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extern crate tess2_sys;
extern crate itertools;
use tess2_sys::*;
use itertools::Itertools;
use std::mem;
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct Vertex {
pub x: f32,
pub y: f32,
}
#[derive(Debug, Clone, PartialEq, Default)]
pub struct Triangles {
pub vertices: Vec<Vertex>,
pub indices: Vec<u32>,
}
struct Tessellator {
tess: *mut TESStesselator,
}
enum Orientation {
Clockwise,
CounterClockwise,
}
impl Tessellator {
fn new() -> Self {
Self { tess: unsafe { tessNewTess(0 as *mut TESSalloc) } }
}
fn add_poly(&mut self, poly: &[Vertex], orientation: Orientation) -> Result<(), String> {
use std::os::raw::c_void;
if poly.len() < 3 {
return Err(String::from("A polygon must have at least 3 vertices."));
}
let format = |v: &Vertex| vec![v.x, v.y];
let formatted_vertices: Vec<f32> = match orientation {
Orientation::Clockwise => poly.iter().flat_map(format).collect(),
Orientation::CounterClockwise => poly.iter().rev().flat_map(format).collect(),
};
unsafe {
tessAddContour(self.tess,
2,
(&formatted_vertices[0] as *const f32) as *const c_void,
mem::size_of_val(&formatted_vertices[0]) as i32 * 2,
poly.len() as i32);
}
Ok(())
}
fn tessellate(&mut self, rule: TessWindingRule) -> Result<Triangles, String> {
unsafe {
use std::slice;
if tessTesselate(self.tess,
rule,
TessElementType::TESS_POLYGONS,
3,
2,
0 as *mut TESSreal) != 1 {
return Err(String::from("Triangulation failed."));
}
let raw_triangle_count = tessGetElementCount(self.tess);
if raw_triangle_count < 1 {
return Err(String::from("Triangulation failed to yield triangles."));
};
let triangle_count = raw_triangle_count as usize;
let vertex_buffer = slice::from_raw_parts(tessGetVertices(self.tess),
tessGetVertexCount(self.tess) as usize * 2);
let triangle_buffer = slice::from_raw_parts(tessGetElements(self.tess),
triangle_count * 3);
let xs = vertex_buffer.iter().step(2);
let ys = vertex_buffer.iter().skip(1).step(2);
let verts = xs.zip(ys);
Ok(Triangles {
vertices: verts.map(|(x, y)| Vertex { x: *x, y: *y }).collect(),
indices: triangle_buffer.iter().map(|i| *i as u32).collect(),
})
}
}
}
impl Drop for Tessellator {
fn drop(&mut self) {
unsafe { tessDeleteTess(self.tess) }
}
}
pub fn fill_union(polies: &[&[Vertex]]) -> Result<Triangles, String> {
let mut tess = Tessellator::new();
for poly in polies {
tess.add_poly(poly, Orientation::Clockwise)?;
}
tess.tessellate(TessWindingRule::TESS_WINDING_NONZERO)
}
pub fn fill_intersection(a: &[Vertex], b: &[Vertex]) -> Result<Triangles, String> {
let mut tess = Tessellator::new();
tess.add_poly(a, Orientation::Clockwise)?;
tess.add_poly(b, Orientation::Clockwise)?;
tess.tessellate(TessWindingRule::TESS_WINDING_ABS_GEQ_TWO)
}
pub fn fill_difference(base: &[Vertex], subtract: &[&[Vertex]]) -> Result<Triangles, String> {
let mut tess = Tessellator::new();
tess.add_poly(base, Orientation::Clockwise)?;
for sub in subtract {
tess.add_poly(sub, Orientation::CounterClockwise)?;
}
tess.tessellate(TessWindingRule::TESS_WINDING_POSITIVE)
}
pub fn fill(poly: &[Vertex]) -> Result<Triangles, String> {
fill_union(&[poly])
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn it_works() {
assert_eq!(fill(&[Vertex { x: 0.0, y: 0.0 },
Vertex { x: 1.0, y: 0.0 },
Vertex { x: 1.0, y: 1.0 },
Vertex { x: 0.0, y: 1.0 }])
.expect("triangulation"),
Triangles {
vertices: vec![Vertex { x: 0.0, y: 1.0 },
Vertex { x: 1.0, y: 0.0 },
Vertex { x: 1.0, y: 1.0 },
Vertex { x: 0.0, y: 0.0 }],
indices: vec![0, 1, 2, 1, 0, 3],
});
}
#[test]
fn intersection() {
assert_eq!(fill_intersection(&[Vertex { x: 0.0, y: 0.0 },
Vertex { x: 1.0, y: 0.0 },
Vertex { x: 1.0, y: 1.0 },
Vertex { x: 0.0, y: 1.0 }],
&[Vertex { x: 0.25, y: 0.25 },
Vertex { x: 0.75, y: 0.25 },
Vertex { x: 0.75, y: 0.75 },
Vertex { x: 0.25, y: 0.75 }])
.expect("triangulation"),
Triangles {
vertices: vec![Vertex { x: 0.25, y: 0.75 },
Vertex { x: 0.75, y: 0.25 },
Vertex { x: 0.75, y: 0.75 },
Vertex { x: 0.25, y: 0.25 }],
indices: vec![0, 1, 2, 1, 0, 3],
});
}
#[test]
fn union() {
assert_eq!(fill_union(&[&[Vertex { x: 0.0, y: 0.0 },
Vertex { x: 2.0, y: 4.0 },
Vertex { x: 4.0, y: 0.0 }],
&[Vertex { x: 0.5, y: 0.0 },
Vertex { x: 2.0, y: 2.0 },
Vertex { x: 3.5, y: 0.0 }]])
.expect("triangulation"),
Triangles {
vertices: vec![Vertex { x: 2.0, y: 2.0 },
Vertex { x: 4.0, y: 0.0 },
Vertex { x: 3.5, y: 0.0 },
Vertex { x: 2.0, y: 4.0 },
Vertex { x: 0.5, y: 0.0 },
Vertex { x: 0.0, y: 0.0 }],
indices: vec![0, 1, 2, 0, 3, 1, 4, 3, 0, 3, 4, 5, 2, 4, 0],
});
}
#[test]
fn difference() {
assert_eq!(fill_difference(&[Vertex { x: 0.0, y: 0.0 },
Vertex { x: 2.0, y: 4.0 },
Vertex { x: 4.0, y: 0.0 }],
&[&[Vertex { x: 0.5, y: 0.0 },
Vertex { x: 2.0, y: 2.0 },
Vertex { x: 3.5, y: 0.0 }]])
.expect("triangulation"),
Triangles {
vertices: vec![Vertex { x: 2.0, y: 2.0 },
Vertex { x: 4.0, y: 0.0 },
Vertex { x: 3.5, y: 0.0 },
Vertex { x: 2.0, y: 4.0 },
Vertex { x: 0.5, y: 0.0 },
Vertex { x: 0.0, y: 0.0 }],
indices: vec![0, 1, 2, 0, 3, 1, 4, 3, 0, 3, 4, 5],
});
}
}