diff --git a/src/main/java/pythagoras/f/AbstractVector.java b/src/main/java/pythagoras/f/AbstractVector.java
new file mode 100644
index 0000000..e12f97a
--- /dev/null
+++ b/src/main/java/pythagoras/f/AbstractVector.java
@@ -0,0 +1,198 @@
+//
+// Pythagoras - a collection of geometry classes
+// http://github.com/samskivert/pythagoras
+
+package pythagoras.f;
+
+import pythagoras.util.Platform;
+
+/**
+ * Provides most of the implementation of {@link IVector}, obtaining only x and y from the derived
+ * class.
+ */
+public abstract class AbstractVector implements IVector
+{
+    @Override // from interface IVector
+    public float dot (IVector other) {
+        return getX()*other.getX() + getY()*other.getY();
+    }
+
+    @Override // from interface IVector
+    public Vector negate () {
+        return negate(new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector negate (Vector result) {
+        return result.set(-getX(), -getY());
+    }
+
+    @Override // from interface IVector
+    public Vector normalize () {
+        return normalize(new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector normalize (Vector result) {
+        return mult(1f / length(), result);
+    }
+
+    @Override // from interface IVector
+    public float angle (IVector other) {
+        float cos = dot(other) / (length() * other.length());
+        return cos >= 1f ? 0f : FloatMath.acos(cos);
+    }
+
+    @Override // from interface IVector
+    public float direction (IVector other) {
+        return FloatMath.atan2(other.getY() - getY(), other.getX() - getX());
+    }
+
+    @Override // from interface IVector
+    public float length () {
+        return FloatMath.sqrt(lengthSq());
+    }
+
+    @Override // from interface IVector
+    public float lengthSq () {
+        float x = getX(), y = getY();
+        return (x*x + y*y);
+    }
+
+    @Override // from interface IVector
+    public float distance (IVector other) {
+        return FloatMath.sqrt(distanceSq(other));
+    }
+
+    @Override // from interface IVector
+    public float distanceSq (IVector other) {
+        float dx = getX() - other.getX(), dy = getY() - other.getY();
+        return dx*dx + dy*dy;
+    }
+
+    @Override // from interface IVector
+    public Vector mult (float v) {
+        return mult(v, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector mult (float v, Vector result) {
+        return result.set(getX()*v, getY()*v);
+    }
+
+    @Override // from interface IVector
+    public Vector mult (IVector other) {
+        return mult(other, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector mult (IVector other, Vector result) {
+        return result.set(getX()*other.getX(), getY()*other.getY());
+    }
+
+    @Override // from interface IVector
+    public Vector add (IVector other) {
+        return add(other, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector add (IVector other, Vector result) {
+        return add(other.getX(), other.getY(), result);
+    }
+
+    @Override // from interface IVector
+    public Vector subtract (IVector other) {
+        return subtract(other, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector subtract (IVector other, Vector result) {
+        return add(-other.getX(), -other.getY(), result);
+    }
+
+    @Override // from interface IVector
+    public Vector add (float x, float y) {
+        return add(x, y, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector add (float x, float y, Vector result) {
+        return result.set(getX() + x, getY() + y);
+    }
+
+    @Override // from interface IVector
+    public Vector addScaled (IVector other, float v) {
+        return addScaled(other, v, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector addScaled (IVector other, float v, Vector result) {
+        return result.set(getX() + other.getX()*v, getY() + other.getY()*v);
+    }
+
+    @Override // from interface IVector
+    public Vector rotate (float angle) {
+        return rotate(angle, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector rotate (float angle, Vector result) {
+        float x = getX(), y = getY();
+        float sina = FloatMath.sin(angle), cosa = FloatMath.cos(angle);
+        return result.set(x*cosa - y*sina, x*sina + y*cosa);
+    }
+
+    @Override // from interface IVector
