Implemented support for explicit mipmap generation in sf::Texture and sf::RenderTexture. (#123)

include/SFML/Graphics/RenderTexture.hpp

@@ -131,6 +131,22 @@ public:
     ////////////////////////////////////////////////////////////
     bool isRepeated() const;
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Generate a mipmap using the current texture data
+    ///
+    /// This function is similar to Texture::generateMipmap and operates
+    /// on the texture used as the target for drawing.
+    /// Be aware that any draw operation may modify the base level image data.
+    /// For this reason, calling this function only makes sense after all
+    /// drawing is completed and display has been called. Not calling display
+    /// after subsequent drawing will lead to undefined behavior if a mipmap
+    /// had been previously generated.
+    ///
+    /// \return True if mipmap generation was successful, false if unsuccessful
+    ///
+    ////////////////////////////////////////////////////////////
+    bool generateMipmap();
+
     ////////////////////////////////////////////////////////////
     /// \brief Activate or deactivate the render-texture for rendering
     ///

include/SFML/Graphics/Texture.hpp

@@ -445,6 +445,31 @@ public:
     ////////////////////////////////////////////////////////////
     bool isRepeated() const;
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Generate a mipmap using the current texture data
+    ///
+    /// Mipmaps are pre-computed chains of optimized textures. Each
+    /// level of texture in a mipmap is generated by halving each of
+    /// the previous level's dimensions. This is done until the final
+    /// level has the size of 1x1. The textures generated in this process may
+    /// make use of more advanced filters which might improve the visual quality
+    /// of textures when they are applied to objects much smaller than they are.
+    /// This is known as minification. Because fewer texels (texture elements)
+    /// have to be sampled from when heavily minified, usage of mipmaps
+    /// can also improve rendering performance in certain scenarios.
+    ///
+    /// Mipmap generation relies on the necessary OpenGL extension being
+    /// available. If it is unavailable or generation fails due to another
+    /// reason, this function will return false. Mipmap data is only valid from
+    /// the time it is generated until the next time the base level image is
+    /// modified, at which point this function will have to be called again to
+    /// regenerate it.
+    ///
+    /// \return True if mipmap generation was successful, false if unsuccessful
+    ///
+    ////////////////////////////////////////////////////////////
+    bool generateMipmap();
+
     ////////////////////////////////////////////////////////////
     /// \brief Overload of assignment operator
     ///
@@ -532,6 +557,15 @@ private:
     ////////////////////////////////////////////////////////////
     static unsigned int getValidSize(unsigned int size);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Invalidate the mipmap if one exists
+    ///
+    /// This also resets the texture's minifying function.
+    /// This function is mainly for internal use by RenderTexture.
+    ///
+    ////////////////////////////////////////////////////////////
+    void invalidateMipmap();
+
     ////////////////////////////////////////////////////////////
     // Member data
     ////////////////////////////////////////////////////////////
@@ -543,6 +577,7 @@ private:
     bool         m_isRepeated;    ///< Is the texture in repeat mode?
     mutable bool m_pixelsFlipped; ///< To work around the inconsistency in Y orientation
     bool         m_fboAttachment; ///< Is this texture owned by a framebuffer object?
+    bool         m_hasMipmap;     ///< Has the mipmap been generated?
     Uint64       m_cacheId;       ///< Unique number that identifies the texture to the render target's cache
 };