1 files changed, 38 insertions, 0 deletions
diff --git a/src/grid.rs b/src/grid.rs
new file mode 100644
index 0000000..1ec49a3
--- /dev/null
+++ b/src/grid.rs
@@ -0,0 +1,38 @@
+use crate::transform::Transform;
+use raylib::drawing::RaylibDraw;
+use raylib::ffi::Color;
+
+pub const LINE_COLOUR: Color = Color {
+    r: 255,
+    g: 255,
+    b: 255,
+    a: 75,
+};
+
+/// Draw an infinite grid that can be moved around on the screen and zoomed in and out of.
+pub fn draw_grid<D>(rld: &mut D, screen_width: i32, screen_height: i32, transform: &Transform)
+where
+    D: RaylibDraw,
+{
+    /* Calculate the actual screen offset of the grid, by modulo-ing the translation of the
+     * transform.
+     */
+    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;
+
+    // Draw the row lines.
+    let mut line_y: f32 = translation_y_px as f32;
+    while line_y <= screen_height as f32 {
+        rld.draw_line(0, line_y as i32, screen_width, line_y as i32, LINE_COLOUR);
+        line_y += transform.pixels_per_m();
+    }
+
+    // Draw the column lines.
+    let mut line_x: f32 = translation_x_px as f32;
+    while line_x <= screen_width as f32 {
+        rld.draw_line(line_x as i32, 0, line_x as i32, screen_height, LINE_COLOUR);
+        line_x += transform.pixels_per_m();
+    }
+}