Extract draw merge branch dispatch helpers

src/canvas.cpp

@@ -537,8 +537,63 @@ static void execute_canvas_draw_merge_branch_body(
         use_blend,
         pp::panopainter::LegacyCanvasDrawMergeLayerCompositeExecution {
             .execute_temporary_erase = [&] {
-                pp::panopainter::execute_legacy_canvas_draw_merge_temporary_composite(
+                execute_canvas_draw_merge_temporary_erase_dispatch(
-                    pp::panopainter::make_legacy_canvas_draw_merge_temporary_erase_composite(
+                    canvas,
+                    plane_index,
+                    layer_index,
+                    layer,
+                    ortho);
+            },
+            .execute_temporary_paint = [&] {
+                canvas.draw_merge_temporary_paint_branch(
+                    layer_index,
+                    plane_index,
+                    layer,
+                    brush,
+                    ortho,
+                    copy_blend_destination,
+                    draw_checkerboard);
+            },
+            .execute_layer_texture = [&] {
+                execute_canvas_draw_merge_layer_texture(
+                    pp::panopainter::LegacyCanvasDrawMergeTextureAlphaUniforms {
+                        .mvp = ortho,
+                        .texture_slot = 0,
+                        .alpha = layer->m_opacity,
+                        .highlight = layer->m_hightlight,
+                    },
+                    make_canvas_draw_merge_layer_texture_dispatch(
+                        canvas,
+                        plane_index,
+                        layer_index));
+            },
+            .execute_layer_blend = [&] {
+                execute_canvas_draw_merge_layer_blend(
+                    pp::panopainter::LegacyCanvasDrawMergeLayerBlendUniforms {
+                        .shader = {
+                            .mvp = ortho,
+                            .texture_slot = 0,
+                            .destination_texture_slot = 2,
+                            .use_destination_texture = copy_blend_destination,
+                            .blend_mode = layer->m_blend_mode,
+                            .alpha = 1.f,
+                        },
+                        .copy_destination = copy_blend_destination,
+                    },
+                    make_canvas_draw_merge_layer_blend_dispatch(
+                        canvas));
+            },
+        });
+}
+
+static auto make_canvas_draw_merge_temporary_erase_dispatch(
+    Canvas& canvas,
+    int plane_index,
+    int layer_index,
+    const std::shared_ptr<Layer>& layer,
+    const glm::mat4& ortho)
+{
+    return pp::panopainter::make_legacy_canvas_draw_merge_temporary_erase_composite(
         [&] {
             pp::panopainter::setup_legacy_stroke_erase_shader(
                 pp::panopainter::LegacyStrokeEraseUniforms {
@@ -572,27 +627,15 @@ static void execute_canvas_draw_merge_branch_body(
             canvas.m_tmp[plane_index].unbindTexture();
             set_active_texture_unit(0);
             canvas.m_layers[layer_index]->rtt(plane_index).unbindTexture();
-                        }));
+        });
-            },
+}
-            .execute_temporary_paint = [&] {
+
-                canvas.draw_merge_temporary_paint_branch(
+static auto make_canvas_draw_merge_layer_texture_dispatch(
-                    layer_index,
+    Canvas& canvas,
-                    plane_index,
+    int plane_index,
-                    layer,
+    int layer_index)
-                    brush,
+{
-                    ortho,
+    return pp::panopainter::LegacyCanvasDrawMergeLayerTextureExecution {
-                    copy_blend_destination,
-                    draw_checkerboard);
-            },
-            .execute_layer_texture = [&] {
-                execute_canvas_draw_merge_layer_texture(
-                    pp::panopainter::LegacyCanvasDrawMergeTextureAlphaUniforms {
-                        .mvp = ortho,
-                        .texture_slot = 0,
-                        .alpha = layer->m_opacity,
-                        .highlight = layer->m_hightlight,
-                    },
-                    pp::panopainter::LegacyCanvasDrawMergeLayerTextureExecution {
         .bind_sampler = [&] {
             canvas.m_cam_fov < 20.f ? canvas.m_sampler_nearest.bind(0) : canvas.m_sampler.bind(0);
         },
@@ -606,22 +649,12 @@ static void execute_canvas_draw_merge_branch_body(
         .unbind_layer_texture = [&] {
             canvas.m_layers[layer_index]->rtt(plane_index).unbindTexture();
         },
-                    });
+    };
-            },
+}
-            .execute_layer_blend = [&] {
+
-                execute_canvas_draw_merge_layer_blend(
+static auto make_canvas_draw_merge_layer_blend_dispatch(Canvas& canvas)
-                    pp::panopainter::LegacyCanvasDrawMergeLayerBlendUniforms {
+{
-                        .shader = {
+    return pp::panopainter::LegacyCanvasDrawMergeLayerBlendExecution {
-                            .mvp = ortho,
-                            .texture_slot = 0,
-                            .destination_texture_slot = 2,
-                            .use_destination_texture = copy_blend_destination,
-                            .blend_mode = layer->m_blend_mode,
-                            .alpha = 1.f,
-                        },
-                        .copy_destination = copy_blend_destination,
-                    },
-                    pp::panopainter::LegacyCanvasDrawMergeLayerBlendExecution {
         .unbind_merge_framebuffer = [&] {
             canvas.m_merge_rtt.unbindFramebuffer();
         },
@@ -651,9 +684,7 @@ static void execute_canvas_draw_merge_branch_body(
             set_active_texture_unit(0);
             canvas.m_merge_rtt.unbindTexture();
         },
-                    });
+    };
-            },
-        });
 }
 
 static void execute_canvas_draw_merge_plane_iteration(