如何在运行时操纵地形的形状区域 - Unity 3D
How to manipulate a shaped area of terrain in runtime - Unity 3D
我的游戏有一个绘图工具 - 一个循环线渲染器,用作标记以线的形状操纵地形区域。一旦玩家停止画线,这一切都会在运行时发生。
到目前为止,我已经设法提高了与线渲染器点坐标相匹配的地形顶点,但我很难提高落在标记形状内的点。这是一张描述我目前拥有的图片:
我尝试使用 "Polygon Fill Algorithm" (http://alienryderflex.com/polygon_fill/),但是一次提升一行地形顶点太费力了(即使算法缩小到只围绕标记的矩形区域)。此外,我的标记的轮廓点之间有间隙,这意味着我需要在抬高地形的线上添加一个半径,但这可能会使结果变得草率。
也许我应该放弃绘图机制并使用带有网格碰撞器的网格作为标记?
任何关于如何以与标记完全相同的形状操纵地形的想法都将受到赞赏。
当前代码:
我使用 this script 来创建线——第一条线和最后一条线的点具有相同的坐标。
用于操纵地形操纵的代码当前在单击 GUI 按钮时触发:
using System;
using System.Collections;
using UnityEngine;
public class changeTerrainHeight_lineMarker : MonoBehaviour
{
public Terrain TerrainMain;
public LineRenderer line;
void OnGUI()
{
//Get the terrain heightmap width and height.
int xRes = TerrainMain.terrainData.heightmapWidth;
int yRes = TerrainMain.terrainData.heightmapHeight;
//GetHeights - gets the heightmap points of the tarrain. Store them in array
float[,] heights = TerrainMain.terrainData.GetHeights(0, 0, xRes, yRes);
if (GUI.Button(new Rect(30, 30, 200, 30), "Line points"))
{
/* Set the positions to array "positions" */
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
/* use this height to the affected terrain verteces */
float height = 0.05f;
for (int i = 0; i < line.positionCount; i++)
{
/* Assign height data */
heights[Mathf.RoundToInt(positions[i].z), Mathf.RoundToInt(positions[i].x)] = height;
}
//SetHeights to change the terrain height.
TerrainMain.terrainData.SetHeights(0, 0, heights);
}
}
}
感谢 Siim's personal help, and thanks to the article: How can I determine whether a 2D Point is within a Polygon? 找到了解决方案。
最终结果在此处可视化:
先是代码,再是解释:
using System;
using System.Collections;
using UnityEngine;
public class changeTerrainHeight_lineMarker : MonoBehaviour
{
public Terrain TerrainMain;
public LineRenderer line;
void OnGUI()
{
//Get the terrain heightmap width and height.
int xRes = TerrainMain.terrainData.heightmapWidth;
int yRes = TerrainMain.terrainData.heightmapHeight;
//GetHeights - gets the heightmap points of the tarrain. Store them in array
float[,] heights = TerrainMain.terrainData.GetHeights(0, 0, xRes, yRes);
//Trigger line area raiser
if (GUI.Button(new Rect(30, 30, 200, 30), "Line fill"))
{
/* Set the positions to array "positions" */
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
float height = 0.10f; // define the height of the affected verteces of the terrain
/* Find the reactangle the shape is in! The sides of the rectangle are based on the most-top, -right, -bottom and -left vertex. */
float ftop = float.NegativeInfinity;
float fright = float.NegativeInfinity;
float fbottom = Mathf.Infinity;
float fleft = Mathf.Infinity;
for (int i = 0; i < line.positionCount; i++)
{
//find the outmost points
if (ftop < positions[i].z)
{
ftop = positions[i].z;
}
if (fright < positions[i].x)
{
fright = positions[i].x;
}
if (fbottom > positions[i].z)
{
fbottom = positions[i].z;
}
if (fleft > positions[i].x)
{
fleft = positions[i].x;
}
}
int top = Mathf.RoundToInt(ftop);
int right = Mathf.RoundToInt(fright);
int bottom = Mathf.RoundToInt(fbottom);
int left = Mathf.RoundToInt(fleft);
int terrainXmax = right - left; // the rightmost edge of the terrain
int terrainZmax = top - bottom; // the topmost edge of the terrain
float[,] shapeHeights = TerrainMain.terrainData.GetHeights(left, bottom, terrainXmax, terrainZmax);
Vector2 point; //Create a point Vector2 point to match the shape
/* Loop through all points in the rectangle surrounding the shape */
for (int i = 0; i < terrainZmax; i++)
{
point.y = i + bottom; //Add off set to the element so it matches the position of the line
for (int j = 0; j < terrainXmax; j++)
{
point.x = j + left; //Add off set to the element so it matches the position of the line
if (InsidePolygon(point, bottom))
{
shapeHeights[i, j] = height; // set the height value to the terrain vertex
}
}
}
//SetHeights to change the terrain height.
