1 files changed, 27 insertions, 18 deletions

diff --git a/src/grid.rs b/src/grid.rs
index c885f19..ec27fa7 100644
--- a/src/grid.rs
+++ b/src/grid.rs
@@ -27,26 +27,35 @@ pub fn draw_grid<D>(rld: &mut D, screen_width: i32, screen_height: i32, transfor
 where
     D: RaylibDraw,
 {
-    /* Calculate the actual screen offset of the grid, by modulo-ing the translation of the
-     * transform.
+    /* Calculate the first whole meter that can be seen on the grid. This is the first meter that
+     * will be seen on screen.
      */
-    let translation_x_px: i32 =
-        transform.translation_px().x as i32 % transform.pixels_per_m() as i32;
-    let translation_y_px: i32 =
-        transform.translation_px().y as i32 % transform.pixels_per_m() as i32;
+    let mut first_cell = *transform.translation_px() / -transform.pixels_per_m();
+    first_cell.x = first_cell.x.floor();
+    first_cell.y = first_cell.y.floor();
 
-    // Draw the row lines. Add back the subpixels to the translation
-    let mut line_y: f64 = translation_y_px as f64
-        + (transform.translation_px().y - transform.translation_px().y as i32 as f64);
-    while line_y <= screen_height as f64 {
-        rld.draw_line(0, line_y as i32, screen_width, line_y as i32, LINE_COLOUR);
-        line_y += transform.pixels_per_m();
+    let mut cell = first_cell;
+    let mut draw_y = transform.point_m_to_px(&cell).y;
+    loop {
+        draw_y = math::round(draw_y, 1.);
+        rld.draw_line(0, draw_y as i32, screen_width, draw_y as i32, LINE_COLOUR);
+        cell.y += 1.;
+        draw_y = transform.point_m_to_px(&cell).y;
+
+        if draw_y as i32 > screen_height {
+            break;
+        }
     }
-    // Draw the column lines.
-    let mut line_x: f64 = translation_x_px as f64
-        + (transform.translation_px().x - transform.translation_px().x as i32 as f64);
-    while line_x <= screen_width as f64 {
-        rld.draw_line(line_x as i32, 0, line_x as i32, screen_height, LINE_COLOUR);
-        line_x += transform.pixels_per_m();
+
+    let mut draw_x = transform.point_m_to_px(&cell).x;
+    loop {
+        draw_x = math::round(draw_x, 1.);
+        rld.draw_line(draw_x as i32, 0, draw_x as i32, screen_height, LINE_COLOUR);
+        cell.x += 1.;
+        draw_x = transform.point_m_to_px(&cell).x;
+
+        if draw_x as i32 > screen_width {
+            break;
+        }
     }
 }