Add Sky Rendering Events by lowercasebtw · Pull Request #5328 · FabricMC/fabric-api

lowercasebtw · 2026-04-15T00:04:14Z

This will be my first contribution to Fabric API. Had to rework some events from my original to work w/ fabric-api's ecosystem and how it handles events.

Events for each portion of the sky rendering, with corresponding important data accessible during those phases. Allowing cancelling of rendering such as the stars/sun/moon.

Also adds a custom element even in which although unused by FAPI, is intended for mod developers to invoke when adding custom elements to the sky when rendering allowing other mods to intercept them and do as please.

Progress:
Everything is implemented, only needs testing & javadoc work now.

…g what it is and from what mod

CallMeEchoCodes · 2026-04-26T05:39:26Z

Seems good to me, but I think it might be useful to add an extraction callback like LevelRenderEvents has. I'd also probably pass CameraRenderState to the SkyRenderContext.

lowercasebtw · 2026-04-30T01:41:19Z

Seems good to me, but I think it might be useful to add an extraction callback like LevelRenderEvents has. I'd also probably pass CameraRenderState to the SkyRenderContext.

Done

CallMeEchoCodes

LGTM, Although unsure about impl details with extraction

CallMeEchoCodes · 2026-04-30T12:54:01Z

 	private void setupContext(ClientLevel level, float partialTicks, Camera camera, SkyRenderState skyRenderState, CallbackInfo ci) {
-		celestialContext.prepare((SkyRenderer) (Object) this, skyRenderState);
+		final CameraRenderState cameraRenderState = new CameraRenderState();
+		camera.extractRenderState(cameraRenderState, partialTicks);


Iffy on extracting the camera a second time (although I don't think it will cause any issues)

Is there some way to pass this down properly?

At a glance it should be possible to put a ScopedValue or ThreadLocal in LevelRenderer::addSkyPass, I'd probably wrap that whole method and add a ScopedValue with the CameraRenderState

Still approved as this can be changed later without breaking api

This code is in SkyRenderer, how would you want me to pass it there?

I don't think this needs to be here. This would be easier LevelRendererMixin. Also, SkyRenderContext could extend AbstractLevelRenderContext, and then you only need to provide skyRenderer. This also means that we don't need a SkyRenderContextImpl and instead just add it to the existing LevelRenderContextImpl.

So basically, add skyRenderer to LevelRenderContextImpl, make it implement SkyRenderContext extends AbstractLevelRenderContext, and set levelRenderContext.skyRenderer in beforeRender.

modmuss50

Needs a testmod as well. This may be a good canidate for auto client tests.

Im not the best at saying if these events are what we need or not, hopefully someone more familar with rendering can chime in.

modmuss50 · 2026-05-03T21:27:40Z

+
+	@Inject(method = "extractRenderState", at = @At("TAIL"))
+	private void afterExtractSky(ClientLevel level, float partialTicks, Camera camera, SkyRenderState state, CallbackInfo ci) {
+		SkyRenderEvents.END_EXTRACTION.invoker().execute(new SkyExtractionContextImpl(level, camera, state, partialTicks));


Should they be "render" events if they happen during extraction?

The LevelRenderEvents has END_EXTRACTION so I matched that

modmuss50 · 2026-05-03T21:28:53Z

+			final boolean cancelled = SkyRenderEvents.PRE_SKY.invoker().execute(skyRenderContext);
+			if (!cancelled) {


Doesnt build, wont pass checkstyle (and many other places)

checkstyle?

modmuss50 · 2026-05-03T21:28:59Z

+@ApiStatus.NonExtendable
+public interface CelestialRenderContext extends SkyRenderContext {


Needs docs.

Will do sometime soon

modmuss50 · 2026-05-03T21:34:23Z

 java.lang.NullPointerException: Cannot invoke "net.fabricmc.fabric.impl.client.rendering.level.LevelExtractionContextImpl.prepare(net.minecraft.client.renderer.GameRenderer, net.minecraft.client.renderer.LevelRenderer, net.minecraft.client.renderer.state.level.LevelRenderState, net.minecraft.client.multiplayer.ClientLevel, net.minecraft.client.DeltaTracker, net.minecraft.client.Camera)" because "this.extractionContext" is null

Client crashes as well.

lowercasebtw · 2026-05-03T21:44:03Z

 java.lang.NullPointerException: Cannot invoke "net.fabricmc.fabric.impl.client.rendering.level.LevelExtractionContextImpl.prepare(net.minecraft.client.renderer.GameRenderer, net.minecraft.client.renderer.LevelRenderer, net.minecraft.client.renderer.state.level.LevelRenderState, net.minecraft.client.multiplayer.ClientLevel, net.minecraft.client.DeltaTracker, net.minecraft.client.Camera)" because "this.extractionContext" is null

Client crashes as well.

