Check for collision is already included somewhat in sfml:
bool spriteOverlap(sf::Sprite& sprite1, sf::Sprite& sprite2) // possibly const, dunno
{
return sprite1.getGlobalBounds().intersects(sprite2.getGlobalBounds());
}
Generally try this: Only move, if the position of the next frame is valid. This prevents objects being stuck, because you already moved them into an invalid position, thus preventing any further movement
edit:
//untested
bool spritesWillOverlap(sf::Sprite& sprite1, sf::Sprite& sprite2, sf::Vector2f vel)
{
top1 = sprite1.getGobalBounds().top + vel.y;
left1 = sprite1.getGlobalBounds().left + vel.x;
right1 = left1 + sprite1.getGlobalBounds().width;
bottom1 = top1 + sprite1.getGlobalBounds().height;
top2 = sprite2.getGobalBounds().top + vel.y;
left2 = sprite2.getGlobalBounds().left + vel.x;
right2 = left2 + sprite1.getGlobalBounds().width;
bottom2 = top2 + sprite1.getGlobalBounds().height;
sf::FloatRect rect1(top1, left1, right1 - left1, bottom1 - top1);
sf::FloatRect rect2(top2, left2, right2 - left2, bottom2 - top2);
return rect1.intersects(rect2);
}
vel: velocity -> an object is moved by this 2D vector every frame
If the concept of "frames" is unfamiliar, read up on framerates/fixed framerate and/or timestep. here's an example article to get started: Fix Your Timestep!