Restore ability to enable stenciling

patches/com/mojang/blaze3d/pipeline/MainTarget.java.patch

@@ -0,0 +1,42 @@
+--- a/com/mojang/blaze3d/pipeline/MainTarget.java
++++ b/com/mojang/blaze3d/pipeline/MainTarget.java
+@@ -16,7 +_,10 @@
+     static final MainTarget.Dimension DEFAULT_DIMENSIONS = new MainTarget.Dimension(854, 480);
+
+     public MainTarget(int p_166137_, int p_166138_) {
+-        super(true);
++        this(p_166137_, p_166138_, false);
++    }
++    public MainTarget(int p_166137_, int p_166138_, boolean enableStencil) {
++        super(true, enableStencil);
+         this.createFrameBuffer(p_166137_, p_166138_);
+     }
+
+@@ -37,6 +_,14 @@
+         GlStateManager._texParameter(3553, 10242, 33071);
+         GlStateManager._texParameter(3553, 10243, 33071);
+         GlStateManager._glFramebufferTexture2D(36160, 36096, 3553, this.depthBufferId, 0);
++        if (this.useStencil) {
++            GlStateManager._glFramebufferTexture2D(
++                    org.lwjgl.opengl.GL32.GL_FRAMEBUFFER,
++                    org.lwjgl.opengl.GL32.GL_STENCIL_ATTACHMENT,
++                    org.lwjgl.opengl.GL32.GL_TEXTURE_2D,
++                    this.depthBufferId,
++                    0);
++        }
+         GlStateManager._bindTexture(0);
+         this.viewWidth = maintarget$dimension.width;
+         this.viewHeight = maintarget$dimension.height;
+@@ -82,7 +_,11 @@
+         RenderSystem.assertOnRenderThreadOrInit();
+         GlStateManager._getError();
+         GlStateManager._bindTexture(this.depthBufferId);
+-        GlStateManager._texImage2D(3553, 0, 6402, p_166145_.width, p_166145_.height, 0, 6402, 5126, null);
++        if (!this.useStencil) {
++            GlStateManager._texImage2D(3553, 0, 6402, p_166145_.width, p_166145_.height, 0, 6402, 5126, null);
++        } else {
++            net.neoforged.neoforge.client.ClientHooks.texImageDepthStencil(p_166145_.width, p_166145_.height);
++        }
+         return GlStateManager._getError() != 1285;
+     }
+

patches/com/mojang/blaze3d/pipeline/RenderTarget.java.patch

@@ -0,0 +1,66 @@
+--- a/com/mojang/blaze3d/pipeline/RenderTarget.java
++++ b/com/mojang/blaze3d/pipeline/RenderTarget.java
+@@ -25,6 +_,7 @@
+     public int viewWidth;
+     public int viewHeight;
+     public final boolean useDepth;
++    public final boolean useStencil;
+     public int frameBufferId;
+     protected int colorTextureId;
+     protected int depthBufferId;
+@@ -32,7 +_,15 @@
+     public int filterMode;
+
+     public RenderTarget(boolean p_166199_) {
+-        this.useDepth = p_166199_;
++        this(p_166199_, false);
++    }
++
++    public RenderTarget(boolean useDepth, boolean useStencil) {
++        if (useStencil && !useDepth) {
++            throw new IllegalArgumentException("Stencil can only be enabled if depth is enabled.");
++        }
++        this.useDepth = useDepth;
++        this.useStencil = useStencil;
+         this.frameBufferId = -1;
+         this.colorTextureId = -1;
+         this.depthBufferId = -1;
+@@ -96,7 +_,11 @@
+                 GlStateManager._texParameter(3553, 34892, 0);
+                 GlStateManager._texParameter(3553, 10242, 33071);
+                 GlStateManager._texParameter(3553, 10243, 33071);
+-                GlStateManager._texImage2D(3553, 0, 6402, this.width, this.height, 0, 6402, 5126, null);
++                if (!this.useStencil) {
++                    GlStateManager._texImage2D(3553, 0, 6402, this.width, this.height, 0, 6402, 5126, null);
++                } else {
++                    net.neoforged.neoforge.client.ClientHooks.texImageDepthStencil(this.width, this.height);
++                }
+             }
+
+             this.setFilterMode(9728, true);
+@@ -109,6 +_,14 @@
+             if (this.useDepth) {
+                 GlStateManager._glFramebufferTexture2D(36160, 36096, 3553, this.depthBufferId, 0);
+             }
++            if (this.useStencil) {
++                GlStateManager._glFramebufferTexture2D(
++                    org.lwjgl.opengl.GL32.GL_FRAMEBUFFER,
++                    org.lwjgl.opengl.GL32.GL_STENCIL_ATTACHMENT,
++                    org.lwjgl.opengl.GL32.GL_TEXTURE_2D,
++                    this.depthBufferId,
++                    0);
++            }
+
+             this.checkStatus();
+             this.clear();
+@@ -217,6 +_,10 @@
+         if (this.useDepth) {
+             GlStateManager._clearDepth(1.0);
+             i |= 256;
++        }
++        if (this.useStencil) {
++            GlStateManager._clearStencil(0);
++            i |= org.lwjgl.opengl.GL32.GL_STENCIL_BUFFER_BIT;
+         }
+
+         GlStateManager._clear(i);

