feat: implement constraint system and PPM rendering

1 files changed, 41 insertions, 0 deletions

diff --git a/src/ppm.rs b/src/ppm.rs
new file mode 100644
index 0000000..01cdebb
--- /dev/null
+++ b/src/ppm.rs
@@ -0,0 +1,41 @@
+use std::{fs::File, io::Write, path::PathBuf};
+
+use crate::particle_system::{Particle, Vector, N, Scalar};
+
+pub struct PPM {
+    pub prefix: PathBuf,
+    pub width: usize,
+    pub height: usize,
+    // pixels_per_unit: usize,
+}
+
+impl PPM {
+    fn render_particles(&self, particles: &Vec<Particle>) -> String {
+        let mut s = format!("P3\n{} {}\n255\n", self.width, self.height);
+        let white = "255 255 255 ";
+        let black = "0 0 0 ";
+
+        for pixel_row in 0..self.height {
+            for pixel_col in 0..self.width {
+                let point = Vector::new(pixel_col as Scalar, (pixel_row as Scalar) * -1.0)
+                    + Vector::new(self.width as Scalar / -2.0, self.height as Scalar / 2.0);
+                let color = match particles.iter().any(|p| {
+                    (p.position - point).coords.norm() <= (p.mass).powf(1.0 / (N as f64))
+                }) {
+                    true => black,
+                    false => white,
+                };
+                s += color;
+            }
+        }
+        s
+    }
+
+    pub fn save_frame(&self, particles: &Vec<Particle>, time: Scalar) {
+        let file_name = format!("frame-{:08.3}", time);
+        let path = self.prefix.join(file_name);
+        let mut file = File::create(path).unwrap();
+        let data = self.render_particles(particles);
+        file.write(data.as_bytes()).unwrap();
+    }
+}