I am quite new to programming and decided to make a little game, so far I have only made a small block that is able to move in all 4 directions (left, right, up and down). Pretty simple and nothing extra-ordinary. However, when I run my program, sometimes it will stop working, not as in crashing causing Processing itself to crash, but my program will just end.
As far as my testing goes, I think this happens when I press two keys at the same time (like W and S). Does anyone happen to know what causes it to stop, and perhaps how to fix it as well?
void setup(){
size(1080,720);
frameRate(30);
}
int shipLR = 0; //Variable for the ship to go left/right
int shipUD = 0; //Variable for the ship to go up / down
void draw(){
background(0);
shipLR = constrain(shipLR, 0, 1040); //Constrain the ship in the window
shipUD = constrain(shipUD,0,680); // Constrain the ship in the window
move();
Shuttle();
}
void Shuttle(){
rect(shipLR, shipUD, 40,40); //Draw the ship
}
void move(){
if (keyPressed) {
if (key == 'a') {
shipLR = shipLR - 20; // Go left
return;}
if (key == 'd') {
shipLR = shipLR + 20; // Go right
return;}
if (key == 'w'){
shipUD = shipUD - 20; // Go up
return;}
if (key == 's') {
shipUD = shipUD + 20; // Go down
return;}
}
}
Any help will be greatly appreciated.
Edit: I found something that causes this problem to occur more frequent; If I implement a frameRate of a value lower than 60 (currently trying with 30) this happens more often.
Edit 2: With the suggestions below of making my move function in a single if block had a lot of good impact. The program no longer stops when I move the ship in the middle of the window it no longer stops, it now only does it at rare occasions when I bump too often against the borders of the window. Perhaps it has something to do with constrain?
in move() (java naming conventions specify that method names start with lower case) you should exit on the first key pressed found. the code can be re-organized to reduce multiple identical conditions:
void move(){
if (keyPressed) {
if (key == 'a') {
shipLR = shipLR - 20; // Go left
return;
}
if (key == 'd') { // still inside if keyPressed
shipLR = shipLR + 20; // Go right
return;
}
if (key == 'w') {
...
}
} // end of if keyPressed
}
My guess it that the program doesn't "stop working" or end- it's just that your rectangle stops moving. If you let go of all the keys, then push just one key, I'd bet that the rectangle starts moving again. (In the future, please try to be more specific- saying "it stops working" isn't very helpful.)
Anyway, that's because of the way you're handling the key presses. What happens if you press a key other than the ones you're checking for?
You'll enter the move() function, and you'll enter the if(keyPressed) block, but you won't enter any if the other if statements inside that block. The key variable only holds the most recently pressed key.
Depending on what you want to do, you should either refactor those if statements to only change the direction if the key was valid, and to ignore all other key presses. Or you might want to use a set of boolean variables to track multiple keys being pressed at the same time. More info on that approach can be found here.
If you still can't get it working, then please try to be more specific about exactly what happens.
Related
I'm quite new to Processing.
I'm trying to make Processing randomly play a video after I clear the screen by mouseclick, so I create an array that contain 3 videos and play one at a time.
Holding 'Spacebar' will play a video and release it will stop the video. Mouseclick will clear the screen to an image. The question is how can it randomize to another video if I press spacebar again after clear the screen.
I've been searching all over the internet but couldn't find any solution for my coding or if my logic is wrong, please help me.
Here's my code.
int value = 0;
PImage photo;
import processing.video.*;
int n = 3; //number of videos
float vidN = random(0, n+1);
int x = int (vidN);
Movie[] video = new Movie[3];
//int rand = 0;
int index = 0;
void setup() {
size(800, 500);
frameRate(30);
video = new Movie[3];
video[0] = new Movie (this, "01.mp4");
video[1] = new Movie (this, "02.mp4");
video[2] = new Movie (this, "03.mp4");
photo = loadImage("1.jpg");
}
void draw() {
}
void movieEvent(Movie video) {
video.read();
}
void keyPressed() {
if (key == ' ') {
image(video[x], 0, 0);
video[x].play();
}
}
void mouseClicked() {
if (value == 0) {
video[x].jump(0);
video[x].stop();
background(0);
image(photo, 0, 0);
}
}
You have this bit of logic in your code which picks a random integer:
float vidN = random(0, n+1);
int x = int (vidN);
In theory, if you want to randomise to another video when the spacebar is pressed again you can re-use this bit of logic:
void keyPressed() {
if (key == ' ') {
x = int(random(n+1));
image(video[x], 0, 0);
video[x].play();
}
}
(Above I've used shorthand of the two lines declaring vidN and x, but the logic is the same. If the logic is harder to follow since two operations on the same line (picking a random float between 0,n+1 and rounding down to an integer value), feel free to expand back to two lines: readability is more important).
