skybox: added moon and stars

src/frontend/graphics/Skybox.h

@@ -1,25 +1,52 @@
 #ifndef FRONTEND_GRAPHICS_SKYBOX_H_
 #define FRONTEND_GRAPHICS_SKYBOX_H_
 
+#include <memory>
+#include <string>
+#include <vector>
 #include "../../typedefs.h"
+#include "../../maths/fastmaths.h"
+#include "../../graphics/GfxContext.h"
 
 class Mesh;
 class Shader;
+class Assets;
+class Camera;
+class Batch3D;
+
+struct skysprite {
+    std::string texture;
+    float phase;
+    float distance;
+    bool emissive;
+};
 
 class Skybox {
     uint fbo;
     uint cubemap;
     uint size;
-    Mesh* mesh;
     Shader* shader;
     bool ready = false;
+    FastRandom random;
+
+    std::unique_ptr<Mesh> mesh;
+    std::unique_ptr<Batch3D> batch3d;
+    std::vector<skysprite> sprites;
+
+    void drawStars(Camera* camera, float angle, float opacity);
+    void drawBackground(Camera* camera, Assets* assets, int width, int height);
 public:
     Skybox(uint size, Shader* shader);
     ~Skybox();
 
-    void draw(Shader* shader);
+    void draw(
+        const GfxContext& pctx, 
+        Camera* camera, 
+        Assets* assets, 
+        float daytime,
+        float fog);
 
-    void refresh(float t, float mie, uint quality);
+    void refresh(const GfxContext& pctx, float t, float mie, uint quality);
     void bind() const;
     void unbind() const;
     bool isReady() const {