Fix text legibility by rounding vertex positions (#151)

Co-authored-by: Madeline Sparkles <[email protected]>

crates/yakui-core/src/paint/paint_dom.rs

@@ -7,10 +7,11 @@ use crate::dom::Dom;
 use crate::geometry::Rect;
 use crate::id::{ManagedTextureId, WidgetId};
 use crate::layout::LayoutDom;
+use crate::paint::{PaintCall, Pipeline};
 use crate::widget::PaintContext;
 
 use super::layers::PaintLayers;
-use super::primitives::{PaintCall, PaintMesh, Vertex};
+use super::primitives::{PaintMesh, Vertex};
 use super::texture::{Texture, TextureChange};
 
 /// Contains all information about how to paint the current set of widgets.
@@ -202,7 +203,18 @@ impl PaintDom {
         let vertices = mesh.vertices.into_iter().map(|mut vertex| {
             let mut pos = vertex.position * self.scale_factor;
             pos += self.unscaled_viewport.pos();
+
+            // Currently, we only round the vertices of geometry fed to the text
+            // pipeline because rounding all geometry causes hairline cracks in
+            // some geometry, like rounded rectangles.
+            //
+            // See: https://github.com/SecondHalfGames/yakui/issues/153
+            if mesh.pipeline == Pipeline::Text {
+                pos = pos.round();
+            }
+
             pos /= self.surface_size;
+
             vertex.position = pos;
             vertex
         });