refactor export equirectangular

src/canvas_layer.h

@@ -1,6 +1,7 @@
 #pragma once
 #include "rtt.h"
 #include "log.h"
+#include "texture.h"
 
 class LayerFrame
 {
@@ -42,6 +43,8 @@ public:
     bool create(int width, int height, std::string name);
     void clear(const glm::vec4& c);
     Snapshot snapshot(std::array<glm::vec4, 6>* dirty_box = nullptr, std::array<bool, 6>* dirty_face = nullptr);
+    TextureCube gen_cube();
+    Texture2D gen_equirect();
     void restore(const Snapshot& snap);
     void destroy();
     void optimize();