Add a way for nodes to set a custom CFG function.

comfy/samplers.py

@@ -211,6 +211,9 @@ def sampling_function(model_function, x, timestep, uncond, cond, cond_scale, con
 
         max_total_area = model_management.maximum_batch_area()
         cond, uncond = calc_cond_uncond_batch(model_function, cond, uncond, x, timestep, max_total_area, cond_concat, model_options)
+        if "sampler_cfg_function" in model_options:
+            return model_options["sampler_cfg_function"](cond, uncond, cond_scale)
+        else:
             return uncond + (cond - uncond) * cond_scale
 
 

comfy/sd.py

@@ -250,6 +250,9 @@ class ModelPatcher:
     def set_model_tomesd(self, ratio):
         self.model_options["transformer_options"]["tomesd"] = {"ratio": ratio}
 
+    def set_model_sampler_cfg_function(self, sampler_cfg_function):
+        self.model_options["sampler_cfg_function"] = sampler_cfg_function
+
     def model_dtype(self):
         return self.model.diffusion_model.dtype