QT how to use setPixmap skin.copy() for do an animation? - c++

Question

I want to do a little animation in my application. I have an asteroid and when he travel to the right the animation go to the right, when he go to the left animation go to the left,
the angle is between 0 and 360°.
I have add the tiles for you explain me how to cut it perfectly.
I have in the class an integer who have number bewteen 0 and 34 (asteroids on the image) I decrease -1 or add +1 to this variable at each animation.
The method that animates the asteroid:
void Asteroid::animation(){
int x = 1;
int y = 1;
int width = 5;
int height = 5;
// what should I add here?
if(this->angle >= 0 && this->angle < 180){
// cut image go to the right
setPixmap(this->skin.copy(x,y,width,height));
this->frame++;
if(frame > 34) this->frame = 1;
} else {
// cut image go to the left
setPixmap(this->skin.copy(x,y,width,height));
this->frame--;
if(frame < 1) this->frame = 34;
}
}
The contents of the skin pixmap:
Interface
#include <QGraphicsPixmapItem>
#include <QGraphicsScene>
#include <QPoint>
#include <QVector>
#include <QPixmap>
#include <QString>
#include <QTimer>
#include <QObject>
#include <time.h>
#include <QtCore/qmath.h>
#include "SettingsAsteroid.h"
class Asteroid : public QObject, public QGraphicsPixmapItem
{
Q_OBJECT
// Animation
QPixmap skin;
int frame; // 32 images
// Data
int speed;
int size;
int pv;
float angle;
public:
Asteroid(int size);
Asteroid(QPointF position, int size);
~Asteroid();
int getPosX();
int getPosY();
void setPosX(int newPos);
void setPosY(int newPos);
int getSpeed();
int getSize();
int getPV();
int getAngle();
// météorite détruite
void destroyed();
// toucher par un tir
void touched(int damage);
bool isDestroyed();
private slots:
// mouvement de la météorite
void move();
// animation de la météorite
void animation();
signals:
//void notKilled();
// transmet la taille du météorite détruit
void killed(int);
};
Implementation
#include "Asteroid.h"
Asteroid::Asteroid(int size)
{
this->skin = QPixmap(SettingsAsteroid::getRandomSkin());
this->speed = SettingsAsteroid::getRandomSpeed(4,8);
this->pv = SettingsAsteroid::getPV(size);
this->angle = SettingsAsteroid::getRandomAngle();
this->frame = 1;
// Position de départ random
QPointF position = QPointF(SettingsAsteroid::getRandomStartPosition());
this->setPos(position.x(), position.y());
this->size = size;
// mouvement de l'astéroide
QTimer* timer2 = new QTimer();
connect(timer2,SIGNAL(timeout()),this,SLOT(move()));
timer2->start(this->speed);
// animation de l'astéroide
QTimer* timer = new QTimer();
connect(timer,SIGNAL(timeout()),this,SLOT(animation()));
timer->start(100);
}
Asteroid::Asteroid(QPointF position, int size)
{
this->skin = QPixmap(SettingsAsteroid::getRandomSkin());
this->speed = SettingsAsteroid::getRandomSpeed(4,8);
this->pv = SettingsAsteroid::getPV(size);
this->angle = SettingsAsteroid::getRandomAngle();
this->frame = 1;
this->setPos(position.x(), position.y());
this->size = size;
QTimer* timer2 = new QTimer();
connect(timer2,SIGNAL(timeout()),this,SLOT(move()));
timer2->start(this->speed);
//Decoupe sprite et anmiation
QTimer* timer = new QTimer();
connect(timer,SIGNAL(timeout()),this,SLOT(animation()));
timer->start(150);
}
Asteroid::~Asteroid()
{
}
int Asteroid::getPosX(){
return this->pos().x();
}
int Asteroid::getPosY(){
return this->pos().y();
}
void Asteroid::setPosX(int newPos){
this->setPos(newPos, this->pos().y());
}
void Asteroid::setPosY(int newPos){
this->setPos(this->pos().x(), newPos);
}
int Asteroid::getSpeed(){
return this->speed;
}
int Asteroid::getSize(){
return this->size;
}
int Asteroid::getPV(){
return this->pv;
}
int Asteroid::getAngle(){
return this->angle;
}
bool Asteroid::isDestroyed(){
if(pv > 0) return false;
else return true;
}
void Asteroid::destroyed(){
// AVERTIR CLASSE PRINCIPALE QUE DETRUIT
}
void Asteroid::touched(int damage){
this->pv -= damage;
if(pv<=0) destroyed();
}
void Asteroid::move(){
double dx = getSpeed() * qCos(qDegreesToRadians(angle)) ;
double dy = getSpeed() * qSin(qDegreesToRadians(angle)) ;
setPos(QPointF(getPosX() + dx, getPosY() + dy)) ;
// place la météorite de l'autre coté de la scène
if (getPosX()<=0) setPosX(799);
else if (getPosY()<=0) setPosY(659);
else if (getPosX()>= 800) setPosX(1);
else if (getPosY()>= 600) setPosY(1);
}
void Asteroid::animation(){
// what add here?
int x = 1;
int y = 1;
int width = 5;
int height = 5;
if(this->angle >= 0 && this->angle < 180){
// cut image go to the right
setPixmap(this->skin.copy(x,y,width,height));
this->frame++;
if(frame > 34) this->frame = 1;
} else {
// cut image go to the left
setPixmap(this->skin.copy(x,y,width,height));
this->frame--;
if(frame < 1) this->frame = 34;
}
}
The angle is the direction of the Asteroid on the scene. There will be a spaceship who should destroyed the asteroid. I want make the animaton of the Asteroids who move on the scene

Answer 1

Assuming that the asteroid images in the skin are square, you can do as follows.
Your skin has only 32 items, not 34, BTW.
void Asteroid::animation() {
int step = skin.height();
int N = skin.width() / step; // Number of images in the skin.
Q_ASSERT(skin.width() % step == 0); // ensure proper format of the skin
if (angle >= 0 && angle < 180) {
frame ++;
if (frame > N) frame -= N;
} else {
frame --;
if (frame < 1) frame += N;
}
int x = (frame - 1) * step;
setPixmap(skin.copy(x, 0, step, step));
}