I have tried to test this myself, and also asked the minecraft subreddit, but to no avail. Here goes:
As we all know, when you break a block in minecraft, particles are emitted that look like smaller "pieces" of the original texture of said block.
My question is this: how are these pieces created? Is it random, or are the pieces selected from a grid?
What I'm trying to do is.. say you break a stone block. I want my particles to instead be custom-drawn chunks of rock. If it IS in fact a grid, I should be able to create an array of rock-like pieces, with each rock taking up a single cell of said grid.
Is this possible?
I can provide visuals that explain what I'm trying to do if needed.
No, I don't mean to say that these "chunks" are 3-D. When I say chunks, I mean the textured particles themselves. I'm asking whether the particles are truly random, or if there are specific parts of the texture it draws from, possibly within an imaginary "grid". That is, perhaps the texture is divided into quadrants, and each particle is a random choice among each quadrant. Does that make sense?
The same kind of particles get created, when falling onto a block from more than 3 1/2 blocks high and when eating an item.
In the item variant, the particles take a random 4x4 pixels from the texture, for example an apple has a border line and invisible spaces, these particles can be invisible, partly have the border in it, have the invisible part, the border and the inside, have a bit of the border and the inside, or have only the inside.
4x4, wonderful! That partially answers my question. The "grid question" is this:
Those 4x4 pixels, which are random, right? But here's what I'm getting at: Are there 16 different possibilities for the 4x4s (since 4x4= 16, divided by the total pixel count of the image, 256, equals 16..) , or are there 256 different ones (one possibility for each upper-left pixel of the 4x4 section)?