feat(camera): render anim using ffmpeg

src/raytracer/camera.rs

@@ -1,11 +1,15 @@
-use std::fmt::Display;
+use std::{fmt::Display, path::Path};
 
 use super::{
     scene::Scene,
     types::{Color, Point3, Ray, Scalar, Vector3},
+    RTError,
 };
 use image::RgbImage;
+use lispers_core::lisp::eval::EvalError;
+use ndarray::Array3;
 use rayon::prelude::*;
+use video_rs::{encode::Settings, Encoder, Time};
 
 /// A camera that can render a scene.
 #[derive(Clone, PartialEq, Debug)]
@@ -119,26 +123,47 @@ impl Camera {
         Camera::new(position, center, up, fovy, self.width, self.height)
     }
 
-    pub fn render_animation<SFn: Fn(u32) -> Scene, CFn: Fn(u32, &Camera) -> Camera>(
+    pub fn render_animation<
+        SFn: Fn(u32) -> Result<Scene, EvalError>,
+        CFn: Fn(u32, &Camera) -> Result<Camera, EvalError>,
+    >(
         &self,
+        path: &Path,
         scene_fn: SFn,
         update_cam: CFn,
         frames: u32,
         fps: u32,
         depth: u32,
         subp: u32,
-    ) {
+    ) -> Result<(), RTError> {
+        let mut encoder = Encoder::new(
+            path,
+            Settings::preset_h264_yuv420p(self.width, self.height, false),
+        )?;
+        let frame_duration = Time::from_nth_of_a_second(fps as usize);
+        let mut timestamp = Time::zero();
+
         let mut cam = self.to_owned();
         for t in 0..frames {
-            println!("Rendering frame {}/{}", t + 1, frames);
-            cam = update_cam(t, &cam);
-            let img = cam.render(&scene_fn(t), depth, subp);
+            println!(
+                "Rendering frame {}/{} for {}",
+                t + 1,
+                frames,
+                path.display()
+            );
+            cam = update_cam(t, &cam)?;
+            let img = cam.render(&scene_fn(t)?, depth, subp);
 
-            match img.save(format!("frame_{:04}.png", t)) {
-                Ok(_) => {}
-                Err(e) => print!("Could not render frame: {}", e),
-            }
+            let frame = Array3::from_shape_fn((self.height, self.width, 3), |(y, x, c)| {
+                img.get_pixel(x as u32, y as u32)[c]
+            });
+
+            encoder.encode(&frame, timestamp)?;
+            timestamp = timestamp.aligned_with(frame_duration).add();
         }
+
+        encoder.finish()?;
+        Ok(())
     }
 }