The information in this section pertains only to applications written in C and C++. See Direct3D Immediate Mode Visual Basic Tutorials.

To prepare the geometry for a cone, you only need to declare a position vector and a normal vector. Therefore, the cone object in the DrawPrims application is defined with the following programmer-defined structure:

struct MyFlexibleVertex
{
    D3DVECTOR vPosition;
    D3DVECTOR vNormal;
};

You define the tip of the cone with the following code fragment:

    g_pvCone[0].vPosition = D3DVECTOR( 0, CONE_HEIGHT/2, 0 );
    g_pvCone[0].vNormal   = Normalize( D3DVECTOR( 0, 1, 0 ) );

You compute each side of the cone with the following trigonometric functions:

    for( i=0; i<NUM_CONE_SIDES; i++ )
    {
        FLOAT x = (FLOAT)sin( 2*g_PI*i/(NUM_CONE_SIDES-1) );
        FLOAT y = -CONE_HEIGHT/2;
        FLOAT z = (FLOAT)cos( 2*g_PI*i/(NUM_CONE_SIDES-1) );
        g_pvCone[i+1].vPosition = CONE_RADIUS * D3DVECTOR( x, y, z );

You calculate the position vector of each side of the cone with the following code fragment:

    g_pvCone[i+1].vNormal   = Normalize( D3DVECTOR( x, 0.5f, z ) );
    }

After defining the wall segments and the cone in geometric space, you can move on to preparing the cube. This process is described in Step 1.3: Prepare the Cube.