demo.design 3D programming FAQ. �� 3D ��. �� .

�� 3D ��
2.4. ��

�� , �� , �� 3D �� . �� .

�� . �� - �� , �� -�� , �� - �� , �� . �� , � �� (�� , �� y �� ), � �� .

�� , �� A �� , C - ��, �� min_y = A.y, max_y = C.y, � �� min_y �� max_y. �� -�� sy, A.y <= sy <= C.y. �� sy < B.y, �� AB � AC; �� sy >= B.y - �� BC � AC. �� , �� y = sy. �� . �� , �� , � �� , �� x � �� , �� . �� , �� - � ��, �� .

�� y = sy (�� ) � �� , �� AB. �� AB � �� x = k*y+b:

x = A.x+(y-A.y)*(B.x-A.x)/(B.y-A.y)

�� y = sy:

x = A.x+(sy-A.y)*(B.x-A.x)/(B.y-A.y)

��, � ��-��, � ��. �� . � �� .

// ...
// ����� ��������� ������� (A,B,C)
// ...
for (sy = A.y; sy <= C.y; sy++) {
  x1 = A.x + (sy - A.y) * (C.x - A.x) / (C.y - A.y);
  if (sy < B.y)
    x2 = A.x + (sy - A.y) * (B.x - A.x) / (B.y - A.y);
  else
    x2 = B.x + (sy - B.y) * (C.x - B.x) / (C.y - B.y);
  if (x1 > x2) { tmp = x1; x1 = x2; x2 = tmp; }
  drawHorizontalLine(sy, x1, x2);
}
// ...

��, ��, �� , �� B.y = C.y - � �� (� �� , �� C.y = A.y, �� , �� ; � �� B.y = A.y, �� sy >= A.y � �� B.y - A.y �� ) �� . �� -��:

// ...
// ����� ��������� ������� (A,B,C)
// ...
for (sy = A.y; sy <= C.y; sy++) {
  x1 = A.x + (sy - A.y) * (C.x - A.x) / (C.y - A.y);
  if (sy < B.y)
    x2 = A.x + (sy - A.y) * (B.x - A.x) / (B.y - A.y);
  else {
    if (C.y == B.y)
      x2 = B.x;
    else
      x2 = B.x + (sy - B.y) * (C.x - B.x) / (C.y - B.y);
  }
  if (x1 > x2) { tmp = x1; x1 = x2; x2 = tmp; }
  drawHorizontalLine(sy, x1, x2);
}
// ...

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