[LIBART] Maybe a bug in art_rgb_svp_alpha or art_svp_union

[Rodolfo Schulz de Lima <rodsoft uol com br>]

Hi everyone, I have been using libart for 2 months (not so long, still a newbie) and I'm having some problems with the alpha blended rendering. The following code should render a 160x160 image as in figure 1, but unfortunately what is being rendered is in figure 2. I'll also attach the code to make it easy to know what I am trying to expect and, if you run the code, what I'm getting. What's the deal here? It's my fault? It's libart's?

 

Peace,

Rodolfo.

 

/* Code */

 

#include <vector>

#include <libart_lgpl\libart.h>

 

using namespace std;

 

struct FPoint

{

    FPoint(double X, double Y) : x(X), y(Y) {};

    FPoint() : x(0), y(0) {};

    double x,y;

};

 

void AddSeg(ArtSVP *&_pSVP, vector<FPoint> &vPoint, int iEsp)
{
    int iPoints=0, iPointsMax=50;
    ArtVpath *pVPath =  art_new(ArtVpath, iPointsMax);

 

    // Create ArtVpath from vector<FPoint>

    art_vpath_add_point(&pVPath, &iPoints, &iPointsMax, ART_MOVETO, vPoint[0].x, vPoint[0].y);
    for(int i=1; i<vPoint.size(); i++)
        art_vpath_add_point(&pVPath, &iPoints, &iPointsMax,ART_LINETO, vPoint[i].x, vPoint[i].y);
    art_vpath_add_point(&pVPath, &iPoints, &iPointsMax,ART_END, 0, 0);

 

    ArtSVP *pSVP = art_svp_vpath_stroke(pVPath,ART_PATH_STROKE_JOIN_ROUND,ART_PATH_STROKE_CAP_ROUND,iEsp,5,2);
    art_free(pVPath);

 

    if(_pSVP != NULL)
    {
        ArtSVP *pSVPaux = art_svp_union(pSVP,_pSVP);    // Maybe the bug is in art_svp_union
        art_free(_pSVP);
        art_free(pSVP);
        _pSVP = pSVPaux; 
    }
    else
        _pSVP = pSVP;
}

 

int void main()

{

    vector<vector<FPoint> > vvParte; 
    vvParte.push_back(vector<FPoint>()); 
    vvParte[0].push_back(FPoint(-8,135));
    vvParte[0].push_back(FPoint(78,136));

 

    vvParte.push_back(vector<FPoint>()); 
    vvParte[1].push_back(FPoint(78,136));

    vvParte[1].push_back(FPoint(78,81));

   

    vvParte.push_back(vector<FPoint>()); 
    vvParte[2].push_back(FPoint(78,136));
    vvParte[2].push_back(FPoint(82,136));
    vvParte[2].push_back(FPoint(159,135));

 

    vvParte.push_back(vector<FPoint>()); 
    vvParte[3].push_back(FPoint(78,196));
    vvParte[3].push_back(FPoint(78,136));

 

    ArtSVP *pSVP = NULL;

 

    for(int p=0; p<vvParte.size(); ++p)  
        AddSeg(pSVP,vvParte[p],11);

 

    unsigned char pBuffer[160][160];

    art_rgb_svp_alpha(pSVP,0,0,160,160,RGB(255,0,255),pBuffer, 160, NULL); // Maybe the bug is here

    // PS: when we change art_rgb_svp_alpha to art_rgb_svp_aa the output looks right

 

    // Render pBuffer on screen

    RenderBuffer(pBuffer);    // Operational system dependent function, make your own...

 

    return 0;

}

Attachment: figure_2.jpg
Description: JPEG image

Attachment: figure_1.jpg
Description: JPEG image