patches/com/mojang/blaze3d/pipeline/TextureTarget.java.patch

@@ -0,0 +1,14 @@
+--- a/com/mojang/blaze3d/pipeline/TextureTarget.java
++++ b/com/mojang/blaze3d/pipeline/TextureTarget.java
+@@ -7,7 +_,10 @@
+ @OnlyIn(Dist.CLIENT)
+ public class TextureTarget extends RenderTarget {
+     public TextureTarget(int p_166213_, int p_166214_, boolean p_166215_) {
+-        super(p_166215_);
++        this(p_166213_, p_166214_, p_166215_, false);
++    }
++    public TextureTarget(int p_166213_, int p_166214_, boolean p_166215_, boolean useStencil) {
++        super(p_166215_, useStencil);
+         RenderSystem.assertOnRenderThreadOrInit();
+         this.resize(p_166213_, p_166214_);
+     }

patches/com/mojang/blaze3d/resource/RenderTargetDescriptor.java.patch

@@ -0,0 +1,18 @@
+--- a/com/mojang/blaze3d/resource/RenderTargetDescriptor.java
++++ b/com/mojang/blaze3d/resource/RenderTargetDescriptor.java
+@@ -6,9 +_,13 @@
+ import net.neoforged.api.distmarker.OnlyIn;
+
+ @OnlyIn(Dist.CLIENT)
+-public record RenderTargetDescriptor(int width, int height, boolean useDepth) implements ResourceDescriptor<RenderTarget> {
++public record RenderTargetDescriptor(int width, int height, boolean useDepth, boolean useStencil) implements ResourceDescriptor<RenderTarget> {
++    public RenderTargetDescriptor(int width, int height, boolean useDepth) {
++        this(width, height, useDepth, false);
++    }
++
+     public RenderTarget allocate() {
+-        return new TextureTarget(this.width, this.height, this.useDepth);
++        return new TextureTarget(this.width, this.height, this.useDepth, this.useStencil);
+     }
+
+     public void free(RenderTarget p_363223_) {

patches/net/minecraft/client/Minecraft.java.patch

@@ -8,7 +8,7 @@
          this.demo = p_91084_.game.demo;
          this.allowsMultiplayer = !p_91084_.game.disableMultiplayer;
          this.allowsChat = !p_91084_.game.disableChat;
-@@ -483,15 +_,17 @@
+@@ -483,15 +_,18 @@
              LOGGER.error("Couldn't set icon", (Throwable)ioexception);
          }
 
