hydra_storm/engine.py

@@ -33,6 +33,14 @@ class StormHydraRenderEngine(bpy_hydra.HydraRenderEngine):
             'maxLights': settings.max_lights,
         }
 
+    def get_sync_settings(self, engine_type):
+        settings = bpy.context.scene.hydra_storm.viewport if engine_type == 'VIEWPORT' else \
+            bpy.context.scene.hydra_storm.final
+        return {
+            'enableAlpha': settings.enable_alpha,
+        }
+
+
 register, unregister = bpy.utils.register_classes_factory((
     StormHydraRenderEngine,
 ))

hydra_storm/properties.py

@@ -48,6 +48,11 @@ class RenderProperties(bpy.types.PropertyGroup):
         description="Limit maximum number of lights",
         default=16, min=0, max=16,
     )
+    enable_alpha: bpy.props.BoolProperty(
+        name="Enable Color Alpha",
+        description="World background is transparent, for compositing the render over another background",
+        default=False,
+    )
 
 
 class SceneProperties(Properties):

hydra_storm/ui.py

@@ -58,6 +58,21 @@ class STORM_HYDRA_RENDER_PT_volume_final(bpy.types.Panel):
         col.prop(settings, "volume_max_texture_memory_per_field")
 
 
+class STORM_HYDRA_RENDER_PT_film_final(bpy.types.Panel):
+    bl_parent_id = STORM_HYDRA_RENDER_PT_final.bl_idname
+    bl_label = "Film"
+    bl_space_type = 'PROPERTIES'
+    bl_region_type = 'WINDOW'
+    bl_options = {'DEFAULT_CLOSED'}
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False
+
+        layout.prop(context.scene.hydra_storm.final, "enable_alpha", text="Transparent Background")
+
+
 #
 # VIEWPORT RENDER SETTINGS
 #
@@ -96,6 +111,21 @@ class STORM_HYDRA_RENDER_PT_volume_viewport(bpy.types.Panel):
         col.prop(settings, "volume_max_texture_memory_per_field")
 
 
+class STORM_HYDRA_RENDER_PT_film_viewport(bpy.types.Panel):
+    bl_parent_id = STORM_HYDRA_RENDER_PT_viewport.bl_idname
+    bl_label = "Film"
+    bl_space_type = 'PROPERTIES'
+    bl_region_type = 'WINDOW'
+    bl_options = {'DEFAULT_CLOSED'}
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False
+
+        layout.prop(context.scene.hydra_storm.viewport, "enable_alpha", text="Transparent Background")
+
+
 class STORM_HYDRA_LIGHT_PT_light(Panel):
     """Physical light sources"""
     bl_label = "Light"
@@ -152,8 +182,11 @@ class STORM_HYDRA_LIGHT_PT_light(Panel):
 register_classes, unregister_classes = bpy.utils.register_classes_factory((
     STORM_HYDRA_RENDER_PT_final,
     STORM_HYDRA_RENDER_PT_volume_final,
+    STORM_HYDRA_RENDER_PT_film_final,
     STORM_HYDRA_RENDER_PT_viewport,
     STORM_HYDRA_RENDER_PT_volume_viewport,
+    STORM_HYDRA_RENDER_PT_film_viewport,
+
 
     STORM_HYDRA_LIGHT_PT_light,
 ))