[JAVA] Unit catcher made by Processing

This article is a reorganization of the materials presented in the circle when I was a student. I plan to fix it from time to time

Advance preparation

Installation of Processing

Download from Official Site

Download image data

Borrowed from Irasutoya, change the image name to the following

• chimpanzee.png
• school.png
• tanni.png

What is a unit catcher?

A devilish web game developed by a friend when he was a student, where chimpanzees desperately take credits

You can play from the following site

https://ukya.tk/

What is Processing?

Open source graphics development environment and programming language

Strengths

--Simple and easy to understand in Java-based language --Light movement --Simple project structure --Easy to output to an executable file

weakness

--Not suitable for large-scale development due to development restrictions

Hello World

//Run only once
void setup() {
  //Create a 1280x720 screen
  size(1280, 720);
  //Displayed on the console screen
  println("Hello, World");
  //Displayed on the execution screen
  text("Hello, World", 100, 100);
}

Basic

Draw a line

void setup() {
  size(1280, 720);
  // (X, Y) = (0, 0)From
  // (X, Y) = (300, 300)Draw a line up to
  line(0, 0, 300, 300);
}

Draw an ellipse

void setup() {
  size(1280, 720);
  // (X, Y) = (80, 200)To
  //Width 50px,Create a circle with a height of 80px
  ellipse(80, 200, 50, 80);
}

Draw background

void setup() {
  size(1280, 720);
  //0 (black) to 255 (white)
  background(0);
}

Color

void setup() {
  size(1280, 720);
  // R, G, B
  background(240, 180, 200);
  // R, G, B,A (transparency)
  background(240, 180, 200, 75);
}

animation

Basic drawing frequency is 60fps

//Execute 60 times per second (update)
void draw() {
  //...
}

Draw a perfect circle that follows the mouse

A circle is drawn every frame

void setup() {
  size(1280, 720);
}

void draw() {
  ellipse(mouseX, mouseY, 50, 50);
}

Erase the drawing of the previous frame with the background fill

void setup() {
  size(1280, 720);
}

void draw() {
  background(255);
  ellipse(mouseX, mouseY, 50, 50);
}

variable

//Prepare a variable that can contain an integer
int number = 10;
//Change the value (only integers can be assigned)
number = -50;
//Code that increments the value of a variable by 1
number = number + 1;
number += 1;
number++;

Variable type

float   //Floating point
boolean //Boolean value
String  //String
PImage  //Image data (Processing original)

Moving circle

//Variable declaration
int positionX;

void setup() {
  //Variable initialization
  positionX = 0;

  size(500, 500);
}

void draw() {
  //The value increases by 1 for each frame
  positionX += 2;
  
  background(255);
  //Use variables instead of numbers
  ellipse(positionX, 100, 50, 50);
}

Conditional branch

int positionX;
//Whether to move to the left
boolean leftMove;

void setup() {
  positionX = 0;
  size(500, 500);
  leftMove = false;
}

void draw() {
  //Change the value calculation by moving to the right
  if (leftMove == false) {
    positionX += 2;
  } else {
    positionX -= 2;
  }
  
  //Move to the left when it exceeds 500
  if (500 < positionX) {
    leftMove = true;
  }

  background(255);
  ellipse(positionX, 100, 50, 50);
}

Conditional branch

Value evaluation notes

a == b // 「=Note that if there is only one, it will be an assignment.
a <= b //Greater equal. "=Is right

Multiple evaluation

S && T             //S and T
S || T             //S or T
(a < b) && (b < c) // a < b <Synonymous with c

Conditional branch of the same value

if / else statement

if (number == 0) {
  // ...
} else if (number == 1) {
  // ...
} else {
  // ...
}

switch statement

switch (number) {
  case: 0 {
    // ...
    break; //Be careful not to forget to put it on!
  }
  case: 1 {
    // ...
    break;
  }
  default: {
    // ....
  }
}

The for statement is not used this time, so it is omitted.

