show some tile related warnings in halt condition panel

properties/config.py

@@ -16,7 +16,7 @@
 )
 
 AA_SAMPLE_DESC = (
-    "How many samples to compute per pass. Higher values increase memory usage, but lead to better performance. "
+    "How many AA samples to compute per pass. Higher values increase memory usage, but lead to better performance. "
     "Note that this number is squared, so e.g. a value of 5 will lead to 25 samples per pixel after one pass"
 )
 
@@ -120,7 +120,7 @@ class LuxCoreConfigTile(PropertyGroup):
     Stored in LuxCoreConfig, accesss with scene.luxcore.config.tile
     """
     # tilepath.sampling.aa.size
-    path_sampling_aa_size = IntProperty(name="Samples per Pass", default=3, min=1, soft_max=13,
+    path_sampling_aa_size = IntProperty(name="AA Samples", default=3, min=1, soft_max=13,
                                         description=AA_SAMPLE_DESC)
 
     # tile.size

ui/halt.py

@@ -26,6 +26,27 @@ def draw(layout, context, halt):
     split.prop(halt, "samples")
 
     config = context.scene.luxcore.config
+
+    if halt.use_samples and config.engine == "PATH" and config.use_tiles:
+        # some special warnings about tile path usage
+        aa = config.tile.path_sampling_aa_size
+        samples_per_pass = aa**2
+
+        if config.tile.multipass_enable and halt.samples % samples_per_pass != 0:
+            layout.label("Should be a multiple of %d" % samples_per_pass, icon=icons.WARNING)
+
+        if context.scene.luxcore.denoiser.enabled:
+            # Denoiser needs one warmup pass plus at least one sample collecting pass
+            min_samples = samples_per_pass * 2
+        else:
+            min_samples = samples_per_pass
+
+        if halt.samples < min_samples:
+            layout.label("Use at least %d samples!" % min_samples, icon=icons.WARNING)
+
+        if not config.tile.multipass_enable and halt.samples > min_samples:
+            layout.label("Samples halt condition overriden by disabled multipass", icon=icons.INFO)
+
     is_adaptive_sampler = config.engine == "PATH" and config.sampler in {"SOBOL", "RANDOM"}
     show_adaptive_sampling_props = halt.use_noise_thresh and is_adaptive_sampler