ncollide_procedural 0.2.2

2 and 3-dimensional collision detection library in Rust: module for procedural generation of discrete geometric objects.
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use na;
use na::Pnt3;
use super::{TriMesh, IndexBuffer};
use super::{sphere, utils};
use math::Scalar;

/// Generates a capsule.
pub fn capsule<N>(caps_diameter:   &N,
                  cylinder_height: &N,
                  ntheta_subdiv:   u32,
                  nphi_subdiv:     u32)
                  -> TriMesh<Pnt3<N>>
    where N: Scalar {
    let top = sphere::unit_hemisphere::<N>(ntheta_subdiv, nphi_subdiv);
    let TriMesh { coords, normals, indices, .. } = top.clone();
    let mut bottom_coords  = coords;
    let mut bottom_normals = normals.unwrap();
    let mut bottom_indices = indices.unwrap_unified();
    utils::reverse_clockwising(&mut bottom_indices[..]);

    let TriMesh { coords, normals, indices, .. } = top;
    let mut top_coords  = coords;
    let top_normals     = normals.unwrap();
    let mut top_indices = indices.unwrap_unified();

    let half_height = *cylinder_height * na::cast(0.5);

    // shift the top
    for coord in top_coords.iter_mut() {
        coord.x = coord.x * *caps_diameter;
        coord.y = coord.y * *caps_diameter + half_height;
        coord.z = coord.z * *caps_diameter;
    }

    // flip + shift the bottom
    for coord in bottom_coords.iter_mut() {
        coord.x = coord.x * *caps_diameter;
        coord.y = -(coord.y * *caps_diameter) - half_height;
        coord.z = coord.z * *caps_diameter;
    }

    // flip the bottom normals
    for normal in bottom_normals.iter_mut() {
        normal.y = -normal.y;
    }

    // shift the top index buffer
    let base_top_coords = bottom_coords.len() as u32;

    for idx in top_indices.iter_mut() {
        idx.x = idx.x + base_top_coords;
        idx.y = idx.y + base_top_coords;
        idx.z = idx.z + base_top_coords;
    }

    // merge all buffers
    bottom_coords.extend(top_coords.into_iter());
    bottom_normals.extend(top_normals.into_iter());
    bottom_indices.extend(top_indices.into_iter());

    // attach the two caps
    utils::push_ring_indices(0, base_top_coords, ntheta_subdiv, &mut bottom_indices);

    // FIXME: uvs
    TriMesh::new(bottom_coords,
                   Some(bottom_normals),
                   None,
                   Some(IndexBuffer::Unified(bottom_indices)))
}