make seperate struct for buffer

src/buffer.rs

@@ -0,0 +1,39 @@
+#[derive(Debug)]
+pub struct Buf {
+    pub width: usize,
+    pub height: usize,
+    pub buf: Vec<f32>,
+}
+
+impl Clone for Buf {
+    fn clone(&self) -> Buf {
+        Buf {
+            width: self.width,
+            height: self.height,
+            buf: self.buf.clone(),
+        }
+    }
+}
+
+impl Buf {
+    pub fn new(width: usize, height: usize, buf: Vec<f32>) -> Self {
+        Buf {
+            width,
+            height,
+            buf,
+        }
+    }
+
+    // Truncate x and y and return a corresponding index into the data slice.
+    fn index(&self, x: f32, y: f32) -> usize {
+        // x/y can come in negative, hence we shift them by width/height.
+        let i = (x + self.width as f32) as usize & (self.width - 1);
+        let j = (y + self.height as f32) as usize & (self.height - 1);
+        j * self.width + i
+    }
+
+    // Get the buffer value at a given position. The implementation effectively treats data as periodic, hence any finite position will produce a value.
+    pub fn get_buf(&self, x: f32, y: f32) -> f32 {
+        self.buf[self.index(x, y)]
+    }
+}