Remap.h

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#ifndef REMAP_H_
#define REMAP_H_

template<typename Triple>
class TripleRemapXYZ
{
    public:
        static float& x (Triple& triple)
        {
            return triple.x();
        }
        static float& y (Triple& triple)
        {
            return triple.y();
        }
        static float& z (Triple& triple)
        {
            return triple.z();
        }
};

template<typename Triple>
class TripleRemapYZX
{
    public:
        static float& x (Triple& triple)
        {
            return triple.y();
        }
        static float& y (Triple& triple)
        {
            return triple.z();
        }
        static float& z (Triple& triple)
        {
            return triple.x();
        }
};

template<typename Triple>
class TripleRemapZXY
{
    public:
        static float& x (Triple& triple)
        {
            return triple.z();
        }
        static float& y (Triple& triple)
        {
            return triple.x();
        }
        static float& z (Triple& triple)
        {
            return triple.y();
        }
};

const float arrowhead_length = 16;
const float arrowhead_radius = 4;

inline void draw_arrowline (const float length, PointVertex* line, const std::size_t axis)
{
    (*line++).vertex = vertex3f_identity;
    (*line).vertex = vertex3f_identity;
    vertex3f_to_array((*line).vertex)[axis] = length - arrowhead_length;
}

template<typename VertexRemap, typename NormalRemap>
inline void draw_arrowhead (const std::size_t segments, const float length, FlatShadedVertex* vertices, VertexRemap,
        NormalRemap)
{
    std::size_t head_tris = (segments << 3);
    const double head_segment = c_2pi / head_tris;
    for (std::size_t i = 0; i < head_tris; ++i) {
        {
            FlatShadedVertex& point = vertices[i * 6 + 0];
            VertexRemap::x(point.vertex) = length - arrowhead_length;
            VertexRemap::y(point.vertex) = arrowhead_radius * static_cast<float> (cos(i * head_segment));
            VertexRemap::z(point.vertex) = arrowhead_radius * static_cast<float> (sin(i * head_segment));
            NormalRemap::x(point.normal) = arrowhead_radius / arrowhead_length;
            NormalRemap::y(point.normal) = static_cast<float> (cos(i * head_segment));
            NormalRemap::z(point.normal) = static_cast<float> (sin(i * head_segment));
        }
        {
            FlatShadedVertex& point = vertices[i * 6 + 1];
            VertexRemap::x(point.vertex) = length;
            VertexRemap::y(point.vertex) = 0;
            VertexRemap::z(point.vertex) = 0;
            NormalRemap::x(point.normal) = arrowhead_radius / arrowhead_length;
            NormalRemap::y(point.normal) = static_cast<float> (cos((i + 0.5) * head_segment));
            NormalRemap::z(point.normal) = static_cast<float> (sin((i + 0.5) * head_segment));
        }
        {
            FlatShadedVertex& point = vertices[i * 6 + 2];
            VertexRemap::x(point.vertex) = length - arrowhead_length;
            VertexRemap::y(point.vertex) = arrowhead_radius * static_cast<float> (cos((i + 1) * head_segment));
            VertexRemap::z(point.vertex) = arrowhead_radius * static_cast<float> (sin((i + 1) * head_segment));
            NormalRemap::x(point.normal) = arrowhead_radius / arrowhead_length;
            NormalRemap::y(point.normal) = static_cast<float> (cos((i + 1) * head_segment));
            NormalRemap::z(point.normal) = static_cast<float> (sin((i + 1) * head_segment));
        }

        {
            FlatShadedVertex& point = vertices[i * 6 + 3];
            VertexRemap::x(point.vertex) = length - arrowhead_length;
            VertexRemap::y(point.vertex) = 0;
            VertexRemap::z(point.vertex) = 0;
            NormalRemap::x(point.normal) = -1;
            NormalRemap::y(point.normal) = 0;
            NormalRemap::z(point.normal) = 0;
        }
        {
            FlatShadedVertex& point = vertices[i * 6 + 4];
            VertexRemap::x(point.vertex) = length - arrowhead_length;
            VertexRemap::y(point.vertex) = arrowhead_radius * static_cast<float> (cos(i * head_segment));
            VertexRemap::z(point.vertex) = arrowhead_radius * static_cast<float> (sin(i * head_segment));
            NormalRemap::x(point.normal) = -1;
            NormalRemap::y(point.normal) = 0;
            NormalRemap::z(point.normal) = 0;
        }
        {
            FlatShadedVertex& point = vertices[i * 6 + 5];
            VertexRemap::x(point.vertex) = length - arrowhead_length;
            VertexRemap::y(point.vertex) = arrowhead_radius * static_cast<float> (cos((i + 1) * head_segment));
            VertexRemap::z(point.vertex) = arrowhead_radius * static_cast<float> (sin((i + 1) * head_segment));
            NormalRemap::x(point.normal) = -1;
            NormalRemap::y(point.normal) = 0;
            NormalRemap::z(point.normal) = 0;
        }
    }
}

#endif /*REMAP_H_*/