recrownedgtk/RecrownedAthenaeum/Render/RectangleRenderer.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using RecrownedAthenaeum.Camera;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace RecrownedAthenaeum.Render
{
    public class RectangleRenderer : IDisposable
    {
        public readonly PrimitiveBatch primitiveBatch;
        private bool disposed;
        private bool began;
        private bool filling;

        public RectangleRenderer(PrimitiveBatch primitiveBatch)
        {
            this.primitiveBatch = primitiveBatch;
        }

        public RectangleRenderer(GraphicsDevice graphicsDevice, Camera2D camera) : this(new PrimitiveBatch(graphicsDevice, camera, 4))
        {

        }

        public void Begin(bool filled)
        {
            filling = filled;
            if (disposed) throw new ObjectDisposedException(GetType().Name);
            if (began) throw new InvalidOperationException("Cannot begin twice.");
            primitiveBatch.Begin(filled ? PrimitiveType.TriangleStrip : PrimitiveType.LineStrip);
            began = true;
        }

        public void End()
        {
            if (disposed) throw new ObjectDisposedException(GetType().Name);
            if (!began) throw new InvalidOperationException("Cannot end before beginning.");
            primitiveBatch.End();
            began = false;
        }


        /// <summary>
        /// Draws a basic rectangle given bottom left and top right.
        /// </summary>
        /// <param name="x">X coordinate of bottom left.</param>
        /// <param name="y">Y coordinate of bottom left.</param>
        /// <param name="width">Width of rectangle.</param>
        /// <param name="height">Height of rectangle.</param>
        /// <param name="color">Color of all vertices of this rectangle.</param>
        /// <param name="rotation">Rotation of rectangle. Default is 0 radians.</param>
        public void DrawRectangle(int x, int y, int width, int height, Color color, double rotation = 0)
        {
            if (disposed) throw new ObjectDisposedException(GetType().Name);
            if (!began) throw new InvalidOperationException("Renderer must be started by calling Begin.");
            Vector2[] corners = new Vector2[4];

            corners[0] = new Vector2(x, y);
            corners[1] = new Vector2(x + (float)Math.Cos(rotation) * width, y + (float)Math.Sin(rotation) * width);
            double topRightAngleFromOrig = Math.Atan(height / (double)width);
            float origDiagonalHypotenuse = (float)Math.Sqrt(width * width * height * height);
            corners[2] = new Vector2(x + (float)Math.Cos(topRightAngleFromOrig + rotation) * origDiagonalHypotenuse, y + (float)Math.Sin(topRightAngleFromOrig + rotation) * origDiagonalHypotenuse);
            corners[3] = new Vector2(x + (float)Math.Cos(rotation + Math.PI / 4f) * height, y + (float)Math.Sin(rotation) * height);

            if (filling)
            {
                primitiveBatch.AddVertex(corners[1], color);
                primitiveBatch.AddVertex(corners[2], color);
                primitiveBatch.AddVertex(corners[0], color);
                primitiveBatch.AddVertex(corners[3], color);
            } else
            {
                primitiveBatch.AddVertex(corners[0], color);
                primitiveBatch.AddVertex(corners[1], color);
                primitiveBatch.AddVertex(corners[2], color);
                primitiveBatch.AddVertex(corners[3], color);
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        public void Dispose(bool disposing)
        {
            if (!disposed && disposing)
            {
                if (primitiveBatch != null)
                {
                    primitiveBatch.Dispose();
                }
            }
            else
            {
                if (disposed) throw new ObjectDisposedException(typeof(PrimitiveBatch).Name);
            }
        }
    }
}