+    public Vector rotateAndAdd (float angle, IVector add, Vector result) {
+        float x = getX(), y = getY();
+        float sina = FloatMath.sin(angle), cosa = FloatMath.cos(angle);
+        return result.set(x*cosa - y*sina + add.getX(), x*sina + y*cosa + add.getY());
+    }
+
+    @Override // from interface IVector
+    public Vector rotateScaleAndAdd (float angle, float scale, IVector add, Vector result) {
+        float x = getX(), y = getY();
+        float sina = FloatMath.sin(angle), cosa = FloatMath.cos(angle);
+        return result.set((x*cosa - y*sina)*scale + add.getX(),
+                          (x*sina + y*cosa)*scale + add.getY());
+    }
+
+    @Override // from interface IVector
+    public Vector lerp (IVector other, float t) {
+        return lerp(other, t, new Vector());
+    }
+
+    @Override // from interface IVector
+    public Vector lerp (IVector other, float t, Vector result) {
+        float x = getX(), y = getY();
+        float dx = other.getX() - x, dy = other.getY() - y;
+        return result.set(x + t*dx, y + t*dy);
+    }
+
+    @Override // from interface IVector
+    public Vector clone () {
+        return new Vector(this);
+    }
+
+    @Override
+    public boolean equals (Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (obj instanceof AbstractVector) {
+            AbstractVector p = (AbstractVector)obj;
+            return getX() == p.getX() && getY() == p.getY();
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode () {
+        return Platform.hashCode(getX()) ^ Platform.hashCode(getY());
+    }
+
+    @Override
+    public String toString () {
+        return Vectors.vectorToString(getX(), getY());
+    }
+}
diff --git a/src/main/java/pythagoras/f/IVector.java b/src/main/java/pythagoras/f/IVector.java
new file mode 100644
index 0000000..87a4734
--- /dev/null
+++ b/src/main/java/pythagoras/f/IVector.java
@@ -0,0 +1,132 @@
+//
+// Pythagoras - a collection of geometry classes
+// http://github.com/samskivert/pythagoras
+
+package pythagoras.f;
+
+/**
+ * Provides read-only access to a {@link Vector}.
+ */
+public interface IVector
+{
+    /** Returns the x-component of this vector. */
+    float getX ();
+
+    /** Returns the y-component of this vector. */
+    float getY ();
+
+    /** Computes and returns the dot product of this and the specified other vector. */
+    float dot (IVector other);
+
+    /** Negates this vector.
+     * @return a new vector containing the result. */
+    Vector negate ();
+
+    /** Negates this vector, storing the result in the supplied object.
+     * @return a reference to the result, for chaining. */
+    Vector negate (Vector result);
+
+    /** Normalizes this vector.
+     * @return a new vector containing the result. */
+    Vector normalize ();
+
+    /** Normalizes this vector, storing the result in the object supplied.
+     * @return a reference to the result, for chaining. */
+    Vector normalize (Vector result);
+
+    /** Returns the angle between this vector and the specified other vector. */
+    float angle (IVector other);
+
+    /** Returns the direction of a vector pointing from this point to the specified other point. */
+    float direction (IVector other);
+
+    /** Returns the length of this vector. */
+    float length ();
+
+    /** Returns the squared length of this vector. */
+    float lengthSq ();
+
+    /** Returns the distance from this vector to the specified other vector. */
+    float distance (IVector other);
+
+    /** Returns the squared distance from this vector to the specified other. */
+    float distanceSq (IVector other);
+
+    /** Multiplies this vector by a scalar.
+     * @return a new vector containing the result. */
+    Vector mult (float v);
+
+    /** Multiplies this vector by a scalar and places the result in the supplied object.
+     * @return a reference to the result, for chaining. */
+    Vector mult (float v, Vector result);
+
+    /** Multiplies this vector by another.
+     * @return a new vector containing the result. */
+    Vector mult (IVector other);
+
+    /** Multiplies this vector by another, storing the result in the object provided.
+     * @return a reference to the result vector, for chaining. */
+    Vector mult (IVector other, Vector result);
+
+    /** Adds a vector to this one.
