read .obj file faces to taichi tensor to render

[Zony-Zhao]

@ti.func
def glTri(A, B, C):
    l = ti.atomic_add(tris_len[None], 1)
    pos1[l] = A
    pos2[l] = B
    pos3[l] = C


path = 'test.obj'
vertices = []
faces = []

def readobj():
    with open(path, "r") as myfile:
        data = myfile.readlines()
        # cache vertices

        for line in data:
            if line.startswith('v '):
                splitted = line.split()
                vertex = [float(splitted[1]),
                          float(splitted[2]),
                          float(splitted[3])
                          ]
                vertices.append(vertex)

        # cache faces
        # DONT merge this 'for loop'
        # must initialize vertices for faces to work
        print('length', len(vertices))
        for line in data:
            # line looks like 'f 5/1/1 1/2/1 4/3/1'
            if line.startswith('f '):
                splitted = line.split()
                faceVertices = []

                for i in range(1, 4):
                    # splitted[i] should look like '5/1/1'
                    # for vertex/vertex UV coords/vertex Normal  (indexes number in the list)
                    # the index in 'f 5/1/1 1/2/1 4/3/1' STARTS AT 1 !!!
                    index = int((splitted[i].split('/'))[0]) - 1
                    print(index)
                    faceVertices.append(vertices[index])
                faces.append(faceVertices)


@ti.kernel
def init():
    for i in range(len(faces)):
        print(faces)
        # vertex=faces[i]
        # glTri(ts.vec3(vertex[0], vertex[1], vertex[2]))


readobj()
# print(faces)
init()

I have tried a lot of methods, but failed to read .obj file to a list obj and iterate it in taichi-kernel scope.

Generally, I read an obj file and store vertices in the faces( a python list object), which is all well. When I try to iterate it in taichi-kernel scope, it fails. The 'faces' list object can neither be use like 'for i in faces' nor 'faces[i]'. Even when I try to print it, error happens.

Should I use a taichi tensor to store faces? However, it seems impossible to read .obj in kernel.

test.zip
For you guys who want the test .obj and source file.
commit 1941110 is required.

[archibate]

Thank for purposing this! You're right, it's impossible to directly copy data from python scope to taichi tensor.
But we may first convert it into a numpy array, which taichi has control, then use tensor.from_numpy to copy the data.

[archibate]

It's working now!

import taichi as ti
import taichi_glsl as ts
import taichi_three as t3
import numpy as np


def readobj(path):
    vertices = []
    faces = []
    with open(path, "r") as myfile:
        data = myfile.readlines()
        # cache vertices

        for line in data:
            if line.startswith('v '):
                splitted = line.split()
                vertex = [float(splitted[1]),
                          float(splitted[2]),
                          float(splitted[3])
                          ]
                vertices.append(vertex)

        # cache faces
        # DONT merge this 'for loop'
        # must initialize vertices for faces to work
        print('length', len(vertices))
        for line in data:
            # line looks like 'f 5/1/1 1/2/1 4/3/1'
            if line.startswith('f '):
                splitted = line.split()
                faceVertices = []

                for i in range(1, 4):
                    # splitted[i] should look like '5/1/1'
                    # for vertex/vertex UV coords/vertex Normal  (indexes number in the list)
                    # the index in 'f 5/1/1 1/2/1 4/3/1' STARTS AT 1 !!!
                    index = int((splitted[i].split('/'))[0]) - 1
                    print(index)
                    faceVertices.append(vertices[index])
                faces.append(faceVertices)

        return np.array(faces)


model = readobj('examples/test.obj') / 2

N = model.shape[0]


ti.init(ti.cpu)

scene = t3.SceneGE()
pos1 = ti.Vector(3, ti.f32)
pos2 = ti.Vector(3, ti.f32)
pos3 = ti.Vector(3, ti.f32)
ti.root.dense(ti.i, N).place(pos1, pos2, pos3)


scene.add_triangle(pos1, pos2, pos3)
scene.set_light_dir([0.4, -1.5, -1.8])
pos1.from_numpy(model[:, 0])
pos2.from_numpy(model[:, 1])
pos3.from_numpy(model[:, 2])


gui = ti.GUI('Loading Model', scene.res)
while gui.running:
    gui.running = not gui.get_event(ti.GUI.ESCAPE)
    scene.camera.from_mouse(gui)
    scene.render()
    gui.set_image(scene.img)
    gui.show()

[Zony-Zhao]

Great!