Function MakeConeGeometry

SampleFramework12/v1.00/Graphics/Model.cpp:913–972

}

void MakeConeGeometry(uint64 divisions, StructuredBuffer& vtxBuffer, FormattedBuffer& idxBuffer, Array<Float3>& positions)
{
    Assert_(divisions >= 3);

    const uint64 numVertices = 2 + divisions;
    const uint64 numIndices = 3 * divisions * 2;
    Assert_(numVertices <= UINT16_MAX);

    positions.Init(numVertices);
    Array<uint16> indices(numIndices, 0);

    // The tip
    uint16 tipIdx = 0;
    positions[0] = Float3(0.0f, 0.0f, 0.0f);

    // The center of the base
    uint16 centerIdx = 1;
    positions[1] =  Float3(0.0f, 0.0f, 1.0f);

    // The ring at the base
    uint16 ringStartIdx = 2;
    for(uint64 i = 0; i < divisions; ++i)
    {
        const float theta = (float(i) / divisions) * Pi2;
        positions[i + ringStartIdx] = Float3(std::cos(theta), std::sin(theta), 1.0f);
    }

    // Tip->ring triangles
    uint64 currIdx = 0;
    for(uint64 i = 0; i < divisions; ++i)
    {
        indices[currIdx++] = tipIdx;
        indices[currIdx++] = uint16(ringStartIdx + i);

        uint64 prevRingIdx = i == 0 ? divisions - 1 : i - 1;
        indices[currIdx++] = uint16(ringStartIdx + prevRingIdx);
    }

    // Ring->center triangles
    for(uint64 i = 0; i < divisions; ++i)
    {
        indices[currIdx++] = uint16(ringStartIdx + i);
        indices[currIdx++] = centerIdx;

        uint64 prevRingIdx = i == 0 ? divisions - 1 : i - 1;
        indices[currIdx++] = uint16(ringStartIdx + prevRingIdx);
    }

    StructuredBufferInit vbInit;
    vbInit.Stride = sizeof(Float3);
    vbInit.NumElements = numVertices;
    vbInit.InitData = positions.Data();
    vtxBuffer.Initialize(vbInit);

    FormattedBufferInit ibInit;
    ibInit.Format = DXGI_FORMAT_R16_UINT;
    ibInit.NumElements = numIndices;
    ibInit.InitData = indices.Data();