From e5b2576c73d02f5991711275d1c202828133c035 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20du=20Hamel?= <stephduh@live.fr>
Date: Tue, 12 Aug 2025 13:19:12 +0200
Subject: [PATCH] add split sigmas node

---
 __init__.py |  8 +++++---
 nodes.py    | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/__init__.py b/__init__.py
index 1b761cf..3e66e6d 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,11 +1,13 @@
-from .nodes import WanMoeKSampler,WanMoeKSamplerAdvanced
+from .nodes import WanMoeKSampler,WanMoeKSamplerAdvanced,SplitSigmasAtT
 
 NODE_CLASS_MAPPINGS = {
     "WanMoeKSampler":WanMoeKSampler,
-    "WanMoeKSamplerAdvanced":WanMoeKSamplerAdvanced
+    "WanMoeKSamplerAdvanced":WanMoeKSamplerAdvanced,
+    "SplitSigmasAtT":SplitSigmasAtT
 }
 
 NODE_DISPLAY_NAME_MAPPINGS = {
     "WanMoeKSampler": "Wan MoE KSampler",
-    "WanMoeKSamplerAdvanced": "Wan MoE KSampler (Advanced)"
+    "WanMoeKSamplerAdvanced": "Wan MoE KSampler (Advanced)",
+    "SplitSigmasAtT": "Split sigmas at timestep"
 }
\ No newline at end of file
diff --git a/nodes.py b/nodes.py
index ad96a29..17676b4 100644
--- a/nodes.py
+++ b/nodes.py
@@ -154,3 +154,44 @@ class WanMoeKSamplerAdvanced:
         if add_noise == "disable":
             disable_noise = True
         return wan_ksampler(model_high_noise, model_low_noise, noise_seed, steps, (cfg_high_noise, cfg_low_noise), sampler_name, scheduler, positive, negative, latent_image, boundary=boundary, denoise=denoise, disable_noise=disable_noise, start_step=start_at_step, last_step=end_at_step, force_full_denoise=force_full_denoise)
+
+class SplitSigmasAtT:
+    @classmethod
+    def INPUT_TYPES(s):
+        return {"required":
+                    {
+                        "boundary": ("FLOAT", {"default": 0.875, "min": 0.0, "max": 1.0, "step": 0.001, "round":0.001}),
+                        "sigmas": ("SIGMAS", ),
+                    },
+                 "optional":                     
+                    {
+                        "model": ("MODEL", {"tooltip": "Used to determine the model type. Assumes FLOW model by default if not provided"}),
+                    }
+                }
+    
+    RETURN_TYPES = ("SIGMAS", "SIGMAS", "INT", )
+    RETURN_NAMES = ("high noise sigmas", "low noise sigmas", "split at", )
+    CATEGORY = "sampling/custom_sampling/schedulers"
+
+    FUNCTION = "split"
+
+    def split(self, boundary, sigmas:torch.Tensor, model = None):
+        if model is None:
+            sampling_base = comfy.model_sampling.ModelSamplingDiscreteFlow  
+            sampling_type = comfy.model_sampling.CONST
+
+            class ModelSamplingAdvanced(sampling_base, sampling_type):
+                pass
+            sampling = ModelSamplingAdvanced()
+        else:
+            sampling = model.get_model_object("model_sampling")
+        timesteps = [sampling.timestep(sigma)/1000 for sigma in sigmas.tolist()]
+        switching_step = sigmas.size(0)
+        for (i,t) in enumerate(timesteps[1:]):
+            if t < boundary:
+                switching_step = i
+                break
+        print(f"splitting sigmas at index {switching_step}")
+        return (sigmas[:switching_step + 1], sigmas[switching_step:], switching_step, )
+
+        
\ No newline at end of file