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extends Node
# Marching cubes algorithm ported from https://graphics.stanford.edu/~mdfisher/MarchingCubes.html
const mc = preload("res://scripts/marching_cubes_data.gd")
class Cell:
var position: Array[Vector3]
var value: Array[float]
func _init():
position.resize(8)
value.resize(8)
func march_cube(cell: Cell, triangles: PackedInt32Array, verticies: PackedVector3Array):
var cube_index : int = 0
var vertex_list: Array[Vector3] = []
vertex_list.resize(12)
var starting_vertex_count = verticies.size()
for i in 8:
if cell.value[i] < 0: cube_index |= (1 << i)
if mc._edge_table[cube_index] == 0:
return
if mc._edge_table[cube_index] & 1 != 0:
vertex_list[0] = (vertex_interpolate(cell.position[0], cell.position[1], cell.value[0], cell.value[1]))
if mc._edge_table[cube_index] & 2 != 0:
vertex_list[1] = (vertex_interpolate(cell.position[1], cell.position[2], cell.value[1], cell.value[2]))
if mc._edge_table[cube_index] & 4 != 0:
vertex_list[2] = (vertex_interpolate(cell.position[2], cell.position[3], cell.value[2], cell.value[3]))
if mc._edge_table[cube_index] & 8 != 0:
vertex_list[3] = (vertex_interpolate(cell.position[3], cell.position[0], cell.value[3], cell.value[0]))
if mc._edge_table[cube_index] & 16 != 0:
vertex_list[4] = (vertex_interpolate(cell.position[4], cell.position[5], cell.value[4], cell.value[5]))
if mc._edge_table[cube_index] & 32 != 0:
vertex_list[5] = (vertex_interpolate(cell.position[5], cell.position[6], cell.value[5], cell.value[6]))
if mc._edge_table[cube_index] & 64 != 0:
vertex_list[6] = (vertex_interpolate(cell.position[6], cell.position[7], cell.value[6], cell.value[7]))
if mc._edge_table[cube_index] & 128 != 0:
vertex_list[7] = (vertex_interpolate(cell.position[7], cell.position[4], cell.value[7], cell.value[4]))
if mc._edge_table[cube_index] & 256 != 0:
vertex_list[8] = (vertex_interpolate(cell.position[0], cell.position[4], cell.value[0], cell.value[4]))
if mc._edge_table[cube_index] & 512 != 0:
vertex_list[9] = (vertex_interpolate(cell.position[1], cell.position[5], cell.value[1], cell.value[5]))
if mc._edge_table[cube_index] & 1024 != 0:
vertex_list[10] = (vertex_interpolate(cell.position[2], cell.position[6], cell.value[2], cell.value[6]))
if mc._edge_table[cube_index] & 2048 != 0:
vertex_list[11] = (vertex_interpolate(cell.position[3], cell.position[7], cell.value[3], cell.value[7]))
var new_vertex_count: int = 0
var local_remap: Array[int] = []
local_remap.resize(12)
local_remap.fill(-1)
var new_vertex_list: Array[Vector3] = []
new_vertex_list.resize(12)
var tri_index: int = 0
while mc._tri_table[cube_index][tri_index] != -1:
if local_remap[mc._tri_table[cube_index][tri_index]] == -1:
new_vertex_list[new_vertex_count] = vertex_list[mc._tri_table[cube_index][tri_index]]
local_remap[mc._tri_table[cube_index][tri_index]] = new_vertex_count
new_vertex_count += 1
tri_index += 1
for i in new_vertex_count:
var vert = new_vertex_list[i]
verticies.push_back(vert)
tri_index = 0
while mc._tri_table[cube_index][tri_index] != -1:
triangles.push_back(local_remap[mc._tri_table[cube_index][tri_index + 0]] + starting_vertex_count)
triangles.push_back(local_remap[mc._tri_table[cube_index][tri_index + 1]] + starting_vertex_count)
triangles.push_back(local_remap[mc._tri_table[cube_index][tri_index + 2]] + starting_vertex_count)
tri_index += 3
func vertex_interpolate(p1: Vector3, p2: Vector3, val1: float, val2: float):
return (p1 + (-val1 / (val2 - val1)) * (p2 - p1))
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