23. Arrays of Shapes¶

Learn how to handle shape classes like Circle and Rect in arrays.

23.1 Creating an Array of Circles¶

Array<Circle> is an array of Circle

# include <Siv3D.hpp>

void Main()
{
	Array<Circle> circles =
	{
		Circle{ 100, 300, 10 },
		Circle{ 200, 300, 20 },
		Circle{ 300, 300, 30 },
		Circle{ 400, 300, 40 },
	};

	Print << circles;

	while (System::Update())
	{

	}
}

23.2 Drawing All Circles¶

Use a range-based for loop (const reference) to draw all Circles

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });
	
	Array<Circle> circles =
	{
		Circle{ 100, 300, 10 },
		Circle{ 200, 300, 20 },
		Circle{ 300, 300, 30 },
		Circle{ 400, 300, 40 },
	};

	while (System::Update())
	{
		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.3 Moving All Circles¶

Use a range-based for loop (reference) to move all Circles

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });
	
	Array<Circle> circles =
	{
		Circle{ 100, 300, 10 },
		Circle{ 200, 300, 20 },
		Circle{ 300, 300, 30 },
		Circle{ 400, 300, 40 },
	};

	while (System::Update())
	{
		const double deltaTime = Scene::DeltaTime();

		// Move all circles
		for (auto& circle : circles)
		{
			circle.y += (deltaTime * 50.0);
		}

		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.4 Adding Circles by Clicking¶

Add a Circle with a random radius at the clicked position

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });
	
	Array<Circle> circles;

	while (System::Update())
	{
		// If left-clicked
		if (MouseL.down())
		{
			// Add a circle with random radius at the clicked position
			circles << Circle{ Cursor::Pos(), Random(5.0, 40.0) };
		}

		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.5 Removing Circles by Clicking (`.remove_if()` Method)¶

Use .remove_if() to remove Circles that are left-clicked
- See Tutorial 22.17 for element removal using .remove_if()
Pass a lambda expression to .remove_if() that determines "whether the circle was left-clicked"

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	Array<Circle> circles =
	{
		Circle{ 100, 300, 10 },
		Circle{ 200, 300, 20 },
		Circle{ 300, 300, 30 },
		Circle{ 400, 300, 40 },
	};

	while (System::Update())
	{
		// Remove circles that were left-clicked
		circles.remove_if([](const Circle& circle) { return circle.leftClicked(); });

		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.6 Removing Circles by Clicking (Iterator Method)¶

Remove Circles that are left-clicked using the iterator method
- See Tutorial 22.16 for element removal using iterators
Compared to the .remove_if() method, this approach makes it easier to write additional processing along with removal (such as adding points, stopping further removals, etc.)
Access to elements must be done before removal with .erase()

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	const Font font{ FontMethod::MSDF, 48 };

	Array<Circle> circles =
	{
		Circle{ 100, 300, 10 },
		Circle{ 200, 300, 20 },
		Circle{ 300, 300, 30 },
		Circle{ 400, 300, 40 },
	};

	// Score
	double score = 0;

	while (System::Update())
	{
		// For each circle
		for (auto it = circles.begin(); it != circles.end();)
		{
			// If the circle was left-clicked
			if (it->leftClicked())
			{
				// Add radius * 10 to the score
				score += (it->r * 10); // Access element before deletion

				// Remove the circle
				it = circles.erase(it);
			}
			else
			{
				++it;
			}
		}

		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}

		font(U"Score: {}"_fmt(score)).draw(40, Vec2{ 40, 40 }, ColorF{ 0.1 });
	}
}

23.7 Removing Circles that Reach a Certain Position¶

Make Circles move automatically and remove them when they reach a certain position
Pass a lambda expression to .remove_if() that determines "whether the Y coordinate exceeded 500.0"

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	Array<Circle> circles;

	for (int32 i = 0; i < 6; ++i)
	{
		circles << Circle{ (100 + i * 100), Random(0.0, 200.0), 30 };
	}

	while (System::Update())
	{
		const double deltaTime = Scene::DeltaTime();

		for (auto& circle : circles)
		{
			circle.y += (deltaTime * 100.0);
		}

		// Remove circles whose Y coordinate exceeded 500.0
		circles.remove_if([](const Circle& circle) { return (500.0 < circle.y); });

