I try to delete a square when I input the number as "1" into the program. How can I delete it?
sf::RectangleShape rec1(sf::Vector2f(50, 100));
rec1.setPosition(200, 700 );
rec1.setFillColor(sf::Color(100, 250, 50));
window.draw(rec1);
int num;
cout << "Please enter a number: ";
cin >> num;
SFML itself won't track what's drawn on screen – you'll have to do that yourself – and you're supposed to redraw the window contents when needed.
A basic "main loop" for a SFML based program would typically look like this:
while (window.isOpen()) {
sf::Event event;
while (window.pollEvent(event)) {
// Handle events here
}
// Update your program logic here
window.clear();
// Draw your stuff here
window.display();
}
Depending on what you draw, you determine what's visible on screen. So if you want your rectangle to no longer appear, simply no longer call window.draw(rectangle);. How you achieve this – e.g. by removing the rectangle from a std::vector<sf::Drawable*> that's iterated over while drawing – is up to you.
You can't delete it when you created it like that. you can color it as transparent using sf::Color::Transparent and it will become unseenable.
If you want to delete it. you have to make it a pointer first. or wrap it out of a class that handles it.
auto rect = make_unique<sf::Rectangle>(sf::Vector2f(50, 100));
and then use std::unique_ptr::reset() to delete it.
rect.reset();
Related
I'm trying to use an animation for a sudoku app. I want for everytime i insert a wrong number, that number would change color and it's scale.
My code is:
override fun onDraw(canvas: Canvas?) {
canvas ?: return
drawBoard(canvas)
drawNumberProblem(canvas)
}
private fun drawNumberProblem(canvas: Canvas){
paint.color=darkcolor
paint.textSize = cellSide*3/4
SudokuGame.numbersproblem.forEach { e->
canvas.drawText("${e.number}", originX + e.col * cellSide+cellSide/5, originX + (e.row+1) * cellSide-cellSide/10, paint)
}
}
And i tried:
private fun initAnimation() {
var animation = RotateAnimation(0f, 360f, 150f, 150f)
animation.setRepeatCount(Animation.INFINITE)
animation.setRepeatMode(Animation.RESTART)
animation.setDuration(7500L)
animation.interpolator = LinearInterpolator()
startAnimation(animation)
}
override fun onDraw(canvas: Canvas?) {
canvas ?: return
if(animation==null)
initAnimation()
drawBoard(canvas)
drawNumberProblem(canvas)
}
private fun drawNumberProblem(canvas: Canvas){
paint.color=darkcolor
paint.textSize = cellSide*3/4
SudokuGame.numbersproblem.forEach { e->
canvas.drawText("${e.number}", originX + e.col * cellSide+cellSide/5, originX + (e.row+1) * cellSide-cellSide/10, paint)
}
}
The animation, the board and the numbers are all good. The animation is only an example, i tried to rotate it to see if it's working. But the only problem is that the animation is working for the whole board, i want to have animation only over numbers.
Is there any way to create a initAnimation with a parameter like initAnimation(drawNumberProblem())?
I am new to kotlin animation, so i don't really care about the best way to do it, i want to find a simple way to understand it.
Thanks
If each cell is its own View (say a TextView) you can animate it the way you're trying to, and the animation framework will take care of the timing, the rotation and scaling, etc. Because each view is separate, they can all be animated independently, using Android's view animation libraries, and a lot of the work is taken care of for you - it's pretty easy to use!
If it's all one view, and you're drawing a bunch of elements which can all be animated, you have to keep track of those elements, any animations that should be happening to each one, and how each animation's state affects the element when it comes time to draw it. Instead of each view having its own state and being drawn separately, you have to draw the whole thing at once, because it's a single view. So you need to keep track of those individual element states yourself, so you can refer to them when drawing the current overall state.
So for example, say you've got an animation where an element needs to scale to 2x the size and then back to normal, and it runs for 1 second total (1000ms). When you come to draw that element, you need to know how far along that animation you are at that moment, so you can scale it appropriately, and draw it at the correct size.
