光线投射引擎的意外结果

Question

我正在尝试使用 C# 和 Monogame 创建一个简单的光线投射引擎。 （我现在不担心纹理。）按照

本教程，我创建了增加光线深度的代码（我知道这是低效且不准确的），直到它撞到墙上。然后我渲染墙，其大小取决于玩家与光线击中位置之间的距离。

用户位于横 3 格、下 4 格的位置，面朝北 30°。预期的结果是在黑色背景上呈现白色倾斜的墙壁。以下是该程序的结果：

我有一个名为

Canvas

 的类，我用它来设置纹理上的像素以使用 

SpriteBatch

 进行渲染。

Canvas.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace Raycaster
{
    public class Canvas
    {
        Texture2D texture;
        Color[] pixels;

        bool changed = false;

        public Canvas(GraphicsDevice graphicsDevice, int width, int height)
        {
            texture = new Texture2D(graphicsDevice, width, height);
            pixels = new Color[width * height];
        }

        public void Draw(SpriteBatch _spriteBatch)
        {
            if (changed)
            {
                changed = false;
                texture.SetData(pixels);
            }
            
            _spriteBatch.Draw(texture, new Vector2(0, 0), Color.White);
        }

        public void SetPixel(int x, int y, Color color)
        {
            int position = x + (y * texture.Width);
            
            if (position >= 0 && position < pixels.Length)
            {
                pixels[position] = color;
                changed = true;
            }
        }

        public void Clear()
        {
            pixels = new Color[texture.Width * texture.Height];
        }
    }
}

以下是我在

Game1.cs

中设置的一些变量和常量

const int Width = 1024;
const int Height = 700;

int[,] map = { 
    { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
    { 1, 0, 1, 0, 0, 0, 0, 0, 0, 1 },
    { 1, 0, 0, 0, 0, 0, 0, 0, 0, 1 },
    { 1, 0, 0, 0, 0, 0, 0, 1, 0, 1 },
    { 1, 0, 0, 0, 0, 1, 0, 0, 0, 1 },
    { 1, 0, 1, 0, 0, 0, 0, 0, 0, 1 },
    { 1, 0, 1, 0, 0, 0, 0, 0, 0, 1 },
    { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }
};

Vector2 playerPosition = new Vector2(192, 256);
double playerRotation = 30;

const double playerFOV = 60;
const double deltaAngle = playerFOV / Width;

const int unitsPerSquare = 64;

Canvas canvas;

这是我在

Draw

方法中使用的代码，在

Game1

中：

GraphicsDevice.Clear(Color.Black);

canvas.Clear();

double angle = playerRotation - (playerFOV / 2);
for (int column = 0; column < Width; column++)
{
    int depth = 0;

    bool wallFound = false;
    Vector2 wallHit = new Vector2(0, 0);

    while (!wallFound)
    {
        if (depth > 1024) break;

        double x = playerPosition.X + depth * Math.Cos(angle);
        double y = playerPosition.Y + depth * Math.Sin(angle);

        if (x < 0 || y < 0 || x > Width || y > Height) break;

        for (int i = 0; i < map.GetLength(0); i++)
        {
            if (wallFound) break;

            for (int j = 0; j < map.GetLength(1); j++)
            {
                if (wallFound) break;

                int value = map[i, j];
                if (value == 0) continue;
                else if (value == 1)
                {
                    Vector2 currentPosition = new Vector2((float)x, (float)y);
                    Rectangle cubeRectangle = new Rectangle(i * unitsPerSquare, j * unitsPerSquare, unitsPerSquare, unitsPerSquare);
                    if (cubeRectangle.Contains(currentPosition))
                    {
                        wallFound = true;
                        wallHit = currentPosition;
                    }
                }
            }
        }

        depth++;
    }

    if (wallFound)
    {
        float distance = Vector2.Distance(playerPosition, wallHit);
        int wallRenderHeight = (int)Math.Round(Width * (1 / (distance / unitsPerSquare)));
        int wallRenderY = (Height / 2) - (wallRenderHeight / 2);
        for (int i = 0; i < wallRenderHeight; i++) canvas.SetPixel(column, i + wallRenderY, Color.White);
    }

    angle += deltaAngle;
}

_spriteBatch.Begin();
canvas.Draw(_spriteBatch);
_spriteBatch.End();

base.Draw(gameTime);

Answer 1

方法

Math.Sin

 和 

Math.Cos

 采用弧度而不是角度。在使用三角函数之前，我通过将角度（以度为单位）转换为弧度来修复该程序：

double angleRadians = Math.PI * angle / 180;
double x = playerPosition.X + depth * Math.Cos(angleRadians);
double y = playerPosition.Y + depth * Math.Sin(angleRadians);