forked from glen/dyna3
27 lines
981 B
Rust
27 lines
981 B
Rust
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use nalgebra::DVector;
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// the sphere with the given center and radius, with inward-pointing normals
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pub fn sphere(center_x: f64, center_y: f64, center_z: f64, radius: f64) -> DVector<f64> {
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let center_norm_sq = center_x * center_x + center_y * center_y + center_z * center_z;
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DVector::from_column_slice(&[
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center_x / radius,
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center_y / radius,
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center_z / radius,
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0.5 / radius,
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0.5 * (center_norm_sq / radius - radius)
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])
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}
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// the sphere of curvature `curv` whose closest point to the origin has position
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// `off * dir` and normal `dir`, where `dir` is a unit vector. setting the
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// curvature to zero gives a plane
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pub fn sphere_with_offset(dir_x: f64, dir_y: f64, dir_z: f64, off: f64, curv: f64) -> DVector<f64> {
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let norm_sp = 1.0 + off * curv;
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DVector::from_column_slice(&[
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norm_sp * dir_x,
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norm_sp * dir_y,
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norm_sp * dir_z,
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0.5 * curv,
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off * (1.0 + 0.5 * off * curv)
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])
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}
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