camera: implement builder pattern on Camera and add it to prelude.

rtchallenge/src/camera.rs

@@ -7,6 +7,7 @@ use std::{
     thread,
 };
 
+use derive_builder::Builder;
 use rand::Rng;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use serde::Deserialize;
@@ -42,21 +43,68 @@ impl FromStr for RenderStrategy {
     }
 }
 
-#[derive(Clone, Default)]
+#[derive(Builder, Clone, Debug, Default)]
+#[builder(setter(skip), build_fn(skip))]
 pub struct Camera {
+    #[builder(setter(skip = "false"))]
     hsize: usize,
+    #[builder(setter(skip = "false"))]
     vsize: usize,
+    #[builder(setter(skip = "false"))]
     field_of_view: Float,
+    #[builder(setter(skip = "false"))]
     transform: Matrix4x4,
     inverse_transform: Matrix4x4,
     pixel_size: Float,
     half_width: Float,
     half_height: Float,
+    #[builder(setter(skip = "false"))]
     pub render_strategy: RenderStrategy,
     /// 0 renders from the center of the pixel, 1 or higher is random sampling of the pixel.
+    #[builder(setter(skip = "false"))]
     pub samples_per_pixel: usize,
 }
 
+impl CameraBuilder {
+    pub fn build(&self) -> Result<Camera, CameraBuilderError> {
+        let hsize = match self.hsize {
+            Some(ref value) => Clone::clone(value),
+            None => {
+                return Err(Into::into(::derive_builder::UninitializedFieldError::from(
+                    "hsize",
+                )))
+            }
+        };
+        let vsize = match self.vsize {
+            Some(ref value) => Clone::clone(value),
+            None => {
+                return Err(Into::into(::derive_builder::UninitializedFieldError::from(
+                    "vsize",
+                )))
+            }
+        };
+        let field_of_view = match self.field_of_view {
+            Some(ref value) => Clone::clone(value),
+            None => {
+                return Err(Into::into(::derive_builder::UninitializedFieldError::from(
+                    "field_of_view",
+                )))
+            }
+        };
+        let mut c = Camera::new(hsize, vsize, field_of_view);
+        if let Some(transform) = self.transform {
+            c.set_transform(transform);
+        }
+        if let Some(render_strategy) = self.render_strategy {
+            c.render_strategy = render_strategy;
+        }
+        if let Some(samples_per_pixel) = self.samples_per_pixel {
+            c.samples_per_pixel = samples_per_pixel;
+        }
+        Ok(c)
+    }
+}
+
 enum Request {
     Line { width: usize, y: usize },
 }

rtchallenge/src/lib.rs

@@ -40,6 +40,7 @@ pub use float::Float;
 
 pub mod prelude {
     pub use crate::{
+        camera::{Camera, CameraBuilder},
         lights::{PointLight, PointLightBuilder},
         materials::{Material, MaterialBuilder},
         matrices::{identity, rotation_x, rotation_y, rotation_z, scaling, shearing, translation},