Examples > Surfaces > Spline surface from clips

Spline surface from clips.

Let's create a smooth surface from three clips - two splines, a line segment and an arc.

This code creates the clips:

SG_POINT tmpPnt;

SG_SPLINE* spl1 = SG_SPLINE::Create();

tmpPnt.x = 98.0; tmpPnt.y = 0.0; tmpPnt.z = -13.0;

spl1->AddKnot(tmpPnt,0);

tmpPnt.x = 85.0; tmpPnt.y = 0.0; tmpPnt.z = 19.0;

spl1->AddKnot(tmpPnt,1);

tmpPnt.x = 43.0; tmpPnt.y = 0.0; tmpPnt.z = -31.0;

spl1->AddKnot(tmpPnt,2);

tmpPnt.x = 5.0; tmpPnt.y = 0.0; tmpPnt.z = -3.0;

spl1->AddKnot(tmpPnt,3);

tmpPnt.x = -11.0; tmpPnt.y = 0.0; tmpPnt.z = -39.0;

spl1->AddKnot(tmpPnt,4);

tmpPnt.x =-48.0; tmpPnt.y = 0.0; tmpPnt.z = 23.0;

spl1->AddKnot(tmpPnt,5);

tmpPnt.x =-125.0; tmpPnt.y = 0.0; tmpPnt.z = 23.0;

spl1->AddKnot(tmpPnt,6);

sgCSpline* spl1_obj = sgCreateSpline(*spl1);

SG_SPLINE::Delete(spl1);

sgGetScene()->AttachObject(spl1_obj);

spl1_obj->SetAttribute(SG_OA_COLOR,12);

spl1_obj->SetAttribute(SG_OA_LINE_THICKNESS, 2);

SG_SPLINE* spl2 = SG_SPLINE::Create();

tmpPnt.x = 96.0; tmpPnt.y = 150.0; tmpPnt.z = 8.0;

spl2->AddKnot(tmpPnt,0);

tmpPnt.x = 66.0; tmpPnt.y = 150.0; tmpPnt.z = -20.0;

spl2->AddKnot(tmpPnt,1);

tmpPnt.x = 12.0; tmpPnt.y = 150.0; tmpPnt.z = 37.0;

spl2->AddKnot(tmpPnt,2);

tmpPnt.x = -128.0; tmpPnt.y = 150.0; tmpPnt.z = -23.0;

spl2->AddKnot(tmpPnt,3);

sgCSpline* spl2_obj = sgCreateSpline(*spl2);

SG_SPLINE::Delete(spl2);

sgGetScene()->AttachObject(spl2_obj);

spl2_obj->SetAttribute(SG_OA_COLOR,12);

spl2_obj->SetAttribute(SG_OA_LINE_THICKNESS, 2);

sgCLine* ln_obj = sgCreateLine(100.0,100.0,50.0, -121.0,100.0,-50.0);

sgGetScene()->AttachObject(ln_obj);

ln_obj->SetAttribute(SG_OA_COLOR,12);

ln_obj->SetAttribute(SG_OA_LINE_THICKNESS, 2);

SG_ARC arcG;

SG_POINT arcBeg = {98.0, 50.0 , -80.0};

SG_POINT arcEnd = {-117.0, 50.0 , -80.0};

SG_POINT arcMid = {-55.0, 50.0 , -50.0};

arcG.FromTreePoints(arcBeg,arcEnd,arcMid,false);

sgCArc* arc_obj = sgCreateArc(arcG);

sgGetScene()->AttachObject(arc_obj);

arc_obj->SetAttribute(SG_OA_COLOR,12);

arc_obj->SetAttribute(SG_OA_LINE_THICKNESS, 2);

Let's create the surface itself from these clips. As the clips are unclosed only contour orientations will be considered when constructing the surface - the contours had the same orientation by its construction. Let's specify the zero array as the array of parameters:

sgC2DObject* objcts[4];

objcts[0] = spl1_obj;

objcts[1] = arc_obj;

objcts[2] = ln_obj;

objcts[3] = spl2_obj;

double param[4];

param[0] = param[1] = param[2] = param[3] = 0.0;

sgCObject* surf = sgSurfaces::SplineSurfaceFromSections((const sgC2DObject**)(objcts),

param,4,false);

sgGetScene()->AttachObject(surf);

surf->SetAttribute(SG_OA_COLOR,24);

Then let's move the obtained surface:

SG_VECTOR transV1 = {0,0,-5};

surf->InitTempMatrix()->Translate(transV1);

surf->ApplyTempMatrix();

surf->DestroyTempMatrix();