Opt-in-Per-Camera Pointlight and Spotlight Shadow Maps by kfc35 · Pull Request #24625 · bevyengine/bevy

kfc35 · 2026-06-14T15:50:32Z

Objective

Fixes Multi-Camera (Per Camera) Shadow Maps #23978
Unblocks Fix: Support RenderLayers filtering for Lights (Adoption of #23265) #23925
The PR description of Render point and spot light shadow maps only once, regardless of the number of cameras. #23713 mentions:

A future patch may want to add flags to cameras that specify that they should have their own point light and spot light shadow maps that inherit the render layer (and HLOD) behavior of their associated cameras. As this patch is fairly large, though, and because my immediate goal is to fix the regression in #23481, I think those flags are best implemented in a follow-up.

This is intended to be that follow-up if I understood the intention correctly 😅
This idea has also floated around on Discord, with an emphasis on this being configurable, so I preserved that desire in this PR.

Solution

A new property, has_own_shadow_maps, has been added to Camera. By default, this is set to false, preserving existing behavior.

If a camera requests its own shadow maps, new depth attachments and ShadowViews are created for these additional views in prepare_lights in light.rs, which is where the meat of this PR is. prepare_lights also manages what happens if the light itself changes or the views that opt in change. There’s also an added optimization that if all the cameras request their own shadow maps, the view-agnostic pointlight/spotlight shadow map is removed/not created.

The shader code changes are to ensure the new shadow maps are actually being used. Two new indices offset, point_spot_shadow_map_index_mult_offset and …_add_offset, are used to correctly index into the correct shadow maps. A lot of the wgsl code changes are to refactor a variable from light_id to array_index, as this more accurately describes its use and it matches the corresponding shadow sampling code for spotlight shadows. (actively soliciting for less verbose names 😆 )

Testing

For correctness:
cargo run --example testbed_3d --features=“area_light_luts” -- renderlayers
I tested with the render_layers (with the changes I put in for the light to be on the 3 render layers). It works as expected now!
I tested both a PointLight and a SpotLight (have to change the Spotlight transform to add a looking_at: Transform::from_xyz(4.0, 8.0, 4.0).looking_at(Vec3::new(3.0, 0.5, 0.0), Vec3::Y)))

I’ll probably run the bevy example runner against this PR to ensure there are no correctness regressions otherwise.

I have not done any performance testing (nor know if it’s necesssary). I don’t know if there is a performance regression in the regular “no camera has their own shadow map” case or if we should be concerned about that. If someone can help with this, I’d be indebted.

Showcase

The render layers scene in the 3d testbed with a PointLight now after the changes in this PR:

The same scene with a SpotLight instead described above in Testing:

kfc35 · 2026-06-14T20:22:03Z

Hm there appears to an issue with rendering when there are multiple PointLights since my index math is messed up on the shader code side. Will figure it out

kfc35 · 2026-06-15T21:09:39Z

I addressed the fog issues reported from the initial example runner with e9f8e87 and fixed the lighting/free_camera_controller/ multi pointlight issue with cf1ab11

So this should be ready for review finally!

…adow_maps

pcwalton · 2026-06-25T05:36:57Z

Awesome! I’ll review this shortly.

pcwalton

Partial review only—I’ll have to finish this tomorrow—but this is really awesome and fiddly work. Thank you for doing it! It really makes our story around shadow maps a lot better.

pcwalton · 2026-06-25T05:37:47Z

+    /// will generate 6 additional shadow maps per camera that opts to have its own shadow maps.
+    ///
+    /// Defaults to `false`.
+    pub has_own_shadow_maps: bool,


has_own_point_and_spot_light_shadow_maps might be better, if verbose, since views always have own directional shadow maps.

pcwalton · 2026-06-25T05:40:00Z

    pub mip_bias: f32,
    pub frame_count: u32,
+    /// This offset is used to fetch the correct point or spot shadow map to use for this view.
+    /// This is used to accommodates views that may be configured to have their own point or spot shadow maps.


typo: should be “to accommodate”

pcwalton · 2026-06-25T05:40:21Z

+    /// This must be multiplied to the initial index.
+    pub point_spot_shadow_map_index_mult_offset: u32,
+    /// This offset is used to fetch the correct point or spot shadow map to use for this view.
+    /// This is used to accommodates views that may be configured to have their own point or spot shadow maps.