		// Draw all circles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.8 Adding Circles at Regular Intervals¶

Apply the "doing something at regular intervals" from Tutorial 19.3 to add a Circle every 0.5 seconds

Add a circle every 0.5 seconds (maximum 10 circles)

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	Array<Circle> circles;

	// Circle spawn interval (seconds)
	const double spawnInterval = 0.5;

	// Maximum number of circles
	const size_t maxCircles = 10;

	// Accumulated time (seconds)
	double accumulatedTime = 0.0;

	while (System::Update())
	{
		// Time elapsed since the previous frame (seconds)
		const double deltaTime = Scene::DeltaTime();

		// Increase accumulated time
		accumulatedTime += deltaTime;

		// If accumulated time exceeds the interval
		if (spawnInterval < accumulatedTime)
		{
			// If the number of circles hasn't reached the maximum
			if (circles.size() < maxCircles)
			{
				// Add a circle
				circles << Circle{ Random(100, 700), Random(100, 500), 30 };
			}

			// Reduce accumulated time by the interval
			accumulatedTime -= spawnInterval;
		}

		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.9 Arrays of Custom Classes (1)¶

Create a ColorCircle class that has a Circle and a hue value, and handle them in an array

# include <Siv3D.hpp>

struct ColorCircle
{
	Circle circle;

	double hue;

	// Function to draw the circle
	void draw() const
	{
		circle.draw(HSV{ hue, 0.75, 0.9 });
	}
};

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	Array<ColorCircle> circles;

	while (System::Update())
	{
		// If left-clicked
		if (MouseL.down())
		{
			// Add a ColorCircle
			circles << ColorCircle{ Circle{ Cursor::Pos(), Random(5.0, 40.0) }, Random(0.0, 360.0) };
		}

		// Draw all ColorCircles
		for (const auto& circle : circles)
		{
			circle.draw();
		}
	}
}

23.10 Arrays of Custom Classes (2)¶

Create a RectCounter class that keeps count of how many times it has been clicked, and handle them in an array
.center() of Rect returns the center coordinates of the rectangle as a Point type

# include <Siv3D.hpp>

struct RectCounter
{
	Rect rect;

	int32 count = 0;

	// Function to update the counter
	void update()
	{
		if (rect.mouseOver())
		{
			Cursor::RequestStyle(CursorStyle::Hand);
		}

		if (rect.leftClicked())
		{
			++count;
		}
	}

	// Function to draw the counter
	void draw(const Font& font) const
	{
		rect.draw();
		rect.drawFrame(2, ColorF{ 0.1 });
		font(U"{}"_fmt(count)).drawAt(rect.center(), ColorF{ 0.1 });
	}
};

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });
	const Font font{ FontMethod::MSDF, 48, Typeface::Bold };

	Array<RectCounter> rectCounters;
	rectCounters << RectCounter{ Rect{ 100, 100, 100, 100 } };
	rectCounters << RectCounter{ Rect{ 300, 100, 100, 100 } };
	rectCounters << RectCounter{ Rect{ 500, 100, 100, 100 } };

	while (System::Update())
	{
		// Update all RectCounters
		for (auto& rectCounter : rectCounters)
		{
			rectCounter.update();
		}

		// Draw all RectCounters
		for (const auto& rectCounter : rectCounters)
		{
			rectCounter.draw(font);
		}
	}
}

23. Arrays of Shapes¶

23.1 Creating an Array of Circles¶

23.2 Drawing All Circles¶

23.3 Moving All Circles¶

23.4 Adding Circles by Clicking¶

23.5 Removing Circles by Clicking (.remove_if() Method)¶

23.6 Removing Circles by Clicking (Iterator Method)¶

23.7 Removing Circles that Reach a Certain Position¶

23.8 Adding Circles at Regular Intervals¶

23.9 Arrays of Custom Classes (1)¶

23.10 Arrays of Custom Classes (2)¶

23.5 Removing Circles by Clicking (`.remove_if()` Method)¶