dxf->writeHatch, but how ?

[bonsalty]

I havent found how to write a hatch into dxf

We have:
void DL_Dxf::writeHatch1 ( DL_WriterA & dw,
const DL_HatchData & data,
const DL_Attributes & attrib
)
where DL_HatchData (int hNumLoops, bool hSolid, double hScale, double hAngle, const string &hPattern)

First question: what shoud hPattern be and whats this hNumLoops all about?
Second question:

If I call :
void DL_Dxf::writeHatchLoop1 ( DL_WriterA & dw,
const DL_HatchLoopData & data
)
should I call the writeHatchEdge functions after this or before the writeHatchLoop?

Third question,why must I call writeHatch2 and how to use it ????

An example would be nice,since its impossible to decode it from the ribbonsofts class reference. Thank you!

[andrew]

The QCAD code has an example:

http://www.google.com/codesearch/p?hl=e ... writeHatch

[bonsalty]

Thanks I managed to use it. I inserted a single loop with 3 edges(a triangle ) and succeded to make a triangle with hatch.

But pattern name is still a mistery.
I tried "EARTH", "ANSI31",... default pattern names,but nothing happens. However I can see that names in autocad when I click on my hatchobject, but it doesnt change the hatch style?!
I tried rotate and scale property too,they doesnt work either. Its always a 45 degree hatch.The solid property works fine.

[wolfhergang]

Im having some troubles in writing a solid arc hatch, i wrote a single hatch, with a single loop with a single edge all of em with the same attributes and it just doesnt work, any advice?

[wolfhergang]

Anyone?

[andrew]

wolfhergang: Can you post your code or the exact example data?
I don't see how a hatch with one loop which contains one arc can form a closed, hatchable contour (unless the arc is in fact a full circle?).

[wolfhergang]

My code is this:

DxfExporter exportador("testingWriting.dxf");
exportador.addEntity(new DxfCircle(0,0,0,100,DL_Attributes()));
DL_Attributes generalAttrib = DL_Attributes("0",2,16776960, -1, "BYLAYER");
exportador.addEntity((new DxfHatch(1,true,1,0,"SOLID",generalAttrib)));
exportador.addEntity(new DxfHatchLoop(1,generalAttrib));
exportador.addEntity(new DxfHatchEdge(0,0,100,0,6.75,true,generalAttrib));

if(exportador.writeToDxfFile()){
std::cout<<"File wrote correctly"<<std::endl;
}else{
std::cout<<"Error at writing"<<std::endl;
}

in my implementation you "add" the entities to a container then you write the container to the file.
the entity constructors are basically the same as the DL_Entity ones, but mine store the attributes, thats it.

the arc is supposed to be a full circle from 0 to 6.74 degrees but it doesnt render.

pd: sorry about my english, if something doesnt make sense let me know and ill try to explain myself.

[wolfhergang]

Maybe im just confused about how im supposed to hatch things....

[andrew]

wolfhergang: this code does not look familiar to me. dxflib does not provide the classes named "DxfExporter", "DxfHatch", "DxfCircle", etc.

Here's a minimal but complete example that writes a DXF file with one hatch entity using dxflib 3.3.4:

#include "dl_dxf.h"
 
int main() {
    DL_Dxf dxf;
    DL_WriterA* dw = dxf.out("hatch.dxf", DL_Codes::AC1015);
 
    // section header:
    dxf.writeHeader(*dw);
    dw->sectionEnd();
 
    // section tables:
    { 
        dw->sectionTables();
 
        // VPORT:
        dxf.writeVPort(*dw);
 
        // LTYPE:
        dw->tableLinetypes(1);
        dxf.writeLinetype(*dw, DL_LinetypeData("CONTINUOUS", "Continuous", 0, 0, 0.0));
        dxf.writeLinetype(*dw, DL_LinetypeData("BYLAYER", "", 0, 0, 0.0));
        dxf.writeLinetype(*dw, DL_LinetypeData("BYBLOCK", "", 0, 0, 0.0));
        dw->tableEnd();
 
        // LAYER:
        dw->tableLayers(1);
        dxf.writeLayer(
            *dw,
            DL_LayerData("0", 0),
            DL_Attributes("", 2, 0, 100, "CONTINUOUS")
        );
        dw->tableEnd();
 
        // STYLE:
        dw->tableStyle(1);
        DL_StyleData style("Standard", 0, 0.0, 1.0, 0.0, 0, 2.5, "txt", "");
        style.bold = false;
        style.italic = false;
        dxf.writeStyle(*dw, style);
        dw->tableEnd();
 
        // VIEW:
        dxf.writeView(*dw);
 
        // UCS:
        dxf.writeUcs(*dw);
 
        // APPID:
        dw->tableAppid(1);
        dxf.writeAppid(*dw, "ACAD");
        dw->tableEnd();
 
        // DIMSTYLE:
        dxf.writeDimStyle(*dw, 2.5, 0.625, 0.625, 0.625, 2.5);
 
        // BLOCK_RECORD:
        dxf.writeBlockRecord(*dw);
        dw->tableEnd();
 
        dw->sectionEnd();
    }
 
    // BLOCK:
    dw->sectionBlocks();
    dxf.writeBlock(*dw, DL_BlockData("*Model_Space", 0, 0.0, 0.0, 0.0));
    dxf.writeEndBlock(*dw, "*Model_Space");
    dxf.writeBlock(*dw, DL_BlockData("*Paper_Space", 0, 0.0, 0.0, 0.0));
    dxf.writeEndBlock(*dw, "*Paper_Space");
    dxf.writeBlock(*dw, DL_BlockData("*Paper_Space0", 0, 0.0, 0.0, 0.0));
    dxf.writeEndBlock(*dw, "*Paper_Space0");
    dw->sectionEnd();
 
    // ENTITIES:
    dw->sectionEntities();
 
    DL_Attributes attributes("0", 2, 0, -1, "BYLAYER");
 
    // start hatch with one loop:
    DL_HatchData data(1, false, 100.0, 0.0, "ESCHER", 0.0, 0.0);
    dxf.writeHatch1(*dw, data, attributes);
 
    // start loop:
    DL_HatchLoopData lData(1);
    dxf.writeHatchLoop1(*dw, lData);
 
    // write edge:
    DL_HatchEdgeData eData(
        0.0,
        0.0,
        100.0,
        0.0,
        M_PI*2,
        true
    );
    dxf.writeHatchEdge(*dw, eData);
 
    // end loop:
    dxf.writeHatchLoop2(*dw, lData);
 
    // end hatch:
    dxf.writeHatch2(*dw, data, attributes);
 
    // end section ENTITIES:
    dw->sectionEnd();
    dxf.writeObjects(*dw, "MY_OBJECTS");
    dxf.writeObjectsEnd(*dw);
 
    dw->dxfEOF();
    dw->close();
    delete dw;
 
    return 0;
}

[wolfhergang]

My problem was that i was writing the hatch edge using degrees when im supposed to use radians.

DL_HatchEdgeData eData(0.0, 0.0, 100.0, 0.0, M_PI*2, true);

that single line solved my problem, than you very much Andrew.