Expose image opacity component (#6635)

### What

Image opacity (for layering images) is now an exposed component that can
be set from blueprint & data store.

Heuristic for opacity is a lot simplified:
* stacked images will no longer be made transparent in general
* only segmentation image will use 0.5 opacity as a fallback if there is
any other image in the scene
Demonstrated here:


https://github.com/rerun-io/rerun/assets/1220815/8b133062-01cf-4bca-bfdc-1cec8c1457ae



---

* prerequisite for #6548 
* almost solves #2192


### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6635?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6635?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/6635)
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

To run all checks from `main`, comment on the PR with `@rerun-bot
full-check`.

crates/re_edit_ui/src/datatype_editors/float_drag.rs

@@ -2,7 +2,7 @@ use egui::NumExt as _;
 use re_types::datatypes;
 
 /// Generic editor for a [`re_types::datatypes::Float32`] value from zero to max float.
-pub fn edit_f32_zero_to_max_float(
+pub fn edit_f32_zero_to_max(
     _ctx: &re_viewer_context::ViewerContext<'_>,
     ui: &mut egui::Ui,
     value: &mut impl std::ops::DerefMut<Target = datatypes::Float32>,
@@ -19,12 +19,34 @@ pub fn edit_f32_zero_to_max_float_raw(
     edit_f32_zero_to_max_float_raw_impl(ui, value)
 }
 
-/// Non monomorphized implementation of [`edit_f32_zero_to_max_float`].
+/// Non monomorphized implementation of [`edit_f32_zero_to_max_float_raw`].
 fn edit_f32_zero_to_max_float_raw_impl(ui: &mut egui::Ui, value: &mut f32) -> egui::Response {
     let speed = (*value * 0.01).at_least(0.001);
     ui.add(
         egui::DragValue::new(value)
-            .clamp_range(0.0..=f32::MAX)
+            .clamp_range(0.0..=f32::MAX) // TODO(#6633): Don't change incoming values
             .speed(speed),
     )
 }
+
+/// Generic editor for a [`re_types::datatypes::Float32`] value from zero to one float.
+pub fn edit_f32_zero_to_one(
+    _ctx: &re_viewer_context::ViewerContext<'_>,
+    ui: &mut egui::Ui,
+    value: &mut impl std::ops::DerefMut<Target = datatypes::Float32>,
+) -> egui::Response {
+    edit_f32_zero_to_one_raw(ui, &mut value.deref_mut().0)
+}
+
+/// Non monomorphized implementation of [`edit_f32_zero_to_one`].
+fn edit_f32_zero_to_one_raw(ui: &mut egui::Ui, value: &mut f32) -> egui::Response {
+    // TODO(#6633): Pre-clamp the value, so the ui won't change the value if there's no interaction.
+    // This means we won't see the real value in the ui if it's outside the range.
+    *value = value.clamp(0.0, 1.0);
+    ui.add(
+        egui::DragValue::new(value)
+            .clamp_range(0.0..=1.0)
+            .speed(0.005)
+            .fixed_decimals(2),
+    )
+}

crates/re_edit_ui/src/datatype_editors/mod.rs

@@ -5,5 +5,5 @@ mod singleline_string;
 
 pub use bool_toggle::{edit_bool, edit_bool_raw};
 pub use enum_combobox::edit_enum;
-pub use float_drag::{edit_f32_zero_to_max_float, edit_f32_zero_to_max_float_raw};
+pub use float_drag::{edit_f32_zero_to_max, edit_f32_zero_to_max_float_raw, edit_f32_zero_to_one};
 pub use singleline_string::edit_singleline_string;

crates/re_edit_ui/src/lib.rs

@@ -10,14 +10,15 @@ mod response_utils;
 mod visual_bounds2d;
 
