diff --git a/src/canvas.cpp b/src/canvas.cpp
index ea5739c..77ff73d 100644
--- a/src/canvas.cpp
+++ b/src/canvas.cpp
@@ -508,6 +508,68 @@ static void execute_canvas_draw_merge_final_plane_composite(
     pp::panopainter::execute_legacy_canvas_draw_merge_final_plane_composite(uniforms, execution);
 }
 
+static void execute_canvas_draw_merge_plane_iteration(
+    Canvas& canvas,
+    const std::array<bool, 6>& faces,
+    const std::vector<std::shared_ptr<Layer>>& layers,
+    const Brush& brush,
+    const glm::mat4& ortho,
+    bool use_blend,
+    bool copy_blend_destination,
+    bool draw_checkerboard)
+{
+    for (int plane_index = 0; plane_index < 6; plane_index++)
+    {
+        if (!faces[plane_index])
+            continue;
+
+        canvas.m_layers_merge.rtt(plane_index).bindFramebuffer();
+        pp::panopainter::execute_legacy_canvas_draw_merge_plane_setup(
+            pp::panopainter::LegacyCanvasDrawMergePlaneSetupUniforms {
+                .checkerboard = {
+                    .mvp = ortho,
+                    .colorize = false,
+                },
+                .use_blend = use_blend,
+                .draw_checkerboard = draw_checkerboard,
+            },
+            pp::panopainter::LegacyCanvasDrawMergePlaneSetupExecution {
+                .clear_plane = [&] {
+                    canvas.m_layers_merge.rtt(plane_index).clear({ 1, 1, 1, 0 });
+                },
+                .disable_blend = [&] {
+                    apply_canvas_capability(blend_state(), false);
+                },
+                .enable_blend = [&] {
+                    apply_canvas_capability(blend_state(), true);
+                },
+                .draw = [&] {
+                    canvas.m_plane.draw_fill();
+                },
+            });
+
+        for (int layer_index = 0; layer_index < layers.size(); layer_index++)
+        {
+            canvas.draw_merge_branch_orchestration(
+                plane_index,
+                layer_index,
+                layers[layer_index],
+                brush,
+                ortho,
+                use_blend,
+                copy_blend_destination,
+                draw_checkerboard);
+        }
+
+        if (use_blend)
+        {
+            canvas.draw_merge_final_plane_composite(ortho, draw_checkerboard);
+        }
+
+        canvas.m_layers_merge.rtt(plane_index).unbindFramebuffer();
+    }
+}
+
 static auto make_canvas_stroke_mix_pass_shell(
     Canvas& canvas,
     const glm::vec2& bb_min,
@@ -1794,56 +1856,15 @@ void Canvas::draw_merge(bool draw_checkerboard, std::array<bool, 6> faces /*= SI
     // if not using shader blend, use gl rasterizer blend
     apply_canvas_capability(depth_test_state(), false);
 
-    for (int plane_index = 0; plane_index < 6; plane_index++)
-    {
-        if (!faces[plane_index])
-            continue;
-
-        m_layers_merge.rtt(plane_index).bindFramebuffer();
-        pp::panopainter::execute_legacy_canvas_draw_merge_plane_setup(
-            pp::panopainter::LegacyCanvasDrawMergePlaneSetupUniforms {
-                .checkerboard = {
-                    .mvp = ortho,
-                    .colorize = false,
-                },
-                .use_blend = use_blend,
-                .draw_checkerboard = draw_checkerboard,
-            },
-            pp::panopainter::LegacyCanvasDrawMergePlaneSetupExecution {
-                .clear_plane = [&] {
-                    m_layers_merge.rtt(plane_index).clear({ 1, 1, 1, 0 });
-                },
-                .disable_blend = [&] {
-                    apply_canvas_capability(blend_state(), false);
-                },
-                .enable_blend = [&] {
-                    apply_canvas_capability(blend_state(), true);
-                },
-                .draw = [&] {
-                    m_plane.draw_fill();
-                },
-            });
-
-        for (int layer_index = 0; layer_index < m_layers.size(); layer_index++)
-        {
-            draw_merge_branch_orchestration(
-                plane_index,
-                layer_index,
-                m_layers[layer_index],
-                *b,
-                ortho,
-                use_blend,
-                copy_blend_destination,
-                draw_checkerboard);
-        }
-
-        if (use_blend)
-        {
-            draw_merge_final_plane_composite(ortho, draw_checkerboard);
-        }
-        
-        m_layers_merge.rtt(plane_index).unbindFramebuffer();
-    }
+    execute_canvas_draw_merge_plane_iteration(
+        *this,
+        faces,
+        m_layers,
+        *b,
+        ortho,
+        use_blend,
+        copy_blend_destination,
+        draw_checkerboard);
 }
 
 void Canvas::stroke_update(glm::vec3 point, float pressure)