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use i_bound::IBound;
use i_shape::{IShape, ShapeType};
use i_vicinity::IVicinity;

use bound::AxisAlignedBBox;
use mat::Mat3x1;

#[derive(Debug, Clone)]
pub struct Sphere {
    pub _ori: Mat3x1<f64>,
    pub _radius: f64,
    pub _bound: AxisAlignedBBox,
    pub _vicinity: f64,
}

impl Sphere {
    pub fn init(origin: &[f64], r: f64) -> Sphere {
        assert!(origin.len() == 3);
        Sphere {
            _ori: Mat3x1 {
                _val: [origin[0], origin[1], origin[2]],
            },
            _radius: r,
            _bound: AxisAlignedBBox::init(ShapeType::Sphere, &[&origin[0..3], &[r]].concat()),
            _vicinity: 0.000001f64,
        }
    }
}

impl IShape for Sphere {
    fn get_shape_data(&self) -> Vec<f64> {
        vec![self._ori[0], self._ori[1], self._ori[2], self._radius]
    }
    fn get_type(&self) -> ShapeType {
        ShapeType::Sphere
    }
    fn get_bound(&self) -> &dyn IBound {
        &self._bound
    }
    // this shall test for intersection of bounding shapes first before procedding to test intersection using algorithms of higher complexity
    fn get_intersect(&self, other: &dyn IShape) -> (bool, Option<Mat3x1<f64>>) {
        if !self.get_bound().intersect(other.get_bound()) {
            return (false, None);
        } else {
            match other.get_type() {
                ShapeType::Sphere => {
                    let other_shape_data = other.get_shape_data();
                    let b_off = Mat3x1 {
                        _val: [
                            other_shape_data[0],
                            other_shape_data[1],
                            other_shape_data[2],
                        ],
                    };
                    let a_r = self._radius;
                    let b_r = other_shape_data[3];

                    let a_off = self._ori;
                    let c = b_off.minus(&a_off).unwrap();
                    let d = c.magnitude().unwrap();
                    if d > b_r + a_r {
                        return (false, None);
                    } else {
                        //calculate a mid point average
                        let f = a_r / (a_r + b_r);
                        let g = c.scale(f).unwrap();
                        return (true, Some(a_off.plus(&g).unwrap()));
                    }
                }
                ShapeType::Ray => {
                    //see Ray3 for ray sphere intersection
                    return other.get_intersect(self);
                }
                ShapeType::Point => {
                    let other_shape_data = other.get_shape_data();
                    let b_off = Mat3x1 {
                        _val: [
                            other_shape_data[0],
                            other_shape_data[1],
                            other_shape_data[2],
                        ],
                    };
                    let d = b_off.minus(&self._ori).unwrap();
                    for i in 0..3 {
                        if d[i] > self._radius {
                            return (false, None);
                        }
                    }
                    return (true, Some(b_off));
                }
                ShapeType::Plane => {
                    let other_shape_data = other.get_shape_data();
                    let b_off = Mat3x1 {
                        _val: [
                            other_shape_data[0],
                            other_shape_data[1],
                            other_shape_data[2],
                        ],
                    };
                    let b_nor = Mat3x1 {
                        _val: [
                            other_shape_data[3],
                            other_shape_data[4],
                            other_shape_data[5],
                        ],
                    };
                    //x = -plane_normal * t + sphere_center
                    //dot( plane_normal, x ) = dot( plane_normal, plane_offset ) = k
                    //substitution:
                    //dot( plane_normal, -plane_normal * t + sphere_center ) = k
                    //-t + dot( plane_normal, sphere_center ) = k
                    //t = dot( plane_normal, sphere_center ) - k

                    let k = b_nor.dot(&b_off).unwrap();
                    let t = b_nor.dot(&self._ori).unwrap() - k;
                    if t > self._radius {
                        return (false, None);
                    } else {
                        return (
                            true,
                            Some(b_nor.scale(-t).unwrap().plus(&self._ori).unwrap()),
                        );
                    }
                }
                _ => {
                    unimplemented!();
                }
            }
        }
    }
    fn get_support(&self, v: &Mat3x1<f64>) -> Option<Mat3x1<f64>> {
        if v.magnitude() != Some(0f64) {
            let v_adjusted = v
                .normalize()
                .expect("normalization unsuccessful")
                .scale(self._radius)
                .expect("scale unsuccessful");
            let o = self
                ._ori
                .plus(&v_adjusted)
                .expect("support operation unsuccessful.");
            Some(o)
        } else {
            None
        }
    }
}

impl IVicinity<f64> for Sphere {
    fn set_vicinity(&mut self, epsilon: f64) {
        self._vicinity = epsilon.abs();
    }
    fn within_vicinity(&self, a: f64, b: f64) -> bool {
        if a + self._vicinity >= b && a - self._vicinity <= b {
            true
        } else {
            false
        }
    }
}