Add rounding to offset and scale of the snarl view to combat rounding…

… errors
zakarumych · Jan 27, 2025 · a42ca64 · a42ca64
1 parent ba6a91c
commit a42ca64
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Showing 2 changed files with 39 additions and 24 deletions.
diff --git a/src/ui.rs b/src/ui.rs
@@ -713,11 +713,12 @@ impl<T> Snarl<T> {
                     if viewport.contains(hover_pos) && ui.rect_contains_pointer(viewport) =>
                 {
                     if input.zoom_delta != 1.0 {
-                        let new_scale = (snarl_state.scale()
-                            * input.zoom_delta.powf(style.get_scale_velocity()))
-                        .clamp(style.get_min_scale(), style.get_max_scale());
-
-                        snarl_state.set_scale(new_scale);
+                        snarl_state.zoom_delta(
+                            input.zoom_delta,
+                            style.get_scale_velocity(),
+                            style.get_min_scale(),
+                            style.get_max_scale(),
+                        );
                     }
                 }
                 _ => {}
@@ -1472,7 +1473,7 @@ impl<T> Snarl<T> {
             .map(|idx| OutPin::new(self, OutPinId { node, output: idx }))
             .collect::<Vec<_>>();
 
-        let node_pos = snarl_state.graph_pos_to_screen(pos, viewport);
+        let node_pos = snarl_state.graph_pos_to_screen(pos, viewport).round();
 
         // Generate persistent id for the node.
         let node_id = snarl_id.with(("snarl-node", node));

diff --git a/src/ui/state.rs b/src/ui/state.rs
@@ -1,6 +1,6 @@
 use std::hash::Hash;
 
-use egui::{ahash::HashSet, style::Spacing, Context, Id, Pos2, Rect, Ui, Vec2};
+use egui::{ahash::HashSet, style::Spacing, vec2, Context, Id, Pos2, Rect, Ui, Vec2};
 
 use crate::{InPinId, NodeId, OutPinId, Snarl};
 
@@ -66,7 +66,8 @@ impl NodeState {
             egui::vec2(
                 self.size.x,
                 f32::max(self.header_height, self.size.y * openness),
-            ),
+            )
+            .round(),
         )
     }
 
@@ -338,36 +339,48 @@ impl SnarlState {
         }
     }
 
+    pub fn set_offset(&mut self, offset: Vec2) {
+        if self.offset != offset {
+            self.offset = offset;
+            self.dirty = true;
+        }
+    }
+
     #[inline(always)]
     pub fn pan(&mut self, delta: Vec2) {
-        self.offset += delta;
-        self.dirty = true;
+        if delta != Vec2::ZERO {
+            self.offset += delta;
+            self.dirty = true;
+        }
     }
 
     #[inline(always)]
-    pub const fn scale(&self) -> f32 {
-        self.scale
+    pub fn scale(&self) -> f32 {
+        rounding(self.scale)
     }
 
     #[inline(always)]
-    pub const fn offset(&self) -> Vec2 {
-        self.offset
+    pub fn offset(&self) -> Vec2 {
+        self.offset.round()
     }
 
     #[inline(always)]
-    pub fn set_scale(&mut self, scale: f32) {
-        self.target_scale = scale;
+    pub fn zoom_delta(&mut self, zoom_delta: f32, velocity: f32, min: f32, max: f32) {
+        if zoom_delta == 1.0 {
+            return;
+        }
+        self.target_scale = (self.target_scale * zoom_delta.powf(velocity)).clamp(min, max);
         self.dirty = true;
     }
 
     #[inline(always)]
     pub fn screen_pos_to_graph(&self, pos: Pos2, viewport: Rect) -> Pos2 {
-        (pos + self.offset - viewport.center().to_vec2()) / self.scale
+        (pos + self.offset() - viewport.center().to_vec2()) / self.scale()
     }
 
     #[inline(always)]
     pub fn graph_pos_to_screen(&self, pos: Pos2, viewport: Rect) -> Pos2 {
-        pos * self.scale - self.offset + viewport.center().to_vec2()
+        pos * self.scale() - self.offset() + viewport.center().to_vec2()
     }
 
     #[inline(always)]
@@ -393,7 +406,7 @@ impl SnarlState {
 
     #[inline(always)]
     pub fn screen_vec_to_graph(&self, size: Vec2) -> Vec2 {
-        size / self.scale
+        size / self.scale()
     }
 
     // #[inline(always)]
@@ -524,11 +537,6 @@ impl SnarlState {
         self.dirty = true;
     }
 
-    pub fn set_offset(&mut self, offset: Vec2) {
-        self.offset = offset;
-        self.dirty = true;
-    }
-
     pub fn selected_nodes(&self) -> &[NodeId] {
         &self.selected_nodes
     }
@@ -634,3 +642,9 @@ impl<T> Snarl<T> {
         })
     }
 }
+
+fn rounding(scale: f32) -> f32 {
+    // Assuming IEEE 754 binary32 format.
+
+    f32::from_bits(scale.to_bits() & 0xFFFFF000)
+}