del-msh-cpu 0.1.46

mesh utility library for computer graphics research and prototyping
Documentation 
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//! polygon mesh in 2D
//! data structure `elem2idx_offset` and `idx2vtx`

pub fn elem2area(elem2idx_offset: &[usize], idx2vtx: &[usize], vtx2xy: &[f32]) -> Vec<f32> {
    let num_elem = elem2idx_offset.len() - 1;
    let mut areas: Vec<f32> = vec![0f32; num_elem];
    for i_elem in 0..num_elem {
        let num_vtx_in_elem = elem2idx_offset[i_elem + 1] - elem2idx_offset[i_elem];
        for i_edge in 0..num_vtx_in_elem {
            let i0_vtx = idx2vtx[elem2idx_offset[i_elem] + i_edge];
            let i1_vtx = idx2vtx[elem2idx_offset[i_elem] + (i_edge + 1) % num_vtx_in_elem];
            areas[i_elem] += 0.5f32 * vtx2xy[i0_vtx * 2] * vtx2xy[i1_vtx * 2 + 1];
            areas[i_elem] -= 0.5f32 * vtx2xy[i0_vtx * 2 + 1] * vtx2xy[i1_vtx * 2];
        }
    }
    areas
}