Unity高度图形成

unity高度图形成主要的原理是对原始模型mesh先形成boundingBox,并在原始模型的上方添加射线方向向下进行碰撞检测，通过碰撞点与射线的截距获得模型的高度值，最后把高度值转换成像素点写入图片中形成最后的高度图

1.先形成boundingBox并获取相关坐标轴的最大值、最小值

    Bounds boundingBox = mesh.bounds;//创建boundingBox

    float minX = boundingBox.min.x;

    float minZ = boundingBox.min.z;

    float maxX = boundingBox.max.x;

    float maxZ = boundingBox.max.z;

    float minY = boundingBox.min.y;

    float maxY = boundingBox.max.y;

2.计算模型宽度和模型高度并设置射线间的宽度和高度

float widthSize = maxX – minX;

float heightSize = maxZ – minZ;

float cellWidth = widthSize / (width – 1);//单元宽度

float cellHeight = heightSize / (height – 1);//单元高度

3.产生射线并设置方向与起始位置

private static Ray ray = new Ray(new Vector3(), new Vector3());//创建一条射线

Vector3 rayDirE = ray.direction;//设置原始的方向
rayDirE.x = 0;
rayDirE.y = -1;
rayDirE.z = 0;
const float heightOffset =1f;
Vector3 originRay = ray.origin;
float rayY = maxY + heightOffset;//增加Y方向的高度
originRay.y = rayY;
ray.direction = new Vector3(rayDirE.x, rayDirE.y, rayDirE.z);

4.通过碰撞检测得到高度值

   private static float getPosition(Vector3 rayOrigin,Vector3 rayDirection)

  {

    float closestIntersection = float.MaxValue;

    RaycastHit hit;

    //Debug.DrawLine(rayOrigin, rayOrigin + new Vector3(0, -1, 0) * 100, Color.red, 1000000f);

    if (Physics.Raycast(rayOrigin, rayDirection, out hit, 10))

    {

        float intersection = hit.distance;

        if ((intersection != 0.0f) && intersection < closestIntersection)

        {

            closestIntersection = intersection;

        }

    }

    return closestIntersection;

}

5.通过得到的高度转化成像素点

float oriHeight =
heightMap.
getHeight(
i,
j);//得到高度

//
Debug.
Log(“orheight:” +
oriHeight);

if (
oriHeight ==
0.
0f)

            {

               color.r = 1;

               color.g = 1;

               color.b = 1;

            }


else

            {

               double h =(oriHeight – minHeight) / compressionRatio / 255;

               float y = Convert.ToSingle(h);

               color.r = y ;

               color.g = y ;

               color.b = y ;

            }

color.
a =
1;

hMap.
SetPixel(
height – 1 – j,
width – 1 – i,
color);

6.把像素点写入到png图片上

    byte[] bytes = hMap.EncodeToPNG();

    string strFile = Application.dataPath + “/heightMap.png”;

    FileStream file = File.Open(strFile, FileMode.Create);

    BinaryWriter writer = new BinaryWriter(file);

    writer.Write(bytes);

    file.Close();

比如原始图片为