I am trying to modify a method in FirstPersonRenderer.

Since it is not declared as a field in many classes, I chose to use reflection rather than coremod.

I have a method shown below in my class that extends FirstPersonRenderer.

public static void patch() {
    FirstPersonRenderer instance = new FirstPersonRenderer(Minecraft.getInstance());
    ObfuscationReflectionHelper.setPrivateValue(Minecraft.class, Minecraft.getInstance(), instance, "field_175620_Y");
    ObfuscationReflectionHelper.setPrivateValue(GameRenderer.class, Minecraft.getInstance().gameRenderer, instance, "field_78516_c");
    ObfuscationReflectionHelper.setPrivateValue(GameRenderer.class, ObfuscationReflectionHelper.getPrivateValue(LightTexture.class, Minecraft.getInstance().gameRenderer.getLightTexture(), "field_205116_g"), instance, "field_78516_c");
}

Is it correct that I cannot call this method in main class when FMLClientSetupEvent is fired as it accesses client only classes?

If so, how can I apply these patches correctly?

what are you trying to do

4 minutes ago, loordgek said:

what are you trying to do

I am trying to recreate sword blocking and it requires me to modify renderItemInFirstPerson method which is private.

Just add a propertyOverride to your Item and change the position that way

5 hours ago, _Cruelar_ said:

Just add a propertyOverride to your Item and change the position that way

I also have considered that but I wanted to use exact values that were used before 1.9 and I do not know how should I change those values to fit in JSON.

Maybe try looking at shield_blocking.json or try applying the patches in your ClientProxy which should be Client-only, however note that any change to these should also be done in Client-only classes/methods