Add buttons to recompute / flip model normals

TODO.md

@@ -88,3 +88,7 @@
 - [ ] Update readme
 - [ ] Make post processing async
 - [ ] Instance meshes in save files / rendering
+- [x] Allow recalculating normals
+- [ ] Alert when model with invalid normals is loaded
+- [ ] Cleanup self intersection resolution
+- [ ] Dont fail to load an stl without normals

mslicer/src/render/dispatch/solid_line/normals.rs

@@ -40,6 +40,7 @@ impl LineDispatch for NormalsDispatch {
 
         let models = resources.models.read();
         let ids = models.iter().map(|x| x.id).collect::<Vec<_>>();
+        let dirty = models.iter().any(|x| x.dirty);
         let transforms = models
             .iter()
             .map(|x| *x.mesh.transformation_matrix())
@@ -48,6 +49,7 @@ impl LineDispatch for NormalsDispatch {
         if ids != self.last_models
             || transforms != self.last_transforms
             || show_normals != self.last_normals
+            || dirty
         {
             self.last_models = ids;
             self.last_transforms = transforms;

mslicer/src/render/rendered_mesh.rs

@@ -19,6 +19,10 @@ pub struct RenderedMesh {
     pub color: Color32,
     pub hidden: bool,
     pub locked_scale: bool,
+    /// Used when the normals are recomputed / flipped and the solid_line
+    /// normals dispatch needs to know to regenerate the lines. Should only be
+    /// set for one frame.
+    pub dirty: bool,
 
     vertices: Vec<ModelVertex>,
     index: Vec<u32>,
@@ -47,6 +51,7 @@ impl RenderedMesh {
             color: Color32::WHITE,
             hidden: false,
             locked_scale: true,
+            dirty: false,
             index,
             vertices,
             buffers: None,
@@ -90,6 +95,16 @@ impl RenderedMesh {
         self.mesh.set_position(pos);
     }
 
+    pub fn recompute_normals(&mut self) {
+        self.mesh.recompute_normals();
+        self.dirty = true;
+    }
+
+    pub fn flip_normals(&mut self) {
+        self.mesh.flip_normals();
+        self.dirty = true;
+    }
+
     pub fn try_get_buffers(&self) -> Option<&RenderedMeshBuffers> {
         self.buffers.as_ref()
     }
@@ -127,6 +142,7 @@ impl Clone for RenderedMesh {
             color: self.color,
             hidden: self.hidden,
             locked_scale: self.locked_scale,
+            dirty: false,
             vertices: self.vertices.clone(),
             index: self.index.clone(),
             buffers: None,

mslicer/src/windows/models.rs

@@ -1,6 +1,9 @@
 use const_format::concatcp;
 use egui::{Context, Grid, Id, Ui};
-use egui_phosphor::regular::{ARROW_LINE_DOWN, COPY, DICE_THREE, EYE, EYE_SLASH, TRASH};
+use egui_phosphor::regular::{
+    ARROWS_CLOCKWISE, ARROW_LINE_DOWN, COPY, DICE_THREE, EYE, EYE_SLASH, FLIP_HORIZONTAL, TRASH,
+    VECTOR_THREE,
+};
 use slicer::Pos;
 
 use crate::{
@@ -28,6 +31,8 @@ pub fn ui(app: &mut App, ui: &mut Ui, _ctx: &Context) {
     let width = ui.available_width();
 
     for (i, mesh) in meshes.iter_mut().enumerate() {
+        mesh.dirty = false;
+
         let id = Id::new(format!("model_show_{}", mesh.id));
         let open = ui.data_mut(|map| *map.get_temp_mut_or_insert_with(id, || false));
 
@@ -53,6 +58,7 @@ pub fn ui(app: &mut App, ui: &mut Ui, _ctx: &Context) {
                 .with_row_color(|row, style| (row % 2 == 0).then_some(style.visuals.faint_bg_color))
                 .show(ui, |ui| {
                     ui.label("Actions");
+                    ui.vertical(|ui| {
                         ui.horizontal(|ui| {
                             ui.button(concatcp!(TRASH, " Delete"))
                                 .clicked()
@@ -64,6 +70,24 @@ pub fn ui(app: &mut App, ui: &mut Ui, _ctx: &Context) {
                                 .clicked()
                                 .then(|| mesh.align_to_bed());
                         });
+
+                        ui.horizontal(|ui| {
+                            ui.menu_button(concatcp!(VECTOR_THREE, " Normals"), |ui| {
+                                if ui
+                                    .button(concatcp!(ARROWS_CLOCKWISE, " Recompute"))
+                                    .clicked()
+                                {
+                                    mesh.recompute_normals();
+                                    ui.close_menu();
+                                }
+
+                                if ui.button(concatcp!(FLIP_HORIZONTAL, " Flip")).clicked() {
+                                    mesh.flip_normals();
+                                    ui.close_menu();
+                                }
+                            });
+                        });
+                    });
                     ui.end_row();
 
                     ui.horizontal(|ui| {

slicer/src/mesh.rs

@@ -80,6 +80,40 @@ impl Mesh {
         self.faces().len()
     }
 
+    /// Makes a copy of the mesh with normals computed from the triangles
+    /// directly. The copy makes this operation kinda expensive.
+    pub fn recompute_normals(&mut self) {
+        let vertices = self.vertices();
+        let normals = self
+            .faces()
+            .iter()
+            .map(|f| {
+                let edge1 = vertices[f[2] as usize] - vertices[f[1] as usize];
+                let edge2 = vertices[f[0] as usize] - vertices[f[1] as usize];
+                edge1.cross(&edge2).normalize()
+            })
+            .collect();
+
+        self.overwrite_normals(normals)
+    }
+
+    /// Makes a copy of the mesh with normals computed from the triangles
+    /// directly. The copy makes this operation kinda expensive.
+    pub fn flip_normals(&mut self) {
+        let normals = self.normals().iter().map(|f| -f).collect();
+        self.overwrite_normals(normals);
+    }
+
+    // The alternaitve is to put normals in a separate Arc to avoid cloning all
+    // verts and faces here, but its proooobly fine.
+    fn overwrite_normals(&mut self, normals: Vec<Vector3<f32>>) {
+        self.inner = Arc::new(MeshInner {
+            vertices: self.inner.vertices.clone(),
+            faces: self.inner.faces.clone(),
+            normals: normals.into_boxed_slice(),
+        });
+    }
+
     /// Intersect the mesh with a plane with linier time complexity. You
     /// should probably use the [`crate::segments::Segments`] struct as it can
     /// massively accelerate slicing of high face count triangles.