The bug
When walking on a light block (defined by the game as a light block being below an iron golem while it walks), iron golems produce particles of the light block, despite the fact that no such particles should be made here as the texture is only meant to be visible for mapmakers.
Related issues
relates to
MC-221861
Light blocks have particles when fallen on, despite not having them in most other cases
MC-122547
Barriers can produce fall particles
MC-221568
Inconsistency: Barriers and structure voids produce particles when broken, but light blocks do not
MC-225958
Structure void particles are produced when an iron golem walks on structure voids
Attachments
Comments
migrated
Avoma
Can confirm.
migrated
Related to MC-1133
Avoma
Can confirm in 21w14a.
Avoma
Can confirm in 21w15a.
Avoma
Can confirm in 21w16a.
Avoma
Can confirm in 21w17a.
migrated
Can confirm in 1.17 pre-release 3
Avoma
Can confirm in 1.17.
Avoma
Can confirm in 1.17.1.
Avoma
I can confirm this behavior in 1.18. Here's a code analysis of this issue.
Code Analysis:
The following is based on a decompiled version of Minecraft 1.19.2 using MCP-Reborn.
net.minecraft.world.entity.animal.IronGolem.java
public class IronGolem extends AbstractGolem implements NeutralMob {
...
public void aiStep() {
super.aiStep();
...
if (this.getDeltaMovement().horizontalDistanceSqr() > (double)2.5000003E-7F && this.random.nextInt(5) == 0) {
int i = Mth.floor(this.getX());
int j = Mth.floor(this.getY() - (double)0.2F);
int k = Mth.floor(this.getZ());
BlockState blockstate = this.level.getBlockState(new BlockPos(i, j, k));
if (!blockstate.isAir()) {
this.level.addParticle(new BlockParticleOption(ParticleTypes.BLOCK, blockstate), this.getX() + ((double)this.random.nextFloat() - 0.5D) * (double)this.getBbWidth(), this.getY() + 0.1D, this.getZ() + ((double)this.random.nextFloat() - 0.5D) * (double)this.getBbWidth(), 4.0D * ((double)this.random.nextFloat() - 0.5D), 0.5D, ((double)this.random.nextFloat() - 0.5D) * 4.0D);
}
}
...If we look at the above class, we can see that there is only one necessary check that is carried out before allowing an iron golem to produce walking particles. This check is to see if the block below them is air, and if it is, walking particles won't be produced, but if it isn't, walking particles based on the block that the iron golem is standing on will be produced. The game doesn't check the RenderShape of the block that the iron golem standing on before allowing it to produce walking particles, therefore resulting in this problem occurring.
Fix:
Simply changing some lines of code to check the RenderShape of the block that the iron golem is standing on before allowing it to produce walking particles, will resolve this problem.
Current Code:
...
BlockState blockstate = this.level.getBlockState(new BlockPos(i, j, k));
if (!blockstate.isAir()) {
...Fixed Code:
...
BlockPos blockpos = new BlockPos(i, j, k);
BlockState blockstate = this.level.getBlockState(blockpos);
if (blockstate.getRenderShape() != RenderShape.INVISIBLE) {
...Can confirm in 1.18.1.
Avoma
Can confirm in 1.18.2 and 22w14a.
Avoma
Can confirm in 1.19.
Avoma
Can confirm in 1.19.2.
Avoma
Following on from my code analysis, I've double-checked my proposed fix and I can confidently confirm that it's fully functioning and works as expected, so I've attached two screenshots to this report, one of which shows the current code and the other that shows the fixed code. I feel this information may be quite insightful hence my reasoning for providing it. 🙂
[media][media]
muzikbike
This does not seem to happen anymore as of 1.20-rc1. Can we find the exact fix version (possibly pre-release 3 as per MC-262505)?
Avoma
This issue was present in 1.20 Pre-release 2, but no longer occurs in versions above or equal to 1.20 Pre-release 3. This issue was fixed in 1.20 Pre-release 3.
muzikbike
I may need to re-test this with carpets on top of light blocks first.
[Mod] markderickson
Closing as Fixed in 1.20pr3 per @unknown's comment.