Hi I'm creating a cleaning game but encountered a problem when I fast draw a straight line the line is broken but when I slow draw a straight line it works fine
Below is my code
private void Update()
{
if (Input.GetMouseButton(0))
{
if (Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out RaycastHit hit))
{
Vector2 textureCoord = hit.textureCoord;
int pixelX = (int)(textureCoord.x * _templateDirtMask.width);
int pixelY = (int)(textureCoord.y * _templateDirtMask.height);
Vector2Int paintPixelPosition = new Vector2Int(pixelX, pixelY);
int paintPixelDistance = Mathf.Abs(paintPixelPosition.x - lastPaintPixelPosition.x) + Mathf.Abs(paintPixelPosition.y - lastPaintPixelPosition.y);
int maxPaintDistance = 7;
if (paintPixelDistance < maxPaintDistance)
{
return;
}
lastPaintPixelPosition = paintPixelPosition;
int pixelXOffset = pixelX - (_brush.width / 2);
int pixelYOffset = pixelY - (_brush.height / 2);
for (int x = 0; x < _brush.width; x++)
{
for (int y = 0; y < _brush.height; y++) {
Color pixelDirt = _brush.GetPixel(x, y);
Color pixelDirtMask = _templateDirtMask.GetPixel(pixelXOffset + x, pixelYOffset + y);
float removedAmount = pixelDirtMask.g - (pixelDirtMask.g * pixelDirt.g);
dirtAmount -= removedAmount;
_templateDirtMask.SetPixel(
pixelXOffset + x,
pixelYOffset + y,
new Color(0, pixelDirtMask.g * pixelDirt.g, 0)
);
}
}
_templateDirtMask.Apply();
}
}
}
Start Paint, and using the pen, try draw circles as fast as you can then look at the result:
Obviously, you didn't draw such straight lines with such clean direction change.
So, how is Paint able to cope up with such huge delta changes?
Interpolation
Some pseudo code:
on mouse down
get current mouse position
if last mouse position has been set
draw all the positions between last to current
use Bresenham algorithm for instance
save current mouse position to last mouse position
You could/should make your algo aware about pen size, with some simple math you can figure out the necessary step in evaluating points in the interpolation.
And don't use SetPixel, keep a copy of the texture pixels with GetPixels32 that you'll update and then upload it all at once using SetPixels32.
//The following game has been designed as an educational resource
//for Key Stage 1 and 2 children. Children are the future of
//civil engineering, and to inspire them to get involved in the
//industry is important for innovation. However, today the
//national curriculum is very structured, and many children
//can find themselves falling behind even at the age of 7 or 8.
//It is essential that children can be supported with material
//they find difficult, and given the resources to learn in a
//fun and engaging manner.
//One of the topics that many children struggle to grasp is
//fractions. It is necessary to prevent young children feeling
//like STEM subjects are too difficult for them, so that they
//have the opportunity and confidence to explore science and
//engineering subjects as they move into secondary education and
//careers.
//This game intends to set a precedent for teaching complex
//subjects to children in a simple, but fun and interactive
//manner. It will show them that fractions can be fun, and that
//they are capable, building confidence once they return to
//the classroom.
//The game will work by challenging the user to split a group
//of balls into three buckets depending on the fraction
//displayed on the bucket.
int number_of_balls;
float bucket_1, bucket_2, bucket_3;
int bucket_1_correct, bucket_2_correct, bucket_3_correct;
PVector basket_position, basket_dimensions;
Ball[] array_of_balls;
int linethickness;
//Random generator to give number of balls, ensuring that
//they can be divided into the number of buckets available.
