Provide more-sane eldritch altar mob-spawning behaviors (#101)

* Pick coordinates for knights and guardians in an even distribution

* Unrelated fix: set remap = false for levitator

* Create an enum setting type

* Provide an origin-centered eldritch altar spawning behavior

* Add documentation for eldritchAltarSpawningMethod

* Inline local variable updates, suppress local param warnings

* Condense two mixins into one

docs/enhancements.md

@@ -117,6 +117,15 @@ Has the side effect of making non-shifting entities, like passive mobs, unable t
 
 By default, pure nodes only change the biome around them if they are either in tainted lands or inside of a silverwood tree. This setting allows pure nodes to change the biome around them regardless of their location.
 
+## Alternate Eldritch Altar Mob Spawning
+
+**Config Option:** `eldritchAltarSpawningMethod`
+
+Override how eldritch altars pick where to try spawning crimson knights and eldritch guardians. [The default approach is... unusual](https://github.com/rndmorris/Salis-Arcana/issues/99).
+
+* `EVEN_SPREAD`: each valid coordinate in range has an equal chance of being selected. Will not try to spawn in spaces occupied by the altar itself.
+* `CENTER_WEIGHTED`: weighted towards coordinates near the altar. Will not try to spawn in spaces occupied by the altar itself.
+
 # Enhancements - Infusion
 
 ## Config option: `useStabilizerRewrite`

src/main/java/dev/rndmorris/salisarcana/config/modules/EnhancementsModule.java

@@ -5,6 +5,7 @@
 import dev.rndmorris.salisarcana.config.ConfigPhase;
 import dev.rndmorris.salisarcana.config.settings.BlockItemListSetting;
 import dev.rndmorris.salisarcana.config.settings.CustomResearchSetting;
+import dev.rndmorris.salisarcana.config.settings.EldritchAltarMobSpawnSetting;
 import dev.rndmorris.salisarcana.config.settings.IntArraySetting;
 import dev.rndmorris.salisarcana.config.settings.IntSetting;
 import dev.rndmorris.salisarcana.config.settings.ReplaceWandComponentSettings;
@@ -48,6 +49,8 @@ public class EnhancementsModule extends BaseConfigModule {
 
     public final IntSetting itemEldritchObjectStackSize;
 
+    public final EldritchAltarMobSpawnSetting eldritchAltarSpawningMethod;
+
     public final ToggleSetting wandPedestalUseCV;
     public final ToggleSetting thaumometerScanContainers;
     public final CustomResearchSetting thaumometerScanContainersResearch;
@@ -218,8 +221,12 @@ public EnhancementsModule() {
                 this,
                 ConfigPhase.EARLY,
                 "pureNodeAlwaysMagicalForest",
-                "By default, pure nodes only change the biome around them if they are either in tainted lands or inside of a silverwood tree. This setting allows pure nodes to change the biome around them regardless of their location.")
-
+                "By default, pure nodes only change the biome around them if they are either in tainted lands or inside of a silverwood tree. This setting allows pure nodes to change the biome around them regardless of their location."),
+            eldritchAltarSpawningMethod = new EldritchAltarMobSpawnSetting(
+                this,
+                ConfigPhase.EARLY,
+                "eldritchAltarSpawningMethod",
+                "Override how eldritch altars pick where to try spawning crimson knights and eldritch guardians.")
         );
 
         // spotless:on

src/main/java/dev/rndmorris/salisarcana/config/settings/EldritchAltarMobSpawnSetting.java

@@ -0,0 +1,72 @@
+package dev.rndmorris.salisarcana.config.settings;
+
+import java.util.Random;
+
+import net.minecraft.util.MathHelper;
+
+import dev.rndmorris.salisarcana.config.ConfigPhase;
+import dev.rndmorris.salisarcana.config.IEnabler;
+
+public class EldritchAltarMobSpawnSetting extends EnumSetting<EldritchAltarMobSpawnSetting.Options> {
+
+    public EldritchAltarMobSpawnSetting(IEnabler dependency, ConfigPhase phase, String name, String comment) {
+        super(dependency, phase, name, comment, Options.DEFAULT);
+    }
+
+    public int randomHorizontal(Random random) {
+        return switch (value) {
+            case EVEN_SPREAD -> horizontalEven(random);
+            case CENTER_WEIGHTED -> horizontalWeighted(random);
+            default -> throw new RuntimeException(
+                String.format(
+                    "%s called while its mixin should be disabled.",
+                    EldritchAltarMobSpawnSetting.class.getName()));
+        };
+    }
+
+    public int randomVertical(Random random) {
+        return switch (value) {
+            case EVEN_SPREAD -> verticalEven(random);
+            case CENTER_WEIGHTED -> verticalWeighted(random);
+            default -> throw new RuntimeException(
+                String.format(
+                    "%s called while its mixin should be disabled.",
+                    EldritchAltarMobSpawnSetting.class.getName()));
+        };
+    }
+
+    private int horizontalEven(Random random) {
+        return (MathHelper.getRandomIntegerInRange(random, 0, 6) + 4) * (random.nextBoolean() ? 1 : -1);
+    }
+
+    private int verticalEven(Random random) {
+        return MathHelper.getRandomIntegerInRange(random, -3, 3);
+    }
+
+    private int horizontalWeighted(Random random) {
+        final var val = MathHelper.getRandomIntegerInRange(random, 0, 6)
+            - MathHelper.getRandomIntegerInRange(random, 0, 6);
+        if (val == 0) {
+            return val + (4 * (random.nextBoolean() ? 1 : -1));
+        }
+        if (val < 0) {
+            return val - 4;
+        }
+        return val + 4;
+    }
+
+    private int verticalWeighted(Random random) {
+        return MathHelper.getRandomIntegerInRange(random, 0, 3) - MathHelper.getRandomIntegerInRange(random, 0, 3);
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return super.isEnabled() && value != Options.DEFAULT;
+    }
+
+    public enum Options {
+        DEFAULT,
+        EVEN_SPREAD,
+        CENTER_WEIGHTED
+    }
+}

