//-----------------------------------------------------------------------------
// PlaneRenderer.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Text;
using RacingGame.Shaders;
using RacingGame.Tracks;

namespace RacingGame.Graphics
{
    /// <summary>
    /// Helper class to render a simple plane, used in some unit tests,
    /// especially for testing the physics engine.
    /// </summary>
    class PlaneRenderer
    {
        Vector3 pos;
        Plane plane;
        Material material;
        float size;
        const float Tiling = 20.0f;
        /// <summary>
        /// Create plane renderer
        /// </summary>
        /// <param name="setPos">Set position</param>
        /// <param name="setPlane">Set plane</param>
        /// <param name="setMaterial">Set material</param>
        /// <param name="setSize">Set size</param>
        public PlaneRenderer(Vector3 setPos,
            Plane setPlane, Material setMaterial, float setSize)
        {
            pos = setPos;
            plane = setPlane;
            material = setMaterial;
            size = setSize;
        }
        /// <summary>
        /// Draw plane vertices
        /// </summary>
        private void DrawPlaneVertices()
        {
            // Calculate right and dir vectors for constructing the plane.
            // The following code might look strange, but we have to make sure
            // that we always get correct up, right and dir vectors. Cross products
            // can return (0, 0, 0) if the vectors are parallel!
            Vector3 up = plane.Normal;
            if (up.Length() == 0)
                up = new Vector3(0, 0, 1);
            Vector3 helperVec = Vector3.Cross(up, new Vector3(1, 0, 0));
            if (helperVec.Length() == 0)
                helperVec = new Vector3(0, 1, 0);
            Vector3 right = Vector3.Cross(helperVec, up);
            Vector3 dir = Vector3.Cross(up, right);
            float dist = plane.D;

            TangentVertex[] vertices = new TangentVertex[]
            {
                // Make plane VERY big and tile texture every 10 meters
                new TangentVertex(
                    (-right-dir)*size+up*dist, -size/Tiling, -size/Tiling, up, right),
                new TangentVertex(
                    (-right+dir)*size+up*dist, -size/Tiling, +size/Tiling, up, right),
                new TangentVertex(
                    (right-dir)*size+up*dist, +size/Tiling, -size/Tiling, up, right),
                new TangentVertex(
                    (right+dir)*size+up*dist, +size/Tiling, +size/Tiling, up, right),
            };

            // Draw the plane (just 2 simple triangles)
            BaseGame.Device.DrawUserPrimitives(
                PrimitiveType.TriangleStrip, vertices, 0, 2);
        }

        /// <summary>
        /// Just renders the plane with the given material.
        /// </summary>
        public void Render()
        {
            BaseGame.WorldMatrix = Matrix.CreateTranslation(pos);
            ShaderEffect.normalMapping.Render(
                material,
                "DiffuseSpecular20",
                new BaseGame.RenderHandler(DrawPlaneVertices));
            BaseGame.WorldMatrix = Matrix.Identity;
        }

    }
}