use gl;
use gl::types::*;

pub struct Framebuffer {
    gl_id: GLuint
}

impl Framebuffer {
    pub fn gl_id(&self) -> GLuint {
        self.gl_id
    }
}

impl Drop for Framebuffer {
    fn drop(&mut self) {
        unsafe {
            gl::DeleteFramebuffers(1, &self.gl_id as *const GLuint);
        }
    }
}

use gl::types::*;

pub struct Framebuffer {
    gl_id: GLuint
}

impl Framebuffer {
    pub fn gl_id(&self) -> GLuint {
        self.gl_id
    }
}

--- 
+++ 
@@ -1,3 +1,4 @@
+use gl;
 use gl::types::*;
 
 pub struct Framebuffer {
@@ -9,3 +10,11 @@
         self.gl_id
     }
 }
+
+impl Drop for Framebuffer {
+    fn drop(&mut self) {
+        unsafe {
+            gl::DeleteFramebuffers(1, &self.gl_id as *const GLuint);
+        }
+    }
+}
Add `Drop` impl for `Framebuffer`