Let's make a game

Put image data

Put the image in (project file) / data

How to load an image

PImage image = loadImage(file name);

Change the display size of the image

image.resize(width,height);

Screen generation & background setting

//Prepare variables for images
PImage backgroundImage;

void setup() {
  //Start in performance-oriented P2D mode
  size(1280, 720, P2D);
  //Read image data
  backgroundImage = loadImage("school.jpg ");
  //Processed to the same size as the screen size
  backgroundImage.resize(width, height);
}

void draw() {
  //Draw background
  background(backgroundImage);
}

width / height is the width / height of the execution screen, Same as the value specified by size ()

Arrangement of player images

/**Add the following*/
PImage playerImage;

void setup() {
  /**Add the following*/
  playerImage = loadImage("chimpanzee.png ");
  playerImage.resize(200, 200);
}

void draw() {
  /**Add the following*/
  //PImage to display,X coordinate,Y coordinate
  image(playerImage, 640, 520);
}

Allow horizontal movement with the mouse

void draw() {
  // image(playerImage, 640, 520);
  /**Changed the above to below*/
  image(playerImage, mouseX, 520);
}

Change the reference point of the coordinates of image drawing to the center point

void setup() {
  /**Add the following*/
  imageMode(CENTER);
}

Installation of units

/**Add the following*/
PImage tanniImage;

void setup() {
  /**Add the following*/
  tanniImage = loadImage("tanni.png ");
  tanniImage.resize(100, 100);
}

void draw() {
  /**Add the following*/
  image(tanniImage, 600, 300);
}

Drop the unit

/**Add the following*/
float tanniY;

void setup() {
  /**Add the following*/
  //If it is 0, it will stick out(Image vertical size/ 2)Installed on
  tanniY = -50;
}

void draw() {
  /**Add the following*/
  //Move down 8px every frame
  tanniY += 8;

  // image(tanniImage, 600, 300);
  /**Changed the above to below*/
  image(tanniImage, 600, tanniY);
}

Reappear the unit

void draw() {
  /**Add the following*/
  //When the image disappears from the screen
  if (height < tanniY - 50) {
    //Substitute the initial value
    tanniY = -50;
  }
}

Randomize the appearance position

Random number generation method

random(100);        //Float value between 0 and 100
random(-40.5, 10);  // -40.Float value between 5 and 10

Randomize the appearance position every time

/**Add the following*/
float tanniX;

void setup() {
  /**Add the following*/
  //Specify the range so that the image is not hidden
  tanniX = random(50, width - 50);
}

void draw() {
  // image(tanniImage, 600, tanniY);
  /**Changed the above to below*/
  image(tanniImage, tanniX, tanniY);

  if (height < tanniY - 50) {
    tanniY = -50;
    /**Add the following*/
    tanniX = random(50, width - 50);
  }
}

Collision detection with player

A method to calculate the distance between two coordinates

dist(A x coordinate,A y coordinate,B x coordinate,B y coordinate)

Abbreviation for distance

Make a collision detection with the player

void draw() {
  /**Add the following*/
  //Judgment distance set to 80 pixels
  if (dist(mouseX, 520, tanniX, tanniY) < 80) {
    tanniY = -50;
    tanniX = random(50, width - 50);
  }
}

Add score function

/**Add the following*/
//0 is set if nothing is specified
int score;

void draw() {
  if (dist(mouseX, 520, tanniX, tanniY) < 80) {
    tanniY = -50;
    tanniX = random(50, width - 50);
    /**Add the following*/
    score++;
    println("score: " + score);     
  }
}

The score is displayed on the console

Display the score on the execution screen

void setup() {
  /**Add the following*/
  //Fill in black
  fill(0);
  //Specify the font size
  textSize(50);
  //Set the reference point of the character in the upper right
  textAlign(RIGHT, TOP);
}

void draw() {
  if (dist(mouseX, 520, tanniX, tanniY) < 80) {
    tanniY = -50;
    tanniX = random(50, width - 50);
    score++;
    /**Deleted below*/
    // println("score: " + score);     
  }
  /**Add the following*/
  text("score: " + score, width, 0);
}

