recrownedgtk/RecrownedAthenaeum/Camera/Camera2D.cs

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2.7 KiB
C#
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using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
namespace RecrownedAthenaeum.Camera
{
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/// <summary>
/// A virtual 2D camera.
/// </summary>
public class Camera2D
{
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/// <summary>
/// Current zoom level.
/// </summary>
public float Zoom;
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/// <summary>
/// Current position in the world.
/// </summary>
public Vector2 Position;
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/// <summary>
/// The matrix representing the zoom and position.
/// </summary>
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public Matrix Matrix { get; private set; }
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private GraphicsDevice graphicsDevice = Configuration.graphicsDeviceManager.GraphicsDevice;
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/// <summary>
/// Constructs 2D camera.
/// </summary>
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/// <param name="graphicsDevice">The graphics device to use. Will use graphics device from <see cref="Configuration"/>'s graphics device manager if this is null which it is by default.</param>
public Camera2D(GraphicsDevice graphicsDevice = null)
{
if (graphicsDevice != null) this.graphicsDevice = graphicsDevice;
if (this.graphicsDevice == null) throw new ArgumentNullException("Graphics device can't be null in setup and argument. One must not be null for use.");
Zoom = 1f;
Position.X = this.graphicsDevice.Viewport.Width * 0.5f;
Position.Y = this.graphicsDevice.Viewport.Height * 0.5f;
}
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/// <summary>
/// Applies any changes made to the properties of this camera and updates to new dimensions of viewport specified by the graphics device.
/// </summary>
public void Update()
{
Rectangle bounds = graphicsDevice.Viewport.Bounds;
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Matrix =
Matrix.CreateTranslation(new Vector3(-Position.X, -Position.Y, 0)) *
Matrix.CreateScale(Zoom) *
Matrix.CreateTranslation(new Vector3(bounds.Width * 0.5f, bounds.Height * 0.5f, 0f));
}
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/// <summary>
/// Lerps to the given position.
/// </summary>
/// <param name="alpha">The multiplier for difference in distance.</param>
/// <param name="targetPosition">The target position to lerp to.</param>
/// <param name="delta">Time between this frame and the previous frame.</param>
public void LinearInterpolationToPosition(float alpha, Vector2 targetPosition, float delta)
{
if (alpha <= 0 && alpha > 1f) throw new ArgumentException("Alpha can't be greater than 1f, less than or equal to 0.");
Vector2 distance = targetPosition - Position;
distance *= (float)(1.0f - Math.Pow(1 - alpha, delta / 0.02f));
Position += distance;
}
}
}