added anisotropic filtering support

include/ACGL/OpenGL/Objects/Texture.hh

@@ -112,6 +112,27 @@ public:
         openGLRareError();
     }
 
+    //! _sampleCount = 1.0 to deactivate anisotrop filtering, maximum is often 16. If a value is too high it will get clamped to the maximum
+    void setAnisotropicFilter( GLfloat _sampleCount )
+    {
+#ifdef ACGL_USE_GLEW
+        if (GLEW_EXT_texture_filter_anisotropic) {
+            GLfloat maxAnisotropicSamples;
+            glGetFloatv( GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &maxAnisotropicSamples );
+            _sampleCount = std::max( 1.0f, _sampleCount );
+            _sampleCount = std::min( maxAnisotropicSamples, _sampleCount );
+            glBindTexture(mTarget, mContext);
+            glTexParameterf( mTarget, GL_TEXTURE_MAX_ANISOTROPY_EXT, _sampleCount);
+            openGLRareError();
+        } else
+#endif
+        {
+            // anisotropic filtering will just increase the image quality, so this is just
+            // a warning and no error
+            ACGL::Utils::warning() << "Anisotropic filtering is not supported, ignored" << std::endl;
+        }
+    }
+
     //! Set texture data for 1D, 2D or 3D textures
     inline void setImageData(const GLvoid* _pData = NULL)
     {