void setup()
{
size(500,500);
linethickness = 4;
number_of_balls = int(random(1,11))*6;
println(number_of_balls);
bucket_1 = 1/6;
bucket_2 = 1/2;
bucket_3 = 1/3;
//Working out the correct answers
bucket_1_correct = number_of_balls*bucket_1;
bucket_2_correct = number_of_balls*bucket_2;
bucket_3_correct = number_of_balls*bucket_3;
println (bucket_1, bucket_2, bucket_3);
println (bucket_1_correct, bucket_2_correct, bucket_3_correct);
//Creating the basket
basket_position = new PVector(width/4, height/8);
basket_dimensions = new PVector(width/2, height/4);
//Creating the balls & placing inside basket
array_of_balls = new Ball[number_of_balls];
for (int index=0; index<number_of_balls; index++)
{
array_of_balls[index] = new Ball();
}
}
//Drawing the balls and basket outline
void draw()
{
background (125,95,225);
for (int index=0; index<number_of_balls; index++)
{
array_of_balls[index].Draw();
}
noFill();
stroke(180,0,0);
strokeWeight(linethickness);
rect(basket_position.x, basket_position.y, basket_dimensions.x, basket_dimensions.y);
}
void mouseDragged()
{
if ((mouseX >= (ball_position.x - radius)) && (mouseX <= (ball_position.x + radius)) && (mouseY >= (ball_position.y - radius)) && (mouseY <= (ball_position.y + radius)))
{
ball_position = new PVector (mouseX, mouseY);
}
}
//Ball_class
int radius;
Ball()
{
radius = 10;
ball_position = new PVector (random(basket_position.x + radius + linethickness, basket_position.x + basket_dimensions.x - radius - linethickness), random(basket_position.y + radius + linethickness, basket_position.y + basket_dimensions.y - radius - linethickness));
colour = color(random(255), random(255), random(255));
}
void Draw()
{
noStroke();
fill(colour);
ellipse(ball_position.x,ball_position.y,radius*2,radius*2);
}
}
Thanks in advance for your help! I am using Processing 2.2.1 which I know is very out of date, so struggling to find help.
I have a piece of code that has created a number of balls, and I would like to be able to 'drag and drop' these to a different location on the screen as part of an educational game. I've tried playing around with mousePressed() and mouseDragged() but no luck yet. Any advice would be appreciated!
There are a lot of ways to approach this, but one way I could suggest is doing something like this:
// "Ellipse" object
function Ellipse (x, y, width, height) {
// Each Ellipse object has their own x, y, width, height, and "selected" values
this.x = x;
this.y = y;
this.width = width;
this.height = height;
this.selected = false;
// You can call the draw function whenever you want something done with the object
this.draw = function() {
// Draw ellipse
ellipse(this.x, this.y, this.width, this.height);
// Check if mouse is touching the ellipse using math
// https://www.desmos.com/calculator/7a9u1bpfvt
var xDistance = this.x - mouseX;
var yDistance = this.y - mouseY;
// Ellipse formula: (x^2)/a + (y^2)/b = r^2
// Assuming r = 1 and y = 0:
// 0 + (x^2)/a = 1 Substitute values
// ((width / 2)^2)/a = 1 x = width / 2 when y = 0
// a = (width / 2)^2 Move numbers around
// a = (width^2) / 4 Evaluate
var a = Math.pow(this.width, 2) / 4;
// Assuming r = 1 and x = 0:
// 0 + (y^2)/b = 1 Substitute values
// ((height / 2)^2)/b = 1 y = height / 2 when x = 0
// b = (height / 2)^2 Move numbers around
// b = (height^2) / 4 Evaluate
var b = Math.pow(this.height, 2) / 4;
// x^2
var x2 = Math.pow(xDistance, 2);
// y^2
var y2 = Math.pow(yDistance, 2);
// Check if coordinate is inside ellipse and mouse is pressed
if(x2 / a + y2 / b < 1 && mouseIsPressed) {
this.selected = true;
}
// If mouse is released, deselect the ellipse
if(!mouseIsPressed) {
this.selected = false;
}
// If selected, then move the ellipse
if(this.selected) {
// Moves ellipse with mouse
this.x += mouseX - pmouseX;
this.y += mouseY - pmouseY;
}
};
}
// New Ellipse object
var test = new Ellipse(100, 100, 90, 60);
draw = function() {
background(255);
// Do everything associated with that object
test.draw();
};
The math is a bit funky, and I might not be using the right version of Processing, but hopefully you found this at least slightly helpful :)
I'm kind of confused about what language you're using. Processing is a wrapper for Java, not JavaScript. Processing.js went up to version 1.6.6 and then was succeeded by p5.js. I'm going to assume you're using p5.js.
I don't know if this is a new thing in p5.js, but for easy, but not very user-friendly click-and-drag functionality I like to use the built-in variable mouseIsPressed.