src/main/java/dev/rndmorris/salisarcana/config/settings/EnumSetting.java

@@ -0,0 +1,48 @@
+package dev.rndmorris.salisarcana.config.settings;
+
+import java.util.Arrays;
+
+import javax.annotation.Nonnull;
+
+import net.minecraftforge.common.config.Configuration;
+
+import dev.rndmorris.salisarcana.config.ConfigPhase;
+import dev.rndmorris.salisarcana.config.IEnabler;
+
+public class EnumSetting<E extends Enum<E>> extends Setting {
+
+    protected final Class<E> enumClass;
+    protected final String name;
+    protected final String comment;
+    protected E value;
+
+    public EnumSetting(IEnabler dependency, ConfigPhase phase, String name, String comment, @Nonnull E defaultValue) {
+        super(dependency, phase);
+        this.name = name;
+        enumClass = defaultValue.getDeclaringClass();
+        value = defaultValue;
+
+        final var sb = new StringBuilder();
+        final var $vals = Arrays.stream(enumClass.getEnumConstants())
+            .iterator();
+        while ($vals.hasNext()) {
+            sb.append(
+                $vals.next()
+                    .toString());
+            if ($vals.hasNext()) {
+                sb.append(", ");
+            }
+        }
+
+        this.comment = comment + " Valid values: [" + sb + "]";
+    }
+
+    @Override
+    public void loadFromConfiguration(Configuration configuration) {
+        final var validValues = Arrays.stream(enumClass.getEnumConstants())
+            .map(Enum::toString)
+            .toArray(String[]::new);
+        final var valueString = configuration.getString(name, getCategory(), value.toString(), comment, validValues);
+        value = Enum.valueOf(enumClass, valueString);
+    }
+}

src/main/java/dev/rndmorris/salisarcana/mixins/Mixins.java

@@ -293,6 +293,12 @@ public enum Mixins {
         .addMixinClasses("tiles.MixinTileNode")
         .addTargetedMod(TargetedMod.THAUMCRAFT)),
 
+    ELDRITCH_ALTAR_EVEN_SPREAD_MOBS(new Builder().setPhase(Phase.LATE)
+        .setSide(Side.BOTH)
+        .setApplyIf(ConfigModuleRoot.enhancements.eldritchAltarSpawningMethod::isEnabled)
+        .addMixinClasses("tiles.MixinTileEldritchAltar_SpawnMobs")
+        .addTargetedMod(TargetedMod.THAUMCRAFT)),
+
     ;
 
     private final List<String> mixinClasses;

src/main/java/dev/rndmorris/salisarcana/mixins/late/tiles/MixinTileEldritchAltar_SpawnMobs.java

@@ -0,0 +1,49 @@
+package dev.rndmorris.salisarcana.mixins.late.tiles;
+
+import java.util.Random;
+
+import net.minecraft.world.IBlockAccess;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
+import com.llamalad7.mixinextras.sugar.Local;
+import com.llamalad7.mixinextras.sugar.ref.LocalIntRef;
+
+import dev.rndmorris.salisarcana.config.ConfigModuleRoot;
+import thaumcraft.api.TileThaumcraft;
+import thaumcraft.common.tiles.TileEldritchAltar;
+
+@Mixin(value = TileEldritchAltar.class, remap = false)
+public abstract class MixinTileEldritchAltar_SpawnMobs extends TileThaumcraft {
+
+    @WrapOperation(
+        method = { "spawnGuards", "spawnGuardian" },
+        at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/util/MathHelper;getRandomIntegerInRange(Ljava/util/Random;II)I"))
+    private int preventRandCalls(Random random, int min, int max, Operation<Integer> original) {
+        return 0;
+    }
+
+    @WrapOperation(
+        method = { "spawnGuards", "spawnGuardian" },
+        at = @At(
+            value = "INVOKE",
+            target = "Lnet/minecraft/world/World;doesBlockHaveSolidTopSurface(Lnet/minecraft/world/IBlockAccess;III)Z"))
+    @SuppressWarnings("ParameterCanBeLocal")
+    private boolean pickAndCheckCoords(IBlockAccess worldIn, int x, int y, int z, Operation<Boolean> original,
+        @Local(name = "i1") LocalIntRef xRef, @Local(name = "j1") LocalIntRef yRef,
+        @Local(name = "k1") LocalIntRef zRef) {
+
+        final var spawnSettings = ConfigModuleRoot.enhancements.eldritchAltarSpawningMethod;
+
+        xRef.set(x = xCoord + spawnSettings.randomHorizontal(worldObj.rand));
+        yRef.set(y = yCoord + spawnSettings.randomVertical(worldObj.rand));
+        zRef.set(z = zCoord + spawnSettings.randomHorizontal(worldObj.rand));
+
+        return original.call(worldIn, x, y - 1, z);
+    }
+}

src/main/java/dev/rndmorris/salisarcana/mixins/late/tiles/MixinTileLifter.java

@@ -14,7 +14,7 @@
 
 import thaumcraft.common.tiles.TileLifter;
 
-@Mixin(TileLifter.class)
+@Mixin(value = TileLifter.class, remap = false)
 public abstract class MixinTileLifter extends TileEntity {
 
     @Shadow