@@ -18,11 +18,13 @@
          this.keyboardHandler = new KeyboardHandler(this);
 -        this.keyboardHandler.setup(this.window.getWindow());
          RenderSystem.initRenderer(this.options.glDebugVerbosity, false);
-         this.mainRenderTarget = new MainTarget(this.window.getWidth(), this.window.getHeight());
+-        this.mainRenderTarget = new MainTarget(this.window.getWidth(), this.window.getHeight());
++        net.neoforged.neoforge.client.loading.ClientModLoader.begin(this);
++        this.mainRenderTarget = net.neoforged.neoforge.client.ClientHooks.instantiateMainTarget(this.window.getWidth(), this.window.getHeight());
          this.mainRenderTarget.setClearColor(0.0F, 0.0F, 0.0F, 0.0F);
          this.mainRenderTarget.clear();
          this.resourceManager = new ReloadableResourceManager(PackType.CLIENT_RESOURCES);
-+        net.neoforged.neoforge.client.loading.ClientModLoader.begin(this, this.resourcePackRepository, this.resourceManager);
++        net.neoforged.neoforge.client.loading.ClientModLoader.finish(this.resourcePackRepository, this.resourceManager);
 +        //Move client bootstrap to after mod loading so that events can be fired for it.
 +        ClientBootstrap.bootstrap();
          this.resourcePackRepository.reload();

patches/net/minecraft/client/renderer/LevelRenderer.java.patch

@@ -1,5 +1,14 @@
 --- a/net/minecraft/client/renderer/LevelRenderer.java
 +++ b/net/minecraft/client/renderer/LevelRenderer.java
+@@ -459,7 +_,7 @@
+         this.targets.main = framegraphbuilder.importExternal("main", this.minecraft.getMainRenderTarget());
+         int i = this.minecraft.getMainRenderTarget().width;
+         int j = this.minecraft.getMainRenderTarget().height;
+-        RenderTargetDescriptor rendertargetdescriptor = new RenderTargetDescriptor(i, j, true);
++        RenderTargetDescriptor rendertargetdescriptor = new RenderTargetDescriptor(i, j, true, this.minecraft.getMainRenderTarget().useStencil);
+         PostChain postchain = this.getTransparencyChain();
+         if (postchain != null) {
+             this.targets.translucent = framegraphbuilder.createInternal("translucent", rendertargetdescriptor);
 @@ -473,6 +_,9 @@
              this.targets.entityOutline = framegraphbuilder.importExternal("entity_outline", this.entityOutlineTarget);
          }

src/main/java/net/neoforged/neoforge/client/ClientHooks.java

@@ -9,6 +9,8 @@
 import com.google.common.collect.HashBiMap;
 import com.google.common.collect.ImmutableMap;
 import com.mojang.blaze3d.framegraph.FrameGraphBuilder;
+import com.mojang.blaze3d.pipeline.MainTarget;
+import com.mojang.blaze3d.platform.GlStateManager;
 import com.mojang.blaze3d.platform.NativeImage;
 import com.mojang.blaze3d.platform.Window;
 import com.mojang.blaze3d.resource.RenderTargetDescriptor;
@@ -144,6 +146,7 @@
 import net.neoforged.neoforge.client.event.ClientPlayerNetworkEvent;
 import net.neoforged.neoforge.client.event.ClientTickEvent;
 import net.neoforged.neoforge.client.event.ComputeFovModifierEvent;
+import net.neoforged.neoforge.client.event.ConfigureMainRenderTargetEvent;
 import net.neoforged.neoforge.client.event.CustomizeGuiOverlayEvent;
 import net.neoforged.neoforge.client.event.EntityRenderersEvent;
 import net.neoforged.neoforge.client.event.FrameGraphSetupEvent;
@@ -182,6 +185,7 @@
 import net.neoforged.neoforge.client.model.data.ModelData;
 import net.neoforged.neoforge.client.renderstate.RegisterRenderStateModifiersEvent;
 import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.NeoForgeConfig;
 import net.neoforged.neoforge.common.NeoForgeMod;
 import net.neoforged.neoforge.forge.snapshots.ForgeSnapshotsModClient;
 import net.neoforged.neoforge.gametest.GameTestHooks;
@@ -195,6 +199,7 @@
 import org.joml.Matrix4f;
 import org.joml.Vector3f;
 import org.joml.Vector4f;
+import org.lwjgl.opengl.GL32;
 
