Shaders: don't test for ES3 at runtime.

This only generates code that will be never executed. Tested with Flat
and Phong, the other shaders don't have rendering tests yet but since
the change is the same, I assume it will work there as well.

src/Magnum/Shaders/DistanceFieldVector.cpp

@@ -67,15 +67,16 @@ template<UnsignedInt dimensions> DistanceFieldVector<dimensions>::DistanceFieldV
 
     GL::AbstractShaderProgram::attachShaders({vert, frag});
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         GL::AbstractShaderProgram::bindAttributeLocation(AbstractVector<dimensions>::Position::Location, "position");
         GL::AbstractShaderProgram::bindAttributeLocation(AbstractVector<dimensions>::TextureCoordinates::Location, "textureCoordinates");
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(GL::AbstractShaderProgram::link());
 

src/Magnum/Shaders/Flat.cpp

@@ -74,15 +74,16 @@ template<UnsignedInt dimensions> Flat<dimensions>::Flat(const Flags flags): _fla
 
     attachShaders({vert, frag});
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         bindAttributeLocation(Position::Location, "position");
         if(flags & Flag::Textured) bindAttributeLocation(TextureCoordinates::Location, "textureCoordinates");
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(link());
 

src/Magnum/Shaders/MeshVisualizer.cpp

@@ -106,10 +106,10 @@ MeshVisualizer::MeshVisualizer(const Flags flags): _flags{flags} {
     if(geom) attachShader(*geom);
     #endif
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         bindAttributeLocation(Position::Location, "position");
@@ -123,6 +123,7 @@ MeshVisualizer::MeshVisualizer(const Flags flags): _flags{flags} {
         }
         #endif
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(link());
 

src/Magnum/Shaders/Phong.cpp

@@ -110,10 +110,10 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
 
     attachShaders({vert, frag});
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         bindAttributeLocation(Position::Location, "position");
@@ -123,6 +123,7 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
         if(flags & (Flag::AmbientTexture|Flag::DiffuseTexture|Flag::SpecularTexture))
             bindAttributeLocation(TextureCoordinates::Location, "textureCoordinates");
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(link());
 

src/Magnum/Shaders/Vector.cpp

@@ -67,15 +67,16 @@ template<UnsignedInt dimensions> Vector<dimensions>::Vector() {
 
     GL::AbstractShaderProgram::attachShaders({vert,  frag});
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         GL::AbstractShaderProgram::bindAttributeLocation(AbstractVector<dimensions>::Position::Location, "position");
         GL::AbstractShaderProgram::bindAttributeLocation(AbstractVector<dimensions>::TextureCoordinates::Location, "textureCoordinates");
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(GL::AbstractShaderProgram::link());
 

src/Magnum/Shaders/VertexColor.cpp

@@ -67,15 +67,16 @@ template<UnsignedInt dimensions> VertexColor<dimensions>::VertexColor() {
 
     attachShaders({vert, frag});
 
+    /* ES3 has this done in the shader directly */
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     #ifndef MAGNUM_TARGET_GLES
     if(!GL::Context::current().isExtensionSupported<GL::Extensions::ARB::explicit_attrib_location>(version))
-    #else
-    if(!GL::Context::current().isVersionSupported(GL::Version::GLES300))
     #endif
     {
         bindAttributeLocation(Position::Location, "position");
         bindAttributeLocation(Color3::Location, "color"); /* Color4 is the same */
     }
+    #endif
 
     CORRADE_INTERNAL_ASSERT_OUTPUT(link());