TerrainMain.terrainData.SetHeightsDelayLOD(left, bottom, shapeHeights);
TerrainMain.ApplyDelayedHeightmapModification();
}
}
//Checks if the given vertex is inside the the shape.
bool InsidePolygon(Vector2 p, int terrainZmax)
{
// Assign the points that define the outline of the shape
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
int count = 0;
Vector2 p1, p2;
int n = positions.Length;
// Find the lines that define the shape
for (int i = 0; i < n; i++)
{
p1.y = positions[i].z;// - p.y;
p1.x = positions[i].x;// - p.x;
if (i != n - 1)
{
p2.y = positions[(i + 1)].z;// - p.y;
p2.x = positions[(i + 1)].x;// - p.x;
}
else
{
p2.y = positions[0].z;// - p.y;
p2.x = positions[0].x;// - p.x;
}
// check if the given point p intersects with the lines that form the outline of the shape.
if (LinesIntersect(p1, p2, p, terrainZmax))
{
count++;
}
}
// the point is inside the shape when the number of line intersections is an odd number
if (count % 2 == 1)
{
return true;
}
else
{
return false;
}
}
// Function that checks if two lines intersect with each other
bool LinesIntersect(Vector2 A, Vector2 B, Vector2 C, int terrainZmax)
{
Vector2 D = new Vector2(C.x, terrainZmax);
Vector2 CmP = new Vector2(C.x - A.x, C.y - A.y);
Vector2 r = new Vector2(B.x - A.x, B.y - A.y);
Vector2 s = new Vector2(D.x - C.x, D.y - C.y);
float CmPxr = CmP.x * r.y - CmP.y * r.x;
float CmPxs = CmP.x * s.y - CmP.y * s.x;
float rxs = r.x * s.y - r.y * s.x;
if (CmPxr == 0f)
{
// Lines are collinear, and so intersect if they have any overlap
return ((C.x - A.x < 0f) != (C.x - B.x < 0f))
|| ((C.y - A.y < 0f) != (C.y - B.y < 0f));
}
if (rxs == 0f)
return false; // Lines are parallel.
float rxsr = 1f / rxs;
float t = CmPxs * rxsr;
float u = CmPxr * rxsr;
return (t >= 0f) && (t <= 1f) && (u >= 0f) && (u <= 1f);
}
}
使用的方法是一次填充一行形状 - "The Ray Casting method"。事实证明,只有当给定的形状有很多边时,这种方法才会开始占用更多的资源。 (形状的一侧是连接形状轮廓中两点的线。)
当我发布这个问题时,我的线渲染器有 134 个点定义线。这也意味着形状具有相同数量的边,需要通过光线投射检查。
当我将点数缩小到 42 时,方法变得足够快,而且形状几乎没有丢失任何细节。
此外,我打算使用一些方法使轮廓更平滑,因此可以用更少的点来定义形状。
简而言之,您需要执行以下步骤才能得到结果:
- 创建形状的轮廓;
- 找到标记形状周围边界框的 4 个点;
- 开始对盒子进行光线投射;
- 检查射线与形状的边相交的次数。奇数点位于形状内部:
- 将您的属性分配给在形状中找到的所有点。
我的游戏有一个绘图工具 - 一个循环线渲染器,用作标记以线的形状操纵地形区域。一旦玩家停止画线,这一切都会在运行时发生。 到目前为止,我已经设法提高了与线渲染器点坐标相匹配的地形顶点,但我很难提高落在标记形状内的点。这是一张描述我目前拥有的图片:
我尝试使用 "Polygon Fill Algorithm" (http://alienryderflex.com/polygon_fill/),但是一次提升一行地形顶点太费力了(即使算法缩小到只围绕标记的矩形区域)。此外,我的标记的轮廓点之间有间隙,这意味着我需要在抬高地形的线上添加一个半径,但这可能会使结果变得草率。
也许我应该放弃绘图机制并使用带有网格碰撞器的网格作为标记?
