Navigation, Input Devices, and Collision - Interactive Web-Based Virtual Reality with Java 3D - page 232

Figure 14. Second code segment for JoystickInputDevice.java

40. public void ProcessInput(Joystick joy, Sensor joySensor) {
41.

int buttons = joy.getButtons(); joySensorRead.setTime(System.currentTimeMillis());

42. x = joy.getXPos(); z = joy.getYPos(); // determine button press on the directional keypad

43. if (Math.abs(x) < 0.3f) x = 0.0f; if (Math.abs(z) < 0.3f) z = 0.0f;

44. if (z<0 && x==0) { direction = 1; System.out.println(direction + " Forward");

45. viewposi.x = viewposi.x-1.0f*SPAN*(float)Math.sin(turningAngle);

46. viewposi.z = viewposi.z-1.0f*SPAN*(float)Math.cos(turningAngle);

47. setPosition3D(tran, viewposi); setPosition3D(bodyTrans, viewposi); }

48. if(z>0 && x==0) { direction = 2; System.out.println(direction+ " Backward");

49. viewposi.x = viewposi.x+1.0f*SPAN*(float)Math.sin(turningAngle);

50. viewposi.z = viewposi.z+1.0f*SPAN*(float)Math.cos(turningAngle);

51. setPosition3D(tran, viewposi); setPosition3D(bodyTrans, viewposi); }

52. if(x<0 && z==0) { direction = 3; System.out.println(direction + " Rotate right");

53. turningAngle += ANGLESTEP; setRotation3D(tran, ANGLESTEP, comMat, 1);

54. setRotation3D(bodyTrans, ANGLESTEP, comMat, 1);

55. setRotation3D(bodyTrans, -ANGLESTEP, comMat, 1); }

56. if(x>0 && z==0) { direction = 4; System.out.println(direction + " Rotate left");

57. turningAngle -= ANGLESTEP; setRotation3D(tran, -ANGLESTEP, comMat, 1);

58. setRotation3D(bodyTrans, -ANGLESTEP, comMat, 1);

59. setRotation3D(bodyTrans, ANGLESTEP, comMat, 1); }

60. if ( ((buttons & Joystick.BUTTON1) != 0)) { direction = 5; System.out.println(direction + " Elevate");

61. viewposi.y = viewposi.y+SPAN/2.0f; setPosition3D(tran, viewposi);

62. setPosition3D(bodyTrans, viewposi); return; }

63. if ( ((buttons & Joystick.BUTTON2) != 0)) { direction = 6; System.out.println(direction + " Land");

64. viewposi.y = viewposi.y-SPAN/2.0f; setPosition3D(tran, viewposi);

65. setPosition3D(bodyTrans, viewposi); return; }

66. if ( ((buttons & Joystick.BUTTON3) != 0)) { direction = 7; System.out.println(direction + " Shift R");

67. viewposi.x = viewposi.x+SPAN*(float)Math.sin(turningAngle+Math.PI/2.0);

68. viewposi.z = viewposi.z+SPAN*(float)Math.cos(turningAngle+Math.PI/2.0);

69. setPosition3D(tran, viewposi); setPosition3D(bodyTrans, viewposi); return; }

70. if ( ((buttons & Joystick.BUTTON4) != 0)) { direction = 8; System.out.println(direction + " Shift left");

71. viewposi.x = viewposi.x-SPAN*(float)Math.sin(turningAngle+Math.PI/2.0);

72. viewposi.z = viewposi.z-SPAN*(float)Math.cos(turningAngle+Math.PI/2.0);

73. setPosition3D(tran, viewposi); setPosition3D(bodyTrans, viewposi); return; }

74. joySensor.setNextSensorRead( joySensorRead ); }

75.
76. public void pollAndProcessInput() { ProcessInput(joy[0], joySensor[0]); }

77.
78.

public void processStreamInput() {}

course is associated with the joystick position. Subsequently, the appropriate transformation
can be calculated and invoked to change the view from the ViewPlatform.

sensors

From a programming point of view, sensors serve to obtain and translate inputs from ex-
ternal devices such as a joystick into digital data that can be used within the scene graph in