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using Unity.Burst;
namespace Pathfinding.Graphs.Navmesh.Voxelization {
/// <summary>Utility for clipping polygons</summary>
internal struct Int3PolygonClipper {
/// <summary>Cache this buffer to avoid unnecessary allocations</summary>
float[] clipPolygonCache;
/// <summary>Cache this buffer to avoid unnecessary allocations</summary>
int[] clipPolygonIntCache;
/// <summary>Initialize buffers if they are null</summary>
public void Init () {
if (clipPolygonCache == null) {
clipPolygonCache = new float[7*3];
clipPolygonIntCache = new int[7*3];
}
}
/// <summary>
/// Clips a polygon against an axis aligned half plane.
///
/// Returns: Number of output vertices
///
/// The vertices will be scaled and then offset, after that they will be cut using either the
/// x axis, y axis or the z axis as the cutting line. The resulting vertices will be added to the
/// vOut array in their original space (i.e before scaling and offsetting).
/// </summary>
/// <param name="vIn">Input vertices</param>
/// <param name="n">Number of input vertices (may be less than the length of the vIn array)</param>
/// <param name="vOut">Output vertices, needs to be large enough</param>
/// <param name="multi">Scale factor for the input vertices</param>
/// <param name="offset">Offset to move the input vertices with before cutting</param>
/// <param name="axis">Axis to cut along, either x=0, y=1, z=2</param>
public int ClipPolygon (Int3[] vIn, int n, Int3[] vOut, int multi, int offset, int axis) {
Init();
int[] d = clipPolygonIntCache;
for (int i = 0; i < n; i++) {
d[i] = multi*vIn[i][axis]+offset;
}
// Number of resulting vertices
int m = 0;
for (int i = 0, j = n-1; i < n; j = i, i++) {
bool prev = d[j] >= 0;
bool curr = d[i] >= 0;
if (prev != curr) {
double s = (double)d[j] / (d[j] - d[i]);
vOut[m] = vIn[j] + (vIn[i]-vIn[j])*s;
m++;
}
if (curr) {
vOut[m] = vIn[i];
m++;
}
}
return m;
}
}
/// <summary>Utility for clipping polygons</summary>
internal struct VoxelPolygonClipper {
public unsafe fixed float x[8];
public unsafe fixed float y[8];
public unsafe fixed float z[8];
public int n;
public UnityEngine.Vector3 this[int i] {
set {
unsafe {
x[i] = value.x;
y[i] = value.y;
z[i] = value.z;
}
}
}
/// <summary>
/// Clips a polygon against an axis aligned half plane.
/// The polygons stored in this object are clipped against the half plane at x = -offset.
/// </summary>
/// <param name="result">Ouput vertices</param>
/// <param name="multi">Scale factor for the input vertices. Should be +1 or -1. If -1 the negative half plane is kept.</param>
/// <param name="offset">Offset to move the input vertices with before cutting</param>
public void ClipPolygonAlongX ([NoAlias] ref VoxelPolygonClipper result, float multi, float offset) {
unsafe {
// Number of resulting vertices
int m = 0;
float dj = multi*x[(n-1)]+offset;
for (int i = 0, j = n-1; i < n; j = i, i++) {
float di = multi*x[i]+offset;
bool prev = dj >= 0;
bool curr = di >= 0;
if (prev != curr) {
float s = dj / (dj - di);
result.x[m] = x[j] + (x[i]-x[j])*s;
result.y[m] = y[j] + (y[i]-y[j])*s;
result.z[m] = z[j] + (z[i]-z[j])*s;
m++;
}
if (curr) {
result.x[m] = x[i];
result.y[m] = y[i];
result.z[m] = z[i];
m++;
}
dj = di;
}
result.n = m;
}
}
/// <summary>
/// Clips a polygon against an axis aligned half plane.
/// The polygons stored in this object are clipped against the half plane at z = -offset.
/// </summary>
/// <param name="result">Ouput vertices. Only the Y and Z coordinates are calculated. The X coordinates are undefined.</param>
/// <param name="multi">Scale factor for the input vertices. Should be +1 or -1. If -1 the negative half plane is kept.</param>
/// <param name="offset">Offset to move the input vertices with before cutting</param>
public void ClipPolygonAlongZWithYZ ([NoAlias] ref VoxelPolygonClipper result, float multi, float offset) {
unsafe {
// Number of resulting vertices
int m = 0;
Unity.Burst.CompilerServices.Hint.Assume(n >= 0);
Unity.Burst.CompilerServices.Hint.Assume(n <= 8);
float dj = multi*z[(n-1)]+offset;
for (int i = 0, j = n-1; i < n; j = i, i++) {
float di = multi*z[i]+offset;
bool prev = dj >= 0;
bool curr = di >= 0;
if (prev != curr) {
float s = dj / (dj - di);
result.y[m] = y[j] + (y[i]-y[j])*s;
result.z[m] = z[j] + (z[i]-z[j])*s;
m++;
}
if (curr) {
result.y[m] = y[i];
result.z[m] = z[i];
m++;
}
dj = di;
}
result.n = m;
}
}
/// <summary>
/// Clips a polygon against an axis aligned half plane.
/// The polygons stored in this object are clipped against the half plane at z = -offset.
/// </summary>
/// <param name="result">Ouput vertices. Only the Y coordinates are calculated. The X and Z coordinates are undefined.</param>
/// <param name="multi">Scale factor for the input vertices. Should be +1 or -1. If -1 the negative half plane is kept.</param>
/// <param name="offset">Offset to move the input vertices with before cutting</param>
public void ClipPolygonAlongZWithY ([NoAlias] ref VoxelPolygonClipper result, float multi, float offset) {
unsafe {
// Number of resulting vertices
int m = 0;
Unity.Burst.CompilerServices.Hint.Assume(n >= 3);
Unity.Burst.CompilerServices.Hint.Assume(n <= 8);
float dj = multi*z[n-1]+offset;
for (int i = 0, j = n-1; i < n; j = i, i++) {
float di = multi*z[i]+offset;
bool prev = dj >= 0;
bool curr = di >= 0;
if (prev != curr) {
float s = dj / (dj - di);
result.y[m] = y[j] + (y[i]-y[j])*s;
m++;
}
if (curr) {
result.y[m] = y[i];
m++;
}
dj = di;
}
result.n = m;
}
}
}
}
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