PixArt KSampler support

Thanks to @lawrence-cj for his help on this!

PixArt/conf.py

@@ -3,22 +3,38 @@ List of all PixArt model types / settings
 """
 pixart_conf = {
 	"PixArtMS_XL_2": { # models/PixArtMS
-		"target"      : "PixArtMS",
-		"input_size"  : 1024//8,
-		"lewei_scale" :    2,
-		"depth"       :   28,
-		"num_heads"   :   16,
-		"patch_size"  :    2,
-		"hidden_size" : 1152,
+		"target": "PixArtMS",
+		"unet_config": {
+			"input_size"  : 1024//8,
+			"lewei_scale" :    2,
+			"depth"       :   28,
+			"num_heads"   :   16,
+			"patch_size"  :    2,
+			"hidden_size" : 1152,
+		},
+		"sampling_settings": {
+			"beta_schedule" : "sqrt_linear",
+			"linear_start"  : 0.0001,
+			"linear_end"    : 0.02,
+			"timesteps"     : 1000,
+		},
 	},
 	"PixArt_XL_2": { # models/PixArt
-		"target"      : "PixArt",
-		"input_size"  :  512//8,
-		"lewei_scale" :    1,
-		"depth"       :   28,
-		"num_heads"   :   16,
-		"patch_size"  :    2,
-		"hidden_size" : 1152,
+		"target": "PixArt",
+		"unet_config": {
+			"input_size"  :  512//8,
+			"lewei_scale" :    1,
+			"depth"       :   28,
+			"num_heads"   :   16,
+			"patch_size"  :    2,
+			"hidden_size" : 1152,
+		},
+		"sampling_settings": {
+			"beta_schedule" : "sqrt_linear",
+			"linear_start"  : 0.0001,
+			"linear_end"    : 0.02,
+			"timesteps"     : 1000,
+		},
 	},
 }
 

PixArt/loader.py

@@ -13,6 +13,14 @@ class EXM_PixArt(comfy.supported_models_base.BASE):
 	unet_extra_config = {}
 	latent_format = comfy.latent_formats.SD15
 
+	def __init__(self, model_conf):
+		self.model_target = model_conf.get("target")
+		self.unet_config = model_conf.get("unet_config", {})
+		self.sampling_settings = model_conf.get("sampling_settings", {})
+		self.latent_format = self.latent_format()
+		# UNET is handled by extension
+		self.unet_config["disable_unet_model_creation"] = True
+
 	def model_type(self, state_dict, prefix=""):
 		return comfy.model_base.ModelType.EPS
 
@@ -22,21 +30,23 @@ def load_pixart(model_path, model_conf):
 	parameters = comfy.utils.calculate_parameters(state_dict)
 	unet_dtype = model_management.unet_dtype(model_params=parameters)
 
+	model_conf = EXM_PixArt(model_conf) # convert to object
+
 	model = comfy.model_base.BaseModel(
-		EXM_PixArt({"disable_unet_model_creation" : True }),
+		model_conf,
 		model_type=comfy.model_base.ModelType.EPS,
 		device=model_management.get_torch_device()
 	)
 
 	model.pixart_config = model_conf
-	if model_conf["target"] == "PixArtMS":
+	if model_conf.model_target == "PixArtMS":
 		from .models.PixArtMS import PixArtMS
-		model.diffusion_model = PixArtMS(**model_conf)
-	elif model_conf["target"] == "PixArt":
+		model.diffusion_model = PixArtMS(**model_conf.unet_config)
+	elif model_conf.model_target == "PixArt":
 		from .models.PixArt import PixArt
-		model.diffusion_model = PixArt(**model_conf)
+		model.diffusion_model = PixArt(**model_conf.unet_config)
 	else:
-		raise NotImplementedError
+		raise NotImplementedError(f"Unknown model target '{model_conf.model_target}'")
 
 	model.diffusion_model.load_state_dict(state_dict)
 	model.diffusion_model.dtype = unet_dtype