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float viewportX = (2.0f * getMousePosX()) / viewportWidth - 1.0f;float viewportY = (2.0f * (viewportHeight - getMousePosY())) / viewportHeight - 1.0f;Vector3 gdxOrigin = new Vector3();gdxOrigin.set(viewportX, viewportY, -1.0f);gdxOrigin.prj(camera.invProjectionView);Vector3 gdxDirection = new Vector3();gdxDirection.set(viewportX, viewportY, 1.0f);gdxDirection.prj(camera.invProjectionView);gdxDirection.sub(gdxOrigin).nor();// collide geometries

Euclid, a performant and comprehensive vector math and geometry library.