Revert "gpui: Improve path rendering & global multisample anti-aliasing" (#34722)

Reverts zed-industries/zed#29718

We've noticed some issues with Zed on Intel-based Macs where typing has
become sluggish, and git bisect has seemed to point towards this PR.
Reverting for now, until we can understand why it is causing this issue.

crates/gpui/src/scene.rs

@@ -6,7 +6,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::{
     AtlasTextureId, AtlasTile, Background, Bounds, ContentMask, Corners, Edges, Hsla, Pixels,
-    Point, Radians, ScaledPixels, Size, bounds_tree::BoundsTree,
+    Point, Radians, ScaledPixels, Size, bounds_tree::BoundsTree, point,
 };
 use std::{fmt::Debug, iter::Peekable, ops::Range, slice};
 
@@ -43,7 +43,13 @@ impl Scene {
         self.surfaces.clear();
     }
 
-    #[allow(dead_code)]
+    #[cfg_attr(
+        all(
+            any(target_os = "linux", target_os = "freebsd"),
+            not(any(feature = "x11", feature = "wayland"))
+        ),
+        allow(dead_code)
+    )]
     pub fn paths(&self) -> &[Path<ScaledPixels>] {
         &self.paths
     }
@@ -683,7 +689,6 @@ pub struct Path<P: Clone + Debug + Default + PartialEq> {
     start: Point<P>,
     current: Point<P>,
     contour_count: usize,
-    base_scale: f32,
 }
 
 impl Path<Pixels> {
@@ -702,35 +707,25 @@ impl Path<Pixels> {
             content_mask: Default::default(),
             color: Default::default(),
             contour_count: 0,
-            base_scale: 1.0,
         }
     }
 
-    /// Set the base scale of the path.
-    pub fn scale(mut self, factor: f32) -> Self {
-        self.base_scale = factor;
-        self
-    }
-
-    /// Apply a scale to the path.
-    pub(crate) fn apply_scale(&self, factor: f32) -> Path<ScaledPixels> {
+    /// Scale this path by the given factor.
+    pub fn scale(&self, factor: f32) -> Path<ScaledPixels> {
         Path {
             id: self.id,
             order: self.order,
-            bounds: self.bounds.scale(self.base_scale * factor),
-            content_mask: self.content_mask.scale(self.base_scale * factor),
+            bounds: self.bounds.scale(factor),
+            content_mask: self.content_mask.scale(factor),
             vertices: self
                 .vertices
                 .iter()
-                .map(|vertex| vertex.scale(self.base_scale * factor))
+                .map(|vertex| vertex.scale(factor))
                 .collect(),
-            start: self
-                .start
-                .map(|start| start.scale(self.base_scale * factor)),
-            current: self.current.scale(self.base_scale * factor),
+            start: self.start.map(|start| start.scale(factor)),
+            current: self.current.scale(factor),
             contour_count: self.contour_count,
             color: self.color,
-            base_scale: 1.0,
         }
     }
 
@@ -745,7 +740,10 @@ impl Path<Pixels> {
     pub fn line_to(&mut self, to: Point<Pixels>) {
         self.contour_count += 1;
         if self.contour_count > 1 {
-            self.push_triangle((self.start, self.current, to));
+            self.push_triangle(
+                (self.start, self.current, to),
+                (point(0., 1.), point(0., 1.), point(0., 1.)),
+            );
         }
         self.current = to;
     }
@@ -754,15 +752,25 @@ impl Path<Pixels> {
     pub fn curve_to(&mut self, to: Point<Pixels>, ctrl: Point<Pixels>) {
         self.contour_count += 1;
         if self.contour_count > 1 {
-            self.push_triangle((self.start, self.current, to));
+            self.push_triangle(
+                (self.start, self.current, to),
+                (point(0., 1.), point(0., 1.), point(0., 1.)),
+            );
         }
 
-        self.push_triangle((self.current, ctrl, to));
+        self.push_triangle(
+            (self.current, ctrl, to),
+            (point(0., 0.), point(0.5, 0.), point(1., 1.)),
+        );
         self.current = to;
     }
 
     /// Push a triangle to the Path.
-    pub fn push_triangle(&mut self, xy: (Point<Pixels>, Point<Pixels>, Point<Pixels>)) {
+    pub fn push_triangle(
+        &mut self,
+        xy: (Point<Pixels>, Point<Pixels>, Point<Pixels>),
+        st: (Point<f32>, Point<f32>, Point<f32>),
+    ) {
         self.bounds = self
             .bounds
             .union(&Bounds {
@@ -780,14 +788,17 @@ impl Path<Pixels> {
 
         self.vertices.push(PathVertex {
             xy_position: xy.0,
+            st_position: st.0,
             content_mask: Default::default(),
         });
         self.vertices.push(PathVertex {
             xy_position: xy.1,
+            st_position: st.1,
             content_mask: Default::default(),
         });
         self.vertices.push(PathVertex {
             xy_position: xy.2,
+            st_position: st.2,
             content_mask: Default::default(),
         });
     }
@@ -803,6 +814,7 @@ impl From<Path<ScaledPixels>> for Primitive {
 #[repr(C)]
 pub(crate) struct PathVertex<P: Clone + Debug + Default + PartialEq> {
     pub(crate) xy_position: Point<P>,
+    pub(crate) st_position: Point<f32>,
     pub(crate) content_mask: ContentMask<P>,
 }
 
@@ -810,6 +822,7 @@ impl PathVertex<Pixels> {
     pub fn scale(&self, factor: f32) -> PathVertex<ScaledPixels> {
         PathVertex {
             xy_position: self.xy_position.scale(factor),
+            st_position: self.st_position,
             content_mask: self.content_mask.scale(factor),
         }
     }