texture freeing + render updates done a bit nicer

src/util/mod.rs

@@ -1,5 +1,8 @@
 mod id;
 mod math;
+mod refcount;
 
 pub use id::*;
 pub use math::*;
+pub use refcount::*;
+

src/util/refcount.rs

@@ -0,0 +1,27 @@
+use std::sync::{
+    Arc,
+    atomic::{AtomicU32, Ordering},
+    mpsc::Sender,
+};
+
+pub struct RefCounter(Arc<AtomicU32>);
+
+impl RefCounter {
+    pub fn new() -> Self {
+        Self(Arc::new(0.into()))
+    }
+    pub fn refs(&self) -> u32 {
+        self.0.load(Ordering::Acquire)
+    }
+    pub fn drop(&mut self) -> bool {
+        let refs = self.0.fetch_sub(1, Ordering::Release);
+        refs == 0
+    }
+}
+
+impl Clone for RefCounter {
+    fn clone(&self) -> Self {
+        self.0.fetch_add(1, Ordering::Release);
+        Self(self.0.clone())
+    }
+}