任何关于如何以与标记完全相同的形状操纵地形的想法都将受到赞赏。
当前代码: 我使用 this script 来创建线——第一条线和最后一条线的点具有相同的坐标。 用于操纵地形操纵的代码当前在单击 GUI 按钮时触发:
using System;
using System.Collections;
using UnityEngine;
public class changeTerrainHeight_lineMarker : MonoBehaviour
{
public Terrain TerrainMain;
public LineRenderer line;
void OnGUI()
{
//Get the terrain heightmap width and height.
int xRes = TerrainMain.terrainData.heightmapWidth;
int yRes = TerrainMain.terrainData.heightmapHeight;
//GetHeights - gets the heightmap points of the tarrain. Store them in array
float[,] heights = TerrainMain.terrainData.GetHeights(0, 0, xRes, yRes);
if (GUI.Button(new Rect(30, 30, 200, 30), "Line points"))
{
/* Set the positions to array "positions" */
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
/* use this height to the affected terrain verteces */
float height = 0.05f;
for (int i = 0; i < line.positionCount; i++)
{
/* Assign height data */
heights[Mathf.RoundToInt(positions[i].z), Mathf.RoundToInt(positions[i].x)] = height;
}
//SetHeights to change the terrain height.
TerrainMain.terrainData.SetHeights(0, 0, heights);
}
}
}
感谢 Siim's personal help, and thanks to the article: How can I determine whether a 2D Point is within a Polygon? 找到了解决方案。
最终结果在此处可视化:
先是代码,再是解释:
using System;
using System.Collections;
using UnityEngine;
public class changeTerrainHeight_lineMarker : MonoBehaviour
{
public Terrain TerrainMain;
public LineRenderer line;
void OnGUI()
{
//Get the terrain heightmap width and height.
int xRes = TerrainMain.terrainData.heightmapWidth;
int yRes = TerrainMain.terrainData.heightmapHeight;
//GetHeights - gets the heightmap points of the tarrain. Store them in array
float[,] heights = TerrainMain.terrainData.GetHeights(0, 0, xRes, yRes);
//Trigger line area raiser
if (GUI.Button(new Rect(30, 30, 200, 30), "Line fill"))
{
/* Set the positions to array "positions" */
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
float height = 0.10f; // define the height of the affected verteces of the terrain
/* Find the reactangle the shape is in! The sides of the rectangle are based on the most-top, -right, -bottom and -left vertex. */
float ftop = float.NegativeInfinity;
float fright = float.NegativeInfinity;
float fbottom = Mathf.Infinity;
float fleft = Mathf.Infinity;
for (int i = 0; i < line.positionCount; i++)
{
//find the outmost points
if (ftop < positions[i].z)
{
ftop = positions[i].z;
}
if (fright < positions[i].x)
{
fright = positions[i].x;
}
if (fbottom > positions[i].z)
{
fbottom = positions[i].z;
}
if (fleft > positions[i].x)
{
fleft = positions[i].x;
}
}
int top = Mathf.RoundToInt(ftop);
int right = Mathf.RoundToInt(fright);
int bottom = Mathf.RoundToInt(fbottom);
int left = Mathf.RoundToInt(fleft);
int terrainXmax = right - left; // the rightmost edge of the terrain
int terrainZmax = top - bottom; // the topmost edge of the terrain
float[,] shapeHeights = TerrainMain.terrainData.GetHeights(left, bottom, terrainXmax, terrainZmax);
Vector2 point; //Create a point Vector2 point to match the shape
/* Loop through all points in the rectangle surrounding the shape */
for (int i = 0; i < terrainZmax; i++)
{
point.y = i + bottom; //Add off set to the element so it matches the position of the line
for (int j = 0; j < terrainXmax; j++)
{
point.x = j + left; //Add off set to the element so it matches the position of the line
if (InsidePolygon(point, bottom))
{
shapeHeights[i, j] = height; // set the height value to the terrain vertex
}
}
}
//SetHeights to change the terrain height.
