/*
* Small diagram for reference :)
* | | /|
* | | / |P1
* | |/ |
* | I1| |
* | /| |
* y| / | |
* | P0/__|___|P2
* | |I2
* | |
* |___________________
*/
public bool TrianglePlaneIntersect(List <Vector3> vertices, List <Vector2> uvs, List <int> triangles, int startIdx, ref Plane plane, TempMesh posMesh, TempMesh negMesh, Vector3[] intersectVectors)
{
int i;
// Store triangle, vertex and uv from indices
for (i = 0; i < 3; ++i)
{
t[i] = triangles[startIdx + i];
v[i] = vertices[t[i]];
u[i] = uvs[t[i]];
}
// Store wether the vertex is on positive mesh
posMesh.ContainsKeys(triangles, startIdx, positive);
// If they're all on the same side, don't do intersection
if (positive[0] == positive[1] && positive[1] == positive[2])
{
// All points are on the same side. No intersection
// Add them to either positive or negative mesh
(positive[0] ? posMesh : negMesh).AddOgTriangle(t);
return(false);
}
// Find lonely point
int lonelyPoint = 0;
if (positive[0] != positive[1])
{
lonelyPoint = positive[0] != positive[2] ? 0 : 1;
}
else
{
lonelyPoint = 2;
}
// Set previous point in relation to front face order
int prevPoint = lonelyPoint - 1;
if (prevPoint == -1)
{
prevPoint = 2;
}
// Set next point in relation to front face order
int nextPoint = lonelyPoint + 1;
if (nextPoint == 3)
{
nextPoint = 0;
}
// Get the 2 intersection points
ValueTuple <Vector3, Vector2> newPointPrev = Intersect(plane, v[lonelyPoint], v[prevPoint], u[lonelyPoint], u[prevPoint]);
ValueTuple <Vector3, Vector2> newPointNext = Intersect(plane, v[lonelyPoint], v[nextPoint], u[lonelyPoint], u[nextPoint]);
//Set the new triangles and store them in respective tempmeshes
(positive[lonelyPoint] ? posMesh : negMesh).AddSlicedTriangle(t[lonelyPoint], newPointNext.Item1, newPointPrev.Item1, newPointNext.Item2, newPointPrev.Item2);
(positive[prevPoint] ? posMesh : negMesh).AddSlicedTriangle(t[prevPoint], newPointPrev.Item1, newPointPrev.Item2, t[nextPoint]);
(positive[prevPoint] ? posMesh : negMesh).AddSlicedTriangle(t[nextPoint], newPointPrev.Item1, newPointNext.Item1, newPointPrev.Item2, newPointNext.Item2);
// We return the edge that will be in the correct orientation for the positive side mesh
if (positive[lonelyPoint])
{
intersectVectors[0] = newPointPrev.Item1;
intersectVectors[1] = newPointNext.Item1;
}
else
{
intersectVectors[0] = newPointNext.Item1;
intersectVectors[1] = newPointPrev.Item1;
}
return(true);
}
public bool TrianglePlaneIntersect(List <Vector3> vertices, List <Vector2> uvs, List <int> triangles, int startIdx, ref Plane plane, TempMesh posMesh, TempMesh negMesh, Vector3[] intersectVectors)
{
int i;
for (i = 0; i < 3; ++i)
{
t[i] = triangles[startIdx + i];
v[i] = vertices[t[i]];
u[i] = uvs[t[i]];
}
// Находится ли вершина на положительной сетке
posMesh.ContainsKeys(triangles, startIdx, positive);
// Если они все на одной стороне, не пересечения нет
if (positive[0] == positive[1] && positive[1] == positive[2])
{
// Все точки на одной стороне, пересечения нет
// Добавляем их в положительный или отрицательный меш
(positive[0] ? posMesh : negMesh).AddOriginalTriangle(t);
return(false);
}
// Поиск одиноой точки
int lonelyPoint = 0;
if (positive[0] != positive[1])
{
lonelyPoint = positive[0] != positive[2] ? 0 : 1;
}
else
{
lonelyPoint = 2;
}
// Устанавливаем предыдущую точку относительно порядка передней грани
int prevPoint = lonelyPoint - 1;
if (prevPoint == -1)
{
prevPoint = 2;
}
// Устанавливаем следующую точку
int nextPoint = lonelyPoint + 1;
if (nextPoint == 3)
{
nextPoint = 0;
}
// Получаем 2 точки пересечения
ValueTuple <Vector3, Vector2> newPointPrev = Intersect(plane, v[lonelyPoint], v[prevPoint], u[lonelyPoint], u[prevPoint]);
ValueTuple <Vector3, Vector2> newPointNext = Intersect(plane, v[lonelyPoint], v[nextPoint], u[lonelyPoint], u[nextPoint]);
// Добавляем новые треугольники и сохраните их в соответствующих буферных мешах
(positive[lonelyPoint] ? posMesh : negMesh).AddSlicedTriangle(t[lonelyPoint], newPointNext.Item1, newPointPrev.Item1, newPointNext.Item2, newPointPrev.Item2);
(positive[prevPoint] ? posMesh : negMesh).AddSlicedTriangle(t[prevPoint], newPointPrev.Item1, newPointPrev.Item2, t[nextPoint]);
(positive[prevPoint] ? posMesh : negMesh).AddSlicedTriangle(t[nextPoint], newPointPrev.Item1, newPointNext.Item1, newPointPrev.Item2, newPointNext.Item2);
// Возвращаем ребро, которое будет в правильной ориентации для положительного меша
if (positive[lonelyPoint])
{
intersectVectors[0] = newPointPrev.Item1;
intersectVectors[1] = newPointNext.Item1;
}
else
{
intersectVectors[0] = newPointNext.Item1;
intersectVectors[1] = newPointPrev.Item1;
}
return(true);
}