+     * @return a new vector containing the result. */
+    Vector add (IVector other);
+
+    /** Adds a vector to this one, storing the result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Vector add (IVector other, Vector result);
+
+    /** Adds a vector to this one.
+     * @return a new vector containing the result. */
+    Vector add (float x, float y);
+
+    /** Adds a vector to this one and stores the result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Vector add (float x, float y, Vector result);
+
+    /** Adds a scaled vector to this one.
+     * @return a new vector containing the result. */
+    Vector addScaled (IVector other, float v);
+
+    /** Adds a scaled vector to this one and stores the result in the supplied vector.
+     * @return a reference to the result, for chaining. */
+    Vector addScaled (IVector other, float v, Vector result);
+
+    /** Subtracts a vector from this one.
+     * @return a new vector containing the result. */
+    Vector subtract (IVector other);
+
+    /** Subtracts a vector from this one and places the result in the supplied object.
+     * @return a reference to the result, for chaining. */
+    Vector subtract (IVector other, Vector result);
+
+    /** Rotates this vector by the specified angle.
+     * @return a new vector containing the result. */
+    Vector rotate (float angle);
+
+    /** Rotates this vector by the specified angle, storing the result in the vector provided.
+     * @return a reference to the result vector, for chaining. */
+    Vector rotate (float angle, Vector result);
+
+    /** Rotates this vector by the specified angle and adds another vector to it, placing the
+     * result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Vector rotateAndAdd (float angle, IVector add, Vector result);
+
+    /** Rotates this vector by the specified angle, applies a uniform scale, and adds another
+     * vector to it, placing the result in the object provided.
+     * @return a reference to the result, for chaining. */
+    Vector rotateScaleAndAdd (float angle, float scale, IVector add, Vector result);
+
+    /** Linearly interpolates between this and the specified other vector by the supplied amount.
+     * @return a new vector containing the result. */
+    Vector lerp (IVector other, float t);
+
+    /** Linearly interpolates between this and the supplied other vector by the supplied amount,
+     * storing the result in the supplied object.
+     * @return a reference to the result, for chaining. */
+    Vector lerp (IVector other, float t, Vector result);
+
+    /** Returns a mutable copy of this vector. */
+    Vector clone ();
+}
diff --git a/src/main/java/pythagoras/f/Transform.java b/src/main/java/pythagoras/f/Transform.java
new file mode 100644
index 0000000..b2bd6f1
--- /dev/null
+++ b/src/main/java/pythagoras/f/Transform.java
@@ -0,0 +1,103 @@
+//
+// Pythagoras - a collection of geometry classes
+// http://github.com/samskivert/pythagoras
+
+package pythagoras.f;
+
+/**
+ * Represents a geometric transform. Specialized implementations exist for identity, rigid body,
+ * uniform, affine and general transforms.
+ */
+public interface Transform
+{
+    /** Sets the translation component of this transform.
+     * @throws UnsupportedOperationException if the transform is not rigid body or greater. */
+    void setTranslation (float tx, float ty);
+
+    /** Sets the x-component of this transform's translation.
+     * @throws UnsupportedOperationException if the transform is not rigid body or greater. */
+    void setTx (float tx);
+
+    /** Sets the y-component of this transform's translation.
+     * @throws UnsupportedOperationException if the transform is not rigid body or greater. */
+    void setTy (float ty);
+
+    /** Sets the rotation component of this transform.
+     * @throws UnsupportedOperationException if the transform is not rigid body or greater. */
+    void setRotation (float angle);
+
+    /** Sets the uniform scale of this transform.
+     * @throws UnsupportedOperationException if the transform is not uniform or greater. */
+    void setScale (float scale);
+
+    /** Sets the x and y scale of this transform.
+     * @throws UnsupportedOperationException if the transform is not affine or greater. */
+    void setScale (float scaleX, float scaleY);
+
+    /** Sets the x scale of this transform.
+     * @throws UnsupportedOperationException if the transform is not affine or greater. */
+    void setScaleX (float scaleX);
+
+    /** Sets the y scale of this transform.
