Fix a WorldRenderEvents.BLOCK_OUTLINE bug (#1319)

* Fix bug related to immediate mode VCP

* Add testmod

fabric-rendering-v1/src/main/java/net/fabricmc/fabric/api/client/rendering/v1/WorldRenderContext.java

@@ -120,7 +120,11 @@ public interface WorldRenderContext {
 	 * {@code WorldRenderer.drawBlockOutline}.
 	 */
 	@Environment(EnvType.CLIENT)
-	public interface BlockOutlineContext {
+	interface BlockOutlineContext {
+		/**
+		 * @deprecated Use {@link #consumers()} directly.
+		 */
+		@Deprecated
 		VertexConsumer vertexConsumer();
 
 		Entity entity();

fabric-rendering-v1/src/main/java/net/fabricmc/fabric/impl/client/rendering/WorldRenderContextImpl.java

@@ -21,6 +21,7 @@ import net.minecraft.client.render.Camera;
 import net.minecraft.client.render.Frustum;
 import net.minecraft.client.render.GameRenderer;
 import net.minecraft.client.render.LightmapTextureManager;
+import net.minecraft.client.render.RenderLayer;
 import net.minecraft.client.render.VertexConsumer;
 import net.minecraft.client.render.VertexConsumerProvider;
 import net.minecraft.client.render.WorldRenderer;
@@ -52,7 +53,6 @@ public final class WorldRenderContextImpl implements WorldRenderContext.BlockOut
 	private boolean advancedTranslucency;
 	private ClientWorld world;
 
-	private VertexConsumer vertexConsumer;
 	private Entity entity;
 	private double cameraX;
 	private double cameraY;
@@ -97,7 +97,6 @@ public final class WorldRenderContextImpl implements WorldRenderContext.BlockOut
 	}
 
 	public void prepareBlockOutline(
-			VertexConsumer vertexConsumer,
 			Entity entity,
 			double cameraX,
 			double cameraY,
@@ -105,7 +104,6 @@ public final class WorldRenderContextImpl implements WorldRenderContext.BlockOut
 			BlockPos blockPos,
 			BlockState blockState
 	) {
-		this.vertexConsumer = vertexConsumer;
 		this.entity = entity;
 		this.cameraX = cameraX;
 		this.cameraY = cameraY;
@@ -186,7 +184,7 @@ public final class WorldRenderContextImpl implements WorldRenderContext.BlockOut
 
 	@Override
 	public VertexConsumer vertexConsumer() {
-		return vertexConsumer;
+		return consumers.getBuffer(RenderLayer.getLines());
 	}
 
 	@Override

fabric-rendering-v1/src/main/java/net/fabricmc/fabric/mixin/client/rendering/MixinWorldRenderer.java

@@ -32,6 +32,7 @@ import net.minecraft.client.render.Camera;
 import net.minecraft.client.render.Frustum;
 import net.minecraft.client.render.GameRenderer;
 import net.minecraft.client.render.LightmapTextureManager;
+import net.minecraft.client.render.RenderLayer;
 import net.minecraft.client.render.VertexConsumer;
 import net.minecraft.client.render.WorldRenderer;
 import net.minecraft.client.util.math.MatrixStack;
@@ -97,6 +98,7 @@ public abstract class MixinWorldRenderer {
 		context.renderBlockOutline = WorldRenderEvents.BEFORE_BLOCK_OUTLINE.invoker().beforeBlockOutline(context, client.crosshairTarget);
 	}
 
+	@SuppressWarnings("ConstantConditions")
 	@Inject(method = "drawBlockOutline", at = @At("HEAD"), cancellable = true)
 	private void onDrawBlockOutline(MatrixStack matrixStack, VertexConsumer vertexConsumer, Entity entity, double cameraX, double cameraY, double cameraZ, BlockPos blockPos, BlockState blockState, CallbackInfo ci) {
 		if (!context.renderBlockOutline) {
@@ -104,11 +106,15 @@ public abstract class MixinWorldRenderer {
 			// fire the BLOCK_OUTLINE event per contract of the API.
 			ci.cancel();
 		} else {
-			context.prepareBlockOutline(vertexConsumer, entity, cameraX, cameraY, cameraZ, blockPos, blockState);
+			context.prepareBlockOutline(entity, cameraX, cameraY, cameraZ, blockPos, blockState);
 
 			if (!WorldRenderEvents.BLOCK_OUTLINE.invoker().onBlockOutline(context, context)) {
 				ci.cancel();
 			}
+
+			// The immediate mode VertexConsumers use a shared buffer, so we have to make sure that the immediate mode VCP
+			// can accept block outline lines rendered to the existing vertexConsumer by the vanilla block overlay.
+			context.consumers().getBuffer(RenderLayer.getLines());
 		}
 	}
 

fabric-rendering-v1/src/testmod/java/net/fabricmc/fabric/test/rendering/client/WorldRenderEventsTests.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.test.rendering.client;
+
+import net.minecraft.block.Blocks;
+import net.minecraft.client.MinecraftClient;
+import net.minecraft.client.render.OverlayTexture;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.Vec3d;
+
+import net.fabricmc.api.ClientModInitializer;
+import net.fabricmc.fabric.api.client.rendering.v1.WorldRenderContext;
+import net.fabricmc.fabric.api.client.rendering.v1.WorldRenderEvents;
+
+public class WorldRenderEventsTests implements ClientModInitializer {
+	private static boolean onBlockOutline(WorldRenderContext wrc, WorldRenderContext.BlockOutlineContext blockOutlineContext) {
+		if (blockOutlineContext.blockState().isOf(Blocks.DIAMOND_BLOCK)) {
+			wrc.matrixStack().push();
+			Vec3d cameraPos = MinecraftClient.getInstance().gameRenderer.getCamera().getPos();
+			BlockPos pos = blockOutlineContext.blockPos();
+			double x = pos.getX() - cameraPos.x;
+			double y = pos.getY() - cameraPos.y;
+			double z = pos.getZ() - cameraPos.z;
+			wrc.matrixStack().translate(x+0.25, y+0.25+1, z+0.25);
+			wrc.matrixStack().scale(0.5f, 0.5f, 0.5f);
+
+			MinecraftClient.getInstance().getBlockRenderManager().renderBlockAsEntity(
+					Blocks.DIAMOND_BLOCK.getDefaultState(),
+					wrc.matrixStack(), wrc.consumers(), 15728880, OverlayTexture.DEFAULT_UV);
+
+			wrc.matrixStack().pop();
+		}
+
+		return true;
+	}
+
+	// Renders a diamond block above diamond blocks when they are looked at.
+	@Override
+	public void onInitializeClient() {
+		WorldRenderEvents.BLOCK_OUTLINE.register(WorldRenderEventsTests::onBlockOutline);
+	}
+}

fabric-rendering-v1/src/testmod/resources/fabric.mod.json

@@ -13,7 +13,8 @@
       "net.fabricmc.fabric.test.rendering.CustomArmorTests"
     ],
     "client": [
-      "net.fabricmc.fabric.test.rendering.client.CustomArmorTestsClient"
+      "net.fabricmc.fabric.test.rendering.client.CustomArmorTestsClient",
+      "net.fabricmc.fabric.test.rendering.client.WorldRenderEventsTests"
     ]
   }
 }