RenderMesh: Make opacity affect mesh when not using background too

comfy_extras/nodes_sam3d_body.py

@@ -669,7 +669,10 @@ def _render_mesh_mode_inputs():
                 "'depth' = linear gray."
             ),
         ),
-        io.Float.Input("opacity", default=1.0, min=0.0, max=1.0, step=0.01),
+        io.Float.Input(
+            "opacity", default=1.0, min=0.0, max=1.0, step=0.01,
+            tooltip="Mesh alpha over the background image, or over black when none is connected.",
+        ),
         io.Float.Input(
             "person_palette_falloff",
             default=0.6, min=0.1, max=1.0, step=0.05,

comfy_extras/sam3d_body/rasterizer.py

@@ -463,5 +463,7 @@ def render_pose_data_torch(
         if opacity != 1.0:
             a = a * float(opacity)
         rendered = torch.lerp(bg, rendered, a)
+    elif opacity != 1.0:
+        rendered = rendered * float(opacity)
 
     return rendered