transparent roughness and diffuse settings from app

src/app_data.rs

@@ -60,6 +60,9 @@ pub struct AppData {
     pub topology: vk::PrimitiveTopology,
 
     pub scene_rt_memory_size: u64,
+    // values passed to shader
     pub num_lights_per_volume: u32,
     pub max_iterations_per_light: u32,
+    pub diffuse_raster_steps: u32,
+    pub diffuse_raster_size: f32,
 }