# Geometry: Create a geometry model

This tutorial shows how to create a `geometry model` with different parts and effects.

This tutorial creates two triangle parts and two polyline parts. All parts has color effects. The second triangle and the second polyline will have the halo effect applied.

Note

This tutorial expect the application to have a correctly configured cee::vis::View in place. See demo applications on how to set up a cee::vis::View in your application.

Create model

Create the model and add it to the view.

```    cee::PtrRef<cee::geo::GeometryModel> gcgeoModel = new cee::geo::GeometryModel();
```

Set vertices and indices

Create data arrays of vertices and indices for the triangle parts and polyline parts. The second triangle will use the same vertices and indices as the first, but apply a transformation. The two polyline parts will have separate vertices, but share the same array of indices. (They have the same connectivities, but different coordinates.)

```    // Triangle vertices and indices
std::vector<cee::Vec3d> triangleVertices;
triangleVertices.push_back(cee::Vec3d(0.0, 0.0, 2.0));
triangleVertices.push_back(cee::Vec3d(2.0, 0.0, 2.0));
triangleVertices.push_back(cee::Vec3d(1.0, 0.0, 3.0));
std::vector<unsigned int> triangleIndices = { 0, 1, 2 };

// First polyline vertices
std::vector<cee::Vec3d> firstPolylinesVertices;
firstPolylinesVertices.push_back(cee::Vec3d(0.0, 0.0,  0.0));
firstPolylinesVertices.push_back(cee::Vec3d(1.0, 0.0,  0.0));
firstPolylinesVertices.push_back(cee::Vec3d(1.5, 0.0,  1.0));
firstPolylinesVertices.push_back(cee::Vec3d(0.0, 0.0, -1.0));
firstPolylinesVertices.push_back(cee::Vec3d(1.0, 0.0, -1.0));
firstPolylinesVertices.push_back(cee::Vec3d(1.5, 0.0,  0.0));

// Second polyline vertices
std::vector<cee::Vec3d> secondPolylinesVertices;
secondPolylinesVertices.push_back(cee::Vec3d(2.0, 0.0,  0.0));
secondPolylinesVertices.push_back(cee::Vec3d(3.0, 0.0,  0.0));
secondPolylinesVertices.push_back(cee::Vec3d(3.5, 0.0,  1.0));
secondPolylinesVertices.push_back(cee::Vec3d(2.0, 0.0, -1.0));
secondPolylinesVertices.push_back(cee::Vec3d(3.0, 0.0, -1.0));
secondPolylinesVertices.push_back(cee::Vec3d(3.5, 0.0,  0.0));

// Polyline indices
std::vector<unsigned int> firstLineIndices = { 0, 1, 2 };
std::vector<unsigned int> secondLineIndices = { 3, 4, 5 };
std::vector<std::vector<unsigned int> > polylinesIndices;
polylinesIndices.push_back(firstLineIndices);
polylinesIndices.push_back(secondLineIndices);
```

Create part data and build parts

Create a `Data` for each of the triangles and polylines. The part data binds vertices and indices and can be used in one or more parts. We only create one part data for triangles, as this will be used for both triangle parts below.

The triangles will be `DataIndexedTriangles` objects, while the polylines will be `DataIndexedPolylines` objects.

```    // Create a triangle data part using the vertices and connectivities
cee::PtrRef<cee::geo::DataIndexedTriangles> triangleDataPart = new cee::geo::DataIndexedTriangles();
triangleDataPart->setVertices(triangleVertices);
triangleDataPart->setIndices(triangleIndices);

// Create first polyline data part using the vertices and connectivities
cee::PtrRef<cee::geo::DataIndexedPolylines> firstLinePartData = new cee::geo::DataIndexedPolylines();
firstLinePartData->setVertices(firstPolylinesVertices);
firstLinePartData->setPolylinesIndices(polylinesIndices);

// Create second polyline data part using the vertices and connectivities
cee::PtrRef<cee::geo::DataIndexedPolylines> secondLinePartData = new cee::geo::DataIndexedPolylines();
secondLinePartData->setVertices(secondPolylinesVertices);
secondLinePartData->setPolylinesIndices(polylinesIndices);
```

Build the parts using the corresponding data parts. Notice that both the triangles uses the same data part, but the second triangle has a transformation to move it to a separate position.

```    // First triangle
cee::PtrRef<cee::geo::Part> trianglePart = new cee::geo::Part();
trianglePart->setData(triangleDataPart.get());

// Second triangle (transformed)
cee::PtrRef<cee::geo::Part> transformedTrianglePart = new cee::geo::Part();
transformedTrianglePart->setData(triangleDataPart.get());
transformedTrianglePart->setTransformation(cee::Mat4d::fromTranslation(cee::Vec3d(3.0, 0.0, 0.0)));

// First polyline
cee::PtrRef<cee::geo::Part> firstLinePart = new cee::geo::Part();
firstLinePart->setData(firstLinePartData.get());

// Second polyline
cee::PtrRef<cee::geo::Part> secondLinePart = new cee::geo::Part();
secondLinePart->setData(secondLinePartData.get());
```

In this tutorial we will draw the triangles with the color red. The lines will be colored blue. The second triangle and the second polyline will get a halo effect. The halo effect draws a part with silhouetted edges.

Create the effects:

```    // Create a color effect
cee::PtrRef<cee::geo::EffectColor> triangleColorEffect = new cee::geo::EffectColor();
triangleColorEffect->setColor(cee::Color3f(1.0f, 0.0f, 0.0f));

// Create a color effect
cee::PtrRef<cee::geo::EffectColor> lineColorEffect = new cee::geo::EffectColor();
lineColorEffect->setColor(cee::Color3f(0.0, 0.0, 1.0));

// Create a halo effect
cee::PtrRef<cee::geo::EffectHalo> haloEffect = new cee::geo::EffectHalo();
```

Add the effects to the parts:

```    // First triangle has color effect

// Second triangle has color and a halo effect

// First polyline has line effect

// Second polyline has line and halo effect
```    gcgeoModel->addPart(trianglePart.get());