Triangulate face

src/main.rs

@@ -1,14 +1,12 @@
 mod global_state;
 mod polygon;
 
-///! This example illustrates how to resize windows, and how to respond to a window being resized.
 use bevy::{
     input::{
         mouse::{MouseButtonInput, MouseWheel},
         ButtonState,
     },
     prelude::*,
-    sprite::MaterialMesh2dBundle,
     window::WindowResized,
 };
 
@@ -22,35 +20,17 @@ fn main() {
         .add_plugin(EguiPlugin)
         .insert_resource(GlobalState::default())
         .insert_resource(ObjectInfos::default())
-        .add_startup_systems((setup_camera, setup))
-        .add_systems((
-            print_mouse_events_system,
-            update_ui_side_panel,
-            on_resize_system,
-        ))
+        .add_startup_system(setup_camera)
+        .add_systems((mouse_event_system, update_ui_side_panel, on_resize_system))
         .run();
 }
 
-fn setup(
-    mut commands: Commands,
-    mut meshes: ResMut<Assets<Mesh>>,
-    mut materials: ResMut<Assets<ColorMaterial>>,
-) {
-    commands.spawn(MaterialMesh2dBundle {
-        mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
-        transform: Transform::default()
-            .with_scale(Vec3::splat(4.))
-            .with_translation(Vec3::new(100.0, 10.0, 0.0)),
-        material: materials.add(ColorMaterial::from(Color::YELLOW)),
-        ..default()
-    });
-}
-
-// Spawns the camera that draws UI
+// Spawns the camera
 fn setup_camera(mut cmd: Commands) {
     cmd.spawn(Camera2dBundle::default());
 }
 
+// Create UI
 fn update_ui_side_panel(mut contexts: EguiContexts, mut global_state: ResMut<GlobalState>) {
     egui::Window::new("Hello").show(contexts.ctx_mut(), |ui| {
         if global_state.polygon_started {
@@ -63,8 +43,8 @@ fn update_ui_side_panel(mut contexts: EguiContexts, mut global_state: ResMut<Glo
     });
 }
 
-/// This system prints out all mouse events as they come in
-fn print_mouse_events_system(
+/// Handles all mouse events
+fn mouse_event_system(
     mut mouse_button_input_events: EventReader<MouseButtonInput>,
     mut cursor_moved_events: EventReader<CursorMoved>,
     mut mouse_wheel_events: EventReader<MouseWheel>,
@@ -78,33 +58,21 @@ fn print_mouse_events_system(
         match event.button {
             MouseButton::Left => match event.state {
                 ButtonState::Pressed => {
-                    println!(
-                        "Left mouse button pressed at {:?}",
-                        global_state.cursor_position
-                    );
+                    // only add new points if "New Polygon" button got pressed
+                    if global_state.polygon_started {
+                        let polygon = match object_infos.active_polygon() {
+                            Some(polygon) => polygon,
+                            None => object_infos.add_polygon(),
+                        };
 
-                    let polygon = match object_infos.active_polygon() {
-                        Some(polygon) => polygon,
-                        None => object_infos.add_polygon(),
-                    };
-
-                    if polygon.add_point(global_state.cursor_position) {
-                        global_state.polygon_started = false;
-
-                        // TODO remove single points -> draw full polygon
-                    } else {
-                        commands.spawn(MaterialMesh2dBundle {
-                            mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
-                            transform: Transform::default()
-                                .with_scale(Vec3::splat(4.0))
-                                .with_translation(
-                                    (global_state.cursor_position
-                                        - (global_state.window_extent * 0.5))
-                                        .extend(0.0),
-                                ),
-                            material: materials.add(ColorMaterial::from(Color::BLACK)),
-                            ..default()
-                        });
+                        if polygon.add_point(
+                            &global_state,
+                            &mut commands,
+                            &mut meshes,
+                            &mut materials,
+                        ) {
+                            global_state.polygon_started = false;
+                        }
                     }
                 }
                 ButtonState::Released => (),
@@ -124,6 +92,7 @@ fn print_mouse_events_system(
     }
 }
 
+// Handles resize events
 fn on_resize_system(
     mut resize_reader: EventReader<WindowResized>,
     mut global_state: ResMut<GlobalState>,

src/polygon.rs

@@ -1,28 +1,134 @@
-use bevy::prelude::*;
+use bevy::{
+    prelude::*,
+    render::{mesh::Indices, render_resource::PrimitiveTopology},
+    sprite::MaterialMesh2dBundle,
+};
+
+use crate::global_state::GlobalState;
+
+#[derive(Default, Debug, PartialEq)]
+struct CollectionIDs {
+    points: Vec<Entity>,
+    lines: Vec<Entity>,
+}
+
+#[derive(Debug, PartialEq)]
+enum PolygonState {
+    Collection(CollectionIDs),
+    Finished(Entity),
+}
+
+impl PolygonState {
+    fn collection_mut(&mut self) -> &mut CollectionIDs {
+        match self {
+            PolygonState::Collection(c) => c,
+            PolygonState::Finished(_) => panic!("called collection on finished state!"),
+        }
+    }
+}
+
+impl Default for PolygonState {
+    fn default() -> Self {
+        Self::Collection(CollectionIDs::default())
+    }
+}
 
