vtk-pure-rs 0.2.0

Pure Rust visualization toolkit — data structures, filters, I/O, rendering
Documentation 
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use crate::data::{Points, PolyData, DataSet};

/// Flatten a mesh onto the XY plane by discarding Z.
pub fn flatten_z(input: &PolyData) -> PolyData {
    let n = input.points.len();
    let mut points = Points::<f64>::new();
    for i in 0..n { let p = input.points.get(i); points.push([p[0], p[1], 0.0]); }
    let mut pd = input.clone();
    pd.points = points;
    pd
}

/// Project mesh onto a plane defined by normal through centroid.
pub fn project_to_plane(input: &PolyData, normal: [f64; 3]) -> PolyData {
    let n = input.points.len();
    if n == 0 { return input.clone(); }

    let nlen = (normal[0]*normal[0]+normal[1]*normal[1]+normal[2]*normal[2]).sqrt();
    if nlen < 1e-15 { return input.clone(); }
    let nn = [normal[0]/nlen, normal[1]/nlen, normal[2]/nlen];

    // Compute centroid
    let bb = input.bounds();
    let c = bb.center();

    let mut points = Points::<f64>::new();
    for i in 0..n {
        let p = input.points.get(i);
        let d = [p[0]-c[0], p[1]-c[1], p[2]-c[2]];
        let dist = d[0]*nn[0]+d[1]*nn[1]+d[2]*nn[2];
        points.push([p[0]-dist*nn[0], p[1]-dist*nn[1], p[2]-dist*nn[2]]);
    }

    let mut pd = input.clone();
    pd.points = points;
    pd
}

/// Scale Z coordinates by a factor (useful for terrain exaggeration).
pub fn scale_z(input: &PolyData, factor: f64) -> PolyData {
    let n = input.points.len();
    let mut points = Points::<f64>::new();
    for i in 0..n { let p = input.points.get(i); points.push([p[0], p[1], p[2]*factor]); }
    let mut pd = input.clone();
    pd.points = points;
    pd
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn flatten() {
        let mut pd = PolyData::new();
        pd.points.push([1.0, 2.0, 3.0]);
        pd.points.push([4.0, 5.0, 6.0]);
        let result = flatten_z(&pd);
        assert_eq!(result.points.get(0)[2], 0.0);
        assert_eq!(result.points.get(1)[2], 0.0);
    }

    #[test]
    fn project() {
        let mut pd = PolyData::new();
        pd.points.push([0.0, 0.0, 1.0]);
        pd.points.push([0.0, 0.0, -1.0]);
        let result = project_to_plane(&pd, [0.0, 0.0, 1.0]);
        // Both projected to z=0 plane through centroid
        let p0 = result.points.get(0);
        let p1 = result.points.get(1);
        assert!((p0[2] - p1[2]).abs() < 1e-10);
    }

    #[test]
    fn scale_z_test() {
        let mut pd = PolyData::new();
        pd.points.push([1.0, 2.0, 3.0]);
        let result = scale_z(&pd, 2.0);
        assert_eq!(result.points.get(0)[2], 6.0);
    }

    #[test]
    fn scale_z_zero() {
        let mut pd = PolyData::new();
        pd.points.push([1.0, 2.0, 3.0]);
        let result = scale_z(&pd, 0.0);
        assert_eq!(result.points.get(0)[2], 0.0);
    }

    #[test]
    fn empty_input() {
        let pd = PolyData::new();
        let _ = flatten_z(&pd);
        let _ = project_to_plane(&pd, [0.0,0.0,1.0]);
    }
}