Hey guys, I'm new to programming and SFML. I'm trying to make something like a canon. It's gonna fire balls that will be flying in an arc. Sounds like a very simple task to accomplish, yet I cannot seem to figure out how angles work in SFML. For example, with ang_const = 0.13 Rad (7.44 Deg), my balls flies in a beautiful arc. However, when I change the value of ang_const to 0.14 Rad (8.021 Deg), the ball flies in the opposite direction! If I change the angle to 0.19 Rad (10.88 Deg), it flies downwards for whatever reason.
So here's my code:
#include <SFML/Graphics.hpp>
#include <math.h>
int WIDTH = 1024, HEIGHT = 704;
class Ball {
private:
float radius = 16.00;
public:
sf::CircleShape shape;
Ball () {
shape.setPosition(0 + radius*2, HEIGHT - radius*2);
shape.setRadius(radius);
shape.setFillColor(sf::Color::Cyan);
shape.setOrigin(radius, radius);
}
void update() {
if (x() - radius > WIDTH) {
this->shape.setPosition(0 - radius, y());
}
if (x() + radius < 0) {
this->shape.setPosition(WIDTH + radius, y());
}
if (y() - radius > HEIGHT) {
this->shape.setPosition(x(), 0 - radius);
}
if (y() + radius < 0) {
this->shape.setPosition(x(), HEIGHT + radius);
}
}
float RadToDeg (float radian) {
double pi = 3.14159;
return radian * (180 / pi);
}
float x() { return shape.getPosition().x; }
float y() { return shape.getPosition().y; }
float getRadius() { return radius; }
};
int main()
{
// Create the main window
sf::RenderWindow window(sf::VideoMode(WIDTH, HEIGHT), "del");
// Some variables
float ang_const = 0.13;
float velX_const = 3.5, velY_const = 3.5;
float grav_const = -0.02;
float ang = ang_const;
float velX = velX_const, velY = velY_const;
float grav = grav_const;
// Text
int size_for_text = 64;
sf::Font f;
f.loadFromFile("Keyboard.ttf");
sf::Text text1;
text1.setFont(f);
text1.setCharacterSize(27);
text1.setFillColor(sf::Color::White);
text1.setPosition(size_for_text, size_for_text);
// Ball
Ball ball;
while (window.isOpen())
{
// Process events
sf::Event event;
while (window.pollEvent(event))
{
// Close window: exit
if (event.type == sf::Event::Closed) {
window.close();
}
// Escape pressed: exit
if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Escape) {
window.close();
}
// Restart
if (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Space) {
ang = ang_const;
velX = velX_const, velY = velY_const;
grav = grav_const;
ball.shape.setPosition(0 + ball.getRadius()*2, HEIGHT - ball.getRadius()*2);
}
}
// Ball movement
ball.update();
velY += grav;
ball.shape.move(velX * cos(ball.RadToDeg(ang)),
velY * -sin(ball.RadToDeg(ang)));
// Clear screen
window.clear(sf::Color(0,0,80,100));
// Draw ball
window.draw(ball.shape);
// Draw text
text1.setString("ang " + std::to_string(ang));
window.draw(text1);
// Update the window
window.display();
}
return EXIT_SUCCESS;
}
The main lines are these:
Variables:
float ang_const = 0.13;
float velX_const = 3.5, velY_const = 3.5;
float grav_const = -0.02;
Ball movement:
velY += grav;
ball.shape.move(velX * cos(ball.RadToDeg(ang)), velY * -sin(ball.RadToDeg(ang)));
Radians to Degrees function:
float RadToDeg (float radian) {
double pi = 3.14159;
return radian * (180 / pi);
}
Could someone explain what's wrong with my code and how angles work in SFML? I'd be appreciated for your help guys.
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