Line Strips

A line strip is a primitive that is composed of connected line segments. Your application can use line strips for creating polygons that are not closed. A closed polygon is a polygon whose last vertex is connected to its first vertex by a line segment. If your application makes polygons based on line strips, the vertices are not guaranteed to be coplanar.

You create a line strip by filling an array of vertices, as in the following code fragment:

const DWORD TOTAL_VERTS=6;
D3DVERTEX lpVerts[TOTAL_VERTS];
 
lpVerts[0] = D3DVERTEX(D3DVECTOR(-5,-5,0),D3DVECTOR(0,0,-1),0,0);
lpVerts[1] = D3DVERTEX(D3DVECTOR(0,5,0),D3DVECTOR(0,0,-1),0,0);
lpVerts[2] = D3DVERTEX(D3DVECTOR(5,-5,0),D3DVECTOR(0,0,-1),0,0);
lpVerts[3] = D3DVERTEX(D3DVECTOR(10,5,0),D3DVECTOR(0,0,-1),0,0);
lpVerts[4] = D3DVERTEX(D3DVECTOR(15,-5,0),D3DVECTOR(0,0,-1),0,0);
lpVerts[5] = D3DVERTEX(D3DVECTOR(20,5,0),D3DVECTOR(0,0,-1),0,0);
 

Render the line list using the IDirect3DDevice3::DrawPrimitive method. The following code fragment illustrates the use of IDirect3DDevice3::DrawPrimitive for drawing the line strip in the preceding example. Remember that all calls to IDirect3DDevice3::DrawPrimitive must occur between IDirect3DDevice3::BeginScene and IDirect3DDevice3::EndScene.

HRESULT hResult;
// This code fragment assumes that lpDirect3DDevice3 is a valid 
// pointer to an IDirect3DDevice3 interface.
hResult = 
    lpDirect3DDevice3 ->DrawPrimitive(D3DPT_LINESTRIP,
                                      D3DFVF_VERTEX,
                                      lpVerts,
                                      TOTAL_VERTS,
                                      D3DDP_WAIT); 
 

The following illustration shows the line strip that the previous code produces.