File:Lightningbolt.png

Below is the script used to generate the OBJ file. The algorithm is derived from LightningBoldRenderer.java. It is then imported into blender using one of the templates from the isometric render help page, centered in the camera view, and rendered with color (0.45, 0.45, 0.5) using the Emission shader with strength 1 and alpha 0.3. Because the model is procedurally generated, this lightning bolt is necessary just one of the many variations that exist. Additionally, the shader used is not a precise match the Minecraft's game engine, but because it is transparent it seemed the most straightforward to approximate the result.

# Generate lightning bolt vertices

from dataclasses import dataclass
import random


@dataclass
class Vertex:
 x: float
 y: float
 z: float
 index: int


def quad(vertices: list[Vertex], faces: list[tuple], xo0, zo0, h, xo1, zo1, rr1, rr2, px1, pz1, px2, pz2):
 i = len(vertices)
 p1 = Vertex(
 xo0 + (rr2 if px1 else -rr2),
 h * 16,
 zo0 + (rr2 if pz1 else -rr2),
 i + 1,
 )
 p2 = Vertex(
 xo1 + (rr1 if px1 else -rr1),
 (h+1) * 16,
 zo1 + (rr1 if pz1 else -rr1),
 i + 2,
 )
 p3 = Vertex(
 xo1 + (rr1 if px2 else -rr1),
 (h+1) * 16,
 zo1 + (rr1 if pz2 else -rr1),
 i + 3,
 )
 p4 = Vertex(
 xo0 + (rr2 if px2 else -rr2),
 h * 16,
 zo0 + (rr2 if pz2 else -rr2),
 i + 4,
 )
 vertices.extend([p1, p2, p3, p4])
 faces.append((p1.index, p2.index, p3.index, p4.index))


def make_lightning():
 x_offsets: list[float] = [0] * 8
 z_offsets: list[float] = [0] * 8
 x_offset = 0
 z_offset = 0


 for h in range(7, -1, -1):
 x_offsets[h] = x_offset
 z_offsets[h] = z_offset
 x_offset += random.randint(0, 10) - 5
 z_offset += random.randint(0, 10) - 5


 final_x_offset = x_offset
 final_z_offset = z_offset


 vertices: list[Vertex] = []
 faces: list[tuple[int, int, int, int]] = []

 seed = random.randint(1000000, 1000000000)
 for r in range(0, 4):
 random.seed(seed)
 for p in range(0, 3):
 hs = 7
 ht = 0
 if p > 0:
 hs = 7 - p
 ht = hs - 2
 xo0 = x_offsets[hs] - final_x_offset
 zo0 = z_offsets[hs] - final_z_offset

 for h in range(hs, ht - 1, -1):
 xo1 = xo0
 zo1 = zo0
 if p == 0:
 xo0 += random.randint(0, 10) - 5
 zo0 += random.randint(0, 10) - 5
 else:
 xo0 += random.randint(0, 30) - 15
 zo0 += random.randint(0, 30) - 15
 
 rr1 = 0.1 + r * 0.2
 if p == 0:
 rr1 *= h * 0.1 + 1
 rr2 = 0.1 + r * 0.2
 if p == 0:
 rr2 *= (h - 1) * 0.1 + 1
 
 quad(vertices, faces, xo0, zo0, h, xo1, zo1, rr1, rr2, False, False, True, False)
 quad(vertices, faces, xo0, zo0, h, xo1, zo1, rr1, rr2, True, False, True, True);
 quad(vertices, faces, xo0, zo0, h, xo1, zo1, rr1, rr2, True, True, False, True);
 quad(vertices, faces, xo0, zo0, h, xo1, zo1, rr1, rr2, False, True, False, False);
 return vertices, faces


vertices, faces = make_lightning()


with open("lightningbolt.obj", "w") as f:
 for vertex in vertices:
 f.write(f"v {vertex.x} {vertex.y} {vertex.z}\n")
 for face in faces:
 face_str = " ".join([str(x) for x in face])
 f.write(f"f {face_str}\n")