/// <summary>
/// Attempts to fix the surface normals. Call this after the shape has been
/// loaded and the data validated.
/// </summary>
/// <param name="vw">Wireframe data.</param>
/// <param name="offset">Initial shape offset.</param>
private void FixNormals(VisWireframe vw, int offset)
{
const int minVisThresh = 0x9;
int edgeOffset = offset + (short)(mFileData[offset + 0x03] |
(mFileData[offset + 0x10] << 8));
int faceOffset = offset + (short)(mFileData[offset + 0x04] |
(mFileData[offset + 0x11] << 8));
float[] verticesX = vw.GetVerticesX();
float[] verticesY = vw.GetVerticesY();
float[] verticesZ = vw.GetVerticesZ();
float[] normalsX = vw.GetNormalsX();
float[] normalsY = vw.GetNormalsY();
float[] normalsZ = vw.GetNormalsZ();
IntPair[] edges = vw.GetEdges();
IntPair[] edgeFaces = vw.GetEdgeFaces();
for (int face = 0; face < normalsX.Length; face++)
{
// Find the first edge that references this face. We ignore anything whose
// visibility threshold is too low.
int edge = -1;
int ef;
for (ef = 0; ef < edgeFaces.Length; ef++)
{
// pull the flags out of the edge data to get the visibility threshold
byte flags = mFileData[edgeOffset + edgeFaces[ef].Val0 * 4];
if (flags > 0x1f)
{
mAppRef.DebugLog("BAD FLAG " + flags.ToString("x2"));
}
if (flags < minVisThresh)
{
continue;
}
if (edgeFaces[ef].Val1 == face)
{
edge = edgeFaces[ef].Val0;
break;
}
}
if (edge < 0)
{
mAppRef.DebugLog("Unable to find first edge for face " + face);
continue;
}
// Extract the two vertices.
int v0 = edges[edge].Val0;
int v1 = edges[edge].Val1;
// Find another edge for this face that has a common vertex.
edge = -1;
for (++ef; ef < edgeFaces.Length; ef++)
{
byte flags = mFileData[edgeOffset + edgeFaces[ef].Val0 * 4];
if (flags > 0x1f)
{
mAppRef.DebugLog("BAD FLAG " + flags.ToString("x2"));
}
if (flags < minVisThresh)
{
continue;
}
if (edgeFaces[ef].Val1 == face)
{
int chkEdge = edgeFaces[ef].Val0;
if (edges[chkEdge].Val0 == v0 || edges[chkEdge].Val0 == v1 ||
edges[chkEdge].Val1 == v0 || edges[chkEdge].Val1 == v1)
{
edge = chkEdge;
break;
}
}
}
if (edge < 0)
{
mAppRef.DebugLog("Unable to find second edge for face " + face);
continue;
}
// Arrange the vertices so the edges are v0-v1 and v1-v2. If the edges have
// v0 in common we shuffle things around.
int v2;
if (edges[edge].Val0 == v0)
{
v2 = v1;
v1 = v0;
v0 = edges[edge].Val1;
}
else if (edges[edge].Val1 == v0)
{
v2 = v1;
v1 = v0;
v0 = edges[edge].Val0;
}
else if (edges[edge].Val0 == v1)
{
v2 = edges[edge].Val1;
}
else if (edges[edge].Val1 == v1)
{
v2 = edges[edge].Val0;
}
else
{
mAppRef.DebugLog("BUG!");
continue;
}
//mAppRef.DebugLog("Face " + face + ": using vertices " + v0 + "," + v1 + "," + v2);
// Create vectors for the edges.
Vector3 vec0 = new Vector3(verticesX[v0], verticesY[v0], verticesZ[v0]);
Vector3 vec1 = new Vector3(verticesX[v1], verticesY[v1], verticesZ[v1]);
Vector3 vec2 = new Vector3(verticesX[v2], verticesY[v2], verticesZ[v2]);
Vector3 evec0 = Vector3.Subtract(vec0, vec1);
Vector3 evec1 = Vector3.Subtract(vec1, vec2);
// Compute the cross product.
Vector3 cross = Vector3.Cross(evec0, evec1);
Vector3 negCross = cross.Multiply(-1);
//mAppRef.DebugLog(" evec0=" + evec0 + " evec1=" + evec1 + " cross=" + cross);
// Check to see if we got the sign backward by adding the new vector to
// one of the vertices. If it moves us farther from the center of the
// object, it's facing outward, and we're good.
if (Vector3.Add(vec0, cross).Magnitude() <
Vector3.Add(vec0, negCross).Magnitude())
{
// flip it
cross = negCross;
}
// Replace the entry.
Vector3 orig =
new Vector3(normalsX[face], normalsY[face], normalsZ[face]).Normalize();
Vector3 subst = cross.Normalize();
vw.ReplaceFaceNormal(face, (float)subst.X, (float)subst.Y, (float)subst.Z);
//double ang = Math.Acos(Vector3.Dot(orig, subst));
//mAppRef.DebugLog("Face " + face.ToString("D2") + ": " + subst +
// " vs. orig " + orig +
// " (off by " + (ang * 180.0 / Math.PI).ToString("N2") + " deg)");
}
}