private static void GenNormals()
{
var faceNormals = new vec3[faceData.Length / 3];
for (int i = 0; i < faceData.Length / 3; i++)
{
ushort vertexId1 = faceData[i * 3 + 0];
ushort vertexId2 = faceData[i * 3 + 1];
ushort vertexId3 = faceData[i * 3 + 2];
vec3 vertex0 = new vec3(
positionData[(vertexId1 - 1) * 3 + 0],
positionData[(vertexId1 - 1) * 3 + 1],
positionData[(vertexId1 - 1) * 3 + 2]);
vec3 vertex1 = new vec3(
positionData[(vertexId2 - 1) * 3 + 0],
positionData[(vertexId2 - 1) * 3 + 1],
positionData[(vertexId2 - 1) * 3 + 2]);
vec3 vertex2 = new vec3(
positionData[(vertexId3 - 1) * 3 + 0],
positionData[(vertexId3 - 1) * 3 + 1],
positionData[(vertexId3 - 1) * 3 + 2]);
vec3 v1 = vertex0 - vertex2;
vec3 v2 = vertex2 - vertex1;
faceNormals[i] = v2.cross(v1).normalize();
}
var normals = new float[positionData.Length];
for (int i = 0; i < positionData.Length / 3; i++)
{
vec3 sum = new vec3();
int shared = 0;
for (int j = 0; j < faceData.Length / 3; j++)
{
ushort vertexId1 = faceData[j * 3 + 0];
ushort vertexId2 = faceData[j * 3 + 1];
ushort vertexId3 = faceData[j * 3 + 2];
if (vertexId1 - 1 == i || vertexId2 - 1 == i || vertexId3 - 1 == i)
{
sum = sum + faceNormals[j];
shared++;
}
}
if (shared > 0)
{
sum = (sum / shared).normalize();
}
normals[i * 3 + 0] = sum.x;
normals[i * 3 + 1] = sum.y;
normals[i * 3 + 2] = sum.z;
}
TeapotModel.normals = normals;
}
