Shaders: set VertexColor::Color attribute location to 3.

Locations 0, 1 and 2 are reserved for positions, texture coordinates and
normals.

src/Shaders/VertexColor.h

@@ -50,7 +50,7 @@ template<UnsignedInt dimensions> class MAGNUM_SHADERS_EXPORT VertexColor: public
         typedef Attribute<0, typename DimensionTraits<dimensions, Float>::VectorType> Position;
 
         /** @brief Vertex color */
-        typedef Attribute<1, Color3> Color;
+        typedef Attribute<3, Color3> Color;
 
         explicit VertexColor();
 

src/Shaders/VertexColor2D.vert

@@ -39,7 +39,7 @@ uniform highp mat3 transformationProjectionMatrix;
 
 #ifdef EXPLICIT_ATTRIB_LOCATION
 layout(location = 0) in highp vec2 position;
-layout(location = 1) in lowp vec3 color;
+layout(location = 3) in lowp vec3 color;
 #else
 in highp vec2 position;
 in lowp vec3 color;

src/Shaders/VertexColor3D.vert

@@ -39,7 +39,7 @@ uniform highp mat4 transformationProjectionMatrix;
 
 #ifdef EXPLICIT_ATTRIB_LOCATION
 layout(location = 0) in highp vec4 position;
-layout(location = 1) in lowp vec3 color;
+layout(location = 3) in lowp vec3 color;
 #else
 in highp vec4 position;
 in lowp vec3 color;