Trying to add history to the Fill tool

engine/canvas.h

@@ -106,6 +106,7 @@ public:
     void clear(const glm::vec4& color = { 1, 1, 1, 0 });
     void snapshot_save(std::string data_path);
     void snapshot_restore();
+    void snap_history(const std::vector<int>& planes);
     void clear_context();
     void export_equirectangular(std::string data_path);
     void export_anim(std::string data_path);
@@ -122,7 +123,7 @@ public:
     bool point_trace(glm::vec2 loc, glm::vec3& ray_origin, glm::vec3& ray_dir,
                      glm::vec3& hit_pos, glm::vec3& hit_normal, int& out_plane_id);
     bool point_trace_plane(glm::vec2 loc, glm::vec3& ray_origin, glm::vec3& ray_dir,
-                     glm::vec3& hit_pos, glm::vec3& hit_normal, int plane_id);
+                     glm::vec3& hit_pos, glm::vec3& hit_normal, glm::vec2& hit_fb_pos, int plane_id);
 };
 
 class ActionStroke : public Action
@@ -134,6 +135,7 @@ public:
     bool m_old_dirty[6];
     glm::ivec4 m_box[6];
     bool m_dirty[6];
+    bool clear_layer = false;
     int m_layer_idx;
     Canvas* m_canvas;
     virtual void run() override
@@ -142,6 +144,8 @@ public:
     }
     virtual void undo() override
     {
+        if (clear_layer)
+            m_canvas->m_layers[m_layer_idx].clear({ 0, 0, 0, 0 });
         for (int i = 0; i < 6; i++)
         {
             // empty data