InvokeAI/invokeai/app/invocations/blend_latents.py

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from typing import Any, Union
import numpy as np
import numpy.typing as npt
import torch
from invokeai.app.invocations.baseinvocation import BaseInvocation, invocation
from invokeai.app.invocations.fields import FieldDescriptions, Input, InputField, LatentsField
from invokeai.app.invocations.primitives import LatentsOutput
from invokeai.app.services.shared.invocation_context import InvocationContext
from invokeai.backend.util.devices import TorchDevice
@invocation(
"lblend",
title="Blend Latents",
tags=["latents", "blend"],
category="latents",
version="1.0.3",
)
class BlendLatentsInvocation(BaseInvocation):
"""Blend two latents using a given alpha. Latents must have same size."""
latents_a: LatentsField = InputField(
description=FieldDescriptions.latents,
input=Input.Connection,
)
latents_b: LatentsField = InputField(
description=FieldDescriptions.latents,
input=Input.Connection,
)
alpha: float = InputField(default=0.5, description=FieldDescriptions.blend_alpha)
def invoke(self, context: InvocationContext) -> LatentsOutput:
latents_a = context.tensors.load(self.latents_a.latents_name)
latents_b = context.tensors.load(self.latents_b.latents_name)
if latents_a.shape != latents_b.shape:
raise Exception("Latents to blend must be the same size.")
device = TorchDevice.choose_torch_device()
def slerp(
t: Union[float, npt.NDArray[Any]], # FIXME: maybe use np.float32 here?
v0: Union[torch.Tensor, npt.NDArray[Any]],
v1: Union[torch.Tensor, npt.NDArray[Any]],
DOT_THRESHOLD: float = 0.9995,
) -> Union[torch.Tensor, npt.NDArray[Any]]:
"""
Spherical linear interpolation
Args:
t (float/np.ndarray): Float value between 0.0 and 1.0
v0 (np.ndarray): Starting vector
v1 (np.ndarray): Final vector
DOT_THRESHOLD (float): Threshold for considering the two vectors as
colineal. Not recommended to alter this.
Returns:
v2 (np.ndarray): Interpolation vector between v0 and v1
"""
inputs_are_torch = False
if not isinstance(v0, np.ndarray):
inputs_are_torch = True
v0 = v0.detach().cpu().numpy()
if not isinstance(v1, np.ndarray):
inputs_are_torch = True
v1 = v1.detach().cpu().numpy()
dot = np.sum(v0 * v1 / (np.linalg.norm(v0) * np.linalg.norm(v1)))
if np.abs(dot) > DOT_THRESHOLD:
v2 = (1 - t) * v0 + t * v1
else:
theta_0 = np.arccos(dot)
sin_theta_0 = np.sin(theta_0)
theta_t = theta_0 * t
sin_theta_t = np.sin(theta_t)
s0 = np.sin(theta_0 - theta_t) / sin_theta_0
s1 = sin_theta_t / sin_theta_0
v2 = s0 * v0 + s1 * v1
if inputs_are_torch:
v2_torch: torch.Tensor = torch.from_numpy(v2).to(device)
return v2_torch
else:
assert isinstance(v2, np.ndarray)
return v2
# blend
bl = slerp(self.alpha, latents_a, latents_b)
assert isinstance(bl, torch.Tensor)
blended_latents: torch.Tensor = bl # for type checking convenience
# https://discuss.huggingface.co/t/memory-usage-by-later-pipeline-stages/23699
blended_latents = blended_latents.to("cpu")
TorchDevice.empty_cache()
name = context.tensors.save(tensor=blended_latents)
return LatentsOutput.build(latents_name=name, latents=blended_latents, seed=self.latents_a.seed)