If the ellipse coordinates are stored in an array of vectors, you might do something like this:
let balls = [];
let radius = 10;
function setup() {
createCanvas(400, 400);
for (let i = 0; i < 10; i++) {
balls.push(createVector(random(width), random(height)));
}
}
function draw() {
background(220);
for (let i = 0; i < balls.length && mouseIsPressed; i++) {
if (dist(mouseX, mouseY, balls[i].x, balls[i].y) < radius) {
balls[i] = createVector(mouseX, mouseY);
i = balls.length;
}
}
for (let i = 0; i < balls.length; i++) {
ellipse(balls[i].x, balls[i].y,
2 * radius, 2 * radius
);
}
}
This is the quickest way I could think of, but there are better ways to do it (at least, there are in p5.js). You could make a Ball class which has numbers for x, y, and radius, as well as a boolean for whether it's being dragged. In that class, you could make a method mouseOn() which detects whether the cursor is within the radius (if it's not a circle, you can use two radii: sq((this.x - mouseX)/r1) + sq((this.y - mouseY)/r2) < 1).
When the mouse is pressed, you can cycle through all the balls in the array of balls, and test each of them with mouseOn(), and set their drag boolean to true. When the mouse is released, you can set all of their drag booleans to false. Here's what it looks like in the current version of p5.js:
function mousePressed() {
for (let i = 0; i < balls.length; i++) {
balls[i].drag = balls[i].mouseOn();
if (balls[i].drag) {
i = balls.length;
}
}
}
function mouseReleased() {
for (let i = 0; i < balls.length; i++) {
balls[i].drag = false;
}
}
I hope this helps.
The way your code is right now doesn't work in the current version of Processing either, but it's a pretty quick fix. I'm going to show you a way to fix that, and hopefully it'll work in the earlier version.
Here's where I think the problem is: when you use mouseDragged(), you try to change ball_position, but you don't specify which ball's position. Here's one solution, changing the mouseDragged() block and the Ball class:
void mouseDragged() {
for (int i = 0; i < array_of_balls.length; i++) {
if ((mouseX > (array_of_balls[i].ball_position.x - array_of_balls[i].radius)) &&
(mouseX < (array_of_balls[i].ball_position.x + array_of_balls[i].radius)) &&
(mouseY > (array_of_balls[i].ball_position.y - array_of_balls[i].radius)) &&
(mouseY < (array_of_balls[i].ball_position.y + array_of_balls[i].radius))
) {
array_of_balls[i].ball_position = new PVector (mouseX, mouseY);
i = array_of_balls.length;
}
}
}
//Ball_class
class Ball {
int radius;
PVector ball_position;
color colour;
Ball() {
radius = 10;
ball_position = new PVector (random(basket_position.x + radius + linethickness, basket_position.x + basket_dimensions.x - radius - linethickness), random(basket_position.y + radius + linethickness, basket_position.y + basket_dimensions.y - radius - linethickness));
colour = color(random(255), random(255), random(255));
}
void Draw() {
noStroke();
fill(colour);
ellipse(ball_position.x, ball_position.y, radius*2, radius*2);
}
}
P.S. Since you're using a language based in Java, you should probably adhere to the finnicky parts of the language:
data types are very strict in Java. Avoid assigning anything that could possibly be a float to a variable that is declared as an int. For example, in your setup() block, you say bucket_1_correct = number_of_balls*bucket_1;. This might seem like not an issue, since number_of_balls*bucket_1 is always going to be a whole number. But since the computer rounds when saving bucket_1 = 1/6, multiplying it by 6 doesn't necessarily give a whole number. In this case, you can just use round(): bucket_1_correct = round(number_of_balls*bucket_1);
Regarding data types, you should always declare your variables with their data type. It's a little hard for me to tell, but it looks to me like you never declared ball_position or colour in your Ball class, and you never opened up the class with the typical class Ball {. This might have been a copy/paste error, though.
Moving a ball with constant velocity
I tried to make a box of balls where the balls move with constant velocity. The shouldn't slow down when they collide with each other. I think I have set all properties right but it didn't work and after 30s all of the balls stopped to move.
The box is set like this:
self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
self.physicsBody.dynamic = false
self.physicsBody.restitution = 1
self.physicsBody.friction = 0
The balls are set like this:
Is this a bug of the physics engine or am I missing something?
