0); // don't worry about tex coords now, we calculate that later
                V3F_C4B_T2F vert = {v3,c4b,t2f};
                verts.push_back(vert);
                indices.push_back(vdx);
                idx++;
                vdx++;
            }
        }
    }
    for(auto j : p2points)
    {
        delete j;
    };

    // now that we know the size of verts and indices we can create the buffers
    V3F_C4B_T2F* vertsBuf = new (std::nothrow) V3F_C4B_T2F[verts.size()];
    memcpy(vertsBuf, verts.data(), verts.size() * sizeof(V3F_C4B_T2F));

    unsigned short* indicesBuf = new (std::nothrow) unsigned short[indices.size()];
    memcpy(indicesBuf, indices.data(), indices.size() * sizeof(short));

    // Triangles should really use std::vector and not arrays for verts and indices. 
    // Then the above memcpy would not be necessary
    TrianglesCommand::Triangles triangles = { vertsBuf, indicesBuf, (unsigned int)verts.size(), (unsigned int)indices.size() };
    return triangles;
}

void AutoPolygon::calculateUV(const Rect& rect, V3F_C4B_T2F* verts, ssize_t count)
{
    /*
     whole texture UV coordination
     0,0                  1,0
     +---------------------+
     |                     |0.1
     |                     |0.2
     |     +--------+      |0.3
     |     |texRect |      |0.4
     |     |        |      |0.5
     |     |        |      |0.6
     |     +--------+      |0.7
     |                     |0.8
     |                     |0.9
     +---------------------+
     0,1                  1,1
     */
    
    CCASSERT(_width && _height, "please specify width and height for this AutoPolygon instance");
    auto texWidth  = _width;
    auto texHeight = _height;

    auto end = &verts[count];
    for(auto i = verts; i != end; ++i)
    {
        // for every point, offset with the center point
        float u = (i->vertices.x*_scaleFactor + rect.origin.x) / texWidth;
        float v = (rect.origin.y+rect.size.height - i->vertices.y*_scaleFactor) / texHeight;
        i->texCoords.u = u;
        i->texCoords.v = v;
    }
}

Rect AutoPolygon::getRealRect(const Rect& rect)
{
    Rect realRect = rect;
    //check rect to see if its zero
    if(realRect.equals(Rect::ZERO))
    {
        //if the instance doesn't have width and height, then the whole operation is kaput
        CCASSERT(_height && _width, "Please specify a width and height for this instance before using its functions");
        realRect = Rect(0,0, (float)_width, (float)_height);
    }
    else{
        //rect is specified, so convert to real rect
        realRect = CC_RECT_POINTS_TO_PIXELS(rect);
    }
    return realRect;
}

PolygonInfo AutoPolygon::generateTriangles(const Rect& rect, float epsilon, float threshold)
{
    Rect realRect = getRealRect(rect);
    auto p = trace(realRect, threshold);
    p = reduce(p, realRect, epsilon);
    p = expand(p, realRect, epsilon);
    auto tri = triangulate(p);
    calculateUV(realRect, tri.verts, tri.vertCount);
    PolygonInfo ret;
    ret.triangles = tri;
    ret.setFilename(_filename);
    ret.setRect(realRect);
    return ret;
}

PolygonInfo AutoPolygon::generatePolygon(const std::string& filename, const Rect& rect, float epsilon, float threshold)
{
    AutoPolygon ap(filename);
    return ap.generateTriangles(rect, epsilon, threshold);
}