Examples > Surfaces > Coons surface by three boundary contours

Coons surface by three boundary contours.

Let's create a Coons surface by three boundary contours - two splines and one arc.

The necessary requirment when creating the Coons surface is matching the end points of boundary contours.

This code creates the first spline:

SG_POINT tmpPnt;

SG_SPLINE* spl1 = SG_SPLINE::Create();

tmpPnt.x = -6.0; tmpPnt.y = 0.0; tmpPnt.z = -1.0;

spl1->AddKnot(tmpPnt,0);

tmpPnt.x = -5.0; tmpPnt.y = 0.0; tmpPnt.z = -2.0;

spl1->AddKnot(tmpPnt,1);

tmpPnt.x = -3.0; tmpPnt.y = 0.0; tmpPnt.z = -1.0;

spl1->AddKnot(tmpPnt,2);

tmpPnt.x = -2.0; tmpPnt.y = 0.0; tmpPnt.z = -2.0;

spl1->AddKnot(tmpPnt,3);

tmpPnt.x = -1.0; tmpPnt.y = 0.0; tmpPnt.z = 1.0;

spl1->AddKnot(tmpPnt,4);

tmpPnt.x =2.0; tmpPnt.y = 0.0; tmpPnt.z = 1.0;

spl1->AddKnot(tmpPnt,5);

tmpPnt.x =2.0; tmpPnt.y = 0.0; tmpPnt.z = 0.0;

spl1->AddKnot(tmpPnt,6);

tmpPnt.x =4.0; tmpPnt.y = 0.0; tmpPnt.z = 1.0;

spl1->AddKnot(tmpPnt,7);

sgCSpline* spl1_obj = sgCreateSpline(*spl1);

SG_SPLINE::Delete(spl1);

sgGetScene()->AttachObject(spl1_obj);

spl1_obj->SetAttribute(SG_OA_COLOR,0);

spl1_obj->SetAttribute(SG_OA_LINE_THICKNESS, 1);

This code creates the second spline:

SG_SPLINE* spl2 = SG_SPLINE::Create();

tmpPnt.x = -6.0; tmpPnt.y = 0.0; tmpPnt.z = -1.0;

spl2->AddKnot(tmpPnt,0);

tmpPnt.x = -6.0; tmpPnt.y = 0.5; tmpPnt.z = 0.0;

spl2->AddKnot(tmpPnt,1);

tmpPnt.x = -6.0; tmpPnt.y = 2.0; tmpPnt.z = -1.0;

spl2->AddKnot(tmpPnt,2);

tmpPnt.x = -6.0; tmpPnt.y = 3.0; tmpPnt.z = 1.0;

spl2->AddKnot(tmpPnt,3);

tmpPnt.x =-4.0; tmpPnt.y = 4.0; tmpPnt.z = 1.0;

spl2->AddKnot(tmpPnt,4);

sgCSpline* spl2_obj = sgCreateSpline(*spl2);

SG_SPLINE::Delete(spl2);

sgGetScene()->AttachObject(spl2_obj);

spl2_obj->SetAttribute(SG_OA_COLOR,50);

spl2_obj->SetAttribute(SG_OA_LINE_THICKNESS, 3);

This code creates the arc:

SG_POINT ArP1;

SG_POINT ArP2;

SG_POINT ArP3;

SG_ARC ArcGeo;

ArP1.x = -4.0; ArP1.y = 4.0; ArP1.z = 1.0;

ArP2.x = 4.0; ArP2.y = 0.0; ArP2.z = 1.0;

ArP3.x = 0.0; ArP3.y = 5.0; ArP3.z = -4.0;

ArcGeo.FromTreePoints(ArP1,ArP2,ArP3,false);

sgCArc* arcObj = sgCreateArc(ArcGeo);

Let's create the Coons surface itself:

sgCObject* coons = sgSurfaces::Coons((const sgC2DObject&)*spl1_obj,

(const sgC2DObject&)*spl2_obj,

(const sgC2DObject&)*arcObj,

NULL,36,36,4,4);

sgGetScene()->AttachObject(coons);

coons->SetAttribute(SG_OA_COLOR,4);

Then let's move the obtained surface:

SG_VECTOR transV1 = {0,0,-0.4};

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

coons->ApplyTempMatrix();

coons->DestroyTempMatrix();