TerrainMain.terrainData.SetHeightsDelayLOD(left, bottom, shapeHeights);
TerrainMain.ApplyDelayedHeightmapModification();
}
}
//Checks if the given vertex is inside the the shape.
bool InsidePolygon(Vector2 p, int terrainZmax)
{
// Assign the points that define the outline of the shape
Vector3[] positions = new Vector3[line.positionCount];
line.GetPositions(positions);
int count = 0;
Vector2 p1, p2;
int n = positions.Length;
// Find the lines that define the shape
for (int i = 0; i < n; i++)
{
p1.y = positions[i].z;// - p.y;
p1.x = positions[i].x;// - p.x;
if (i != n - 1)
{
p2.y = positions[(i + 1)].z;// - p.y;
p2.x = positions[(i + 1)].x;// - p.x;
}
else
{
p2.y = positions[0].z;// - p.y;
p2.x = positions[0].x;// - p.x;
}
// check if the given point p intersects with the lines that form the outline of the shape.
if (LinesIntersect(p1, p2, p, terrainZmax))
{
count++;
}
}
// the point is inside the shape when the number of line intersections is an odd number
if (count % 2 == 1)
{
return true;
}
else
{
return false;
}
}
// Function that checks if two lines intersect with each other
bool LinesIntersect(Vector2 A, Vector2 B, Vector2 C, int terrainZmax)
{
Vector2 D = new Vector2(C.x, terrainZmax);
Vector2 CmP = new Vector2(C.x - A.x, C.y - A.y);
Vector2 r = new Vector2(B.x - A.x, B.y - A.y);
Vector2 s = new Vector2(D.x - C.x, D.y - C.y);
float CmPxr = CmP.x * r.y - CmP.y * r.x;
float CmPxs = CmP.x * s.y - CmP.y * s.x;
float rxs = r.x * s.y - r.y * s.x;
if (CmPxr == 0f)
{
// Lines are collinear, and so intersect if they have any overlap
return ((C.x - A.x < 0f) != (C.x - B.x < 0f))
|| ((C.y - A.y < 0f) != (C.y - B.y < 0f));
}
if (rxs == 0f)
return false; // Lines are parallel.
float rxsr = 1f / rxs;
float t = CmPxs * rxsr;
float u = CmPxr * rxsr;
return (t >= 0f) && (t <= 1f) && (u >= 0f) && (u <= 1f);
}
}
使用的方法是一次填充一行形状 - "The Ray Casting method"。事实证明,只有当给定的形状有很多边时,这种方法才会开始占用更多的资源。 (形状的一侧是连接形状轮廓中两点的线。) 当我发布这个问题时,我的线渲染器有 134 个点定义线。这也意味着形状具有相同数量的边,需要通过光线投射检查。 当我将点数缩小到 42 时,方法变得足够快,而且形状几乎没有丢失任何细节。 此外,我打算使用一些方法使轮廓更平滑,因此可以用更少的点来定义形状。
简而言之,您需要执行以下步骤才能得到结果:
- 创建形状的轮廓;
- 找到标记形状周围边界框的 4 个点;
- 开始对盒子进行光线投射;
- 检查射线与形状的边相交的次数。奇数点位于形状内部:
- 将您的属性分配给在形状中找到的所有点。