fix: effect does not work well with flip_x

Closes #749

Author: Mivik

prpr/src/core/chart.rs

@@ -170,8 +170,15 @@ impl Chart {
                 }
             }
             if !res.no_effect {
-                for effect in &self.extra.effects {
-                    effect.render(res);
+                let render = |res: &mut Resource| {
+                    for effect in &self.extra.effects {
+                        effect.render(res);
+                    }
+                };
+                if res.config.flip_x() {
+                    res.apply_model_of(&Matrix::identity().append_nonuniform_scaling(&Vector::new(-1., 1.)), render);
+                } else {
+                    render(res);
                 }
             }
         });