If you want them to have a constant velocity all the time, no change at all, you're going to have to set their velocity to a fixed-length vector in SKScene update. Physics engines aren't designed to adhere strictly to the conservation of energy law ... or one could argue that some energy is dissipated through heating the device. ;)
General principle for keeping the same direction but adjusting vector length/speed to a fixed value (pseudo-code):
CGPoint velocity = somePhysicsBody.velocity;
velocity = normalized(velocity);
velocity = multiply(velocity, desiredSpeed);
somePhysicsBody.velocity = velocity;
In addition to Steffen's (LearnCocos2D) answer, the methods mentioned in the pseudo-code can be found in this very good Ray Wenderlich tutorial.
static inline CGPoint rwAdd(CGPoint a, CGPoint b) {
return CGPointMake(a.x + b.x, a.y + b.y);
}
static inline CGPoint rwSub(CGPoint a, CGPoint b) {
return CGPointMake(a.x - b.x, a.y - b.y);
}
static inline CGPoint rwMult(CGPoint a, float b) {
return CGPointMake(a.x * b, a.y * b);
}
static inline float rwLength(CGPoint a) {
return sqrtf(a.x * a.x + a.y * a.y);
}
// Makes a vector have a length of 1
static inline CGPoint rwNormalize(CGPoint a) {
float length = rwLength(a);
return CGPointMake(a.x / length, a.y / length);
}
They use CGPoint as the parameters and return value, but this can be easily converted to use CGVector.
These methods are very useful for physics calculations, and you will find use for them at many points. It is best to keep these methods in a separate header file, and use them in the code throughout your project.
I made an app which there is an object that moves towards a moving point all the time - that is why I didn't use any animated function. The problem is that I made this function:
CGPoint center = self.im.center; // "i" is a CGPoint, im is an imageview.
if (!CGPointEqualToPoint(self.im.center, i))
{
a = (i.y-center.y)/(i.x-center.x);
//Y = a*X+b - this is a linear function in math
b = (center.y-(a*center.x));
if (i.y>center.y) {
self.im.center = CGPointMake(((center.y+1)-b)/a, center.y+1);
}
else
{
self.im.center = CGPointMake(((center.y-1)-b)/a, center.y-1);
}
}
The problem is that the closer the functions is becoming a straight horizontal line its faster because the change is mostly to the X axis which means that if I add 1 to Y the change to X is bigger which means it will move faster..
If there is another way to do this i will be glad to try it so if you know other ways tell me!
Managed to find a different solution
CGPoint center = self.im.center;//im = the image view
x = center.x;//starting point
y = center.y;//starting point
double distance = sqrtf(powf(i.x - x, 2) + powf(i.y - y, 2));// i = cgpoint (ending point)
float speedX = (2 * (i.x - x)) / distance;//(the 2 is the speed)
float speedY = (2 * (i.y - y)) / distance;//(the 2 is the speed)
self.im.center = CGPointMake(center.x+speedX, center.y+speedY);//im = the image view
I am currently in the process of creating a sort of drawing program in openFrameworks that needs to calculate the angle of mouse movement. The reason for this is that the program needs to be able to draw brush strokes similar to the way photoshop does it.
I've been able to get it to work in a very jaggy way. I've placed my code in the MouseDragged event in openFrameworks, but the calculated angle is extremely jaggy and not smooth in anyway. It needs to be smooth in order for the drawing part to look good.
void testApp::mouseMoved(int x, int y ){
dxX = x - oldX;
dxY = y - oldY;
movementAngle = (atan2(dxY, dxX) * 180.0 / PI);
double movementAngleRad;
movementAngleRad = movementAngle * TO_RADIANS;
if (movementAngle < 0) {
movementAngle += 360;
}
testString = "X: " + ofToString(dxX) + " ,";
testString += "Y: " + ofToString(dxY) + " ,";
testString += "movementAngle: " + ofToString(movementAngle);
oldX = x;
oldY = y;
}
I've tried different ways of optimizing the code to work smooth but alas without results.
If you sit with a brilliant idea on how this could be fixed or optimized, I will be very grateful.
I solved it to some degree by using an ofPolyline object.
The following code shows how it works.
void testApp::mouseMoved(int x, int y ){
float angleRad;
if (movement.size() > 4)
{ angleRad = atan2(movement[movement.size()-4].y - y, movement[movement.size()-4].x -x);}
movementAngle = (angleRad * 180 / PI) + 180;
movement.addVertex(x,y,0);
}
As seen in the code I'm using the point recorded 4 steps back to increase the smoothness of the angle. This works if the mouse is moved in stroke like movements. If the mouse is moved slow, jaggyness will still occur.