question about blockstate and variant

[obfish]

When I looked through the blockstate files of the Minecraft resource pack, I found that 'grass' in the 'normal' state has 4 variants.As the Minecraft Wiki points out, the grass block chooses one variant from the four at random.So I want to know whether there's a way to figure out the specific variant of a grass block using Forge API?(In other words,distinguish a grass block from other normal grass blocks )

[stucuk]

2 hours ago, obfish said:

When I looked through the blockstate files of the Minecraft resource pack, I found that 'grass' in the 'normal' state has 4 variants.As the Minecraft Wiki points out, the grass block chooses one variant from the four at random.So I want to know whether there's a way to figure out the specific variant of a grass block using Forge API?(In other words,distinguish a grass block from other normal grass blocks )

 

Since models are client side and its not based on a State/MetaData (Like snowy being true/false) i don't think there is any way to know.

[obfish]

That is really confusing.I'd like to know on which side(server side or client side) is the block's information of random model determined.And how is such information stored In the filesystem?

Edited April 8, 2017 by obfish

[stucuk]

The random numbers are based on the blocks position in the world. BlockModelRenderer::renderModel() uses MathHelper.getPositionRandom(blockPosIn) for the random number. Which is passed to the WeightedBakedModel::getRandomModel which in turn uses Math.abs((int)p_188627_1_ >> 16) % this.totalWeight to work out the "Weight" which is used by WeightedRandom::getRandomItem .

 

So basically the following would give you the weight:

Math.abs((int)MathHelper.getPositionRandom(blockPosIn) >> 16) % totalWeight

 

But you would have to work out what the totalWeight was as well as which model is picked based on the weight.

[obfish]

Does it mean that the so-called randomness of variants is to some extent pseudo-randomness? Does the model of the block in a specific position is determined and predictable once the world is generated?

For instance,I set a grass block, destroy it and again set a grass block in the same position. I should see the model corresponding to the former one, should I?

[stucuk]

11 hours ago, obfish said:

Does it mean that the so-called randomness of variants is to some extent pseudo-randomness? Does the model of the block in a specific position is determined and predictable once the world is generated?

For instance,I set a grass block, destroy it and again set a grass block in the same position. I should see the model corresponding to the former one, should I?

 

The way the weight system works is basically each item (Or model in your case) is given a value. The total weight is all the values added together. The WeightedRandom::getRandomItem just goes through all the items and subtracts their value from the number passed to it until the value is below 0. If it gets to below zero that item is returned.

 

So lets say you had items each with a weight of 2. If you supply it with a value of 1 or 0, the first item is picked. If you supply it with a value of 2 or 3 the 2nd is picked, etc. It will always give you the exact same results with the same values passed to it. MathHelper.getPositionRandom gives you the same number each time for the same block position.