diff --git a/.gitignore b/.gitignore
index 0580b8c..c0f36ab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,10 @@
+.DS_Store
+*~
+
 bin
 /dist
-/**/.DS_Store
 /library/macosx*
 /library/windows*
 /library/linux*
+
+local.properties
\ No newline at end of file
diff --git a/build.properties b/build.properties
deleted file mode 100644
index aa679cf..0000000
--- a/build.properties
+++ /dev/null
@@ -1,2 +0,0 @@
-core.classpath.location=../processing/core/library/
-compiler.classpath.location=../processing/java/mode/
diff --git a/build.xml b/build.xml
index 862d8a4..73c7cec 100755
--- a/build.xml
+++ b/build.xml
@@ -1,13 +1,40 @@
 <?xml version="1.0"?>
 <project name="Processing Video Library" default="build">
-  
-  <property file="./build.properties" />
+
+  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
+
+  <property file="local.properties" />
+
+  <condition property="props.present">
+    <available file="local.properties" />
+  </condition>
+
+  <fail unless="processing.dir"
+        message="To make the build work, create a file named local.properties, with a line that reads:
+${line.separator}processing.dir=/path/to/processing-git
+${line.separator}with the path to where you have the code for Processing 3 checked out. ${line.separator}(This script will look for the 'core' directory inside that folder.)" />
+
+  <subant buildpath="${processing.dir}/core" />
+
+  <property name="core.dir" value="${processing.dir}/core/library" />
+
+  <condition property="processing.built">
+    <available file="${core.dir}/core.jar" />
+  </condition>
+
+  <fail unless="processing.built"
+        message="Please first build Processing so that we have a usable core.jar to bundle with the app." />
+
+  <property name="core.classpath.location" value="${processing.dir}/core/library/" />
+  <property name="compiler.classpath.location" value="${processing.dir}/java/mode/" />
+
+  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
 
   <target name="clean" description="Clean the build directories">
     <delete dir="bin" />
     <delete file="library/video.jar" />
   </target>
-  
+
   <target name="compile" description="Compile sources">
     <condition property="core-built">
       <available file="${core.classpath.location}/core.jar" />
@@ -17,29 +44,29 @@
     <mkdir dir="bin" />
     <javac source="1.8"
 	   target="1.8"
-	   srcdir="src" destdir="bin" 
+	   srcdir="src" destdir="bin"
 	   encoding="UTF-8"
 	   includeAntRuntime="false"
 	   classpath="${core.classpath.location}/core.jar; library/gst1-java-core-1.2.0.jar; library/jna.jar"
 	   nowarn="true">
-      <compilerclasspath path="${compiler.classpath.location}/org.eclipse.jdt.core.jar; 
+      <compilerclasspath path="${compiler.classpath.location}/org.eclipse.jdt.core.jar;
                                ${compiler.classpath.location}/jdtCompilerAdapter.jar" />
     </javac>
   </target>
-  
+
   <target name="build" depends="compile" description="Build video library">
     <jar basedir="bin" destfile="library/video.jar" />
     <delete dir="bin" />
   </target>
-  
+
   <target name="dist" depends="build" description="Creates distribution package">
     <mkdir dir="dist/tmp/video" />
-    
+
    	<!-- copy library files (jar and gstreamer natives) -->
   	<copy todir="dist/tmp/video/library">
   		<fileset dir="library" />
 	  </copy>
-    
+
   	<!-- copy examples -->
   	<copy todir="dist/tmp/video/examples">
   		<fileset dir="examples" />
@@ -48,21 +75,21 @@
   	<!-- copy source -->
     <copy todir="dist/tmp/video/src">
   		<fileset dir="src" />
-	  </copy>	
-  	
+	  </copy>
+
     <!-- copy properties -->
-    <copy file="library.properties" tofile="dist/tmp/video/library.properties" /> 
-    
+    <copy file="library.properties" tofile="dist/tmp/video/library.properties" />
+
     <!-- create the java reference of the library -->
-    <mkdir dir="dist/tmp/video/reference" />	
-	  <javadoc bottom="Processing video library by The Processing Foundation. (c) 2011-20" 
+    <mkdir dir="dist/tmp/video/reference" />
+	  <javadoc bottom="Processing video library by The Processing Foundation. (c) 2011-20"
 			classpath="${core.classpath.location}/core.jar;library/gst1-java-core-1.2.0.jar;library/jna.jar;bin"
 			destdir="dist/tmp/video/reference"
-			verbose="false" 
-			stylesheetfile="resources/stylesheet.css" 
-			doctitle="Javadocs: Video" 
-			public="true" version="false" 
-			windowtitle="Javadocs: Video"> 			
+			verbose="false"
+			stylesheetfile="resources/stylesheet.css"
+			doctitle="Javadocs: Video"
+			public="true" version="false"
+			windowtitle="Javadocs: Video">
  		<link href="http://java.sun.com/javase/6/docs/api/" />
 		<link href="http://processing.googlecode.com/svn/trunk/processing/build/javadoc/core/" />
 		<taglet name="ExampleTaglet" path="resources/code" />
@@ -70,18 +97,18 @@
 		<!-- add packages to be added to reference. -->
 			<include name="**/*"/>
 		</fileset>
-	  </javadoc>    
-        
+	  </javadoc>
+
     <!-- create zip package -->
     <delete file="dist/video.zip"/>
 	  <zip destfile="dist/video.zip"
   		basedir="dist/tmp"
   		excludes="**/.DS_Store"
-	  />	
-	
+	  />
+
 	  <!-- copy properties to use by download manager -->
-    <copy file="library.properties" tofile="dist/video.txt" />	
-	
+    <copy file="library.properties" tofile="dist/video.txt" />
+
 	  <delete dir="dist/tmp" />
   </target>
 </project>