Distance field EffectMode (#1546)

* Distance field EffectMode (supports MSDF and the regular sort)

Data/Shaders/GLSL/Distance field.frag

@@ -0,0 +1,27 @@
+uniform sampler2D Texture1;
+
+varying vec2 texCoords;
+varying vec4 vertexColor;
+
+float aastep(float threshold, float dist) {
+	float afwidth = 0.75 * length(vec2(dFdx(dist), dFdy(dist)));
+	return smoothstep(threshold - afwidth, threshold + afwidth, dist);
+}
+
+float median(float r, float g, float b) {
+	return max(min(r, g), min(max(r, g), b));
+}
+
+const float distanceThreshold = 0.5;
+
+float sample(vec2 tc) {
+	vec3 texel = texture2D(Texture1, tc).rgb;
+	float dist = median(texel.r, texel.g, texel.b);
+	return aastep(distanceThreshold, dist);
+}
+
+void main(void)
+{
+	float dfValue = sample(texCoords);
+	gl_FragColor = vec4(vertexColor.rgb, vertexColor.a * dfValue);
+}

Data/Shaders/GLSL/Distance field.vert

@@ -0,0 +1,10 @@
+//We need this shader to pass the vertex color to the frag shader
+
+varying vec4 vertexColor;
+varying vec2 texCoords;
+
+void main(void) {
+	vertexColor = gl_Color;
+	texCoords = gl_MultiTexCoord0.st;
+	gl_Position = gl_Vertex * gl_ModelViewProjectionMatrix;
+}