0 Make Your Own Game - Moving 2D Sprite On the Game Screen By GTGE

As the video link that you see, in this post I will show you how to move the Character 2D Sprites on the game area, but before I get started I will discuss about anything that should be done before moving the 2D character sprites in the game area, certainly on this review I still use 2D game engine library: Golden T game Engine. If you read my previous article titled "animated character 2 Dimensions with GTGE" there is a method named "update" through this metod we can specify the buttons that can be used to move the character sprites in the game.

public void update(long elapsedTime) { // TODO Auto-generated method stub playField.update(elapsedTime); //pada method ini kita akan memberikan fungsi untuk //menggerakkan karakter sprite pada permainan }

In this experiment we will make this 2D Charater Sprite move to the left and  the right by using the button "left arrow and right arrow" on the keyboard, and the this 2D Charater Sprite  is still used as in the previous post that the game's character named "bill rizer" with the 6 columns index and 2 rows index as on the picture below:

First, prepare the three abstract methods as a basic foundation in building a game-based Golden T Game Engine, if you do not understand how to make the three abstract methods please visit the following article "animated character 2 Dimensions with GTGE" and download souce code example, well here we already know that to to the left we use sprite index from 1 to 6, to the right we use sprite index from 7 to 14. Implementation of the code is as follows, place the following function into the metod "update"

if (keyDown(KeyEvent.VK_LEFT)) { bill_rizer.setHorizontalSpeed(-0.3); bill_rizer.setAnimationFrame(0, 5); bill_rizer.setAnimate(true); bill_rizer.setLoopAnim(true); } else if (keyDown(KeyEvent.VK_RIGHT)) { bill_rizer.setHorizontalSpeed(0.3); bill_rizer.setAnimationFrame(6, 11); bill_rizer.setAnimate(true); bill_rizer.setLoopAnim(true); } // bill_rizer.setHorizontalSpeed(0.0); else if(bill_rizer.getHorizontalSpeed()>0) { bill_rizer.setAnimationFrame(8, 8); bill_rizer.setHorizontalSpeed(0.0); } else if(bill_rizer.getHorizontalSpeed()<0) { bill_rizer.setAnimationFrame(3, 3); bill_rizer.setHorizontalSpeed(0.0); } }

As seen in the source code, look at lines of code numbers 2 to 8, the left button expressed by method "keyDown" with parameters "KeyEvent. VK_LEFT" in the function above, if the user presses the left button, then the character sprite will move to the left, where the method "sethorizontalSpeed" that makes the character sprites move horizontally as shown in line 4 number code, there are parameters in the method with a value of (-0.3), minus value is used if we want to move the character sprites to the left, the value of 0.3 magnitudes of motion speed stating the character sprites, the greater the value of parameters make the slower movement.

The code at line 17 to 26 has an important function, when users are not pressing the left button and the right button then the character sprite will not move as well as an animated. the code at line number 5 stated that if the character sprites from the left direction, then stop the animation and point sprite index frames to 8 as in lines of code number 19, and stop the movement of the horizontal with the given parameter values of 0.0, as seen on line number 20. the same functionality shown in lines of code numbers 22 to 26, the difference is functionality of checking on this line says if the character sprites from the right direction then stop the animation, and stop the movement of horizontalnya.

As the final phase we create a function that the character sprite is standing upright and not doing animation when a new game is started, therefore use the frame index number 8 and put on a method "initresources ()" on line number 18. If the source code is executed and the result should be like on the video link above.
public void initResources() { // TODO Auto-generated method stub bill_rizer = new AnimatedSprite(getImages("D:/mdktool/contra.png", 6, 2)); BufferedImage image = getImage("D:/mdktool/bg2.png"); image = ImageUtil.resize(image, 400, 600); background = new ImageBackground(image); playField = new PlayField(background); bill_rizer.setLocation(50, 50); SOLDIER = playField.addGroup(new SpriteGroup("Marines")); SOLDIER.add(bill_rizer); bill_rizer.setAnimationFrame(0, 5); bill_rizer.setAnimate(true); bill_rizer.setLoopAnim(true); bill_rizer.getAnimationTimer().setDelay(BILL_RIZER_DELAY); bill_rizer.setAnimationFrame(8, 8); } }

from here we can draw conclusions : in order to control the Sprite Characther with keyboard keys, things that must be done is to put the function of checking in the update method and provide one additional function to do some checking as the user in not pressing the left and right keys on the keyboard. For the complete source code can be downloaded at the following link

Characther Sprite Movement Using GTGE

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