Flux 2 (#10879)

comfy_extras/nodes_flux.py

@@ -2,7 +2,10 @@ import node_helpers
 import comfy.utils
 from typing_extensions import override
 from comfy_api.latest import ComfyExtension, io
-
+import comfy.model_management
+import torch
+import math
+import nodes
 
 class CLIPTextEncodeFlux(io.ComfyNode):
     @classmethod
@@ -30,6 +33,27 @@ class CLIPTextEncodeFlux(io.ComfyNode):
 
     encode = execute  # TODO: remove
 
+class EmptyFlux2LatentImage(io.ComfyNode):
+    @classmethod
+    def define_schema(cls):
+        return io.Schema(
+            node_id="EmptyFlux2LatentImage",
+            display_name="Empty Flux 2 Latent",
+            category="latent",
+            inputs=[
+                io.Int.Input("width", default=1024, min=16, max=nodes.MAX_RESOLUTION, step=16),
+                io.Int.Input("height", default=1024, min=16, max=nodes.MAX_RESOLUTION, step=16),
+                io.Int.Input("batch_size", default=1, min=1, max=4096),
+            ],
+            outputs=[
+                io.Latent.Output(),
+            ],
+        )
+
+    @classmethod
+    def execute(cls, width, height, batch_size=1) -> io.NodeOutput:
+        latent = torch.zeros([batch_size, 128, height // 16, width // 16], device=comfy.model_management.intermediate_device())
+        return io.NodeOutput({"samples": latent})
 
 class FluxGuidance(io.ComfyNode):
     @classmethod
@@ -154,6 +178,58 @@ class FluxKontextMultiReferenceLatentMethod(io.ComfyNode):
     append = execute  # TODO: remove
 
 
+def generalized_time_snr_shift(t, mu: float, sigma: float):
+    return math.exp(mu) / (math.exp(mu) + (1 / t - 1) ** sigma)
+
+
+def compute_empirical_mu(image_seq_len: int, num_steps: int) -> float:
+    a1, b1 = 8.73809524e-05, 1.89833333
+    a2, b2 = 0.00016927, 0.45666666
+
+    if image_seq_len > 4300:
+        mu = a2 * image_seq_len + b2
+        return float(mu)
+
+    m_200 = a2 * image_seq_len + b2
+    m_10 = a1 * image_seq_len + b1
+
+    a = (m_200 - m_10) / 190.0
+    b = m_200 - 200.0 * a
+    mu = a * num_steps + b
+
+    return float(mu)
+
+
+def get_schedule(num_steps: int, image_seq_len: int) -> list[float]:
+    mu = compute_empirical_mu(image_seq_len, num_steps)
+    timesteps = torch.linspace(1, 0, num_steps + 1)
+    timesteps = generalized_time_snr_shift(timesteps, mu, 1.0)
+    return timesteps
+
+
+class Flux2Scheduler(io.ComfyNode):
+    @classmethod
+    def define_schema(cls):
+        return io.Schema(
+            node_id="Flux2Scheduler",
+            category="sampling/custom_sampling/schedulers",
+            inputs=[
+                io.Int.Input("steps", default=20, min=1, max=4096),
+                io.Int.Input("width", default=1024, min=16, max=nodes.MAX_RESOLUTION, step=1),
+                io.Int.Input("height", default=1024, min=16, max=nodes.MAX_RESOLUTION, step=1),
+            ],
+            outputs=[
+                io.Sigmas.Output(),
+            ],
+        )
+
+    @classmethod
+    def execute(cls, steps, width, height) -> io.NodeOutput:
+        seq_len = (width * height / (16 * 16))
+        sigmas = get_schedule(steps, round(seq_len))
+        return io.NodeOutput(sigmas)
+
+
 class FluxExtension(ComfyExtension):
     @override
     async def get_node_list(self) -> list[type[io.ComfyNode]]:
@@ -163,6 +239,8 @@ class FluxExtension(ComfyExtension):
             FluxDisableGuidance,
             FluxKontextImageScale,
             FluxKontextMultiReferenceLatentMethod,
+            EmptyFlux2LatentImage,
+            Flux2Scheduler,
         ]