cone.h

/*****************************************************************************
 * VCLib                                                                     *
 * Visual Computing Library                                                  *
 *                                                                           *
 * Copyright(C) 2021-2025                                                    *
 * Visual Computing Lab                                                      *
 * ISTI - Italian National Research Council                                  *
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 * All rights reserved.                                                      *
 *                                                                           *
 * This program is free software; you can redistribute it and/or modify      *
 * it under the terms of the Mozilla Public License Version 2.0 as published *
 * by the Mozilla Foundation; either version 2 of the License, or            *
 * (at your option) any later version.                                       *
 *                                                                           *
 * This program is distributed in the hope that it will be useful,           *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the              *
 * Mozilla Public License Version 2.0                                        *
 * (https://www.mozilla.org/en-US/MPL/2.0/) for more details.                *
 ****************************************************************************/
 
#ifndef VCL_ALGORITHMS_MESH_CREATE_CONE_H
#define VCL_ALGORITHMS_MESH_CREATE_CONE_H
 
#include <vclib/mesh.h>
 
namespace vcl {
 
template<FaceMeshConcept MeshType>
MeshType createCone(
    auto       radiusBottom,
    auto       radiusTop,
    auto       height,
    const uint subdivisions = 36)
{
    using PositionType = MeshType::VertexType::PositionType;
    using ScalarType   = PositionType::ScalarType;
 
    uint vn, fn;
    if (radiusBottom == 0 || radiusTop == 0) {
        vn = subdivisions + 2;
        fn = subdivisions * 2;
    }
    else {
        vn = subdivisions * 2 + 2;
        fn = subdivisions * 4;
    }
 
    MeshType mesh;
 
    mesh.reserveVertices(vn);
    mesh.reserveFaces(fn);
 
    mesh.addVertex(PositionType(0, -height / 2.0, 0));
    mesh.addVertex(PositionType(0, height / 2.0, 0));
 
    uint b1 = 2;
    uint b2 = 2;
 
    if (radiusBottom != 0) {
        for (uint i = 0; i < subdivisions; ++i) {
            ScalarType a = toRad(i * 360.0 / subdivisions);
            mesh.addVertex(PositionType(
                radiusBottom * std::cos(a),
                -height / 2.0,
                radiusBottom * std::sin(a)));
        }
 
        b2 += subdivisions;
    }
 
    if (radiusTop != 0) {
        for (uint i = 0; i < subdivisions; ++i) {
            ScalarType a = toRad(i * 360.0 / subdivisions);
            mesh.addVertex(PositionType(
                radiusTop * std::cos(a),
                height / 2.0,
                radiusTop * std::sin(a)));
        }
    }
 
    if (radiusBottom != 0) {
        for (uint i = 0; i < subdivisions; ++i) {
            mesh.addFace(0, b1 + i, b1 + (i + 1) % subdivisions);
        }
    }
    else {
        for (uint i = 0; i < subdivisions; ++i) {
            mesh.addFace(0, b2 + i, b2 + (i + 1) % subdivisions);
        }
    }
 
    if (radiusTop != 0) {
        for (uint i = 0; i < subdivisions; ++i) {
            mesh.addFace(1, b2 + (i + 1) % subdivisions, b2 + i);
        }
    }
    else {
        for (uint i = 0; i < subdivisions; ++i) {
            mesh.addFace(1, b1 + (i + 1) % subdivisions, b1 + i);
        }
    }
 
    // side triangles
    if (radiusBottom != 0 && radiusTop != 0) {
        for (uint i = 0; i < subdivisions; ++i) {
            mesh.addFace(b1 + i, b2 + i, b2 + (i + 1) % subdivisions);
            mesh.addFace(
                b1 + i,
                b2 + (i + 1) % subdivisions,
                b1 + (i + 1) % subdivisions);
        }
    }
 
    return mesh;
}
 
template<FaceMeshConcept MeshType>
MeshType createCylinder(auto radius, auto height, const uint subdivisions = 36)
{
    return createCone<MeshType>(radius, radius, height, subdivisions);
}
 
} // namespace vcl
 
#endif // VCL_ALGORITHMS_MESH_CREATE_CONE_H