Small neighbor indices optimization

README.md

@@ -41,4 +41,22 @@ This might be a bit slow, alternatively, you can use `cargo run --release`.
 `backend-rust/download_data.sh` will download some data for the digital evelation model (DEM). Change `backend-rust/download_data.sh`
 according to your needs if you do not want to download all the data.
 
-There is also an older (and slower) python backend in the `backend` folder.
+There is also an older (and slower) python backend in the `backend` folder.
+
+## Performance testing
+
+You can run performance tests using
+```
+$ cargo bench
+```
+
+A flamegraph can be generated by adding the following to `Cargo.toml`:
+```
+[profile.release]
+#debug = 1
+```
+and then running
+```
+$ kernel.perf_event_paranoid = -1 #Only needed once to enable event counting for flamegraph
+$ cargo flamegraph --bench search_benchmark -- --bench
+```

backend-rust/src/pqueue.rs

@@ -86,6 +86,13 @@ impl<P, V, K, MapType: MapLike<K, usize>> PriorityQueue<P, V, K, MapType> {
             positions: map,
         }
     }
+
+    pub fn new_with_map_and_capacity(map: MapType, capacity: usize) -> Self {
+        Self {
+            heap: Vec::with_capacity(capacity),
+            positions: map,
+        }
+    }
 }
 
 impl<P: PartialOrd + Copy, V, K: Eq + Hash + Copy, MapType: MapLike<K, usize>>

backend-rust/src/search.rs

@@ -9,6 +9,7 @@ use ndarray::{linspace, s};
 
 use crate::{
     height_data::{get_height_at_point, get_height_data_around_point, HeightGrid},
+    line::Line,
     pqueue::{MapLike, PriorityQueue},
 };
 
@@ -245,18 +246,19 @@ impl SearchConfig {
 }
 
 pub fn get_neighbor_indices(ix: GridIx, height_grid: &HeightGrid) -> Vec<GridIx> {
-    let mut result = Vec::new();
-
-    let x = ix.0 as i32;
-    let y = ix.1 as i32;
-    for (a, b) in vec![(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)] {
-        if a >= 0
-            && a < (height_grid.heights.shape()[0]) as i32
-            && b >= 0
-            && b < (height_grid.heights.shape()[1]) as i32
-        {
-            result.push((a as GridIxType, b as GridIxType));
-        }
+    let mut result = Vec::with_capacity(4);
+
+    if ix.0 > 0 {
+        result.push((ix.0 - 1, ix.1));
+    }
+    if ix.1 > 0 {
+        result.push((ix.0, ix.1 - 1));
+    }
+    if ix.0 < (height_grid.heights.shape()[0] - 1) as GridIxType {
+        result.push((ix.0 + 1, ix.1));
+    }
+    if ix.1 < (height_grid.heights.shape()[1] - 1) as GridIxType {
+        result.push((ix.0, ix.1 + 1));
     }
 
     return result;
@@ -667,6 +669,47 @@ pub fn f32_usize(x: f32) -> usize {
     usize::from(x as u16)
 }
 
+pub fn is_line_intersecting_smart(to: &Node, ix: GridIx, config: &SearchConfig) -> bool {
+    let effective_glide = get_effective_glide_ratio_from_to(config, ix, to.ix);
+    if f32::is_infinite(effective_glide.glide_ratio) {
+        return true;
+    }
+
+    let length = l2_distance(to.ix, ix);
+
+    let grid_indices = Line::new((to.ix.0 as i16, to.ix.1 as i16), (ix.0 as i16, ix.1 as i16));
+
+    let distance = length * config.grid.cell_size;
+    let height_loss = distance * effective_glide.glide_ratio;
+    let final_height = to.height - height_loss;
+
+    let mut real_height = if grid_indices.iterator_reversed() {
+        final_height
+    } else {
+        to.height
+    };
+    let height_step = if grid_indices.iterator_reversed() {
+        height_loss / (grid_indices.num_pixels() - 1) as f32
+    } else {
+        -height_loss / (grid_indices.num_pixels() - 1) as f32
+    };
+
+    if config.safety_margin == 0.0 || to.distance + distance <= config.start_distance {
+        for (x_i, y_i) in grid_indices.iter() {
+            if real_height < config.grid.heights[(x_i as usize, y_i as usize)] as f32 {
+                return true;
+            }
+            real_height += height_step;
+        }
+    } else if to.distance < config.start_distance && to.distance + distance > config.start_distance
+    {
+        // TODO
+    } else {
+        // TODO
+    }
+    return false;
+}
+
 pub fn is_line_intersecting(to: &Node, ix: GridIx, config: &SearchConfig) -> bool {
     let effective_glide = get_effective_glide_ratio_from_to(config, ix, to.ix);
     if f32::is_infinite(effective_glide.glide_ratio) {
@@ -746,6 +789,7 @@ pub fn reindex(explored: Explored, grid: &HeightGrid) -> (Explored, HeightGrid)
     let mut lat_max = GridIxType::MIN;
     let mut lon_min = GridIxType::MAX;
     let mut lon_max = GridIxType::MIN;
+
     for node in explored.values.iter() {
         if node.is_some() {
             let n = node.as_ref().unwrap();