/// <summary>
/// Calculate the polygon normals. By convention, LW's polygon normals
/// are found as the cross product of the first and last edges. It's
/// undefined for one- and two-point polygons.
/// </summary>
/// <param name="lwPolygonList"></param>
public void GetPolyNormals(ref lwPolygonList polygon)
{
float[] p1 = new float[3];
float[] p2 = new float[3];
float[] pn = new float[3];
float[] v1 = new float[3];
float[] v2 = new float[3];
for (int i = 0; i < polygon.count; i++)
{
if (polygon.pol[i].nverts < 3)
{
continue;
}
for (int j = 0; j < 3; j++)
{
p1[j] = pt[polygon.pol[i].v[0].index].pos[j];
p2[j] = pt[polygon.pol[i].v[1].index].pos[j];
pn[j] = pt[polygon.pol[i].v[polygon.pol[i].nverts - 1].index].pos[j];
}
for (int j = 0; j < 3; j++)
{
v1[j] = p2[j] - p1[j];
v2[j] = pn[j] - p1[j];
}
LwVecMath.cross(v1, v2, polygon.pol[i].norm);
LwVecMath.normalize(polygon.pol[i].norm);
}
}
/// <summary>
/// Calculate the vertex normals. For each polygon vertex, sum the
/// normals of the polygons that share the point. If the normals of the
/// current and adjacent polygons form an angle greater than the max
/// smoothing angle for the current polygon's surface, the normal of the
/// adjacent polygon is excluded from the sum. It's also excluded if the
/// polygons aren't in the same smoothing group.
///
/// Assumes that lwGetPointPolygons(), lwGetPolyNormals() and
/// lwResolvePolySurfaces() have already been called.
/// </summary>
/// <param name="lwPolygonList"></param>
public void GetVertNormals(ref lwPolygonList polygon)
{
int h, p;
float a;
for (int j = 0; j < polygon.count; j++)
{
for (int n = 0; n < polygon.pol[j].nverts; n++)
{
for (int k = 0; k < 3; k++)
{
polygon.pol[j].v[n].norm[k] = polygon.pol[j].norm[k];
}
if (polygon.pol[j].surf.smooth <= 0)
{
continue;
}
p = polygon.pol[j].v[n].index;
for (int g = 0; g < pt[p].npols; g++)
{
h = pt[p].pol[g];
if (h == j)
{
continue;
}
if (polygon.pol[j].smoothgrp != polygon.pol[h].smoothgrp)
{
continue;
}
a = LwVecMath.vecangle(polygon.pol[j].norm, polygon.pol[h].norm);
if (a > polygon.pol[j].surf.smooth)
{
continue;
}
for (int k = 0; k < 3; k++)
{
polygon.pol[j].v[n].norm[k] += polygon.pol[h].norm[k];
}
}
LwVecMath.normalize(polygon.pol[j].v[n].norm);
}
}
}
