如何在 Blender 2.80 Python 中导出切线？

Question

我正在编写一个导出器并且已经可以使用法线、位置和纹理坐标，但是如何访问切线？这是我的出口商的代码示例：

def get_vertex_pnt( self, obj_prop, mesh, face, face_vi ):
    # position
    co = obj_prop[ OBJ.LOC ] + mathutils.Vector( obj_prop[ OBJ.ROT ] @ mathutils.Vector([ \
                                                                                    mesh.vertices[ face.vertices[ face_vi ] ].co[ 0 ] * obj_prop[ OBJ.SCA ][ 0 ], \
                                                                                    mesh.vertices[ face.vertices[ face_vi ] ].co[ 1 ] * obj_prop[ OBJ.SCA ][ 1 ], \
                                                                                    mesh.vertices[ face.vertices[ face_vi ] ].co[ 2 ] * obj_prop[ OBJ.SCA ][ 2 ] \
                                                                                    ]))
    # normal
    if face.use_smooth:
        if mesh.use_auto_smooth:
            no = mathutils.Vector( obj_prop[ OBJ.ROT ] @ get_autosmooth_normal( mesh, face, face.vertices[ face_vi ] ))
        else:
            no = mathutils.Vector( obj_prop[ OBJ.ROT ] @ mesh.vertices[ face.vertices[ face_vi ] ].normal )
    else:
            no = mathutils.Vector( obj_prop[ OBJ.ROT ] @ face.normal )

    color = ( 1.0, 1.0, 1.0, 1.0 )

    outVertex = Vertex()
    outVertex.co = co
    outVertex.normal = no
    outVertex.color = color
    outVertex.tangent = (1.0, 0.0, 0.0, 1.0)

    return outVertex


def readMeshes( self, context ):
    ...

    for face in obj.data.loop_triangles:
        for vertex_id in (0, 1, 2):
            vertex_pnt = self.get_vertex_pnt(object, obj.data, face, vertex_id)
            mesh.vertices.append( vertex_pnt )
        tri = [ f * 3 + 0, f * 3 + 1, f * 3 + 2 ]
        mesh.faces.append( tri )
        f = f + 1

    for uv_layer in obj.data.uv_layers:
        for tri in obj.data.loop_triangles:
            for loop_index in tri.loops:
                mesh.vertices[ u ].uv = uv_layer.data[ loop_index ].uv
                u = u + 1

我应该如何修改代码以导出切线？我正在使用 Blender 2.80。

Answer 1

我找到了阅读它们的方法：

for p in obj.data.loops:
    print( "tangent: " + str( p.tangent ) + ", bitangent sign: " + str( p.bitangent_sign ) )

如何在 Blender 2.80 Python 中导出切线？

How to export tangents in Blender 2.80 Python?

python

blender