Index: src/OFMatrix4x4.h
==================================================================
--- src/OFMatrix4x4.h
+++ src/OFMatrix4x4.h
@@ -68,8 +68,22 @@
  *	  and the receiver on the right side.
  *
  * @param matrix The matrix to multiply the receiver with
  */
 - (void)multiplyWithMatrix: (OFMatrix4x4 *)matrix;
+
+/**
+ * @brief Transforms the specified 3D vector according to the matrix.
+ *
+ * As multiplying a 4x4 matrix with a 3D vector is not defined, this extends
+ * the 3D vector to a 4D vector with its `w` value being set to 0 and just
+ * discards the `w` value of the resulting 4D vector for the returned 3D
+ * vector. This allows reducing the number number of calculations performed and
+ * is mostly useful for 3D graphics.
+ *
+ * @param vector The 3D vector to transform
+ * @return The transformed 3D vector
+ */
+- (OFVector3D)transformedVector3D: (OFVector3D)vector;
 @end
 
 OF_ASSUME_NONNULL_END

Index: src/OFMatrix4x4.m
==================================================================
--- src/OFMatrix4x4.m
+++ src/OFMatrix4x4.m
@@ -181,10 +181,21 @@
 	_values[15] = matrix->_values[3] * copy[12] +
 	    matrix->_values[7] * copy[13] +
 	    matrix->_values[11] * copy[14] +
 	    matrix->_values[15] * copy[15];
 }
+
+- (OFVector3D)transformedVector3D: (OFVector3D)vector
+{
+	return OFMakeVector3D(
+	    _values[0] * vector.x + _values[4] * vector.y +
+	    _values[8] * vector.z,
+	    _values[1] * vector.x + _values[5] * vector.y +
+	    _values[9] * vector.z,
+	    _values[2] * vector.x + _values[6] * vector.y +
+	    _values[10] * vector.z);
+}
 
 - (OFString *)description
 {
 	return [OFString stringWithFormat:
 	    @"<OFMatrix4x4: {\n"

Index: tests/OFMatrix4x4Tests.m
==================================================================
--- tests/OFMatrix4x4Tests.m
+++ tests/OFMatrix4x4Tests.m
@@ -22,10 +22,11 @@
 @implementation TestsAppDelegate (OFMatrix4x4Tests)
 - (void)matrix4x4Tests
 {
 	void *pool = objc_autoreleasePoolPush();
 	OFMatrix4x4 *matrix, *matrix2;
+	OFVector3D vec3;
 
 	TEST(@"+[identityMatrix]",
 	    memcmp([[OFMatrix4x4 identityMatrix] values], (float [16]){
 		1, 0, 0, 0,
 		0, 1, 0, 0,
@@ -84,8 +85,12 @@
 		10000, 22800, 35600, 48400,
 		11000, 25400, 39800, 54200,
 		12000, 28000, 44000, 60000
 	    }]])
 
+	TEST(@"-[transformedVector3D:]",
+	    R((vec3 = [matrix transformedVector3D: OFMakeVector3D(1, 2, 3)])) &&
+	    vec3.x == 14 && vec3.y == 38 && vec3.z == 62)
+
 	objc_autoreleasePoolPop(pool);
 }
 @end