As side notes, these bit of logic look a bit off:
the if (value == 0) condition will always be true since value never changes, making both value and the condition redundant. (Perhaps you plan to use for something else later ? If so, you could save separate sketches, but start with the simplest version and exclude anything you don't need, otherwise, in general, remove any bit of code you don't need. It will be easier to read, follow and change.)
Currently your logic says that whenever you click current video resets to the start and stops playing and when you hit the spacebar. Once you add the logic to randomise the video that the most recent frame of the current video (just randomised) will display (image(video[x], 0, 0);), then that video will play. Unless you click to stop the current video, previously started videos (via play()) will play in the background (e.g. if they have audio you'll hear them in the background even if you only see one static frame from the last time space was pressed).
Maybe this is the behaviour you want ? You've explained a localised section of what you want to achieve, but not overall what the whole of the program you posted should do. That would help others provide suggestions regarding logic.
In general, try to break the problem down to simple steps that you can test in isolation. Once you've found a solid solution for each part, you can add each part into a main sketch one at a time, testing each time you add something. (This way if something goes wrong it's easy to isolate/fix).
Kevin Workman's How To Program is a great article on this.
As a mental excercise it will help to read through the code line by line and imagine what it might do. Then run it and see if the code behaves as you predicted/intended. Slowly and surely this will get better and better. Have fun learning!
Unsquashed Sprite Squashed Sprite
My brother has issues with his sprite squashing whilst moving horizontally. The squashing is permanent after moving. I have found the line that causes the problem but cannot figure out what is causing this issue. When I remove this line the squashing stops however the sprite does not turn. He is following Shaun Spalding's Complete Platformer Tutorial and though I've watched it over I cannot find any issues with the actual code.
/// #description Insert description here
// You can write your code in this editor
// get player input
key_left=keyboard_check(vk_left);
key_right=keyboard_check(vk_right);
key_jump=keyboard_check_pressed(vk_up);
// calculate movement
var move=key_right-key_left;
hsp=move*walksp;
vsp=vsp+grv;
if(place_meeting(x,y+1,o_wall)) and (key_jump)
{
vsp=-7;
}
// horizontal collision
if (place_meeting(x+hsp,y,o_wall))
{
while(!place_meeting(x+sign(hsp),y,o_wall))
{
x=x+sign(hsp);
}
hsp=0;
}
x=x+hsp;
// vertical collision
if (place_meeting(x,y+vsp,o_wall))
{
while(!place_meeting(x,y+sign(vsp),o_wall))
{
y=y+sign(vsp);
}
vsp=0;
}
y=y+vsp;
// animation
if(!place_meeting(x,y+1,o_wall))
{
sprite_index=splayerA;
image_speed=0;
if (sign(vsp) > 0) image_index = 1; else image_index = 0;
}
else
{
image_speed=1;
if (hsp==0)
{
sprite_index=s_player;
}
else
{
sprite_index=splayerR;
}
}
if (hsp != 0) image_xscale = sign(hsp); //this line is wrong and causes the squishing
A possible cause of this is that you've set the image_xscale to a different value before using the line:
if (hsp != 0) image_xscale = sign(hsp);
For example, you may have set this in the Create Event to enlarge the sprite:
image_xscale = 2;
But that value is reset after setting image_xscale again, as that line will only return -1 or 1 because of the Sign().
One quick solution is to apply the scale change to that line of code, like this:
if (hsp != 0) image_xscale = 2 * sign(hsp);
(Once again, presuming you've changed it's scale value somewhere else)
Though another solution is to enlarge the sprite itself in the sprite editor, so the scale doesn't have to be kept in mind everytime.
I need to write a Processing program so that "When the user presses the space key a missile is fired from the front of the ship and moves rightwards until leaving the screen. The user can't fire another missile until the first is off the screen."
What I have written doesn't allow the missile to stay on the screen if other keys are pressed. I have tried adding the function under void keyPressed() with boolean true/false statements which only stopped the whole program from working.
How can I make sure it stays on the page? Also, how can I make sure the player can't shoot another missile until their previous one moves off the screen?
This is the code I have:
//global
int ship_y;
int angle;
int missileX;
void setup(){
size(500, 500);
ship_y = 10;
missileX = 55;
}
void draw(){
background(175);
fill(50);
rectMode(CENTER);
rect(30, ship_y, 50, 25);
//missile moves rightwards after spacebar is pressed
if (key == ' '){
circle(missileX, ship_y, 25);
missileX = missileX + 1;
}
}
//ship moves down when 's' is pressed and up when 'w' is pressed
void keyPressed(){
if (key == 's'){
ship_y = ship_y + 2;
}
if (key == 'w'){
ship_y = ship_y - 2;
}
}
Code within the draw() function runs every frame.