+     * @throws UnsupportedOperationException if the transform is not affine or greater. */
+    void setScaleY (float scaleY);
+
+    /** Sets the affine transform matrix.
+     * @throws UnsupportedOperationException if the transform is not affine or greater. */
+    void setTransform (float m00, float m01, float m10, float m11,
+                       float tx, float ty);
+
+    /** Sets the general transform matrix.
+     * @throws UnsupportedOperationException if the transform is not general. */
+    void setTransform (float m00, float m01, float m02,
+                       float m10, float m11, float m12,
+                       float m20, float m21, float m22);
+
+    /** Returns the x-coordinate of the translation component. */
+    float getTx ();
+
+    /** Returns the y-coordinate of the translation component. */
+    float getTy ();
+
+    /** Returns the rotation applied by this transform. Note that the rotation is extracted and
+     * therefore approximate for affine and general transforms. */
+    float getRotation (); // will be extracted from affine+
+
+    /** Returns the uniform scale applied by this transform. Note that the uniform scale will be
+     * approximated for non-uniform transforms (affine and general). */
+    float getScale (); // will be extracted/approximated for affine+
+
+    /** Returns the x-component of the scale applied by this transform. */
+    float getScaleX (); // will be extracted from affine+
+
+    /** Returns the y-component of the scale applied by this transform. */
+    float getScaleY (); // will be extracted from affine+
+
+    /** Returns the inverse of this transform.
+     * @throws NoninvertibleTransformException if the transform is not invertible. */
+    Transform invert ();
+
+    /** Composes this transform with the supplied transform (i.e. {@code this x other}). */
+    Transform compose (Transform other);
+
+    /** Returns the linear interpolation between this transform and the specified other. */
+    Transform lerp (Transform other, float t);
+
+    /** Transforms the supplied point, writing the result into {@code into}, which may reference
+     * the same object as {@code p}. */
+    void transform (IPoint p, Point into);
+
+    /** Inverse transforms the supplied point, writing the result into {@code into}, which may
+     * reference the same object as {@code p}.
+     * @throws NoninvertibleTransformException if the transform is not invertible. */
+    void inverseTransform (IPoint p, Point into);
+
+    /** Transforms the supplied vector, writing the result into {@code into}, which may reference
+     * the same object as {@code v}. */
+    void transform (IVector v, Vector into);
+
+    /** Inverse transforms the supplied vector, writing the result into {@code into}, which may
+     * reference the same object as {@code v}.
+     * @throws NoninvertibleTransformException if the transform is not invertible. */
+    void inverseTransform (IVector v, Vector into);
+}
diff --git a/src/main/java/pythagoras/f/Vector.java b/src/main/java/pythagoras/f/Vector.java
new file mode 100644
index 0000000..43751f7
--- /dev/null
+++ b/src/main/java/pythagoras/f/Vector.java
@@ -0,0 +1,121 @@
+//
+// Pythagoras - a collection of geometry classes
+// http://github.com/samskivert/pythagoras
+
+package pythagoras.f;
+
+/**
+ * Represents a vector in a plane.
+ */
+public class Vector extends AbstractVector
+{
+    /** The x-component of the vector. */
+    public float x;
+
+    /** The y-component of the vector. */
+    public float y;
+
+    /** Creates a vector with the specified x and y components. */
+    public Vector (float x, float y) {
+        set(x, y);
+    }
+
+    /** Creates a vector equal to {@code other}. */
+    public Vector (IVector other) {
+        set(other);
+    }
+
+    /** Creates a vector with zero x and y components. */
+    public Vector () {
+    }
+
+    @Override // from AbstractVector
+    public float getX () {
+        return x;
+    }
+
+    @Override // from AbstractVector
+    public float getY () {
+        return y;
+    }
+
+    /** Negates this vector in-place.
+     * @return a reference to this vector, for chaining. */
+    public Vector negateLocal () {
+        return negate(this);
+    }
+
+    /** Normalizes this vector in-place.
+     * @return a reference to this vector, for chaining. */
+    public Vector normalizeLocal () {
+        return normalize(this);
+    }
+
+    /** Multiplies this vector in-place by a scalar.
