Only sample 3 points

Simplify code to only sample 3 points, since that is enough for
cicrcles and lines.

crates/fj-kernel/src/validate/mod.rs

@@ -75,11 +75,6 @@ pub struct ValidationConfig {
     /// that distance is less than the one defined in this field, can not be
     /// considered identical.
     pub identical_max_distance: Scalar,
-
-    /// How often to sample edges when checking if they coincide. This
-    /// represents the number of points we check on each Edge.
-    /// The higher this is the more precise our validation is, and the slower it is.
-    pub sample_count: usize,
 }
 
 impl Default for ValidationConfig {
@@ -92,9 +87,6 @@ impl Default for ValidationConfig {
             // false positives due to floating-point accuracy issues), we can
             // adjust it.
             identical_max_distance: Scalar::from_f64(5e-14),
-
-            // This value is completely arbitrary, but seems good enough for now.
-            sample_count: 16,
         }
     }
 }

crates/fj-kernel/src/validate/shell.rs

@@ -63,8 +63,12 @@ fn are_coincident(
         .distance_to(&sample(0.0, (&edge2, surface2)))
         > config.identical_max_distance;
 
-    for i in 0..config.sample_count {
-        let percent = i as f64 * (1.0 / config.sample_count as f64);
+    // Three samples (start, middle, end), are enough to detect weather lines
+    // and circles match. If we were to add more complicated curves, this might
+    // need to change.
+    let sample_count = 3;
+    for i in 0..sample_count {
+        let percent = i as f64 * (1.0 / sample_count as f64);
         let sample1 = sample(percent, (&edge1, surface1));
         let sample2 = sample(
             if flip { 1.0 - percent } else { percent },