So every frame, you're clearing the background, drawing the ship, and drawing the missile. Good.
But.
You put the missile drawing code inside this if statement:
if (key == ' '){
that only draws the missile if the most recent key pressed was space. So as soon as you you press a different key, key is no longer equal to space and your missile doesn't get drawn.
One way to fix it would be to create a variable to indicate whether or not the missile was fired, and use that to determine whether or not to draw the missile (instead of checking the key variable).
Like this:
if (missileFired == true){
circle(missileX, ship_y, 25);
missileX = missileX + 1;
}
Code inside the keyPressed() function only runs once each time a key is pressed. This would be a better place to detect when the spacebar is pressed and turn on the missileFired flag:
void keyPressed(){
// code for other keypresses...
if(key == ' '){
missileFired = true;
}
}
To detect when the missile goes off screen, you'll just need to check whether missileX is greater than the width of the window. draw() would be a good place for that, since you probably want to check for it every time the missile moves.
When missileX gets larger than the window width, you can reset missileFired to false so a new missile can be fired. You'll also need to reset missileX to its original position so it originates from the ship position.
This may be a stupid question, but here goes. Is there a way to forcefully end an iteration of a for-loop and ignore all other conditional statements within the loop, and move onto the next iteration?
I'm trying to make a tool where whenever a user types a letter, it's printed to the canvas.
I'm using a for loop to do this, with each iteration making the next letter move to the right each time.
Inside the for-loop includes the conditional statements for typing the letter:
function draw(){
}
function keyPressed(){
for(i=0; i<100; i++){
if(keyCode == 65){
text("a", 60 + i*10, 60)
}
...
...
...
}
}
and so on, and so forth. However, this would only work if after each letter it moved onto the next iteration (otherwise the letters would be printed in the same place due to 'i' not increasing, making it unreadable).
Using 'return' at the end of each condition statement doesn't work for me as 'return' ends the entire for-loop, whereas I just want to end that specific iteration.
All help is appreciated, thank you.
It sounds like you're looking for the continue keyword. Here's an example from W3Schools:
for (i = 0; i < 10; i++) {
if (i === 3) { continue; }
text += "The number is " + i + "<br>";
}
Here is a linke to try the code yourself.
But taking a step back, this feels like a flawed design. If you want to get the key they user pressed, you don't have to use a bunch of if statements. You can just use the key variable. From the P5.js reference:
function setup() {
fill(245, 123, 158);
textSize(50);
}
function draw() {
background(200);
text(key, 33, 65); // Display last key pressed.
}
Even if that won't work for some reason (if you want to display something for the arrow keys, for example), there are probably better ways to solve this problem than a bunch of if statements in a for loop. For example you could create a mapping from keyCode to the string you want to display, and then call that mapping. Something like:
var m = new Map()
m.set(65, 'a');
m.set(66, 'b');
//..
function keyPressed(){
text(m.get(keyCode), 50, 50);
}
I am developing a Java 2D Game, in which I have used a KeyListener, but as you probably can guess, it has focusing issues, mainly when the Player is running and you keep the same key pressed for long, for example pressing "W" to run forward, but after some seconds of keep pressing W, the KeyListener dies and no key works, I want to use KeyBindings, as most people suggest it for game development, but I cannot find any usefull tutorials, most of them use some form of Buttons, and other useless features for my game, so how can i avoid the KeyListener from losing focus, or how can I write a simple KeyBinding code, that only moves the player, and other simple stuff used in a game.
This is the kind of Key Binding that I want, I KNOW IT DOES NOT WORK, it is an example:
component.getInputMap().put(KeyStroke.getKeyStroke(VK_W),
"move forward")
component.getActionMap().put("released",
releasedAction);
if(releasedAction == true){
Player.playerSpeedY = 7;
} else{
Player.playerSpeedY = 0;
}
FWI: this is the current KeyListener code:
if(HUD.PlayerHealth > 0){
if(key == KeyEvent.VK_W) {Player.playerSpeedY = -5; keyDown[0]= true;}
if(key == KeyEvent.VK_S) {Player.playerSpeedY = 5; keyDown [1]= true;}
if(key == KeyEvent.VK_A) {Player.playerSpeedX = -5; keyDown [2]= true;}
if(key == KeyEvent.VK_D) {Player.playerSpeedX = 5; keyDown [3]= true;}
}
I keep looking for Actions and Input maps tutorials, or KeyBinding ones, and I just don't find anything useful, another dough, the component in action and input map, what is it for?, should my entire code be based on that, and is there any way to only make the action map move the player, and only that?
Try something like this:
this.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, false), "right");
this.getActionMap().put("right", new AbstractAction() {
public void actionPerformed(ActionEvent e) {
//Do Something Here
Player.playerSpeedX = 5;
}
});
How to use KeyBindings