Let's put together the same code

Added the following methods

/**Add the following*/
void resetTanni() {
  tanniY = -50;
  tanniX = random(50, width - 50);
}

Replace the following three codings with methods

  tanniY = -50;
  tanniX = random(50, width - 50);
  /**Changed the above to below*/
  resetTanni();

Let's make a title screen and a result screen

Manage which screen you are in by putting it in a variable

/**Add the following*/
int state;

state is managed as follows

state == 0 // =>title screen
state == 1 // =>Game screen
state == 2 // =>Result screen

Creating a function called each state

/**Add the following*/

void titleScene() {
  
}

void gameScene() {
  
}

void resultScene() {
  
}

Move some processing to gameScene ()

void setup() {
  /**Deleted below*/
  textSize(50);
  textAlign(RIGHT, TOP);  
}

void draw() {
  background(backgroundImage);
  /**Delete all of the following*/
  tanniY += 8;
  image(playerImage, mouseX, 520); 
  //(Omitted below)
}

void gameScene() {
  /**Add the following*/
  textSize(50);
  textAlign(RIGHT, TOP);  
  tanniY += 8;
  image(playerImage, mouseX, 520); 
}

Display characters in each scene

void titleScene() {
  textSize(70);
  //Set the coordinate reference point to the center of the text
  textAlign(CENTER, CENTER);
  //Draw text in the center of the screen
  text("Title Scene", width / 2, height / 2);
}

void resultScene() {
  textSize(70);
  textAlign(CENTER, CENTER);
  text("Result Scene", width / 2, height / 2);
}

Q. Are there any Japanese bugs?

A. Fonts need to be loaded

void setup() {
  /**Add the following*/
  //Generate and load Arial font of size 50
  textFont(createFont("Arial", 50));
}

Branch by the value of the state variable

void draw() {
  /**Add the following*/
  //Be careful not to forget to put a break
  switch(state) {
    case 0:
      titleScene();
      break;
    case 1:
      gameScene();
      break;
    case 2:
      resultScene();
      break;
  }
}

Since the initial value of state is 0, the title screen is displayed when starting

Keyboard judgment

Is the key pressed

isPressed()

Comparison of entered character keys

//Please note that the following two are treated differently
key == 'a'
key == 'A'

Comparison of entered modifier keys

keyCode == ENTER
keyCode == SHIFT

Title screen-> Game screen

Press Enter to proceed

void titleScene() {
  /**Add the following*/
  //Display below the title in small letters
  textSize(30);
  text("ENTER to Start", width / 2, height / 2 + 80);
  //Change the value when the pressed key is the ENTER key
  if (keyCode == ENTER) {
    state = 1;
  }
}

Game screen-> Result screen

Proceed after getting 10 credits

void gameScene() {
  /**Add the following*/
  //Let's do ≤ in case the score increases by 2 at one time
  if (10 <= score) {
    state = 2;
  }
}

Result screen

Enter key to exit the game screen, ESC key to exit

void resultScene() {
  /**Add the following*/
  textSize(30);
  text("ENTER to play again / ESC to exit", width / 2, height / 2 + 80);
  //Change the value when the pressed key is the ENTER key
  if (keyCode == ENTER) {
    //Reset score
    score = 0;
    state = 1;
  } else if (keyCode == ESC) {
    //End the game
    exit();
  }
}

Note that if you do not reset the score, it will loop.

Let's export the executable file

"File" / "Export as application"

Summary

You can make simple games using Processing

If you want to expand further from here ...

--Set a time limit --Drop multiple units --Make compulsory credits that cannot be dropped

etc…

Looking back

Processing was the first programming language I worked on properly, but I thought it was a good programming language to learn happily because it wraps Java, so it's linguistically friendly, and above all, you can quickly create graphical apps. ..