Same typo as above

pcwalton · 2026-06-25T05:40:52Z

+    /// This is used to accommodates views that may be configured to have their own point or spot shadow maps.
+    /// This represents the additive index of the point/spot shadow map that this view should use.
+    /// This must be added to the index after the multiplicative offset has been applied.
+    pub point_spot_shadow_map_index_add_offset: u32,


I think I’d prefer calling this something like point_spot_shadow_map_index.

pcwalton · 2026-06-25T05:41:11Z

+    /// This represents the total number of shadow maps (not counting shadow maps of different face indices)
+    /// that have been generated to be utilized by all possible views.
+    /// This must be multiplied to the initial index.
+    pub point_spot_shadow_map_index_mult_offset: u32,


I think I’d prefer calling this something like point_spot_shadow_map_count.

pcwalton · 2026-06-25T05:44:10Z

+#[derive(Component)]
+pub struct SpotLightShadowViewEntity {
+    /// The spotlight shadow view associated with a camera that has opted
+    /// in to its own shadow maps.


Same comment above.

pcwalton · 2026-06-25T05:44:52Z

+            Some((entity, MainEntity::from(main_entity)))
+        })
+        .collect();
+    if views_count - point_spot_shadow_aux_entities.len() > 0 {


Suggested change

if views_count - point_spot_shadow_aux_entities.len() > 0 {

if views_count > point_spot_shadow_aux_entities.len() {

pcwalton · 2026-06-25T05:48:55Z

+                let insert_shadow_map = match auxiliary_entity {
+                    Some((entity, _)) => point_and_spot_light_view_entities.1.get(entity).is_none(),
+                    None => point_and_spot_light_view_entities.0.is_empty(),
+                };


Suggested change

let insert_shadow_map = match auxiliary_entity {

Some((entity, _)) => point_and_spot_light_view_entities.1.get(entity).is_none(),

None => point_and_spot_light_view_entities.0.is_empty(),

};

match auxiliary_entity {

Some((entity, _)) => {

if point_and_spot_light_view_entities.1.get(entity).is_some() {

continue;

}

}

None => {

if !point_and_spot_light_view_entities.0.is_empty() {

continue;

}

}

}

And then remove the if insert_shadow_map check below, eliminating some rightward drift.

pcwalton · 2026-06-25T05:49:35Z

        maybe_layers,
        no_indirect_drawing,
        maybe_ambient_override,
+        _extracted_camera,


Remove the _ here since the variable is now used.

pcwalton · 2026-06-25T05:49:55Z

-/// Creates six point shadow maps for a `RetainedViewEntity` identified by the `light_main_entity`
-/// and the six cube face rotation indices. These shadow maps are shared across
-/// all cameras.
+/// Creates six point shadow map for a `RetainedViewEntity` identified by the `light_main_entity`,


Suggested change

/// Creates six point shadow map for a `RetainedViewEntity` identified by the `light_main_entity`,

/// Creates six point shadow maps for a `RetainedViewEntity` identified by the `light_main_entity`,

kfc35 added 17 commits June 14, 2026 01:47

Add flag to Camera for its own shadow maps

176b3ee

wip: additional point and spot light shadow maps per opt-in view

df77727

point lights are fixed! testbed 3d render layers looks good

d3bd801

refactor: create_point_shadow_maps function extracted

0c40e77

finish impl for point light shadow maps

9d48c13

simplify some logic

975df5a

refactor: separate out create spot light shadow map into fn

8c5a50b

include spot shadow views in gpu preprocess

219bf58

add spot light to shadow pass code

0acefb4

finish impl for prepare spot light shadow maps

335a132

use correct index for spot shadows

d01ff65

refactor: light_index -> array_index

63fc417

more words for has_own_shadow_maps doc comment

979ede1

Fix 3d render layers testbed

e877e17

remove println statements

c6ea45d

clean up additional shadow maps if light does not have them enabled

34ccba8

add comment on potentially confusing code in prepare_view_uniforms

692cf82

kfc35 added C-Feature A new feature, making something new possible A-Rendering Drawing game state to the screen D-Complex Quite challenging from either a design or technical perspective. Ask for help! S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Jun 14, 2026