There are lots of ways to do this, probably some smarter ones, but this is the most basic hands-on example I think. I'm not testing this, but hopefully it gives you the idea:
// for brevity, so we can just say "now" instead of writing out the whole function call
val now: Long get() = System.currentTimeMillis()
// store a start time for each grid cell (or null if there's no anim running)
val animStartTimes = Array(CELL_COUNT)<Long?>
val animLength = 1000 // millis
// Basic function to start an animation - you could adapt this to prevent restarts
// while an anim is already running, etc
fun startAnim(cellIndex: Int) {
animStartTimes[cellIndex] = now
// tell the view it needs to redraw (since we're animating something now)
invalidate()
}
// Get the current progress of an animation in a cell, from 0% to 100% (0.0 to 1.0)
// I'm treating a finished item as "reset" to its original state
fun getAnimProgress(cellIndex: Int): Float {
val start = animStartTimes[cellIndex]
if (start == null) return 0f
val progress = (now - start) / animLength
if (progress > 1f) {
// animation has ended (past 100% of its runtime) so let's clear it
animStartTimes[cellIndex] = null
return 0f // like I said, I'm treating finished animations as "reset" to 0%
} else return progress
}
override fun onDraw(canvas: Canvas) {
// this flag can be set to true if we find an element that's still animating,
// so we can decide whether to call invalidate() again (forcing a redraw next frame)
var animating = false
items.forEachIndexed { i, item ->
val animProgress = getAnimProgress(i)
if (animProgress > 0f) animating = true // set that flag
// now you need to use that 0.0-1.0 value to calculate your animation state,
// e.g. adjusting the text size by some factor - 0.0 should produce your "default" state
}
// finally, force a redraw next frame if necessary - only do this when your view
// contents might need to change, otherwise you're wasting resources
if (animating) invalidate()
}
I hope that makes sense - obviously I haven't shown how to actually draw the states of your animation, that depends on exactly what you're doing - but that's the basics of it. It's a lot more work than using view animation, but it's not too bad when you get the idea.
The drawing part is a little more complex, and you'll probably want to get familiar with manipulating the Canvas - e.g. to draw a rotated character, you turn the canvas, draw the character as normal, then undo the canvas rotation so it's the right way up again, and the character is tilted. I don't have time to look for any tutorials about it, but this article covers the matrix operations that scale/rotate/etc the canvas
So yeah, it's a bit involved - and depending on what you want to do, a grid of TextViews might be a better shout
I've read window(3NCURSES) man page, but I can't fully understand what mvwin() function actually does and what happens to its subwindows.
The code below creates a window with a title "Window" and a border, it also creates a subwindow that is used for printing y,x position without corrupting parent window border. It then moves the parent window to a new location, but the result is not what I expected:
After the window is moved, the outline of the windows border + text is not automatically erased at the old location.
After the move, writing text to a subwindow, outputs it at the old and new location.
After the move, parent window has new y,x coordinates, but subwindow still shows old coordinates.
I don't have a lot of experience with ncurses, and maybe I'm missing something, but this behaviour is completely illogical. If I have to manually erase windows at old location and manually move all subwindows, then this negates the benefit of using ncurses in the first place. I was expecting ncurses to automatically handle these low-level details.
My understanding of subwindows was that they are used to partition one large window into smaller non-overlapping areas. So when the parent window is moved or refreshed, all its subwindows should be moved or refreshed automatically. Is this correct?