 #[derive(Default, Debug, PartialEq)]
 pub struct Polygon {
     points: Vec<Vec2>,
-    finished: bool,
+    state: PolygonState,
 }
 
 impl Polygon {
-    const PROXIMITY_THRESHOLD: f32 = 5.0;
+    const PROXIMITY_THRESHOLD: f32 = 10.0;
 
-    pub fn add_point(&mut self, point: Vec2) -> bool {
-        debug_assert_eq!(self.finished, false);
+    pub fn add_point(
+        &mut self,
+        global_state: &GlobalState,
+        commands: &mut Commands,
+        meshes: &mut ResMut<Assets<Mesh>>,
+        materials: &mut ResMut<Assets<ColorMaterial>>,
+    ) -> bool {
+        debug_assert_eq!(self.finished(), false);
+
+        let point = global_state.cursor_position;
 
         // polygon must be at least an triangle
         // and check if we can close up the polygon
         if self.points.len() >= 3 && self.check_first_for_proximity(point) {
-            self.points.push(point);
-            self.finished = true;
+            // remove points and lines from collection state
+            {
+                let collection_ids = self.state.collection_mut();
+
+                for point_id in collection_ids.points.iter() {
+                    commands.entity(*point_id).despawn();
+                }
+
+                for line_id in collection_ids.lines.iter() {
+                    commands.entity(*line_id).despawn();
+                }
+            }
+
+            // create triangle mesh
+            let triangle_mesh = self.create_triangulated_mesh();
+
+            let triangle_id = commands
+                .spawn(MaterialMesh2dBundle {
+                    mesh: meshes.add(triangle_mesh).into(),
+                    transform: Transform::default()
+                        .with_translation((-global_state.window_extent * 0.5).extend(0.0)),
+                    material: materials.add(ColorMaterial::from(Color::BLACK)),
+                    ..default()
+                })
+                .id();
+
+            // store triangle entity id in state
+            self.state = PolygonState::Finished(triangle_id);
 
             return true;
         }
 
         // deny too close points
         if !self.check_all_for_proximity(point) {
+            let collection_ids = self.state.collection_mut();
+
+            // create point mesh at click position
+            let point_id = commands
+                .spawn(MaterialMesh2dBundle {
+                    mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
+                    transform: Transform::default()
+                        .with_scale(Vec3::splat(4.0))
+                        .with_translation(
+                            (global_state.cursor_position - (global_state.window_extent * 0.5))
+                                .extend(0.0),
+                        ),
+                    material: materials.add(ColorMaterial::from(Color::BLACK)),
+                    ..default()
+                })
+                .id();
+
+            collection_ids.points.push(point_id);
+
+            // draw a line between new point and last point
+            if let Some(&last_point) = self.points.last() {
+                let a = Vec2::X.angle_between((point - last_point).normalize());
+
+                let line_id = commands
+                    .spawn(MaterialMesh2dBundle {
+                        mesh: meshes.add(Self::create_line_mesh(last_point, point)).into(),
+                        transform: Transform::default()
+                            .with_translation(
+                                (last_point - (global_state.window_extent * 0.5)).extend(0.0),
+                            )
+                            .with_rotation(Quat::from_rotation_z(a)),
+                        material: materials.add(ColorMaterial::from(Color::BLACK)),
+                        ..default()
+                    })
+                    .id();
+
+                collection_ids.lines.push(line_id);
+            }
+
             self.points.push(point);
         }
 
@@ -30,7 +136,10 @@ impl Polygon {
     }
 
     pub fn finished(&self) -> bool {
-        self.finished
+        match &self.state {
+            PolygonState::Collection(_) => false,
+            PolygonState::Finished(_) => true,
+        }
     }
 
     fn check_all_for_proximity(&self, point: Vec2) -> bool {
@@ -44,6 +153,42 @@ impl Polygon {
 
         self.points.first().unwrap().distance(point) < Self::PROXIMITY_THRESHOLD
     }
+
+    fn create_triangulated_mesh(&self) -> Mesh {
+        let vertices: Vec<_> = self.points.iter().map(|p| p.extend(0.0)).collect();
+
+        let indices = Indices::U32({
+            let mut v = Vec::new();
+
+            for i in 2..self.points.len() as u32 {
+                v.push(0);
+                v.push(i - 1);
+                v.push(i);
+            }
+
+            v
+        });
+
+        let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
+        mesh.set_indices(Some(indices));
+        mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, vertices);
+
+        mesh
+    }
+
+    fn create_line_mesh(start: Vec2, end: Vec2) -> Mesh {
+        let d = start.distance(end);
+
+        let vertices = [[0.0, 0.0, 0.0], [d, 0.0, 0.0]];
+
+        let mut mesh = Mesh::new(PrimitiveTopology::LineList);
+        mesh.insert_attribute(
+            Mesh::ATTRIBUTE_POSITION,
+            vertices.into_iter().map(|v| v).collect::<Vec<_>>(),
+        );
+
+        mesh
+    }
 }
 
 #[derive(Resource, Default, Debug, PartialEq)]