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