13.4-Full Stack Java notes: Combat Aircraft Game Project |offscreenimage| Gameobject| Plane

Dual buffering technology to solve flicker problems

In the previous section, we realized the animation effect, but found that the window will not stop flashing, experience is very poor. In practical development, drawing graphics is very complex, drawing may take a few seconds or longer, and often flicker, in order to solve this problem, we usually use "double buffering technology."

1) The "Double buffering technology" drawing process is as follows:

A. Creating a buffer that is consistent with the canvas in memory

B. Drawing in Buffer

C. Copying a buffer bitmap to the current canvas

E. Freeing memory buffers

Double buffering creates an object in memory that is consistent with the screen drawing area, drawing the graphic to the object in memory, and then copying the graphics on the object to the screen at once, which can greatly speed up the drawing.

We simply put the following "double-buffered" implementation code into the Mygrameframe class, you can:

"Example 1" adds a double buffering technique

Image offscreenimage = null; public void Update (Graphics g) { if (offscreenimage = = null) Offscreenimage = This.createimage (500,500);//This is the width and height of the game window Graphics Goff = Offscreenimage.getgraphics (); Paint (Goff); G.drawimage (offscreenimage, 0, 0, NULL); }

Gameobject class Design

1) Definition of Gameobject class

We found that all objects in the window (airplanes, shells, and so on) have a lot in common: "Picture object, coordinate position, running speed, width and height". In order to facilitate the development of the program, we need to design a Gameobject class, which can be used as the parent of all game objects to facilitate our programming.

"Example 2" Gameobject class

Package cn.sxt.game; Import Java.awt.Graphics; Import Java.awt.Image; Import Java.awt.Rectangle; public class Gameobject { Image img; The object of the object corresponding to the picture Double x, y; The coordinates of the object int speed; The speed at which the object runs int width,height; The width and height of the rectangular area where the object is located /** * How to draw this object * @param g */ public void Drawmyself (Graphics g) { G.drawimage (IMG, (int) x, (int) y, null); } Public gameobject (Image img, double x, double y) { This.img = img; this.x = x; This.y = y; if (img!=null) { This.width = Img.getwidth (null); This.height = Img.getheight (null); } } Public gameobject (Image img, double x, double y, int speed, int width, int height) { This.img = img; this.x = x; This.y = y; This.speed = speed; This.width = width; This.height = height; } Public Gameobject () { } /** * Returns the corresponding rectangular area of the object for subsequent use in collision detection * @return */ Public Rectangle GetRect () { return new Rectangle ((int) x, (int) y, width, height); } }

2) Design Aircraft class

With Gameobject this parent class, we design aircraft class is particularly simple, the current aircraft class is not particularly complex requirements. We can use it simply by inheriting it:

"Example 3" plane class

Package cn.sxt.game; Import Java.awt.Graphics; Import Java.awt.Image; public class Plane extends Gameobject { @Override public void Drawmyself (Graphics g) { Super.drawmyself (g); This.x +=3;//aircraft flying horizontally, we can also adjust the x, Y algorithm to fly according to the path we specify } Public Plane (Image img, double x, double y) { Super (Img,x,y); } }

Through inheritance, we find that implementing new classes is a lot more fun!

3) Adjustment of Mygameframe class invocation mode

We encapsulate the plane class, and we don't need to add so many aircraft properties to the Mygameframe class, we're all encapsulated in the plane class, so it's easier to call.

Mygameframe class After "Example 4" is encapsulated

public class Mygameframe extends Frame { Image bgimg = gameutil.getimage ("images/bg.jpg"); Image planeimg = gameutil.getimage ("Images/plane.png"); Plane Plane = new Plane (planeimg,300,300); The Paint method works by drawing the entire window and internal content. Automatically called by the system. @Override public void Paint (Graphics g) { G.drawimage (bgimg, 0, 0, NULL); Plane.drawmyself (g); Draw the plane itself } The rest of the code, without any changes, is not attached, refer to the previous version yourself. }

With object-oriented encapsulation, if we want to create multiple planes again, it becomes surprisingly simple.

"Example 5" creates multiple aircraft

public class Mygameframe extends Frame { Image bgimg = gameutil.getimage ("images/bg.jpg"); Image planeimg = gameutil.getimage ("Images/plane.png"); Plane Plane = new Plane (planeimg,300,300); Plane plane2 = new Plane (planeimg,300,350); Plane plane3 = new Plane (planeimg,300,400); The Paint method works by drawing the entire window and internal content. Automatically called by the system. @Override public void Paint (Graphics g) { G.drawimage (bgimg, 0, 0, NULL); Plane.drawmyself (g); Draw the plane itself Plane2.drawmyself (g); Draw the plane itself Plane3.drawmyself (g); Draw the plane itself } The rest of the code, which is consistent with the previous version, is not attached to the highlighted focus for space saving. }

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13.4-Full Stack Java notes: Combat Aircraft Game Project |offscreenimage| Gameobject| Plane