Make grid "infinite"

1 files changed, 63 insertions, 0 deletions

diff --git a/src/infinite_grid.rs b/src/infinite_grid.rs
new file mode 100644
index 0000000..163c2b2
--- /dev/null
+++ b/src/infinite_grid.rs
@@ -0,0 +1,63 @@
+//! Grid that can be moved and scaled, and which gives the appearance of being infinite, while
+//! staying easily renderable.
+
+use crate::transform::Transform;
+use piston_window::grid::Grid;
+use piston_window::line::{Line, Shape};
+use piston_window::{Context, Graphics, Size, Transformed};
+
+/// The line used to draw the grids lines
+const GRID_LINE: Line = Line {
+    color: [1., 1., 1., 0.3],
+    radius: 1.2,
+    shape: Shape::Square,
+};
+
+pub struct InfiniteGrid(Grid);
+
+impl InfiniteGrid {
+    pub fn new(transform: &Transform, draw_size: Size) -> InfiniteGrid {
+        /* Create a grid with two extra columns and rows per draw_size, so when the user moves the
+         * grid up and down they can be seen, before the grid position is reset to create the
+         * infinitness illusion.
+         * The +3 instead of the +2 is necessary, since the amount needed may be underestimated
+         * because of rounding errors (I think)
+         */
+        InfiniteGrid(Grid {
+            cols: (draw_size.width / transform.pixels_per_m()) as u32 + 3,
+            rows: (draw_size.height / transform.pixels_per_m()) as u32 + 3,
+            units: transform.pixels_per_m(),
+        })
+    }
+
+    // TODO: Yes, this is ugly af
+    pub fn on_scale_change(&mut self, transform: &Transform, draw_size: Size) {
+        self.0.cols = (draw_size.width / transform.pixels_per_m()) as u32 + 3;
+        self.0.rows = (draw_size.height / transform.pixels_per_m()) as u32 + 3;
+        self.0.units = transform.pixels_per_m()
+    }
+
+    pub fn draw<G>(&self, map_trans: &Transform, context: &Context, g: &mut G)
+    where
+        G: Graphics,
+    {
+        /* Since mouse movement is actually always provided as whole pixels, this is fine.
+         * the - cell_size (i.e. pixels_per_m) is provided, so that the grid is centered in the
+         * screen,and not at position 0.x, 0.x, which would mean there would be no row at the top
+         * and/or no column to the left.
+         */
+        let actual_trans_px = [
+            (map_trans.translation_px()[0] as i64 % self.0.units as i64) as f64
+                - map_trans.pixels_per_m(),
+            (map_trans.translation_px()[1] as i64 % self.0.units as i64) as f64
+                - map_trans.pixels_per_m(),
+        ];
+
+        self.0.draw(
+            &GRID_LINE,
+            &context.draw_state,
+            context.trans_pos(actual_trans_px).transform,
+            g,
+        );
+    }
+}