Marking some non-implemented features as "won't be supported".

doc/required-extensions.dox

@@ -24,6 +24,7 @@ supported on Intel GPUs even if they are capable of OpenGL 2.1 only).
 - @subpage requires-extension
 - @subpage requires-gles30
 - @subpage requires-es-extension
+- @subpage unsupported
 
 @page requires-gl Functionality requiring desktop OpenGL (not available on OpenGL ES)
 @page requires-gl30 Functionality requiring OpenGL 3.0

doc/unsupported.dox

@@ -0,0 +1,22 @@
+/** @page unsupported Unsupported OpenGL features
+
+Some functionality, which is either soon-to-be deprecated or isn't proven to
+add any performance gains, is not supported in %Magnum.
+
+@section unsupported-features Unsupported features
+
+- Luminance texture formats (OpenGL ES) are not supported, as they are
+  deprecated in OpenGL ES 3.0 and not present in core desktop OpenGL.
+- Fixed precision data types (OpenGL ES) are not supported, as they occupy the
+  same memory as floats and they aren't faster than floats on current hardware
+  anymore.
+
+@section unsupported-extensions Unsupported extensions
+
+- @extension{INTEL,map_texture} negatively affects texture access performance.
+  Combination of buffer mapping and pixel buffers might be of the same or
+  better performance, without affecting texture access speed.
+- @extension{NV,draw_texture} can be done with framebuffer blitting and
+  doesn't make any full-screen postprocessing easier, as shaders are excluded.
+
+*/

src/Extensions.h

@@ -127,11 +127,14 @@ namespace GL {
         _extension(GL,EXT,transform_feedback,           GL210, GL300) // #352
         _extension(GL,EXT,direct_state_access,          GL210,  None) // #353
         _extension(GL,EXT,texture_snorm,                GL300, GL310) // #365
+    } namespace INTEL {
+        /* INTEL_map_texture not supported */                         // #429
     } namespace NV {
         _extension(GL,NV,half_float,                    GL210, GL300) // #283
         _extension(GL,NV,primitive_restart,             GL210, GL310) // #285
         _extension(GL,NV,depth_buffer_float,            GL210, GL300) // #334
         _extension(GL,NV,conditional_render,            GL210, GL300) // #346
+        /* NV_draw_texture not supported */                           // #430
     }
 }
 #undef _extension

src/Mesh.h

@@ -97,7 +97,6 @@ more information.
 @todo Support for normalized values (e.g. for color as char[4] passed to
      shader as floating-point vec4)
 @todo Support for packed unsigned integer types for attributes (OpenGL 3.3, @extension{ARB,vertex_type_2_10_10_10_rev})
-@todo Support for fixed precision type for attributes (OpenGL 4.1, @extension{ARB,ES2_compatibility})
 @todo Support for double type for attributes (OpenGL 4.1, @extension{ARB,vertex_attrib_64bit})
 @todo Support for indirect draw buffer (OpenGL 4.0, @extension{ARB,draw_indirect})
 @todo Redo in a way that allows glMultiDrawArrays, glDrawArraysInstanced etc.