1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155

extern crate byteorder;

use std::io::{Result, Write, ErrorKind, Error};
use byteorder::{ReadBytesExt, LittleEndian, WriteBytesExt};

pub struct Triangle {
    normal: [f32; 3],
    v1: [f32; 3],
    v2: [f32; 3],
    v3: [f32; 3],
    attr_byte_count: u16
}

fn point_eq(lhs: [f32; 3], rhs: [f32; 3]) -> bool {
    lhs[0] == rhs[0] && lhs[1] == rhs[1] && lhs[2] == rhs[2]
}

impl PartialEq for Triangle {
    fn eq(&self, rhs: &Triangle) -> bool {
        point_eq(self.normal, rhs.normal)
            && point_eq(self.v1, rhs.v1)
            && point_eq(self.v2, rhs.v2)
            && point_eq(self.v3, rhs.v3)
            && self.attr_byte_count == rhs.attr_byte_count
    }
}

impl Eq for Triangle {}

pub struct BinaryStlHeader {
    pub header: [u8; 80],
    pub num_triangles: u32
}

pub struct BinaryStlFile {
    pub header: BinaryStlHeader,
    pub triangles: Vec<Triangle>
}

fn read_point<T: ReadBytesExt>(input: &mut T) -> Result<[f32; 3]> {
    let x1 = try!(input.read_f32::<LittleEndian>());
    let x2 = try!(input.read_f32::<LittleEndian>());
    let x3 = try!(input.read_f32::<LittleEndian>());
    
    Ok([x1, x2, x3])
}

fn read_triangle<T: ReadBytesExt>(input: &mut T) -> Result<Triangle> {
    let normal = try!(read_point(input));
    let v1 = try!(read_point(input));
    let v2 = try!(read_point(input));
    let v3 = try!(read_point(input));
    let attr_count = try!(input.read_u16::<LittleEndian>());

    Ok(Triangle { normal: normal,
                  v1: v1, v2: v2, v3: v3,
                  attr_byte_count: attr_count })
}

fn read_header<T: ReadBytesExt>(input: &mut T) -> Result<BinaryStlHeader> {
    let mut header = [0u8; 80];

    match input.read(&mut header) {
        Ok(n) => if n == header.len() {
            ()
        }
        else {
            return Err(Error::new(ErrorKind::Other,
                                  "Couldn't read STL header"));
        },
        Err(e) => return Err(e)
    };

    let num_triangles = try!(input.read_u32::<LittleEndian>());

    Ok(BinaryStlHeader{ header: header, num_triangles: num_triangles })
}

pub fn read_stl<T: ReadBytesExt>(input: &mut T) -> Result<BinaryStlFile> {

    // read the header
    let header = try!(read_header(input));

    let mut triangles = Vec::new();
    for _ in 0 .. header.num_triangles {
        triangles.push(try!(read_triangle(input)));
    }

    Ok(BinaryStlFile {
        header: header,
        triangles: triangles
    })
}

fn write_point<T: WriteBytesExt>(out: &mut T, p: [f32; 3]) -> Result<()> {
    for x in p.iter() {
        try!(out.write_f32::<LittleEndian>(*x));
    }
    Ok(())
}

pub fn write_stl<T: WriteBytesExt>(out: &mut T,
                                   stl: &BinaryStlFile) -> Result<()> {
    assert!(stl.header.num_triangles as usize == stl.triangles.len());

    //write the header.
    try!(out.write(&stl.header.header));
    try!(out.write_u32::<LittleEndian>(stl.header.num_triangles));
    
    // write all the triangles
    for t in stl.triangles.iter() {
        try!(write_point(out, t.normal));
        try!(write_point(out, t.v1));
        try!(write_point(out, t.v2));
        try!(write_point(out, t.v3));
        try!(out.write_u16::<LittleEndian>(t.attr_byte_count));
    }

    Ok(())
}

#[cfg(test)]
mod test {
    use super::{BinaryStlFile, BinaryStlHeader, write_stl, read_stl, Triangle};
    use std::io::Cursor;
    #[test]
    fn write_read() {
        // Make sure we can write and read a simple file.
        let file = BinaryStlFile {
            header: BinaryStlHeader { header: [0u8; 80],
                                      num_triangles: 1 },
            triangles: vec![Triangle { normal: [0f32, 1f32, 0f32],
                                       v1: [0f32, 0f32, 0f32],
                                       v2: [0f32, 0f32, 1f32],
                                       v3: [1f32, 0f32, 1f32],
                                       attr_byte_count: 0 }]
        };

        let mut buffer = Vec::new();

        match write_stl(&mut buffer, &file) {
            Ok(_) => (),
            Err(_) => panic!()
        }

        match read_stl(&mut Cursor::new(buffer)) {
            Ok(stl) => {
                assert!(stl.header.num_triangles == file.header.num_triangles);
                assert!(stl.triangles.len() == 1);
                assert!(stl.triangles[0] == file.triangles[0])
            },
            Err(_) => panic!()
        }
    }
}