public static void SoftNormalsInTangents(Mesh mesh)
{
var mVerts = mesh.vertices;
var mTangents = new Vector4[mVerts.Length];
var mTris = mesh.triangles;
Dictionary <Vector3, SoftNormal> vertDict = new Dictionary <Vector3, SoftNormal>();
for (int i = 0; i < mTris.Length; i += 3)
{
int i0 = mTris[i];
int i1 = mTris[i + 1];
int i2 = mTris[i + 2];
var v0 = mVerts[i0];
var v1 = mVerts[i1];
var v2 = mVerts[i2];
Vector3 dir = v1 - v0;
Vector3 tan = v2 - v0;
if (dir == Vector3.zero)
{
continue;
}
if (tan == Vector3.zero)
{
continue;
}
var normal = Vector3.Cross(tan, dir).normalized;
float dirLength = dir.magnitude;
float height = Vector3.Dot(tan, Vector3.Cross(dir / dirLength, normal));
float area = (dirLength * height) / 2f;
normal *= area;
Vector4 tangent = new Vector4(normal.x, normal.y, normal.z, 0);
for (int j = 0; j < 3; j++)
{
SoftNormal softNormal;
int vertIndex = mTris[i + j];
Vector3 vert = mVerts[vertIndex];
if (!vertDict.TryGetValue(mVerts[mTris[i + j]], out softNormal))
{
softNormal = new SoftNormal();
vertDict.Add(vert, softNormal);
}
if (!softNormal.indexs.Contains(vertIndex))
{
softNormal.indexs.Add(vertIndex);
}
softNormal.normal += tangent;
}
}
var softNormals = vertDict.Values;
foreach (var softNormal in softNormals)
{
for (int i = 0; i < softNormal.indexs.Count; i++)
{
mTangents[softNormal.indexs[i]] += softNormal.normal;
}
}
for (int i = 0; i < mTangents.Length; i++)
{
mTangents[i] = -mTangents[i].normalized;
}
mesh.tangents = mTangents;
}
/// Credit to:
/// · https://stackoverflow.com/questions/45477806/general-method-for-calculating-smooth-vertex-normals-with-100-smoothness
/// · Oskar Stålberg (@OskSta)
public static void SoftNormalsAsColors(this Mesh mesh)
{
var tris = mesh.triangles;
var verts = mesh.vertices;
var tans = new Vector4[verts.Length];
var dicVerts = new Dictionary <Vector3, SoftNormal> ();
for (var v = 0; v < tris.Length; v += 3)
{
int i1 = tris[v + 0];
int i2 = tris[v + 1];
int i3 = tris[v + 2];
// p1, p2 and p3 are the points in the face
var p1 = verts[i1];
var p2 = verts[i2];
var p3 = verts[i3];
// Calculate normal of the surface using edges
var edge1 = p2 - p1;
var edge2 = p3 - p1;
if (edge1 == Vector3.zero)
{
continue;
}
if (edge2 == Vector3.zero)
{
continue;
}
var n = Vector3.Cross(edge1, edge2).normalized;
// Get the angle between the two other points for each point
var angles = new float[3];
angles[0] = Vector3.Angle(p2 - p1, p3 - p1); // p1 is the 'base' here
angles[1] = Vector3.Angle(p3 - p2, p1 - p2); // p2 is the 'base' here
angles[2] = Vector3.Angle(p1 - p3, p2 - p3); // p3 is the 'base' here
// Store the weighted normal in an structured array
var tangent = new Vector4(n.x, n.y, n.z, 0f);
for (var i = 0; i != 3; i++)
{
SoftNormal softNormal;
int vertIndex = tris[v + i];
var vert = verts[vertIndex];
if (!dicVerts.TryGetValue(vert, out softNormal))
{
softNormal = new SoftNormal();
dicVerts.Add(vert, softNormal);
}
if (!softNormal.indexs.Contains(vertIndex))
{
softNormal.indexs.Add(vertIndex);
}
softNormal.normal += tangent * angles[i];
}
}
//okay
foreach (var softNormal in dicVerts.Values)
{
foreach (var index in softNormal.indexs)
{
tans[index] += softNormal.normal;
}
}
var colors = new Color32[tans.Length];
// Normalize sum
for (int i = 0; i != tans.Length; i++)
{
tans[i] = tans[i].normalized;
// Get corresponding color
var color =
new Color32
(
// Tranform to range [0,1] and then [0,255]
(byte)(((tans[i].x + 1) / 2) * 255),
(byte)(((tans[i].y + 1) / 2) * 255),
(byte)(((tans[i].z + 1) / 2) * 255),
1);
colors[i] = color;
}
// Save to mesh
mesh.colors32 = colors;
}
