Improve normal scaling fix

src/main/java/com/simibubi/create/foundation/mixin/FixInverseCbrtMixin.java

@@ -1,32 +0,0 @@
-package com.simibubi.create.foundation.mixin;
-
-import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.injection.At;
-import org.spongepowered.asm.mixin.injection.Inject;
-import org.spongepowered.asm.mixin.injection.ModifyVariable;
-import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
-
-import net.minecraft.util.math.MathHelper;
-
-/**
- * Vanilla's fast inverse cube root function returns nonsensical results for negative
- * numbers, which results in incorrect vertex normal scaling. By negating the input
- * and output accordingly, this issue can be prevented.
- */
-@Mixin(MathHelper.class)
-public class FixInverseCbrtMixin {
-	@ModifyVariable(at = @At("HEAD"), method = "fastInverseCbrt(F)F")
-	private static float negateAtHead(float input) {
-		if (input < 0) {
-			input *= -1;
-		}
-		return input;
-	}
-
-	@Inject(at = @At("TAIL"), method = "fastInverseCbrt(F)F", cancellable = true)
-	private static void negateAtTail(float input, CallbackInfoReturnable<Float> cir) {
-		if (input < 0) {
-			cir.setReturnValue(cir.getReturnValueF() * -1);
-		}
-	}
-}

src/main/java/com/simibubi/create/foundation/mixin/FixNormalScalingMixin.java

@@ -0,0 +1,36 @@
+package com.simibubi.create.foundation.mixin;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.At.Shift;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.mojang.blaze3d.matrix.MatrixStack;
+
+@Mixin(MatrixStack.class)
+public class FixNormalScalingMixin {
+	/**
+	 * Minecraft negates the normal matrix if all scales are equal and negative, but
+	 * does not return afterward. This allows the rest of the method's logic to be
+	 * applied, which negates the matrix again, resulting in the matrix being the
+	 * same as in the beginning.
+	 */
+	@Inject(at = @At(value = "INVOKE", target = "Lnet/minecraft/util/math/vector/Matrix3f;multiply(F)V", shift = Shift.AFTER), method = "scale(FFF)V", cancellable = true)
+	private void returnAfterNegate(float x, float y, float z, CallbackInfo ci) {
+		ci.cancel();
+	}
+
+	/**
+	 * Minecraft takes the inverse cube root of the product of all scales to provide a
+	 * rough estimate for normalization so that it does not need to be done later. It
+	 * does not make sense for this "normalization factor" to be negative though, as
+	 * that would invert all normals. Additionally, Minecraft's fastInverseCbrt method
+	 * does not work for negative numbers.
+	 */
+	@ModifyArg(at = @At(value = "INVOKE", target = "Lnet/minecraft/util/math/MathHelper;fastInverseCbrt(F)F"), method = "scale(FFF)V")
+	private float absInvCbrtInput(float input) {
+		return Math.abs(input);
+	}
+}

src/main/resources/create.mixins.json

@@ -9,7 +9,7 @@
   "client": [
     "CancelTileEntityRenderMixin",
     "EntityContraptionInteractionMixin",
-    "FixInverseCbrtMixin",
+    "FixNormalScalingMixin",
     "FogColorTrackerMixin",
     "HeavyBootsOnPlayerMixin",
     "LightUpdateMixin",