 <p>I'm not sure what you want do, but if I understand what you want to do, you can create a sensor fixture type, this pseudo example:</p> <pre><code>FixtureDef fd1 = new FixtureDef(); //fd1.friction = 0.5f; PolygonShape pSTest = new PolygonShape(); //size you want for example: pSTest.setAsBox(4f / PIXEL_POR_METRO, 1f / PIXEL_POR_METRO, new Vector2(22f / PIXEL_POR_METRO, -1f / PIXEL_POR_METRO), 0f); fd1.shape = pSTest; fd1.isSensor = true; yourBody.createFixture(fd1).setUserData("yourId"); </code></pre> <p>looks ContactListener interface, for example preSolve</p> <p>note that sensor, this is not called for sensors.</p> <p><strong>info</strong></p> <pre><code>setAsBox(float hx, float hy, Vector2 center, float angle) Parameters: hx the half-width. hy the half-height. center the center of the box in local coordinates. angle the rotation in radians of the box in local coordinates. </code></pre>