Hmm will check out

kevinthegreat1

While I don't think many of the events are needed, we are still discussing that. Meanwhile, I have commented on some implementation things that I think should be done regardless of which approach we take in the end.

kevinthegreat1 · 2026-05-04T04:51:57Z

 	private void setupContext(ClientLevel level, float partialTicks, Camera camera, SkyRenderState skyRenderState, CallbackInfo ci) {
-		celestialContext.prepare((SkyRenderer) (Object) this, skyRenderState);
+		final CameraRenderState cameraRenderState = new CameraRenderState();
+		camera.extractRenderState(cameraRenderState, partialTicks);


I don't think this needs to be here. This would be easier LevelRendererMixin. Also, SkyRenderContext could extend AbstractLevelRenderContext, and then you only need to provide skyRenderer. This also means that we don't need a SkyRenderContextImpl and instead just add it to the existing LevelRenderContextImpl.

So basically, add skyRenderer to LevelRenderContextImpl, make it implement SkyRenderContext extends AbstractLevelRenderContext, and set levelRenderContext.skyRenderer in beforeRender.

kevinthegreat1 · 2026-05-04T04:56:45Z

+	 * <p>To attach modded data to vanilla render states, see {@link net.fabricmc.fabric.api.client.rendering.v1.FabricRenderState FabricRenderState}.
+	 * Only attach the minimum data needed for rendering. Do not attach objects that are not thread-safe such as {@link net.minecraft.client.multiplayer.ClientLevel}.
+	 */
+	public static final Event<EndExtraction> END_EXTRACTION = EventFactory.createArrayBacked(EndExtraction.class, callbacks -> context -> {


This is not needed, use LevelRenderEvents.END_EXTRACTION instead. We intentionally only added one extraction event.

FlashyReese

I think this is a good direction. Proper sky render events would be useful for mods that modify vanilla sky rendering and mods that fully replace or layer custom skies.

My main concern is that the API currently feels split between vanilla sky element interception and a broader custom sky render hook. For full custom sky renderers, the important part is having one clear sky render phase with documented render-state guarantees, otherwise mods may still need their own LevelRenderer/SkyRenderer mixins.

The things I think should be clarified before this becomes API:

should cancellable PRE events still call every listener before returning the final cancel result?
should all sky events share one context source/lifecycle?
what render state is guaranteed during PRE_SKY?
should PRE_CUSTOM_ELEMENT / POST_CUSTOM_ELEMENT be typed, or left out for now?

I am mostly looking at this from the perspective of custom sky rendering where mods need to stack or replace skies, not only cancel vanilla sun/moon/stars.

FlashyReese · 2026-06-14T18:47:58Z

+	 */
+	public static final Event<PreSky> PRE_SKY = EventFactory.createArrayBacked(PreSky.class, callbacks -> context -> {
+		for (final PreSky callback : callbacks) {
+			if (callback.execute(context)) {


Should this call every callback and OR the cancellation result instead of returning immediately?

If one mod cancels here, later listeners never see the event at all. That seems rough for compatibility between multiple sky mods.

FlashyReese · 2026-06-14T18:48:51Z

+import net.minecraft.client.renderer.state.level.SkyRenderState;
+
+@ApiStatus.NonExtendable
+public interface SkyRenderContext {


Should this extend AbstractLevelRenderContext?

Sky rendering is still part of the level render frame, so access to levelRenderer/gameRenderer/levelState seems useful and keeps this consistent with the rest of the rendering API.

FlashyReese · 2026-06-14T18:49:28Z

+	/**
+	 * Called at the start of the "addSkyPass" lambda.
+	 */
+	public static final Event<PreSky> PRE_SKY = EventFactory.createArrayBacked(PreSky.class, callbacks -> context -> {


This seems like the event custom sky renderers would depend on the most.

Can the javadocs define what render state is guaranteed here? Mainly fog state, matrix/projection expectations, and whether returning true skips all vanilla sky rendering.