 use datatype_editors::{
-    edit_bool, edit_bool_raw, edit_enum, edit_f32_zero_to_max_float,
-    edit_f32_zero_to_max_float_raw, edit_singleline_string,
+    edit_bool, edit_bool_raw, edit_enum, edit_f32_zero_to_max, edit_f32_zero_to_max_float_raw,
+    edit_f32_zero_to_one, edit_singleline_string,
 };
 use re_types::{
     blueprint::components::{BackgroundKind, Corner2D, LockRangeDuringZoom, ViewFit, Visible},
     components::{
         AggregationPolicy, AxisLength, Color, Colormap, DepthMeter, FillRatio, GammaCorrection,
-        ImagePlaneDistance, MagnificationFilter, MarkerSize, Name, Radius, StrokeWidth, Text,
+        ImagePlaneDistance, MagnificationFilter, MarkerSize, Name, Opacity, Radius, StrokeWidth,
+        Text,
     },
 };
 use re_viewer_context::ViewerContext;
@@ -48,22 +49,24 @@ pub fn register_editors(registry: &mut re_viewer_context::ComponentUiRegistry) {
     registry.add_singleline_editor_ui(marker_shape::edit_marker_shape_ui);
     registry.add_singleline_editor_ui(range1d::edit_range1d);
 
-    registry.add_singleline_editor_ui::<AxisLength>(edit_f32_zero_to_max_float);
-    registry.add_singleline_editor_ui::<FillRatio>(edit_f32_zero_to_max_float);
-    registry.add_singleline_editor_ui::<ImagePlaneDistance>(edit_f32_zero_to_max_float);
-    registry.add_singleline_editor_ui::<GammaCorrection>(edit_f32_zero_to_max_float);
+    registry.add_singleline_editor_ui::<AxisLength>(edit_f32_zero_to_max);
+    registry.add_singleline_editor_ui::<FillRatio>(edit_f32_zero_to_max);
+    registry.add_singleline_editor_ui::<ImagePlaneDistance>(edit_f32_zero_to_max);
+    registry.add_singleline_editor_ui::<GammaCorrection>(edit_f32_zero_to_max);
+
+    registry.add_singleline_editor_ui::<DepthMeter>(edit_f32_zero_to_max_float_raw);
+    registry.add_singleline_editor_ui::<MarkerSize>(edit_f32_zero_to_max_float_raw);
+    registry.add_singleline_editor_ui::<Radius>(edit_f32_zero_to_max_float_raw);
+    registry.add_singleline_editor_ui::<StrokeWidth>(edit_f32_zero_to_max_float_raw);
+
+    registry.add_singleline_editor_ui::<Opacity>(edit_f32_zero_to_one);
 
     registry.add_singleline_editor_ui::<Visible>(edit_bool_raw);
     registry.add_singleline_editor_ui::<LockRangeDuringZoom>(edit_bool);
 
     registry.add_singleline_editor_ui::<Text>(edit_singleline_string);
     registry.add_singleline_editor_ui::<Name>(edit_singleline_string);
 
-    registry.add_singleline_editor_ui::<DepthMeter>(edit_f32_zero_to_max_float_raw);
-    registry.add_singleline_editor_ui::<MarkerSize>(edit_f32_zero_to_max_float_raw);
-    registry.add_singleline_editor_ui::<Radius>(edit_f32_zero_to_max_float_raw);
-    registry.add_singleline_editor_ui::<StrokeWidth>(edit_f32_zero_to_max_float_raw);
-
     registry.add_singleline_editor_ui(|_ctx, ui, value| edit_enum::<BackgroundKind>(ui, value));
     registry.add_singleline_editor_ui(|_ctx, ui, value| edit_enum::<Colormap>(ui, value));
     registry.add_singleline_editor_ui(|_ctx, ui, value| edit_enum::<Corner2D>(ui, value));

crates/re_space_view_spatial/src/ui.rs

@@ -25,13 +25,13 @@ use re_viewer_context::{
 };
 use re_viewport_blueprint::SpaceViewBlueprint;
 
-use crate::scene_bounding_boxes::SceneBoundingBoxes;
 use crate::{
     contexts::AnnotationSceneContext,
     picking::{PickableUiRect, PickingContext, PickingHitType, PickingResult},
     view_kind::SpatialSpaceViewKind,
     visualizers::{CamerasVisualizer, ImageVisualizer, UiLabel, UiLabelTarget},
 };
+use crate::{contexts::PrimitiveCounter, scene_bounding_boxes::SceneBoundingBoxes};
 use crate::{eye::EyeMode, heuristics::auto_size_world_heuristic};
 
 use super::{eye::Eye, ui_3d::View3DState};
@@ -67,6 +67,9 @@ pub struct SpatialSpaceViewState {
     /// Estimated number of primitives last frame. Used to inform some heuristics.
     pub scene_num_primitives: usize,
 