kfc35 requested a review from pcwalton June 14, 2026 15:50

github-project-automation Bot added this to Rendering Jun 14, 2026

github-project-automation Bot moved this to Needs SME Triage in Rendering Jun 14, 2026

kfc35 requested a review from tychedelia June 14, 2026 15:50

kfc35 added the M-Deliberate-Rendering-Change An intentional change to how tests and examples are rendered label Jun 14, 2026

fmt

57c7b8d

kfc35 changed the title ~~Per-Camera Pointlight and Spotlight Shadow Maps~~ Opt-in Per-Camera Pointlight and Spotlight Shadow Maps Jun 14, 2026

kfc35 changed the title ~~Opt-in Per-Camera Pointlight and Spotlight Shadow Maps~~ Opt-in-Per-Camera Pointlight and Spotlight Shadow Maps Jun 14, 2026

lint

89ced9c

clippy

6c2da6b

github-actions Bot mentioned this pull request Jun 14, 2026

24625 bevyengine/bevy-example-runner#239

Closed

fix volumetric fog

e9f8e87

kfc35 marked this pull request as draft June 14, 2026 20:22

kfc35 added 2 commits June 14, 2026 18:01

wip: fix wgsl indexing of point and spot shadow maps

c84d702

fix removal bug in light.rs

40c1ba5

kfc35 added S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged and removed S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Jun 14, 2026

ensure limits to shadow maps are respected

ad3d74b

kfc35 force-pushed the 23978_per_camera_shadow_maps branch from 3d1be2a to ad3d74b Compare June 15, 2026 00:43

kfc35 added 3 commits June 14, 2026 20:45

clippy

57090ff

readjust depth_or_array_layers

793914f

fix usage of depth attachment hash maps

cf1ab11

kfc35 marked this pull request as ready for review June 15, 2026 20:34

kfc35 added S-Needs-Review Needs reviewer attention (from anyone!) to move forward and removed S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged labels Jun 15, 2026

github-actions Bot mentioned this pull request Jun 15, 2026

24625 bevyengine/bevy-example-runner#240

Closed

kfc35 added 3 commits June 17, 2026 09:54

Merge branch 'main' of github.com:kfc35/bevy into 23978_per_camera_sh…

9135a89

…adow_maps

fix clippy

881db76

remove unnecessary newline

9703056

pcwalton reviewed Jun 25, 2026

View reviewed changes

	if views_count - point_spot_shadow_aux_entities.len() > 0 {
	if views_count > point_spot_shadow_aux_entities.len() {

-                let insert_shadow_map = match auxiliary_entity {
-                    Some((entity, _)) => point_and_spot_light_view_entities.1.get(entity).is_none(),
-                    None => point_and_spot_light_view_entities.0.is_empty(),
-                };
+                match auxiliary_entity {
+                    Some((entity, _)) => {
+                        if point_and_spot_light_view_entities.1.get(entity).is_some() {
+                            continue;
+                        }
+                    }
+                    None => {
+                        if !point_and_spot_light_view_entities.0.is_empty() {
+                            continue;
+                        }
+                    }
+                }

	/// Creates six point shadow map for a `RetainedViewEntity` identified by the `light_main_entity`,
	/// Creates six point shadow maps for a `RetainedViewEntity` identified by the `light_main_entity`,

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kfc35 commented Jun 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Objective

Solution

Testing

Showcase

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kfc35 commented Jun 15, 2026

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pcwalton commented Jun 25, 2026

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kfc35 commented Jun 14, 2026 •

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kfc35 commented Jun 14, 2026 •

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