1 files changed, 58 insertions, 0 deletions
diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..695baf5
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,58 @@
+use crate::{
+    config::{PIXEL_BUFFER_HEIGHT, PIXEL_BUFFER_WIDTH},
+    sim::{board::Board, materials::MATERIALS},
+};
+
+pub struct CameraState {
+    // centre coords
+    pub x: f64,
+    pub y: f64,
+    // zoom scale factor, 1.0 = board <-> frame
+    pub zoom: f64,
+}
+
+pub fn screen_position_to_board(
+    board: &Board,
+    camera: &CameraState,
+    screen_x: f64,
+    screen_y: f64,
+) -> (f64, f64) {
+    let camera_width = camera.zoom * f64::from(board.size_x);
+    let camera_height = camera.zoom * f64::from(board.size_y);
+    let camera_start_x = camera.x - camera_width / 2.0;
+    let camera_start_y = camera.y - camera_height / 2.0;
+    (
+        (screen_x / PIXEL_BUFFER_WIDTH as f64 * camera_width) + camera_start_x,
+        (screen_y / PIXEL_BUFFER_HEIGHT as f64 * camera_height) + camera_start_y,
+    )
+}
+
+pub fn write_frame_view(
+    frame: &mut [u8],
+    board: &Board,
+    camera: &CameraState,
+    get_overlay: impl Fn(i32, i32) -> (u8, u8, u8, u8),
+) {
+    for frame_y in 0..PIXEL_BUFFER_HEIGHT {
+        for frame_x in 0..PIXEL_BUFFER_WIDTH {
+            let (x_coord, y_coord) =
+                screen_position_to_board(board, camera, frame_x as f64, frame_y as f64);
+
+            let cell = board.cell_at_position(x_coord as i32, y_coord as i32);
+            let cell_color: Option<(u8, u8, u8, u8)> = cell.map(|c| {
+                let m = MATERIALS[c.material as usize];
+                (m.r, m.g, m.b, 0xFF)
+            });
+            let off_grid_color: (u8, u8, u8, u8) = (0x00, 0x00, 0x00, 0xFF);
+
+            let target_color: (u8, u8, u8, u8) = cell_color.unwrap_or(off_grid_color);
+            let overlay = get_overlay(x_coord as i32, y_coord as i32);
+
+            let frame_idx = ((frame_y * PIXEL_BUFFER_WIDTH + frame_x) * 4) as usize;
+            frame[frame_idx] = target_color.0.saturating_add(overlay.0);
+            frame[frame_idx + 1] = target_color.1.saturating_add(overlay.1);
+            frame[frame_idx + 2] = target_color.2.saturating_add(overlay.2);
+            frame[frame_idx + 3] = target_color.3.saturating_add(overlay.3);
+        }
+    }
+}