Add the cposteffect command

src/main/java/net/earthcomputer/clientcommands/ClientCommands.java

@@ -175,6 +175,7 @@ public static void registerCommands(CommandDispatcher<FabricClientCommandSource>
         // PlayerInfoCommand.register(dispatcher);
         PluginsCommand.register(dispatcher);
         PosCommand.register(dispatcher);
+        PostEffectCommand.register(dispatcher);
         PredictBrushablesCommand.register(dispatcher);
         RelogCommand.register(dispatcher);
         RenderCommand.register(dispatcher);

src/main/java/net/earthcomputer/clientcommands/command/PostEffectCommand.java

@@ -0,0 +1,32 @@
+package net.earthcomputer.clientcommands.command;
+
+import com.mojang.brigadier.Command;
+import com.mojang.brigadier.CommandDispatcher;
+import net.fabricmc.fabric.api.client.command.v2.FabricClientCommandSource;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.ResourceLocation;
+import org.jetbrains.annotations.Nullable;
+
+import static net.earthcomputer.clientcommands.command.arguments.PostEffectArgument.*;
+import static net.fabricmc.fabric.api.client.command.v2.ClientCommandManager.*;
+
+public class PostEffectCommand {
+    public static void register(CommandDispatcher<FabricClientCommandSource> dispatcher) {
+        dispatcher.register(literal("cposteffect")
+            .then(argument("posteffect", postEffect())
+                .executes(ctx -> applyPostEffect(ctx.getSource(), getPostEffect(ctx, "posteffect"))))
+            .then(literal("reset")
+                .executes(ctx -> applyPostEffect(ctx.getSource(), null))));
+    }
+
+    private static int applyPostEffect(FabricClientCommandSource source, @Nullable ResourceLocation postEffect) {
+        if (postEffect == null) {
+            source.getClient().gameRenderer.clearPostEffect();
+            source.sendFeedback(Component.translatable("commands.cposteffect.reset.success"));
+            return Command.SINGLE_SUCCESS;
+        }
+        source.getClient().gameRenderer.setPostEffect(postEffect);
+        source.sendFeedback(Component.translatable("commands.cposteffect.apply.success", postEffect));
+        return Command.SINGLE_SUCCESS;
+    }
+}

src/main/java/net/earthcomputer/clientcommands/command/arguments/PostEffectArgument.java

@@ -0,0 +1,69 @@
+package net.earthcomputer.clientcommands.command.arguments;
+
+import com.mojang.brigadier.StringReader;
+import com.mojang.brigadier.arguments.ArgumentType;
+import com.mojang.brigadier.context.CommandContext;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import com.mojang.brigadier.exceptions.DynamicCommandExceptionType;
+import com.mojang.brigadier.suggestion.Suggestions;
+import com.mojang.brigadier.suggestion.SuggestionsBuilder;
+import net.fabricmc.fabric.api.client.command.v2.FabricClientCommandSource;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.LevelTargetBundle;
+import net.minecraft.client.renderer.PostChainConfig;
+import net.minecraft.commands.SharedSuggestionProvider;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.ResourceLocation;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Stream;
+
+public class PostEffectArgument implements ArgumentType<ResourceLocation> {
+
+    private static final Collection<String> EXAMPLES = Arrays.asList("invert", "minecraft:spider", "clientcommands:crt");
+
+    private static final DynamicCommandExceptionType UNKNOWN_POST_EFFECT_EXCEPTION = new DynamicCommandExceptionType(postEffect -> Component.translatable("commands.cposteffect.unknownPostEffect", postEffect));
+
+    public static PostEffectArgument postEffect() {
+        return new PostEffectArgument();
+    }
+
+    public static ResourceLocation getPostEffect(final CommandContext<FabricClientCommandSource> context, final String name) {
+        return context.getArgument(name, ResourceLocation.class);
+    }
+
+    @Override
+    public ResourceLocation parse(StringReader reader) throws CommandSyntaxException {
+        int start = reader.getCursor();
+        ResourceLocation postEffectId = ResourceLocation.read(reader);
+
+        boolean valid = getValidPostChains().anyMatch(id -> id.equals(postEffectId));
+        if (!valid) {
+            reader.setCursor(start);
+            throw UNKNOWN_POST_EFFECT_EXCEPTION.createWithContext(reader, postEffectId);
+        }
+        return postEffectId;
+    }
+
+    @Override
+    public <S> CompletableFuture<Suggestions> listSuggestions(CommandContext<S> context, SuggestionsBuilder builder) {
+        return SharedSuggestionProvider.suggestResource(getValidPostChains(), builder);
+    }
+
+    @Override
+    public Collection<String> getExamples() {
+        return EXAMPLES;
+    }
+
+    private Stream<ResourceLocation> getValidPostChains() {
+        return Minecraft.getInstance().getShaderManager().compilationCache.configs.postChains().entrySet().stream()
+            .filter(entry -> entry.getValue().passes().stream()
+                .flatMap(PostChainConfig.Pass::referencedTargets)
+                .filter(location -> !entry.getValue().internalTargets().containsKey(location))
+                .allMatch(LevelTargetBundle.MAIN_TARGETS::contains))
+            .map(Map.Entry::getKey);
+    }
+}

