From 4f1ab9556a303f9b0aa2283f48f44f72883cdc0b Mon Sep 17 00:00:00 2001
From: Mikkel Troels Kongsted <mtkongsted@gmail.com>
Date: Mon, 30 Mar 2026 10:04:10 +0200
Subject: [PATCH] add despawn and don't render objects behind camera

---
 game/src/engine/scene.rs |  3 ++
 game/src/main.rs         | 83 +++++++++++++++++++++++++++-------------
 2 files changed, 59 insertions(+), 27 deletions(-)

diff --git a/game/src/engine/scene.rs b/game/src/engine/scene.rs
index 1f53856..31e97fe 100644
--- a/game/src/engine/scene.rs
+++ b/game/src/engine/scene.rs
@@ -39,6 +39,9 @@ impl Scene {
         let drawn_triangles = self
             .objects
             .iter()
+            .filter(|v| {
+                v.triangle.0 .2 >= -1.0 && v.triangle.1 .2 >= -1.0 && v.triangle.2 .2 >= -1.0
+            })
             .map(|v| (v.triangle.project_2d(), v.outline_color, v.fill_color));
         for (triangle, outline_color, fill_color) in drawn_triangles {
             r.draw_triangle(triangle.clone(), fill_color);
diff --git a/game/src/main.rs b/game/src/main.rs
index 75ab0fb..1ddc692 100644
--- a/game/src/main.rs
+++ b/game/src/main.rs
@@ -9,17 +9,33 @@ mod vermiparous;
 
 struct Game {
     objects: Vec<Object>,
+    next_object_id: u32,
 }
 
 impl Game {
     fn new() -> Self {
         Self {
             objects: Vec::new(),
+            next_object_id: 0,
         }
     }
 
-    fn spawn(&mut self, object: Object) {
+    fn spawn(&mut self, object_kind: ObjectKind) {
+        let object = Object {
+            kind: object_kind,
+            id: self.next_object_id,
+        };
         self.objects.push(object);
+        self.next_object_id += 1
+    }
+
+    fn despawn(&mut self, id: u32) {
+        let index = self
+            .objects
+            .iter()
+            .position(|o| o.id == id)
+            .expect("doesn't exist");
+        self.objects.remove(index);
     }
 }
 
@@ -41,41 +57,41 @@ impl<R: Renderer> engine::Game<R> for Game {
     fn event(&mut self, event: engine::Event) {}
 }
 
-enum Object {
+struct Object {
+    kind: ObjectKind,
+    id: u32,
+}
+
+enum ObjectKind {
     Player { pos: V3, vel: V3 },
-    Obstacle { pos: V3, vel_z: f64 },
+    Obstacle { pos: V3, vel: V3 },
     Ground { pos: V3, vel_z: f64 },
 }
 
 impl Object {
     fn update(&mut self, delta_time: Duration) {
-        match self {
-            Object::Player { pos, vel } => {
+        match &mut self.kind {
+            ObjectKind::Player { pos, vel } => {
                 *pos += *vel * delta_time.as_secs_f64();
                 if pos.0 >= 2.1 {
                     pos.0 = -2.0;
                 }
             }
-            Object::Obstacle { pos, vel_z } => {
-                pos.2 += *vel_z * delta_time.as_secs_f64();
+            ObjectKind::Obstacle { pos, vel } => {
+                *pos += *vel * delta_time.as_secs_f64();
             }
-            Object::Ground { pos, vel_z } => {
+            ObjectKind::Ground { pos, vel_z } => {
+                println!("z pos {}", pos.2);
                 pos.2 += *vel_z * delta_time.as_secs_f64();
             }
         }
     }
 
     fn render(&mut self, scene: &mut Scene) {
-        match self {
-            Object::Player { pos, .. } => {
+        match &mut self.kind {
+            ObjectKind::Player { pos, .. } => {
                 scene.draw_shape(
-                    *pos + V3(0.0, 0.2, 0.0),
-                    &Shape::new_cube(V3(0.2, 0.1, 0.2)),
-                    Color::Green,
-                    Color::Black,
-                );
-                scene.draw_shape(
-                    *pos + V3(-0.8, -0.2, 0.0),
+                    *pos,
                     &Shape::new_cube(V3(0.2, 0.2, 0.2))
                         .translate(V3(-0.1, -0.1, -0.1))
                         .rotate(V3(pos.0 * 5.0, pos.0 * 5.0, pos.0 * 5.0)),
@@ -83,8 +99,15 @@ impl Object {
                     Color::Black,
                 );
             }
-            Object::Obstacle { pos, vel_z } => todo!(),
-            Object::Ground { pos, .. } => {
+            ObjectKind::Obstacle { pos, .. } => {
+                scene.draw_shape(
+                    *pos,
+                    &Shape::new_cube(V3(0.2, 0.1, 0.2)),
+                    Color::Green,
+                    Color::Black,
+                );
+            }
+            ObjectKind::Ground { pos, .. } => {
                 for z in 0..10 {
                     for x in -10..10 {
                         scene.draw_shape(
@@ -103,17 +126,23 @@ impl Object {
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut sdl_io = engine::SdlIo::new()?;
     let mut game = Game::new();
-
-    let player = Object::Player {
-        pos: V3(-1.0, -0.1, 0.0),
+    let mut objects: Vec<ObjectKind> = Vec::new();
+    objects.push(ObjectKind::Player {
+        pos: V3(-1.8, -0.3, 0.0),
         vel: V3(0.4, 0.0, 0.0),
-    };
-    game.spawn(player);
-    let ground = Object::Ground {
+    });
+    objects.push(ObjectKind::Ground {
         pos: V3(0.0, -0.3, -0.5),
         vel_z: -0.1,
-    };
-    game.spawn(ground);
+    });
+    objects.push(ObjectKind::Obstacle {
+        pos: V3(0.5, -0.2, 0.0),
+        vel: V3(0.0, 0.0, -0.1),
+    });
+
+    for object in objects {
+        game.spawn(object)
+    }
 
     sdl_io.run(&mut game);
     Ok(())