I'm trying to follow this Actionscript tutorial for homing missiles, translating it to C++ with SFML.

But I seem to have a problem with this piece of code:

**In Actionscript:**

var rotation:int = Math.atan2(targetY, targetX) * 180 / Math.PI; if (Math.abs(rotation - missile.rotation) > 180) { if (rotation > 0 && missile.rotation < 0) missile.rotation -= (360 - rotation + missile.rotation) / ease; else if (missile.rotation > 0 && rotation < 0) missile.rotation += (360 - rotation + missile.rotation) / ease; } else if (rotation < missile.rotation) missile.rotation -= Math.abs(missile.rotation - rotation) / ease; else missile.rotation += Math.abs(rotation - missile.rotation) / ease;

**Translated in C++ with SFML:**

int current = rocket_sprite.getRotation(); if( abs( rotation - current ) > 180 ) { if( rotation > 0 && current < 0 ) rotation -= ( 360 - rotation + current ) / ease; else if( current > 0 && rotation < 0 ) rotation += ( 360 - rotation + current ) / ease; } else if( rotation < current ) rotation -= abs( current - rotation ) / ease; else rotation += abs( rotation - current ) / ease;

With this code, the missile acts crazy, getting stuck in places, continually rotating in place for no reason and other stuff like that.

I suspect that the problem lies in the fact that .getRotation() returns absolute values, but I don't know how to even test it.

Here is my complete code:

#include <math.h> #define PI 3.14159265 class rocket { private: sf::Texture rocket_texture; sf::Sprite rocket_sprite; sf::Vector2f position; int rotation; public: rocket(); bool rocket_load(); void rocket_show( sf::RenderWindow * window ); void set_position( sf::Vector2f new_position ); void rocket_rotate( sf::RenderWindow * window ); void rocket_move(); }; rocket::rocket() { rotation = 0.f; } bool rocket::rocket_load() { rocket_texture.loadFromFile( "rocket.png" ); rocket_sprite.setTexture( rocket_texture ); return true; } void rocket::rocket_show( sf::RenderWindow * window ) { rocket_sprite.setOrigin( rocket_texture.getSize().x / 2 , rocket_texture.getSize().y / 2 ); rocket_sprite.setPosition( position ); window->draw( rocket_sprite ); } void rocket::set_position( sf::Vector2f new_position ) { position = new_position; } void rocket::rocket_rotate( sf::RenderWindow * window ) { sf::Vector2i mouse_position = sf::Mouse::getPosition( *window ); int targetx = mouse_position.x - position.x; int targety = mouse_position.y - position.y; rotation = atan2( targety , targetx ) * 180 / PI; int ease = 5; int current = rocket_sprite.getRotation(); if( abs( rotation - current ) > 180 ) { if( rotation > 0 && current < 0 ) rotation -= ( 360 - rotation + current ) / ease; else if( current > 0 && rotation < 0 ) rotation += ( 360 - rotation + current ) / ease; } else if( rotation < current ) rotation -= abs( current - rotation ) / ease; else rotation += abs( rotation - current ) / ease; rocket_sprite.setRotation( rotation ); } void rocket::rocket_move() { int speed = 5; float speedx = 0; float speedy = 0; speedx = speed * ( 90 - abs( rotation ) ) / 90; if( rotation < 0 ) speedy = -speed + abs( speedx ); else speedy = speed - abs( speedx ); position.x += speedx; position.y += speedy; }

If anyone can point me to the right direction, I would really appreciate it. :-)

Thank you in advance. :-)

**Edited by Kain5056, 05 June 2014 - 07:30 AM.**