I was working on a brick breaker game in proccessing, and was trying to create the collision system for the game. I was able to identify when a collision happens between the ball and the brick, but I was not able to to make the brick dissapear when it gets hit by the ball. How do I do this? I would also appreciate a explanation, as I am a beginner.
Thanks.
color black = color(0,0,0);
color red = color(255,0,0);
color white = color(255,255,255);
float ballx = 412.5, bally = 600, balld = 20, ballr = balld/2, paddleX = 362.5, paddleY = 650;
float paddleW = 100, paddleH = 15;
float ballspdX, ballspdY;
boolean ball_drop = true;
float direction_choice;
float[] brickX = new float[10];
float[] brickY = new float[5];
float brickW = 50, brickH = 25;
void setup(){
size(825,800);
surface.setTitle("Brick breaker");
noCursor();
smooth();
brickX[0] = 50;
brickX[1] = 125;
brickX[2] = 200;
brickX[3] = 275;
brickX[4] = 350;
brickX[5] = 425;
brickX[6] = 500;
brickX[7] = 575;
brickX[8] = 650;
brickX[9] = 725;
brickY[0] = 50;
brickY[1] = 125;
brickY[2] = 200;
brickY[3] = 275;
brickY[4] = 350;
}
void paddle(){
noStroke();
fill(white);
rect(paddleX, paddleY, paddleW, paddleH);
}
void ball(){
noStroke();
fill(red);
circle(ballx, bally, balld);
}
void draw(){
background(black);
paddle();
ball();
if (bally ballr == paddleY && ballx > paddleX && ballx < paddleX (paddleW / 2)){
ball_drop = false;
ballspdY = -ballspdY;
ballspdX = -4;
}
/*
if (bally ballr == paddleY && ballx > paddleX && ballx < paddleX paddleW){
ball_drop = false;
ballspdY = -ballspdY;
direction_choice = int(random(1,3));
if (direction_choice == 1){
ballspdX = 4;
}
if (direction_choice == 2){
ballspdX = -4;
}
}
println(direction_choice);
*/
if (bally ballr == paddleY && ballx > paddleX (paddleW /2) && ballx < paddleX paddleW){
ball_drop = false;
ballspdY = -ballspdY;
ballspdX = 4;
}
if (ballx ballr > width || ballx - ballr < 0){
ballspdX = -ballspdX;
}
if (bally - ballr < 0){
ballspdY = -ballspdY;
}
if (ball_drop){
ballspdX = 0;
ballspdY = 1;
}
for (int i = 0; i < brickX.length; i ){
for(int j = 0; j < brickY.length; j ){
fill(red);
rect(brickX[i], brickY[j], brickW, brickH);
if (collideLineCircle(brickX[i], brickY[j] brickH, brickX[i] brickW, brickY[j] brickH, ballx, bally, ballr)){
ballspdY = -ballspdY;
}
}
}
if (bally >= 800){
bally = 600;
ballx = 412.5;
ball_drop = true;
}
bally = ballspdY;
ballx = ballspdX;
}
boolean collideLineCircle(float x1, float y1, float x2, float y2, float cx, float cy, float cr){
float A = y2 - y1, B = x1 - x2, C = x2*y1 - x1 y2;
float denom = A A B*B;
if (denom == 0){
return dist(x1,y1, cx, cy) < cr;
}
float Ix = (B*B*cx-A*B*cy - A*C)/denom, Iy = (A*A*cy-A*B*cx - B*C)/denom;
if (Ix >= min(x1,x2) && Ix <= max(x1,x2) & Iy >= min(y1,y2) && Iy <= max(y1,y2)) {
return abs (A*cx B*cy C)/sqrt(denom) < cr;
}
float d1 = dist(x1,y1,cx,cy), d2 = dist(x2,y2,cx,cy);
return min(d1,d2) < cr;
}
void mouseMoved(MouseEvent evt){
paddleX = evt.getX();
}
CodePudding user response：
There are a number of ways this can be done. Perhaps the simplest change, given the data structures you already have is to create another array, this time a boolean array, and call it something like brickIsVisible.
