pass specialized generate function to generic base function for globject

src/GLObject.cpp

@@ -1,11 +1,17 @@
 #include "GLObject.hpp"
 
-/* A deleter function is required for freeing the memory allocated to the object (this could be, for example,
- * glDeleteTextures for a Texture object, or a custom function that does something in addition to calling
- * the appropriate GL deleter function) */
-GLObject::GLObject(std::function<void(GLuint*)> deleter)
+/* The deleter function is used for freeing the memory allocated to the object (for example, glDeleteTextures,
+ * or a custom function that does something in addition to calling the appropriate GL deleter function). */
+GLObject::GLObject(deleter_function deleter) : deleter(deleter) {}
+
+/* This generator passed in from the derived class will be called to generate a new ID. It is limited to a
+ * single ID. For generating and managing multiple IDs with a single class, this method and others will have
+ * to be overwritten. */
+void GLObject::generate(generator_function generator)
 {
-    this->deleter = deleter;
+    GLuint id;
+    generator(1, &id);
+    this->id(id);
 }
 
 /* Set the shared pointer to point to a new GLuint with specified ID value */

src/GLObject.hpp

@@ -10,9 +10,13 @@
 
   [GLObject.hpp]
 
-  The abstract GLObject class is meant to be inherited by specific types of OpenGL objects,
-  for example Textures or Buffer objects. It stores the object's ID and declares virtual
-  functions for generating, binding, and destroying the object.
+  The abstract GLObject class is meant to be inherited and implemented by more specific
+  types of OpenGL objects, for example Textures or Buffer objects. It stores the object's
+  ID and declares virtual functions for generating, binding, and destroying the object.
+
+  An appropriate deleter function must be passed in to the constructor from the derived
+  class. It can be a custom function, or it can be one of the GL deleter functions like
+  glDeleteTextures.
   
 */
 
@@ -33,19 +37,25 @@
 class GLObject
 {
 
-protected:
+private:
+
+    typedef std::function<void(GLsizei, GLuint*)> generator_function;
+    typedef std::function<void(GLuint*)> deleter_function;
 
     std::shared_ptr<GLuint> object_id = nullptr;
-    std::function<void(GLuint*)> deleter = nullptr;
+    deleter_function deleter = nullptr;
+
+protected:
+
+    GLObject(deleter_function);
+    virtual void bind() const = 0;
+    void generate(generator_function);
 
 public:
 
-    GLObject(std::function<void(GLuint*)>);
-    virtual void generate() = 0;
-    virtual void bind() const = 0;
-    void id(GLuint);
-    GLuint id() const;
-    bool generated() const;
+    virtual void id(GLuint);
+    virtual GLuint id() const;
+    virtual bool generated() const;
     virtual ~GLObject() = default;
 
 };

src/Texture.cpp

@@ -16,12 +16,10 @@ void Texture::associate(fs::path path)
     this->path = path;
 }
 
-/* Generate an ID for this Texture and save it */
+/* Forward the GL texture generate function to the base class */
 void Texture::generate()
 {
-    GLuint id;
-    glGenTextures(1, &id);
-    this->id(id);
+    GLObject::generate(glGenTextures);
 }
 
 /* Generate a GL_TEXTURE_2D texture ID and allocate GL_RGB8 storage for the given size */

src/Texture.hpp

@@ -13,7 +13,9 @@
   The Texture class abstracts the file opening, data loading and binding steps of Open GL
   texture creation. Currently it only supports loading GL_TEXTURE_2D with GL_RGB8 pixels
   and automatic GL_NEAREST mipmapping. Support may be added for users to pass in their own
-  pixel data, to customize mipmapping, and more.
+  pixel data, to customize mipmapping, and more. The class can also be used in a custom
+  way by passing the Texture ID to GL functions instead of using the class's member
+  functions.
   
 */
 
@@ -47,7 +49,7 @@ public:
     Texture();
     Texture(fs::path);
     void associate(fs::path);
-    void generate() override;
+    void generate();
     void generate(glm::vec2);
     void load();
     void load(fs::path);