Reverted interval in distancefield-related things.

1.0 is taken as shape center (white), 0.0 as shape surroundings (black).
It was unintuitive to have it reverted, updated documentation to make it
right.

src/Shaders/DistanceFieldVector.frag

@@ -32,12 +32,12 @@
 #ifdef EXPLICIT_UNIFORM_LOCATION
 layout(location = 1) uniform lowp vec4 color;
 layout(location = 2) uniform lowp vec4 outlineColor;
-layout(location = 3) uniform lowp vec2 outlineRange = vec2(0.5, 0.0);
+layout(location = 3) uniform lowp vec2 outlineRange = vec2(0.5, 1.0);
 layout(location = 4) uniform lowp float smoothness = 0.04;
 #else
 uniform lowp vec4 color;
 uniform lowp vec4 outlineColor;
-uniform lowp vec2 outlineRange = vec2(0.5, 0.0);
+uniform lowp vec2 outlineRange = vec2(0.5, 1.0);
 uniform lowp float smoothness = 0.04;
 #endif
 #else
@@ -66,9 +66,9 @@ void main() {
     fragmentColor = smoothstep(outlineRange.x-smoothness, outlineRange.x+smoothness, intensity)*color;
 
     /* Outline */
-    if(outlineRange.x < outlineRange.y) {
+    if(outlineRange.x > outlineRange.y) {
         lowp float mid = (outlineRange.x + outlineRange.y)/2.0;
-        lowp float half = (outlineRange.y - outlineRange.x)/2.0;
+        lowp float half = (outlineRange.x - outlineRange.y)/2.0;
         fragmentColor += smoothstep(half+smoothness, half-smoothness, distance(mid, intensity))*outlineColor;
     }
 }

src/Shaders/DistanceFieldVector.h

@@ -81,12 +81,12 @@ template<UnsignedInt dimensions> class MAGNUM_SHADERS_EXPORT DistanceFieldVector
          * @return Pointer to self (for method chaining)
          *
          * Parameter @p start describes where fill ends and possible outline
-         * starts. Initial value is `0.5f`, smaller values will make the vector
-         * art look thinner, larger will make it look thicker.
+         * starts. Initial value is `0.5f`, larger values will make the vector
+         * art look thinner, smaller will make it look thicker.
          *
          * Parameter @p end describes where outline ends. If set to value
-         * smaller than @p start the outline is not drawn. Initial value is
-         * `0.0f`.
+         * larger than @p start the outline is not drawn. Initial value is
+         * `1.0f`.
          *
          * @see setOutlineColor()
          */

src/TextureTools/DistanceField.h

@@ -56,9 +56,9 @@ foundation for features like outlining, glow or drop shadow essentialy for free.
 For each pixel inside @p rectangle the algorithm looks at corresponding pixel in
 @p input and tries to find nearest pixel of opposite color in area given by
 @p radius. Signed distance between the points is then saved as value of given
-pixel in @p output. Value of `0` means that the pixel was originally colored
-white and nearest black pixel is farther than @p radius, value of `1` means that
-the pixel was originally black and nearest white pixel is farther than
+pixel in @p output. Value of `1.0` means that the pixel was originally colored
+white and nearest black pixel is farther than @p radius, value of `0.0` means
+that the pixel was originally black and nearest white pixel is farther than
 @p radius. Values around `0.5` are around edges.
 
 The resulting texture can be used with bilinear filtering. It can be converted