FlashyReese · 2026-06-14T18:55:23Z

+
+	@FunctionalInterface
+	public interface PreCustomElement {
+		boolean execute(Identifier key, Object context);


I am not sure about Object context here.

If Fabric does not invoke this itself and the context is untyped, it seems hard for mods to rely on. I think this should either be typed more strongly or left out for now.

W.I.P: Add sky rendering events for each part of the sky

b797d63

sylv256 added enhancement New feature or request area: rendering labels Apr 15, 2026

lowercasebtw added 9 commits April 14, 2026 19:10

Refactor events

b87ed55

Fix event ancestry

7af7c63

Add pre/post events

429df8a

Remove AbstractSkyInjectionContext

f02f2b4

Add SkyRenderContextImpl

d060467

Add Pre/Post Custom Element events

be794fd

Add identifier key field to custom element events to allow determinin…

cf6ac67

…g what it is and from what mod

Add mixins & Refactor classes

11209ec

Move shadow field

70ee75b

HerrChaos reviewed Apr 15, 2026

View reviewed changes

Comment thread ...1/src/client/java/net/fabricmc/fabric/api/client/rendering/v1/level/sky/SkyRenderEvents.java

HerrChaos reviewed Apr 15, 2026

View reviewed changes

Comment thread ...1/src/client/java/net/fabricmc/fabric/api/client/rendering/v1/level/sky/SkyRenderEvents.java

lowercasebtw and others added 3 commits April 15, 2026 10:36

Fix javadoc mistake

3c8e2ad

Merge branch '26.1.2' into 26.1.2

8605aae

Add pre/post sky render events

b2136dc

lowercasebtw marked this pull request as ready for review April 15, 2026 19:39

lowercasebtw changed the title ~~DRAFT: Add Sky Rendering Events~~ Add Sky Rendering Events Apr 15, 2026

Merge branch '26.1.2' into 26.1.2

7c95451

CelDaemon reviewed Apr 17, 2026

View reviewed changes

Comment thread ...dering-v1/src/client/java/net/fabricmc/fabric/mixin/client/rendering/LevelRendererMixin.java Outdated

lowercasebtw and others added 3 commits April 29, 2026 21:23

Merge branch '26.1.2' into 26.1.2

bbd8849

Add cameraRenderState & END_EXTRACTION event

ed7d537

Only invoke POST events if the PRE was not cancelled

79f2a88

CallMeEchoCodes approved these changes Apr 30, 2026

View reviewed changes

LlamaLad7 reviewed Apr 30, 2026

View reviewed changes

Comment thread ...dering-v1/src/client/java/net/fabricmc/fabric/mixin/client/rendering/LevelRendererMixin.java Outdated

LlamaLad7 reviewed Apr 30, 2026

View reviewed changes

Comment thread ...dering-v1/src/client/java/net/fabricmc/fabric/mixin/client/rendering/LevelRendererMixin.java Outdated

Apply requested changes

50306fe

modmuss50 requested review from PepperCode1 and kevinthegreat1 May 3, 2026 21:26

modmuss50 requested changes May 3, 2026

View reviewed changes

lowercasebtw added 2 commits May 3, 2026 22:43

Refactors

909da98

Pass down cancelled status

5796f86

kevinthegreat1 suggested changes May 4, 2026

View reviewed changes

FlashyReese reviewed Jun 14, 2026

View reviewed changes

		final boolean cancelled = SkyRenderEvents.PRE_SKY.invoker().execute(skyRenderContext);
		if (!cancelled) {

		@ApiStatus.NonExtendable
		public interface CelestialRenderContext extends SkyRenderContext {

Conversation

lowercasebtw commented Apr 15, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

CallMeEchoCodes commented Apr 26, 2026

Uh oh!

lowercasebtw commented Apr 30, 2026

Uh oh!

CallMeEchoCodes left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

CallMeEchoCodes Apr 30, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

modmuss50 left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

modmuss50 commented May 3, 2026

Uh oh!

lowercasebtw commented May 3, 2026

Uh oh!

kevinthegreat1 left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

FlashyReese left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

9 participants

lowercasebtw commented Apr 15, 2026 •

edited

Loading

CallMeEchoCodes Apr 30, 2026 •

edited

Loading

modmuss50 left a comment •

edited

Loading