+     * @return a reference to this vector, for chaining. */
+    public Vector multLocal (float v) {
+        return mult(v, this);
+    }
+
+    /** Multiplies this vector in-place by another.
+     * @return a reference to this vector, for chaining. */
+    public Vector multLocal (IVector other) {
+        return mult(other, this);
+    }
+
+    /** Adds a vector in-place to this one.
+     * @return a reference to this vector, for chaining. */
+    public Vector addLocal (IVector other) {
+        return add(other, this);
+    }
+
+    /** Subtracts a vector in-place from this one.
+     * @return a reference to this vector, for chaining. */
+    public Vector subtractLocal (IVector other) {
+        return subtract(other, this);
+    }
+
+    /** Adds a vector in-place to this one.
+     * @return a reference to this vector, for chaining. */
+    public Vector addLocal (float x, float y) {
+        return add(x, y, this);
+    }
+
+    /** Adds a scaled vector in-place to this one.
+     * @return a reference to this vector, for chaining. */
+    public Vector addScaledLocal (IVector other, float v) {
+        return addScaled(other, v, this);
+    }
+
+    /** Rotates this vector in-place by the specified angle.
+     * @return a reference to this vector, for chaining. */
+    public Vector rotateLocal (float angle) {
+        return rotate(angle, this);
+    }
+
+    /** Linearly interpolates between this and {@code other} in-place by the supplied amount.
+     * @return a reference to this vector, for chaining. */
+    public Vector lerpLocal (IVector other, float t) {
+        return lerp(other, t, this);
+    }
+
+    /** Copies the elements of another vector.
+     * @return a reference to this vector, for chaining. */
+    public Vector set (IVector other) {
+        return set(other.getX(), other.getY());
+    }
+
+    /** Copies the elements of an array.
+     * @return a reference to this vector, for chaining. */
+    public Vector set (float[] values) {
+        return set(values[0], values[1]);
+    }
+
+    /** Sets all of the elements of the vector.
+     * @return a reference to this vector, for chaining. */
+    public Vector set (float x, float y) {
+        this.x = x;
+        this.y = y;
+        return this;
+    }
+}
diff --git a/src/main/java/pythagoras/f/Vectors.java b/src/main/java/pythagoras/f/Vectors.java
new file mode 100644
index 0000000..7f1dfc8
--- /dev/null
+++ b/src/main/java/pythagoras/f/Vectors.java
@@ -0,0 +1,40 @@
+//
+// Pythagoras - a collection of geometry classes
+// http://github.com/samskivert/pythagoras
+
+package pythagoras.f;
+
+/**
+ * Vector-related utility methods.
+ */
+public class Vectors
+{
+    /** A unit vector in the X+ direction. */
+    public static final IVector UNIT_X = new Vector(1f, 0f);
+
+    /** A unit vector in the Y+ direction. */
+    public static final IVector UNIT_Y = new Vector(0f, 1f);
+
+    /** The zero vector. */
+    public static final IVector ZERO = new Vector(0f, 0f);
+
+    /** A vector containing the minimum floating point value for all components
+     * (note: the components are -{@link Float#MAX_VALUE}, not {@link Float#MIN_VALUE}). */
+    public static final IVector MIN_VALUE = new Vector(-Float.MAX_VALUE, -Float.MAX_VALUE);
+
+    /** A vector containing the maximum floating point value for all components. */
+    public static final IVector MAX_VALUE = new Vector(Float.MAX_VALUE, Float.MAX_VALUE);
+
+    /**
+     * Returns a string describing the supplied vector, of the form <code>+x+y</code>,
+     * <code>+x-y</code>, <code>-x-y</code>, etc.
+     */
+    public static String vectorToString (float x, float y) {
+        StringBuilder buf = new StringBuilder();
+        if (x >= 0) buf.append("+");
+        buf.append(x);
+        if (y >= 0) buf.append("+");
+        buf.append(y);
+        return buf.toString();
+    }
+}