 /**
  * Class for various client-side-only hooks.
@@ -1099,4 +1104,29 @@ public static Map<ResourceLocation, ResourceLocation> gatherMaterialAtlases(Map<
     public static FrameGraphSetupEvent fireFrameGraphSetup(FrameGraphBuilder builder, LevelTargetBundle targets, RenderTargetDescriptor renderTargetDescriptor, Frustum frustum, Camera camera, Matrix4f modelViewMatrix, Matrix4f projectionMatrix, DeltaTracker deltaTracker, ProfilerFiller profiler) {
         return NeoForge.EVENT_BUS.post(new FrameGraphSetupEvent(builder, targets, renderTargetDescriptor, frustum, camera, modelViewMatrix, projectionMatrix, deltaTracker, profiler));
     }
+
+    @ApiStatus.Internal
+    public static MainTarget instantiateMainTarget(int width, int height) {
+        var e = ModLoader.postEventWithReturn(new ConfigureMainRenderTargetEvent());
+        return new MainTarget(width, height, e.isStencilEnabled());
+    }
+
+    /**
+     * Called by our stencil hooks to specify the depth+stencil texture.
+     */
+    @ApiStatus.Internal
+    public static void texImageDepthStencil(int width, int height) {
+        var reducedPrecision = NeoForgeConfig.CLIENT.reducedDepthStencilFormat.getAsBoolean();
+        GlStateManager._texImage2D(
+                GL32.GL_TEXTURE_2D,
+                0,
+                reducedPrecision ? GL32.GL_DEPTH24_STENCIL8 : GL32.GL_DEPTH32F_STENCIL8,
+                width, height,
+                0,
+                GL32.GL_DEPTH_STENCIL,
+                // Since data is null, the format here does not matter as long as it matches internalFormat.
+                // So the usage, for depth, of unsigned int in one case and float in the other case, is not a problem.
+                reducedPrecision ? GL32.GL_UNSIGNED_INT_24_8 : GL32.GL_FLOAT_32_UNSIGNED_INT_24_8_REV,
+                null);
+    }
 }

src/main/java/net/neoforged/neoforge/client/event/ConfigureMainRenderTargetEvent.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.client.event;
+
+import com.mojang.blaze3d.pipeline.MainTarget;
+import net.neoforged.bus.api.Event;
+import net.neoforged.bus.api.ICancellableEvent;
+import net.neoforged.fml.LogicalSide;
+import net.neoforged.fml.event.IModBusEvent;
+
+/**
+ * Fired when configuring the {@linkplain MainTarget main render target} during startup.
+ * <p>
+ * This event is not {@linkplain ICancellableEvent cancellable}.
+ * <p>
+ * This event is fired on the mod-specific event bus, only on the {@linkplain LogicalSide#CLIENT logical client}.
+ */
+public class ConfigureMainRenderTargetEvent extends Event implements IModBusEvent {
+    private boolean enableStencil;
+
+    /**
+     * Returns whether enabling the stencil buffer on the main render target was requested.
+     *
+     * @return <code>true</code>, if the stencil buffer is enabled, or <code>false</code> otherwise.
+     */
+    public boolean isStencilEnabled() {
+        return this.enableStencil;
+    }
+
+    /**
+     * Enables the stencil buffer for the main render target.
+     */
+    public void enableStencil() {
+        this.enableStencil = true;
+    }
+}

src/main/java/net/neoforged/neoforge/client/loading/ClientModLoader.java

@@ -47,7 +47,7 @@ public class ClientModLoader extends CommonModLoader {
     @Nullable
     private static ModLoadingException error;
 