#include <assert.h>
#include <ncurses.h>
#include <unistd.h>
int main()
{
WINDOW *win, *swin;
int lines, cols, y, x;
initscr();
keypad(stdscr, TRUE);
noecho();
// Create window
lines = 10; cols = 40;
y = 5; x = 5;
win = newwin(lines, cols, y, x);
assert(win != NULL);
// Create window border
box(win, 0, 0);
mvwprintw(win, 0, 2, " Window ");
// Create subwindow
swin = subwin(win, lines-2, cols-2, y+1, x+1);
assert(swin != NULL);
// Print window and subwindow y,x
mvwprintw(swin, 0, 0, "win y,x=%d,%d swin y,x=%d,%d\n",
getbegy(win), getbegx(win), getbegy(swin), getbegx(swin));
// Refresh
wnoutrefresh(stdscr);
wnoutrefresh(win);
wnoutrefresh(swin);
doupdate();
sleep(2);
// Move window
y = 20; x = 40;
mvwin(win, y, x);
mvwprintw(swin, 0, 0, "win y,x=%d,%d swin y,x=%d,%d\n",
getbegy(win), getbegx(win), getbegy(swin), getbegx(swin));
// Refresh
wnoutrefresh(stdscr);
wnoutrefresh(win);
wnoutrefresh(swin);
doupdate();
wgetch(swin);
endwin();
return 0;
}
Apparently not: a quick check with Solaris 10 gives the same behavior. You might find some scenario where ncurses differs unintentionally, but this is not one of those. The FAQ makes this point about compatibility:
extensions (deviations from SVr4 curses) are allowed only if they do not modify the documented/observed behavior of the API.
The Solaris manual page does not make this clear, since the only mention of subwindows is in regard to moving them:
The mvwin() routine moves the window so that the upper left-hand corner is at position (x, y). If the move would cause the window to be off the screen, it is an error and the window is not moved. Moving subwindows is allowed, but should be avoided.
The Solaris source code tells the story for that: it does nothing with subwindows. Some retesting a while back (early 2006) in response to a user's comment about differences pointed out that ncurses was incorrectly attempting to copy subwindows. That part is ifdef'd out (since it's too interesting to just delete). Since there's not much left for mvwin to do, the actual code is fairly similar.
X/Open's description of mvwin is too brief and vague to be of any use.
I made a galaxy sketch in p5.js using rotates and radians, but it's erased each time the background() is loaded as draw() runs. Is there a way to over-ride the background() function? I want the galaxies to remain in view.
var stars;
function preload(){
//for (var i = 0; i < planetArray.length; i++) {
//stars = loadImage('Assets/stars.png');
}
function setup(){
createCanvas(windowWidth, windowHeight);
}
function draw() {
//background(0);
star()
//function mousepressed(){
}
function star(){
//angle = map(mouseX, 0,width, 0,360);
//rotate(radians(angle*100));
noStroke();
//translate(width/2, height/2);
translate(mouseX,mouseY);
fill(0);
rotate(radians(frameCount%360)); //rotates output of ellipses
rotate(radians(1000*frameCount%360));
for(var i =0; i < 20; i++){
push();
noStroke();
fill(random(200),0,random(150),random(2));
// fill(random(125),random(250),random(100));
ellipse(10*frameCount % (width/10),0,10,10);
//image(stars, 10*frameCount % (width/2),0,10,10)
//image((10*frameCount % (width/2),0,10,10)
//
pop();
}
}
Well, there really isn't any magic to it. Calling the background() function fills the window with a solid color (or image) and draws over anything you've previously drawn.
The solution to this problem isn't to "over-ride" the background() function. It's to restructure your program so your stuff gets drawn properly. Exactly how you do that depends on exactly what you want to happen.
Option 1: Only call the background() function once.
If you just want a black background at the beginning, and everything you do from the draw() function should still add up, then maybe you just want to call the background() function once. You could do it as the last line in your setup() function, for example.
Option 2: Store everything you want to draw in a data structure.
This is probably the most typical case. If you want a background to be drawn behind shapes that are moving around, you're going to have to store those shapes in some kind of data structure, and then draw all of them every single frame.
Option 3: Draw to an off-screen image, and then draw that image on top of your background.
This is a bit of a mix between the first two options. You can draw everything (except the background) to an off-screen PImage, and then draw the background to the screen, then draw the image to the screen. This allows you to have a background that changes colors without having to redraw everything else.
Which option you choose really depends on exactly what you want to happen.
