diff --git a/core/test/processing/core/PMatrix3DTest.java b/core/test/processing/core/PMatrix3DTest.java
new file mode 100644
index 000000000..7cb03a63a
--- /dev/null
+++ b/core/test/processing/core/PMatrix3DTest.java
@@ -0,0 +1,226 @@
+package processing.core;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+public class PMatrix3DTest {
+
+  @Test
+  public void testConstructorsResetAndGet() {
+    PMatrix3D m = new PMatrix3D();
+    float[] vals = m.get(null);
+    assertEquals(1, vals[0], 1e-6);
+    assertEquals(1, vals[5], 1e-6);
+    assertEquals(1, vals[10], 1e-6);
+    assertEquals(1, vals[15], 1e-6);
+    
+    m.m00 = 2;
+    m.reset();
+    vals = m.get(null);
+    assertEquals(1, vals[0], 1e-6);
+  }
+
+  @Test
+  public void testSetAndGetMethods() {
+    PMatrix3D m = new PMatrix3D();
+    float[] source = {
+      2, 3, 4, 5,
+      6, 7, 8, 9,
+      10,11,12,13,
+      14,15,16,17
+    };
+    m.set(source);
+    float[] target = m.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(source[i], target[i], 1e-6);
+    }
+    
+    m.set(1, 2, 3, 4, 5, 6);
+    target = m.get(null);
+    assertEquals(1, target[0], 1e-6);
+    assertEquals(2, target[1], 1e-6);
+    assertEquals(0, target[2], 1e-6);
+    assertEquals(3, target[3], 1e-6);
+    
+    PMatrix2D m2d = new PMatrix2D(1, 2, 3, 4, 5, 6);
+    m.set(m2d);
+    target = m.get(null);
+    assertEquals(1, target[0], 1e-6);
+    assertEquals(2, target[1], 1e-6);
+    assertEquals(0, target[2], 1e-6);
+    assertEquals(3, target[3], 1e-6);
+  }
+
+  @Test
+  public void testTranslate() {
+    PMatrix3D m = new PMatrix3D();
+    m.translate(0, 0, 0);
+    float[] original = new PMatrix3D().get(null);
+    float[] result = m.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(original[i], result[i], 1e-6);
+    }
+    
+    m.reset();
+    m.translate(10, -5, 3);
+    result = m.get(null);
+    assertEquals(10, result[3], 1e-6);
+    assertEquals(-5, result[7], 1e-6);
+    assertEquals(3, result[11], 1e-6);
+    assertEquals(1, result[15], 1e-6);
+  }
+
+  @Test
+  public void testRotateAndShear() {
+    PMatrix3D m = new PMatrix3D();
+    m.reset();
+    m.rotate(0);
+    float[] original = new PMatrix3D().get(null);
+    float[] result = m.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(original[i], result[i], 1e-6);
+    }
+    
+    m.reset();
+    m.rotateZ((float) Math.PI / 2);
+    result = m.get(null);
+    assertEquals(0, result[0], 1e-6);
+    assertEquals(-1, result[1], 1e-6);
+    assertEquals(1, result[4], 1e-6);
+    assertEquals(0, result[5], 1e-6);
+    
+    m.reset();
+    m.shearX((float) Math.PI / 4);
+    result = m.get(null);
+    float expectedT = (float) Math.tan(Math.PI / 4);
+    assertEquals(expectedT, result[1], 1e-6);
+    
+    m.reset();
+    m.shearY((float) Math.PI / 4);
+    result = m.get(null);
+    assertEquals(expectedT, result[4], 1e-6);
+  }
+
+  @Test
+  public void testScale() {
+    PMatrix3D m = new PMatrix3D();
+    m.reset();
+    m.scale(1);
+    float[] original = new PMatrix3D().get(null);
+    float[] result = m.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(original[i], result[i], 1e-6);
+    }
+    
+    m.reset();
+    m.scale(2, 3, 4);
+    result = m.get(null);
+    assertEquals(2, result[0], 1e-6);
+    assertEquals(3, result[5], 1e-6);
+    assertEquals(4, result[10], 1e-6);
+    
+    m.reset();
+    m.scale(0, 1, 1);
+    result = m.get(null);
+    assertEquals(0, result[0], 1e-6);
+  }
+
+  @Test
+  public void testApplyAndPreApply() {
+    PMatrix3D m = new PMatrix3D();
+    m.reset();
+    PMatrix3D n = new PMatrix3D(
+      2, 3, 4, 5,
+      6, 7, 8, 9,
+      10,11,12,13,
+      14,15,16,17
+    );
+    m.apply(n);
+    float[] result = m.get(null);
+    float[] expected = n.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(expected[i], result[i], 1e-6);
+    }
+    
+    m.reset();
+    m.preApply(n);
+    result = m.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(expected[i], result[i], 1e-6);
+    }
+  }
+
+  @Test
+  public void testMultMethods() {
+    PMatrix3D m = new PMatrix3D();
+    m.reset();
+    PVector p = new PVector(1, 2, 3);
+    PVector resultP = m.mult(p, null);
+    assertEquals(1, resultP.x, 1e-6);
+    assertEquals(2, resultP.y, 1e-6);
+    assertEquals(3, resultP.z, 1e-6);
+    
+    float[] vec3 = {1, 2, 3};
+    float[] out3 = m.mult(vec3, new float[3]);
+    assertEquals(1, out3[0], 1e-6);
+    assertEquals(2, out3[1], 1e-6);
+    assertEquals(3, out3[2], 1e-6);
+    
+    float[] vec4 = {1, 2, 3, 4};
+    float[] out4 = m.mult(vec4, new float[4]);
+    for (int i = 0; i < 4; i++) {
+      assertEquals(vec4[i], out4[i], 1e-6);
+    }
+    
+    try {
+      m.mult(vec3, vec3);
+      fail("Expected RuntimeException for identical source and target arrays.");
+    } catch (RuntimeException e) {
+      // Exception expected.
+    }
+    
+    m.reset();
+    m.translate(10, 20, 30);
+    float x = m.multX(1, 2, 3);
+    float y = m.multY(1, 2, 3);
+    float z = m.multZ(1, 2, 3);
+    float w = m.multW(1, 2, 3);
+    assertEquals(1 + 10, x, 1e-6);
+    assertEquals(2 + 20, y, 1e-6);
+    assertEquals(3 + 30, z, 1e-6);
+    assertEquals(1, w, 1e-6);
+  }
+
+  @Test
+  public void testTransposeAndDeterminant() {
+    PMatrix3D m = new PMatrix3D(
+      2, 3, 4, 5,
+      6, 7, 8, 9,
+      10,11,12,13,
+      14,15,16,17
+    );
+    float det = m.determinant();
+    m.transpose();
+    float det2 = m.determinant();
+    assertEquals(det, det2, 1e-6);
+  }
+
+  @Test
+  public void testInvert() {
+    PMatrix3D m = new PMatrix3D();
+    m.reset();
+    boolean inverted = m.invert();
+    assertTrue(inverted);
+    float[] result = m.get(null);
+    PMatrix3D identity = new PMatrix3D();
+    float[] idArr = identity.get(null);
+    for (int i = 0; i < 16; i++) {
+      assertEquals(idArr[i], result[i], 1e-6);
+    }
+    
+    m.reset();
+    m.scale(0, 1, 1);
+    inverted = m.invert();
+    assertFalse(inverted);
+  }
+}