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

@@ -234,6 +234,10 @@
   "commands.cpos.level.the_end": "the End",
   "commands.cpos.level.the_nether": "the Nether",
 
+  "commands.cposteffect.apply.success": "Successfully applied post effect %s",
+  "commands.cposteffect.reset.success": "Successfully reset post effect",
+  "commands.cposteffect.unknownPostEffect": "Unknown post effect %s",
+
   "commands.cpredictbrushables.foundBrushableBlock": "Found %s at %s with item %s %s",
   "commands.cpredictbrushables.notFound": "No brushable blocks found",
   "commands.cpredictbrushables.starting": "Searching for brushable blocks",

src/main/resources/assets/clientcommands/post_effect/crt.json

@@ -0,0 +1,44 @@
+{
+    "targets": {
+        "swap": {}
+    },
+    "passes": [
+        {
+            "vertex_shader": "minecraft:core/screenquad",
+            "fragment_shader": "clientcommands:post/crt",
+            "inputs": [
+                {
+                    "sampler_name": "In",
+                    "target": "minecraft:main"
+                }
+            ],
+            "output": "swap",
+            "uniforms": {}
+        },
+        {
+            "vertex_shader": "minecraft:core/screenquad",
+            "fragment_shader": "minecraft:post/bits",
+            "inputs": [
+                {
+                    "sampler_name": "In",
+                    "target": "swap"
+                }
+            ],
+            "output": "minecraft:main",
+            "uniforms": {
+                "BitsConfig": [
+                    {
+                        "name": "Resolution",
+                        "type": "float",
+                        "value": 16.0
+                    },
+                    {
+                        "name": "MosaicSize",
+                        "type": "float",
+                        "value": 4.0
+                    }
+                ]
+            }
+        }
+    ]
+}

src/main/resources/assets/clientcommands/shaders/post/crt.fsh

@@ -0,0 +1,32 @@
+#version 330
+
+uniform sampler2D InSampler;
+
+in vec2 texCoord;
+
+layout(std140) uniform SamplerInfo {
+    vec2 OutSize;
+    vec2 InSize;
+};
+
+out vec4 fragColor;
+
+void main() {
+    vec2 oneTexel = 1.0 / InSize;
+
+    float aberr = 0.002;
+    vec3 col;
+    col.r = texture(InSampler, texCoord + vec2(aberr, 0.0)).r;
+    col.g = texture(InSampler, texCoord).g;
+    col.b = texture(InSampler, texCoord - vec2(aberr, 0.0)).b;
+
+    // Add scanlines
+    float scan = sin(texCoord.y * 800.0) * 0.1; // adjust frequency
+    col *= 1.0 - scan * 0.3;
+
+    // Vignette
+    float vignette = smoothstep(1.2, 0.6, length(texCoord - 0.5));
+    col *= vignette;
+
+    fragColor = vec4(col, 1.0);
+}

src/main/resources/clientcommands.aw

@@ -50,6 +50,12 @@ accessible method net/minecraft/client/Screenshot getFile (Ljava/io/File;)Ljava/
 # cpermissionlevel
 accessible method net/minecraft/client/player/LocalPlayer getPermissionLevel ()I
 
+# cposteffect
+accessible field net/minecraft/client/renderer/GameRenderer BLUR_POST_CHAIN_ID Lnet/minecraft/resources/ResourceLocation;
+accessible method net/minecraft/client/renderer/GameRenderer setPostEffect (Lnet/minecraft/resources/ResourceLocation;)V
+accessible field net/minecraft/client/renderer/ShaderManager compilationCache Lnet/minecraft/client/renderer/ShaderManager$CompilationCache;
+accessible field net/minecraft/client/renderer/ShaderManager$CompilationCache configs Lnet/minecraft/client/renderer/ShaderManager$Configs;
+
 # Game Options
 accessible field net/minecraft/client/OptionInstance value Ljava/lang/Object;