Use floor for coordinate transformation (#229)

This solves artifacts from asymmetric rounding around zero. See t-rex-tileserver/t-rex#319
georust · Aug 23, 2024 · 2e4476d · 2e4476d
1 parent 9645970
commit 2e4476d
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/geozero/src/mvt/mvt_writer.rs b/geozero/src/mvt/mvt_writer.rs
@@ -74,8 +74,8 @@ impl GeomProcessor for MvtWriter {
         if !last_ring_coord {
             let (x, y) = if self.extent != 0 {
                 // scale to tile coordinate space
-                let x = ((x_coord - self.left) * self.x_multiplier) as i32;
-                let y = ((y_coord - self.bottom) * self.y_multiplier) as i32;
+                let x = ((x_coord - self.left) * self.x_multiplier).floor() as i32;
+                let y = ((y_coord - self.bottom) * self.y_multiplier).floor() as i32;
                 // Y is stored as reversed
                 (x, self.extent.saturating_sub(y))
             } else {