1 files changed, 47 insertions, 0 deletions
diff --git a/physics/src/constraint/slider.rs b/physics/src/constraint/slider.rs
new file mode 100644
index 0000000..fa7e840
--- /dev/null
+++ b/physics/src/constraint/slider.rs
@@ -0,0 +1,47 @@
+use nalgebra::{DVector, RowDVector};
+
+use crate::{
+    algebra::{subspace::Line, Point, Scalar, Vector, N},
+    particle_system::ParticleSystem,
+};
+
+use super::Constraint;
+
+pub struct SliderConstraint {
+    pub particle_id: usize,
+
+    pub line: Line,
+
+    jacobian: RowDVector<Scalar>,
+}
+
+impl ParticleSystem {
+    pub fn add_slider_constraint(&mut self, particle_id: usize, direction: Vector) {
+        let point = self.particles[particle_id].position;
+        self.constraints.push(Box::new(SliderConstraint {
+            particle_id,
+            line: Line::new(point, [direction]),
+            jacobian: RowDVector::zeros(self.particles.len() * N),
+        }));
+    }
+}
+
+impl Constraint for SliderConstraint {
+    fn get_particles(&self) -> Vec<usize> {
+        vec![self.particle_id]
+    }
+
+    fn c(&self, q: &DVector<Scalar>) -> Scalar {
+        let position = q.fixed_rows::<N>(self.particle_id * N);
+        let point = Point::from_coordinates(position.into());
+        self.line.distance(point)
+    }
+
+    fn set_jacobian(&mut self, jacobian: RowDVector<Scalar>) {
+        self.jacobian = jacobian
+    }
+
+    fn jacobian_prev(&self) -> RowDVector<Scalar> {
+        self.jacobian.clone()
+    }
+}