-    public static void begin(final Minecraft minecraft, final PackRepository defaultResourcePacks, final ReloadableResourceManager mcResourceManager) {
+    public static void begin(final Minecraft minecraft) {
         // force log4j to shutdown logging in a shutdown hook. This is because we disable default shutdown hook so the server properly logs it's shutdown
         Runtime.getRuntime().addShutdownHook(new Thread(LogManager::shutdown));
         ImmediateWindowHandler.updateProgress("Loading mods");
@@ -60,6 +60,9 @@ public static void begin(final Minecraft minecraft, final PackRepository default
         } catch (ModLoadingException e) {
             error = e;
         }
+    }
+
+    public static void finish(final PackRepository defaultResourcePacks, final ReloadableResourceManager mcResourceManager) {
         if (error == null) {
             ResourcePackLoader.populatePackRepository(defaultResourcePacks, PackType.CLIENT_RESOURCES, false);
             DataPackConfig.DEFAULT.addModPacks(ResourcePackLoader.getPackNames(PackType.SERVER_DATA));

src/main/java/net/neoforged/neoforge/common/NeoForgeConfig.java

@@ -99,6 +99,8 @@ public static class Client {
 
         public final BooleanValue logUntranslatedConfigurationWarnings;
 
+        public final BooleanValue reducedDepthStencilFormat;
+
         Client(ModConfigSpec.Builder builder) {
             experimentalForgeLightPipelineEnabled = builder
                     .comment("EXPERIMENTAL: Enable the NeoForge block rendering pipeline - fixes the lighting of custom models.")
@@ -114,6 +116,11 @@ public static class Client {
                     .comment("A config option mainly for developers. Logs out configuration values that do not have translations when running a client in a development environment.")
                     .translation("neoforge.configgui.logUntranslatedConfigurationWarnings")
                     .define("logUntranslatedConfigurationWarnings", true);
+
+            reducedDepthStencilFormat = builder
+                    .comment("Configures how many bits are used for the depth buffer when stenciling has been enabled by a mod. Set to true for 24+8 bits and to false for 32+8 bits. Setting to true will slightly reduce VRAM usage, but risks introducing visual artifacts.")
+                    .translation("neoforge.configgui.reducedDepthStencilFormat")
+                    .define("reducedDepthStencilFormat", false);
         }
     }
 

src/main/resources/assets/neoforge/lang/en_us.json

@@ -206,6 +206,8 @@
   "neoforge.configgui.logUntranslatedItemTagWarnings.tooltip": "A config option mainly for developers. Logs out modded item tags that do not have translations when running on integrated server. Format desired is tag.item.<namespace>.<path> for the translation key. Defaults to SILENCED.",
   "neoforge.configgui.permissionHandler": "Permission Handler",
   "neoforge.configgui.permissionHandler.tooltip": "The permission handler used by the server. Defaults to neoforge:default_handler if no such handler with that name is registered.",
+  "neoforge.configgui.reducedDepthStencilFormat": "Reduced Depth+Stencil Format",
+  "neoforge.configgui.reducedDepthStencilFormat.tooltip": "Configures how many bits are used for the depth buffer when stenciling has been enabled by a mod. Set to true for 24+8 bits and to false for 32+8 bits. Setting to true will slightly reduce VRAM usage, but risks introducing visual artifacts.",
   "neoforge.configgui.removeErroringBlockEntities": "Remove Erroring Block Entities",
   "neoforge.configgui.removeErroringBlockEntities.tooltip": "Set this to true to remove any BlockEntity that throws an error in its update method instead of closing the server and reporting a crash log.",
   "neoforge.configgui.removeErroringBlockEntities.tooltip.warning": "BE WARNED THIS COULD SCREW UP EVERYTHING.\nUSE SPARINGLY.\nWE ARE NOT RESPONSIBLE FOR DAMAGES.",