Then you can use a simple if statement, e.g., if (brickIsVisible[i]) in your loops to determine how to color the brick. The same variable can be used to tell whether or not to do a collision test between the ball and the brick.
As for the coloring itself, there are a couple options.
I'm not sure how you are drawing your board. If you redraw the entire board with each gameloop frame, then presumably you first draw the background (which covers over the bricks) and then you draw the bricks. If this what is happening, then if brickIsVisible[i] is false you can simply omit drawing that brick on top of the background.
Another technique that is sometimes used is to make use of a transparent color. This is done by adding an alpha channel value to the color definition. Thus there are four variables instead of three. They are referred to as RGBA instead of RGB. If the fourth variable is 0, the color will be transparent. If it is 255 it will be fully visible. Intermediate values in sequence can be used if you want to create a fade in or fade out.
I am guessing you are using java.awt.Color. Following is an example that uses the four argument constructor, with the fourth being the alpha channel.
Color invisiblePurple = new Color(255, 0, 255, 0);
If the color is invisible, the RGB values don't really matter.
These days I mostly use JavaFX for graphics, so I might not be up on all the tricks of the trade with AWT/Swing. With JavaFX, one can directly set an opacity property for a graphic being displayed, which is pretty convenient. I think part of the reason that this is available in JavaFX is that screen graphics are structured more like a DOM tree (like an HTML domain object model), and the redrawing is handled behind the scenes on the current state of the tree, rather than explicitly for each object, as it is with AWT/Swing.
CodePudding user response：
Another possible technique shown below uses a brick class array. The class has a 'show' boolean associated with it and the bricks are only displayed when brick[id].show is true. In this demo when the brick is selected with a mouse brick[id].show is set to false and that brick is not displayed. For your project you would have to do this when a brick is hit by the ball.
/*
Creates a grid of rectangles from a Brick class array.
Syntax: brick[id] = new Brick( x, y, w, h, "title", bkgrndColor, txtColor);
ID is taken from position in array.
*/
final int _brickGridX = 40;
final int _brickGridY = 60;
final int _brickW = 120;
final int _brickH = 60;
color BLUE = color(64, 124, 188);
color LTGRAY = color(185, 180, 180);
color YELLOW = color(245, 250, 13);
color RED = color(255, 0, 0);
color BLACK = color(0, 0, 0);
color WHITE = color(255, 255, 255);
Brick[] brick;
class Brick {
float x, y, w, h;
String title;
color bkgrnd;
color txtColor;
boolean show;
// Constructor
Brick(int xpos, int ypos, float wt, float ht, String titleStr, color background, color foreground) {
x = xpos;
y = ypos;
w = wt;
h = ht;
title = titleStr;
bkgrnd = background;
txtColor = foreground;
}
void display(int id) {
if (brick[id].show) {
fill(bkgrnd); // background color
stroke(0);
rect(x, y, w, h);
fill(txtColor); // text color
textSize(42);
textAlign(CENTER, CENTER);
text(title, x, y, w, h);
}
}
void press(int id) {
println("brick id = ", id ": show =", brick[id].show);
}
}
void brickGrid() {
int left = 0;
int top = 0;
int vg = 0; // Space between cols (vert.gutter)
int hg = 0; // Space between rows (horz.gutter)
int rows = 5;
int cols = 5;
int id = 0;
brick = new Brick[rows*cols]; // creates brick array
for (int k = 0; k < cols; k ) {
for (int j = 0; j < rows; j ) {
left = _brickGridX j * (_brickW vg);
top = _brickGridY k * (_brickH hg);
brick[id] = new Brick(left, top, _brickW, _brickH, str(id), LTGRAY, BLACK);
brick[id].show = true;
id ;
}
}
}
void setup() {
size(800, 600);
background(BLUE);
brickGrid();
}
void draw() {
background(BLUE);
for (int i = 0; i < brick.length; i ) {
brick[i].display(i);
}
}
void mousePressed() {
for (int i = 0; i < brick.length; i ) {
if ((mouseX >= brick[i].x) && (mouseX <= brick[i].x _brickW) && (mouseY >= brick[i].y) && (mouseY <= brick[i].y _brickH)) {
brick[i].show = false;
// brick[i].press(i);
}
}
}