.obj .mtl 解释

 

写.obj文件。

def write_obj_with_colors_texture(obj_name, vertices, triangles, colors, texture, uv_coords):
 Args:
 obj_name: str
 vertices: shape = (nver, 3)；triangles: shape = (ntri, 3)； colors: shape = (nver, 3) （由exmaple1.mat得到）
 texture: shape = (256,256,3) （由uv_texture_map.jpg得到）
 uv_coords: shape = (nver, 3) max value<=1 （由BFM_UV.mat得到）
 '''
 if obj_name.split('.')[-1] != 'obj':
 obj_name = obj_name + '.obj'
 mtl_name = obj_name.replace('.obj', '.mtl')
 texture_name = obj_name.replace('.obj', '_texture.png')
 
 triangles = triangles.copy()
 triangles += 1 # mesh lab start with 1
 
 # write obj
 with open(obj_name, 'w') as f:
 # first line: write mtlib(material library)
 s = "mtllib {}\n".format(os.path.abspath(mtl_name))
 f.write(s)

        # write vertices
        #v:{x,y,z,r,g,b}
        for i in range(vertices.shape[0]):
            s = 'v {} {} {} {} {} {}\n'.format(vertices[i, 0], vertices[i, 1], vertices[i, 2], colors[i, 0], colors[i, 1], colors[i, 2])
            f.write(s)
 
        # write uv coords
        #vt:{x,y}
        for i in range(uv_coords.shape[0]):
            # s = 'vt {} {}\n'.format(uv_coords[i,0], 1 - uv_coords[i,1])
            s = 'vt {} {}\n'.format(uv_coords[i,0], uv_coords[i,1])
            f.write(s)


        f.write("usemtl FaceTexture\n")


        # write f: ver ind/ uv ind
        for i in range(triangles.shape[0]):
            # s = 'f {}/{} {}/{} {}/{}\n'.format(triangles[i,0], triangles[i,0], triangles[i,1], triangles[i,1], triangles[i,2], triangles[i,2])
            s = 'f {}/{} {}/{} {}/{}\n'.format(triangles[i,2], triangles[i,2], triangles[i,1], triangles[i,1], triangles[i,0], triangles[i,0])
            f.write(s)


    # write mtl
    with open(mtl_name, 'w') as f:
        f.write("newmtl FaceTexture\n")
        s = 'map_Kd {}\n'.format(os.path.abspath(texture_name)) # map to image
        f.write(s)


    # write texture as png
    io.imsave(texture_name, texture)

输出的.ojb文件格式如下：

mtllib /home/zsl/faceswap_workspace_zsl/face3d-master/examples/results/io/numpy.mtl
v 79.39030456542969 86.16109466552734 20.938037872314453 0.7569913864135742 0.5408705472946167 0.44164004921913147
v 79.43241119384766 86.39189147949219 20.96391487121582 0.7891361713409424 0.5776993036270142 0.47755759954452515

...

vt 0.2362661212682724 0.7827212810516357
vt 0.23682615160942078 0.7814681529998779

...

usemtl FaceTexture
f 2/2 131/131 1/1
f 131/131 130/130 1/1

...

v 顶点坐标（x,y,z）像素（r,g,b）

vt uv纹理坐标（x,y）

vn 法线坐标 eg:vn -0.679327 0.446122 -0.582657

f v/vt/vn v/vt/vn v/vt/vn 三角面的顶点索引(顶点坐标索引/纹理索引/法线索引)

 

输出的.mtl为材质文件。mtl格式为：

 

# 为漫反射指定颜色纹理文件
map_Kd /home/xx/results/io/numpy_texture.png

# 定义一个名为 'xxx'的材质
newmtl xxx
# 材质的环境光（ambient color）
Ka 0 0 0
# 散射光（diffuse color）用Kd
Kd 0.784314 0.784314 0.784314
# 镜面光（specular color）用Ks
Ks 0 0 0
# 折射值 可在0.001到10之间进行取值。若取值为1.0，光在通过物体的时候不发生弯曲。玻璃的折射率为1.5。
Ni 1
# 反射指数 定义了反射高光度。该值越高则高光越密集，一般取值范围在0~1000。
Ns 400
# 滤光透射率
Tf 1 1 1
# 渐隐指数描述 参数factor表示物体融入背景的数量，取值范围为0.0~1.0，取值为1.0表示完全不透明，取值为0.0时表示完全透明。
d 1