+    /// Number of images & depth images processed last frame.
+    pub num_non_segmentation_images_last_frame: usize,
+
     /// Last frame's picking result.
     pub previous_picking_result: Option<PickingResult>,
 
@@ -90,6 +93,32 @@ impl SpaceViewState for SpatialSpaceViewState {
 }
 
 impl SpatialSpaceViewState {
+    /// Updates the state with statistics from the latest system outputs.
+    pub fn update_frame_statistics(
+        &mut self,
+        system_output: &re_viewer_context::SystemExecutionOutput,
+    ) -> Result<(), SpaceViewSystemExecutionError> {
+        re_tracing::profile_function!();
+
+        self.bounding_boxes.update(&system_output.view_systems);
+
+        self.scene_num_primitives = system_output
+            .context_systems
+            .get::<PrimitiveCounter>()?
+            .num_primitives
+            .load(std::sync::atomic::Ordering::Relaxed);
+
+        self.num_non_segmentation_images_last_frame = system_output
+            .view_systems
+            .get::<ImageVisualizer>()?
+            .images
+            .iter()
+            .filter(|i| i.meaning != TensorDataMeaning::ClassId)
+            .count();
+
+        Ok(())
+    }
+
     pub fn auto_size_config(&self) -> re_renderer::AutoSizeConfig {
         let mut config = self.auto_size_config;
         if config.point_radius.is_auto() {

crates/re_space_view_spatial/src/view_2d.rs

@@ -18,7 +18,7 @@ use re_viewer_context::{
 };
 
 use crate::{
-    contexts::{register_spatial_contexts, PrimitiveCounter},
+    contexts::register_spatial_contexts,
     heuristics::default_visualized_entities_for_visualizer_kind,
     max_image_dimension_subscriber::{ImageDimensions, MaxImageDimensions},
     spatial_topology::{SpatialTopology, SubSpaceConnectionFlags},
@@ -249,12 +249,7 @@ impl SpaceViewClass for SpatialSpaceView2D {
         re_tracing::profile_function!();
 
         let state = state.downcast_mut::<SpatialSpaceViewState>()?;
-        state.bounding_boxes.update(&system_output.view_systems);
-        state.scene_num_primitives = system_output
-            .context_systems
-            .get::<PrimitiveCounter>()?
-            .num_primitives
-            .load(std::sync::atomic::Ordering::Relaxed);
+        state.update_frame_statistics(&system_output)?;
 
         self.view_2d(ctx, ui, state, query, system_output)
     }

crates/re_space_view_spatial/src/view_3d.rs

@@ -21,7 +21,7 @@ use re_viewer_context::{
 
 use crate::visualizers::{CamerasVisualizer, Transform3DArrowsVisualizer, Transform3DDetector};
 use crate::{
-    contexts::{register_spatial_contexts, PrimitiveCounter},
+    contexts::register_spatial_contexts,
     heuristics::default_visualized_entities_for_visualizer_kind,
     spatial_topology::{HeuristicHints, SpatialTopology, SubSpaceConnectionFlags},
     ui::{format_vector, SpatialSpaceViewState},
@@ -429,13 +429,7 @@ impl SpaceViewClass for SpatialSpaceView3D {
         re_tracing::profile_function!();
 
         let state = state.downcast_mut::<SpatialSpaceViewState>()?;
-
-        state.bounding_boxes.update(&system_output.view_systems);
-        state.scene_num_primitives = system_output
-            .context_systems
-            .get::<PrimitiveCounter>()?
-            .num_primitives
-            .load(std::sync::atomic::Ordering::Relaxed);
+        state.update_frame_statistics(&system_output)?;
 
         self.view_3d(ctx, ui, state, query, system_output)
     }