Disable glow scissor test after painting (#905)

Author: Hperigo

egui_glow/examples/pure_glow.rs

@@ -37,6 +37,8 @@ fn create_display(
 }
 
 fn main() {
+    let mut clear_color = [0.1, 0.1, 0.1];
+
     let event_loop = glutin::event_loop::EventLoop::with_user_event();
     let (gl_window, gl) = create_display(&event_loop);
 
@@ -52,6 +54,7 @@ fn main() {
                     if ui.button("Quit").clicked() {
                         quit = true;
                     }
+                    ui.color_edit_button_rgb(&mut clear_color);
                 });
             });
 
@@ -65,10 +68,9 @@ fn main() {
             };
 
             {
-                let color = egui::Rgba::from_rgb(0.1, 0.3, 0.2);
                 unsafe {
                     use glow::HasContext as _;
-                    gl.clear_color(color[0], color[1], color[2], color[3]);
+                    gl.clear_color(clear_color[0], clear_color[1], clear_color[2], 1.0);
                     gl.clear(glow::COLOR_BUFFER_BIT);
                 }
 

egui_glow/src/painter.rs

@@ -265,7 +265,6 @@ impl Painter {
         let height_in_points = height_in_pixels as f32 / pixels_per_point;
 
         gl.viewport(0, 0, width_in_pixels as i32, height_in_pixels as i32);
-
         gl.use_program(Some(self.program));
 
         gl.uniform_2_f32(Some(&self.u_screen_size), width_in_points, height_in_points);
@@ -324,6 +323,9 @@ impl Painter {
             if let Some(ref post_process) = self.post_process {
                 post_process.end(gl);
             }
+
+            gl.disable(glow::SCISSOR_TEST);
+
             assert_eq!(glow::NO_ERROR, gl.get_error(), "GL error occurred!");
         }
     }