I'm using Phaser 2.4.2 with P2 physics. I have a sort of jar shaped body containing some circular bodies (balls). I want to move the jar offscreen but the balls are colliding with the world bounds.
I tried setting collideWorldBounds on the balls like so:
ball.body.setCircle(64);
ball.body.collideWorldBounds = false;
but this stops them colliding with the jar which I want -- the result is gravity makes them drop offscreen.
You can see a demo here: https://output.jsbin.com/vuyexo
Click the red button to make the jar move.
Uncomment collideWorldBounds=false in the 'balls' section.
Why is this happening and how can I make the balls collide with the jar body but not the world bounds when the jar is moved offscreen?
You can set the P2 world bounds using setBoundsToWorld so like this
//..
game.physics.p2.gravity.y = 300;
game.physics.p2.setBoundsToWorld(false, false, true, true); // left=false, right=false, top=true, bottom=true
Alternatively you could just make the P2 world larger, so for example make the width 2000 instead of 768.
game.world.setBounds(0, 0, 2000, 1024);
By default p2 collides everything with everything else, but if you want it to do something different then you have to explicitly list which objects collide with each other by adding each body to a collision group and then calling body.collides like this:
var jarCG = this.physics.p2.createCollisionGroup();
var ballsCG = this.physics.p2.createCollisionGroup();
jar.body.setCollisionGroup(jarCG);
jar.body.collides(ballsCG);
for (var i = 0; i < 9; i++)
{
var ball = balls.create(250+(i%3)*128,300+Math.floor(i/3)*128);
ball.body.setCircle(64);
ball.body.debug = true;
ball.body.collideWorldBounds = false;
ball.body.setCollisionGroup(ballsCG);
ball.body.collides([jarCG, ballsCG]);
}
This is working for me, but using a tween to move the jar still makes the physics act weird. You can fix it by either using jar.body.velocity.x instead of tweening or by also tweening all the balls. You can also try tweening stack.x if you just want to move the sprites, but for some reason this isn't moving their bodies.
I have the thread where the worker object is running infinite cycle. Here I have the following code that I would like it to read coordinates from list and place QGraphicsEllipseItem on these coordinates. The list can be updated by another thread, so I protect it by mutex. But sometimes the size of list may grow up so I would like to create new QGraphicsEllipse items for it if needed.
int meter_to_pixel_ratio = 20;
int x_pixel, y_pixel;
int i;
forever {
visualizationDataMutex->lock();
while(ellipseList->count()<visualizationData->count())
{
qDebug() << "Creating new visual item...";
ellipseList->append(new QGraphicsEllipseItem(0.0, 0.0, 10.0, 10.0));
ellipseList->last()->setVisible(false);
visualizationScene->addItem(ellipseList->last());
}
for(i=0; i<visualizationData->count(); i++)
{
x_pixel = meter_to_pixel_ratio*visualizationData->at(i)->x();
y_pixel = meter_to_pixel_ratio*visualizationData->at(i)->y();
ellipseList->at(i)->setPos(x_pixel, y_pixel);
ellipseList->at(i)->setBrush(QBrush(*visualizationColor->at(i)));
if(!ellipseList->at(i)->isVisible()) ellipseList->at(i)->setVisible(true);
}
visualizationDataMutex->unlock();
// repaint scene
visualizationScene->update();
QThread::msleep(100);
}
The problem I have is, that when I try to run the program I´ll obtain a runtime error. Tried to qDebug() the ellipseList->count() and seems to have the exactly same number of elements as needed (as visualizationData->count()). When commented these three lines:
//ellipseList->at(i)->setPos(x_pixel, y_pixel);
//ellipseList->at(i)->setBrush(QBrush(*visualizationColor->at(i)));
//if(!ellipseList->at(i)->isVisible()) ellipseList->at(i)->setVisible(true);
program can run without crashing. I do not understand why is this happening since there is no other function working with QGraphicsView/QGraphicsScene. (QGraphicsView was added from Qt Designer environment into mainwindow).