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#include "primitive/Torus.h"

namespace cc {
IGeometry torus(float radius, float tube, const ccstd::optional<ITorusOptions> &opts) {
    const uint32_t radialSegments = opts.has_value() ? opts->radialSegments : 32;
    const uint32_t tubularSegments = opts.has_value() ? opts->tubularSegments : 32;
    const float arc = opts.has_value() ? opts->arc : math::PI_2;

    ccstd::vector<float> positions;
    ccstd::vector<float> normals;
    ccstd::vector<float> uvs;
    ccstd::vector<uint32_t> indices;
    const Vec3 minPos(-radius - tube, -tube, -radius - tube);
    const Vec3 maxPos(radius + tube, tube, radius + tube);
    const float boundingRadius = radius + tube;

    for (uint32_t j = 0; j <= radialSegments; j++) {
        for (uint32_t i = 0; i <= tubularSegments; i++) {
            const float u = static_cast<float>(i) / static_cast<float>(tubularSegments);
            const float v = static_cast<float>(j) / static_cast<float>(radialSegments);

            const float u1 = u * arc;
            const float v1 = v * math::PI_2;

            // vertex
            const float x = (radius + tube * cos(v1)) * sin(u1);
            const float y = tube * sin(v1);
            const float z = (radius + tube * cos(v1)) * cos(u1);

            // this vector is used to calculate the normal
            const float nx = sin(u1) * cos(v1);
            const float ny = sin(v1);
            const float nz = cos(u1) * cos(v1);

            positions.emplace_back(x);
            positions.emplace_back(y);
            positions.emplace_back(z);
            normals.emplace_back(nx);
            normals.emplace_back(ny);
            normals.emplace_back(nz);

            uvs.emplace_back(u);
            uvs.emplace_back(v);

            if ((i < tubularSegments) && (j < radialSegments)) {
                const uint32_t seg1 = tubularSegments + 1;
                const uint32_t a = seg1 * j + i;
                const uint32_t b = seg1 * (j + 1) + i;
                const uint32_t c = seg1 * (j + 1) + i + 1;
                const uint32_t d = seg1 * j + i + 1;

                indices.emplace_back(a);
                indices.emplace_back(d);
                indices.emplace_back(b);

                indices.emplace_back(d);
                indices.emplace_back(c);
                indices.emplace_back(b);
            }
        }
    }

    IGeometry info;
    info.positions = positions;
    info.normals = normals;
    info.uvs = uvs;
    info.boundingRadius = boundingRadius;
    info.minPos = minPos;
    info.maxPos = maxPos;
    info.indices = indices;
    return info;
}

} // namespace cc