Add DistanceFade.hx shader

h3d/shader/DistanceFade.hx

@@ -0,0 +1,31 @@
+package h3d.shader;
+
+class DistanceFade extends hxsl.Shader {
+
+	static var SRC = {
+		@param @const var nearFadeEnabled : Bool;
+		@param var nearMinFade : Float;
+		@param var nearMaxFade : Float;
+
+		@param @const var farFadeEnabled : Bool;
+		@param var farMinFade : Float;
+		@param var farMaxFade : Float;
+
+		@:import h3d.shader.BaseMesh;
+
+		function fragment() {
+			var distFromCam = length(transformedPosition - camera.position);
+
+			var alphaNear = 1.0;
+			var alphaFar =  1.0;
+
+			if (farFadeEnabled)
+				alphaFar = 1.0 - saturate((distFromCam - farMinFade) / (farMaxFade - farMinFade));
+
+			if (nearFadeEnabled)
+				alphaNear = saturate((distFromCam - nearMinFade) / (nearMaxFade - nearMinFade));
+
+			pixelColor.a *= min(alphaFar, alphaNear);
+		}
+	};
+}