我正在使用 Unity3D，并且有一個(gè)多邊形（Vector2 數(shù)組）以及要檢查的點(diǎn)。在過(guò)去的幾天里，我一直在尋找包括 pnpoly 和其他算法在內(nèi)的解決方案。問(wèn)題是我的誤差高達(dá) 0.001f，因?yàn)槲以谑褂?TransformPoint（以獲取網(wǎng)格頂點(diǎn)的世界位置）后立即乘以四元數(shù)，將 3D 面投影到 2D 平面上。我對(duì)多邊形一無(wú)所知，因?yàn)樗鼈兪怯稍S多網(wǎng)格三角形組成的 - 它們可以具有任何形狀。我如何處理這種極端的不準(zhǔn)確性并找到多邊形內(nèi)部或邊界上的所有點(diǎn)？ public static bool IsInsidePolygon(Vector2[] vertices, Vector2 checkPoint) { float[] vertX = new float[vertices.Length]; float[] vertY = new float[vertices.Length]; for (int i = 0; i < vertices.Length; i++) { vertX[i] = vertices[i].x; vertY[i] = vertices[i].y; } return IsInsidePolygon(vertices.Length, vertX, vertY, checkPoint.x, checkPoint.y); } public static bool IsInsidePolygon3(int nvert, float[] vertx, float[] verty, float testx, float testy) { int i, j = 0; bool c = false; for (i = 0, j = nvert - 1; i < nvert; j = i++) { if (((verty[i] > testy) != (verty[j] > testy)) && (testx < (vertx[j] - vertx[i]) * (testy - verty[i]) / (verty[j] - verty[i]) + vertx[i])) c = !c; } return c; }
1 回答
明月笑刀無(wú)情
TA貢獻(xiàn)1828條經(jīng)驗(yàn) 獲得超4個(gè)贊
解決方案是找到到多邊形的最近距離，如果距離在邊距內(nèi)，則返回 true，以下是完整代碼：
'''
public static float DistancePointLine2D(Vector2 point, Vector2 lineStart, Vector2 lineEnd)
{
return (ProjectPointLine2D(point, lineStart, lineEnd) - point).magnitude;
}
public static Vector2 ProjectPointLine2D(Vector2 point, Vector2 lineStart, Vector2 lineEnd)
{
Vector2 rhs = point - lineStart;
Vector2 vector2 = lineEnd - lineStart;
float magnitude = vector2.magnitude;
Vector2 lhs = vector2;
if (magnitude > 1E-06f)
{
lhs = (Vector2)(lhs / magnitude);
}
float num2 = Mathf.Clamp(Vector2.Dot(lhs, rhs), 0f, magnitude);
return (lineStart + ((Vector2)(lhs * num2)));
}
public static float ClosestDistanceToPolygon(Vector2[] verts, Vector2 point)
{
int nvert = verts.Length;
int i, j = 0;
float minDistance = Mathf.Infinity;
for (i = 0, j = nvert - 1; i < nvert; j = i++)
{
float distance = DistancePointLine2D(point, verts[i], verts[j]);
minDistance = Mathf.Min(minDistance, distance);
}
return minDistance;
}
public static bool IsInsidePolygon(Vector2[] vertices, Vector2 checkPoint, float margin = 0.01f)
{
if(ClosestDistanceToPolygon(vertices, checkPoint) < margin)
{
return true;
}
float[] vertX = new float[vertices.Length];
float[] vertY = new float[vertices.Length];
for (int i = 0; i < vertices.Length; i++)
{
vertX[i] = vertices[i].x;
vertY[i] = vertices[i].y;
}
return IsInsidePolygon(vertices.Length, vertX, vertY, checkPoint.x, checkPoint.y);
}
public static bool IsInsidePolygon(int nvert, float[] vertx, float[] verty, float testx, float testy)
{
bool c = false;
int i, j = 0;
for (i = 0, j = nvert - 1; i < nvert; j = i++)
{
if ((((verty[i] <= testy) && (testy < verty[j])) ||
((verty[j] <= testy) && (testy < verty[i]))) &&
(testx < (vertx[j] - vertx[i]) * (testy - verty[i]) / (verty[j] - verty[i]) + vertx[i]))
c = !c;
}
return c;
}
'''
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