[MC-190817] Players' arms follow the position of sneaking players when holding loaded crossbows or fully charged bows

The Bug:

If you crouch while holding a loaded crossbow, the arms follow the position of the crouching/sneaking player. It also happens when a player is loading a crossbow. It also affects bows.

Steps to Reproduce:

Have a loaded crossbow
Crouch/sneak
→ ❌ The player arms follow the position of crouching while holding a loaded crossbow

Code Analysis:

Code analysis by @unknown can be found in this comment.

Comparison:

[media]

Linked issues

relates to 2

MC-264135 Players' arms follow the position of sneaking players when blocking with shields Open

MC-190303 Players' arms are not correctly positioned when holding a charged crossbow and looking straight up or down Reopened

Attachments

Minecraft 1.15.2 - Singleplayer 2020-06-21 14-55-28.mp4

Minecraft 1.16 Release Candidate 1 - Singleplayer 2020-06-21 14-50-39.mp4

Comments 12

Avoma 2020-11-28T11:19:29Z

Can confirm in 20w48a.

Avoma 2021-01-15T15:25:40Z

Can confirm in 20w51a.

Avoma 2021-01-21T11:06:19Z

Can confirm in 21w03a.

Avoma 2021-02-18T14:15:17Z

Can confirm in 21w07a.

Avoma 2021-06-23T17:35:30Z

Can confirm in 1.17.

2 more comments

Avoma 2022-03-09T19:45:47Z

Can confirm in 1.18.2.

Avoma 2022-06-23T16:05:25Z

Can confirm in 1.19 and 1.19.1 Pre-release 1.

Avoma 2022-09-25T12:28:02Z

Can confirm in 1.19.2.

Avoma 2023-07-10T18:24:11Z

Relates to MC-264134 and MC-264135.

Apollo30 2023-08-20T15:37:03Z

Fix:

The following is based on a decompiled version of Minecraft 1.20.1 using MCP-Reborn.
To fix this, we will have to determine if the LivingEntity is crouching. If so, we will add 0.35157994 to the x and y rot.

net.minecraft.client.model.AnimationUtils.java // Updated

@OnlyIn(Dist.CLIENT)
public class AnimationUtils {
    public static void animateCrossbowHold(ModelPart p_102098_, ModelPart p_102099_, ModelPart p_102100_, LivingEntity livingEntity, boolean p_102101_) {
        ModelPart modelpart = p_102101_ ? p_102098_ : p_102099_;
        ModelPart modelpart1 = p_102101_ ? p_102099_ : p_102098_;
        modelpart.yRot = (p_102101_ ? -0.3 F : 0.3 F) + p_102100_.yRot;
        modelpart1.yRot = (p_102101_ ? 0.6 F : -0.6 F) + p_102100_.yRot;
        modelpart.xRot = (-(float) Math.PI / 2 F) + p_102100_.xRot + 0.1 F - (livingEntity.isCrouching() ? 0.3517994 F : 0.0 F);
        modelpart1.xRot = -1.5 F + p_102100_.xRot - (livingEntity.isCrouching() ? 0.3517994 F : 0.0 F);
    }    

    public static void animateCrossbowCharge(ModelPart p_102087_, ModelPart p_102088_, LivingEntity p_102089_, boolean p_102090_) {
        ModelPart modelpart = p_102090_ ? p_102087_ : p_102088_;
        ModelPart modelpart1 = p_102090_ ? p_102088_ : p_102087_;
        modelpart.yRot = p_102090_ ? -0.8 F : 0.8 F;
        modelpart.xRot = -0.97079635 F - (p_102089_.isCrouching() ? 0.3517994 F : 0.0 F);
        modelpart1.xRot = modelpart.xRot - (p_102089_.isCrouching() ? 0.3517994 F : 0.0 F);
        float f = (float) CrossbowItem.getChargeDuration(p_102089_.getUseItem());
        float f1 = Mth.clamp((float) p_102089_.getTicksUsingItem(), 0.0 F, f);
        float f2 = f1 / f;
        modelpart1.yRot = Mth.lerp(f2, 0.4 F, 0.85 F) * (float)(p_102090_ ? 1 : -1);
        modelpart1.xRot = Mth.lerp(f2, modelpart1.xRot, (-(float) Math.PI / 2 F));
    }
}

Since we added another parameter to the method, we must update any references to this method.
As an example:

net.minecraft.client.model.HumanoidModel.java // Updated

AnimationUtils.animateCrossbowHold(this.rightArm, this.leftArm, this.head, livingEntity, true);

There if you were to crouch whilst holding or charging up a crossbow, the elevation should remain consistent.

Yet again, we have another underlying issue of the opposite hand not connecting when looking up or down.