diff --git a/src/camera.rs b/src/camera.rs
index 6231c32..f54d38e 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -12,6 +12,22 @@ impl Camera {
         let image_height = ((image_width as f32 / aspect_ratio) as i32).max(1);
         let viewport_width = viewport_height * (image_width as f32 / image_height as f32);
 
+        let viewport_u = Vec3::new(viewport_width, 0.0, 0.0);
+        // image x--> right
+        //       |
+        //       y
+        // space: y up , x right , z back, -z front
+        let viewport_v = Vec3::new(0.0, -viewport_height, 0.0);
+        // width per pix
+        let viewport_u_delta = viewport_u / (image_width as f32);
+        // height per pix
+        let viewport_v_delta = viewport_v / (image_height as f32);
+        let viewport_top_left_pixel =
+            camera_center + focal_length - viewport_u / 2.0 - viewport_v / 2.0;
+        // padding 0.5* delta u/v
+        let viewport_top_left_pixel_center =
+            viewport_top_left_pixel - viewport_u_delta / 2.0 - viewport_v_delta / 2.0;
+
         Camera {
             image_width,
             image_height,
@@ -20,26 +36,15 @@ impl Camera {
             viewport_height,
             camera_center,
             focal_length,
+            viewport_u,
+            viewport_v,
+            viewport_u_delta,
+            viewport_v_delta,
+            viewport_top_left_pixel_center,
         }
     }
 
     pub fn render(&self, world: &HittableList) -> String {
-        let viewport_u = Vec3::new(self.viewport_width, 0.0, 0.0);
-        // image x--> right
-        //       |
-        //       y
-        // space: y up , x right , z back, -z front
-        let viewport_v = Vec3::new(0.0, -self.viewport_height, 0.0);
-        // width per pix
-        let viewport_u_delta = viewport_u / (self.image_width as f32);
-        // height per pix
-        let viewport_v_delta = viewport_v / (self.image_height as f32);
-        let viewport_top_left_pixel =
-            self.camera_center + self.focal_length - viewport_u / 2.0 - viewport_v / 2.0;
-        // padding 0.5* delta u/v
-        let viewport_top_left_pixel_center =
-            viewport_top_left_pixel - viewport_u_delta / 2.0 - viewport_v_delta / 2.0;
-
         let mut img_content = format!("P3\n{} {}\n255\n", self.image_width, self.image_height);
 
         for j in 0..self.image_height {
@@ -49,9 +54,9 @@ impl Camera {
 
             for i in 0..self.image_width {
                 // every pixcel's position
-                let pixel_center = viewport_top_left_pixel_center
-                    + (i as f32 * viewport_u_delta)
-                    + (j as f32 * viewport_v_delta);
+                let pixel_center = self.viewport_top_left_pixel_center
+                    + (i as f32 * self.viewport_u_delta)
+                    + (j as f32 * self.viewport_v_delta);
                 // Vector(camera, pixcel)
                 let ray_direction = pixel_center - self.camera_center;
                 // ray
diff --git a/src/types_defined.rs b/src/types_defined.rs
index 0235af5..a4ee75b 100644
--- a/src/types_defined.rs
+++ b/src/types_defined.rs
@@ -36,6 +36,11 @@ pub struct Camera {
     pub viewport_height: f32,
     pub camera_center: Point,
     pub focal_length: Vec3,
+    pub viewport_u: Vec3,
+    pub viewport_v: Vec3,
+    pub viewport_u_delta: Vec3,
+    pub viewport_v_delta: Vec3,
+    pub viewport_top_left_pixel_center: Vec3,
 }
 
 /*