GeometricPrimitive.cs

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// Copyright (c) 2014 Silicon Studio Corp. (http://siliconstudio.co.jp)
// This file is distributed under GPL v3. See LICENSE.md for details.
//
// Copyright (c) 2010-2013 SharpDX - Alexandre Mutel
// 
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// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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using System;
using SiliconStudio.Core;

namespace SiliconStudio.Paradox.Graphics
{
    /// <summary>
    /// A geometric primitive used to draw a simple model built from a set of vertices and indices.
    /// </summary>
    public class GeometricPrimitive<T> : ComponentBase where T : struct, IVertex
    {
        /// <summary>
        /// The index buffer used by this geometric primitive.
        /// </summary>
        public readonly Buffer IndexBuffer;

        /// <summary>
        /// The vertex buffer used by this geometric primitive.
        /// </summary>
        public readonly Buffer VertexBuffer;

        /// <summary>
        /// The default graphics device.
        /// </summary>
        protected readonly GraphicsDevice GraphicsDevice;

        /// <summary>
        /// The input layout used by this geometric primitive (shared for all geometric primitive).
        /// </summary>
        private readonly VertexArrayObject vertexArrayObject;

        /// <summary>
        /// True if the index buffer is a 32 bit index buffer.
        /// </summary>
        public readonly bool IsIndex32Bits;

        /// <summary>
        /// Initializes a new instance of the <see cref="GeometricPrimitive{T}"/> class.
        /// </summary>
        /// <param name="graphicsDevice">The graphics device.</param>
        /// <param name="geometryMesh">The geometry mesh.</param>
        /// <exception cref="System.InvalidOperationException">Cannot generate more than 65535 indices on feature level HW <= 9.3</exception>
        public GeometricPrimitive(GraphicsDevice graphicsDevice, GeometricMeshData<T> geometryMesh)
        {
            GraphicsDevice = graphicsDevice;

            var vertices = geometryMesh.Vertices;
            var indices = geometryMesh.Indices;

            if (geometryMesh.IsLeftHanded)
                ReverseWinding(vertices, indices);

            if (indices.Length < 0xFFFF)
            {
                var indicesShort = new ushort[indices.Length];
                for (int i = 0; i < indicesShort.Length; i++)
                {
                    indicesShort[i] = (ushort)indices[i];
                }
                IndexBuffer = Buffer.Index.New(graphicsDevice, indicesShort).RecreateWith(indicesShort).DisposeBy(this);
            }
            else
            {
                if (graphicsDevice.Features.Profile <= GraphicsProfile.Level_9_3)
                {
                    throw new InvalidOperationException("Cannot generate more than 65535 indices on feature level HW <= 9.3");
                }

                IndexBuffer = Buffer.Index.New(graphicsDevice, indices).RecreateWith(indices).DisposeBy(this);
                IsIndex32Bits = true;
            }

            // For now it will keep buffers for recreation.
            // TODO: A better alternative would be to store recreation parameters so that we can reuse procedural code.
            VertexBuffer = Buffer.Vertex.New(graphicsDevice, vertices).RecreateWith(vertices).DisposeBy(this);

            vertexArrayObject = VertexArrayObject.New(graphicsDevice, new IndexBufferBinding(IndexBuffer, IsIndex32Bits, indices.Length), new VertexBufferBinding(VertexBuffer, new T().GetLayout(), vertices.Length)).DisposeBy(this);
        }

        /// <summary>
        /// Draws this <see cref="GeometricPrimitive" />.
        /// </summary>
        public void Draw()
        {
            Draw(GraphicsDevice);
        }

        /// <summary>
        /// Draws this <see cref="GeometricPrimitive" />.
        /// </summary>
        /// <param name="graphicsDevice">The graphics device.</param>
        public void Draw(GraphicsDevice graphicsDevice)
        {
            // Setup the Vertex Buffer
            graphicsDevice.SetVertexArrayObject(vertexArrayObject);

            // Finally Draw this mesh
            graphicsDevice.DrawIndexed(PrimitiveType.TriangleList, IndexBuffer.ElementCount);
        }

        /// <summary>
        /// Helper for flipping winding of geometric primitives for LH vs. RH coordinates
        /// </summary>
        /// <typeparam name="TIndex">The type of the T index.</typeparam>
        /// <param name="vertices">The vertices.</param>
        /// <param name="indices">The indices.</param>
        private void ReverseWinding<TIndex>(T[] vertices, TIndex[] indices)
        {
            for (int i = 0; i < indices.Length; i += 3)
            {
                Utilities.Swap(ref indices[i], ref indices[i + 2]);
            }

            for (int i = 0; i < vertices.Length; i++)
            {
                vertices[i].FlipWinding();
            }
        }
    }

    /// <summary>
    /// A geometric primitive. Use <see cref="Cube"/>, <see cref="Cylinder"/>, <see cref="GeoSphere"/>, <see cref="Plane"/>, <see cref="Sphere"/>, <see cref="Teapot"/>, <see cref="Torus"/>. See <see cref="Draw+vertices"/> to learn how to use it.
    /// </summary>
    public partial class GeometricPrimitive : GeometricPrimitive<VertexPositionNormalTexture>
    {
        public GeometricPrimitive(GraphicsDevice graphicsDevice, GeometricMeshData<VertexPositionNormalTexture> geometryMesh) : base(graphicsDevice, geometryMesh)
        {
        }
    }
}