Shaders: fix port of *Vector shaders to old GLSL.

Texture layer binding was never set and there were various GLSL
compilation errors.

src/Shaders/DistanceFieldVector.cpp

@@ -85,8 +85,16 @@ template<UnsignedInt dimensions> DistanceFieldVector<dimensions>::DistanceFieldV
 
     #ifndef MAGNUM_TARGET_GLES
     if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::shading_language_420pack>())
+    #endif
+    {
         AbstractShaderProgram::setUniform(AbstractShaderProgram::uniformLocation("vectorTexture"),
                                           AbstractVector<dimensions>::VectorTextureLayer);
+    }
+
+    /* Set defaults in OpenGL ES (for desktop they are set in shader code itself) */
+    #ifdef MAGNUM_TARGET_GLES
+    setOutlineRange(0.5f, 1.0f);
+    setSmoothness(0.04f);
     #endif
 }
 

src/Shaders/DistanceFieldVector.frag

@@ -25,6 +25,7 @@
 #ifndef NEW_GLSL
 #define in varying
 #define fragmentColor gl_FragColor
+#define texture texture2D
 #endif
 
 #ifndef GL_ES
@@ -52,10 +53,10 @@ layout(binding = 16) uniform sampler2D vectorTexture;
 uniform lowp sampler2D vectorTexture;
 #endif
 
-in vec2 fragmentTextureCoordinates;
+in mediump vec2 fragmentTextureCoordinates;
 
 #ifdef NEW_GLSL
-out vec4 fragmentColor;
+out lowp vec4 fragmentColor;
 #endif
 
 void main() {

src/Shaders/Vector.cpp

@@ -82,8 +82,10 @@ template<UnsignedInt dimensions> Vector<dimensions>::Vector(): transformationPro
 
     #ifndef MAGNUM_TARGET_GLES
     if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::shading_language_420pack>())
-        AbstractShaderProgram::setUniform(AbstractShaderProgram::uniformLocation("vectorTexture"), AbstractVector<dimensions>::VectorTextureLayer);
     #endif
+    {
+        AbstractShaderProgram::setUniform(AbstractShaderProgram::uniformLocation("vectorTexture"), AbstractVector<dimensions>::VectorTextureLayer);
+    }
 }
 
 template class Vector<2>;

src/Shaders/Vector.frag

@@ -25,6 +25,7 @@
 #ifndef NEW_GLSL
 #define in varying
 #define fragmentColor gl_FragColor
+#define texture texture2D
 #endif
 
 #ifdef EXPLICIT_UNIFORM_LOCATION
@@ -39,10 +40,10 @@ layout(binding = 16) uniform sampler2D vectorTexture;
 uniform lowp sampler2D vectorTexture;
 #endif
 
-in vec2 fragmentTextureCoordinates;
+in mediump vec2 fragmentTextureCoordinates;
 
 #ifdef NEW_GLSL
-out vec4 fragmentColor;
+out lowp vec4 fragmentColor;
 #endif
 
 void main() {