Node boxes vs mesh memory?

[Skulls]

As an experiment I replaced the 'default:stone' block with a cube mesh to add a little "pizzazz". There were about 26 or so vertices and I got some interesting behavior where my framerate plummeted (kind of expected) and the memory skyrocketed. Using a simple cube mesh (8 vertices) was much better but not nearly as good as the regular node box type blocks.

'Pizzazz' 26 vert mesh
20 fps
5+ Gb RAM

Simple cube mesh
58 fps
1.5 Gb RAM

Default node drawtype as in 'default' game
60 fps (capped)
200 Mb RAM

Are the regular node boxes handled differently than meshes?

[stu]

AFAIK, regular node-boxes are converted to meshes anyway. Do you mean just regular cubic nodes?

Interesting info all the same, though I guess some performance hit is to be expected if you replace default stone =)

[Skulls]

AFAIK, regular node-boxes are converted to meshes anyway.

That's what I thought too so I was surprised to see such a big memory change between the defaults and a blender supplied cube. Blender tossed in some extra things so maybe scaling that by a few hundred vs the default nodes makes up the memory difference.

Over a gigabyte of memory difference between the 'default:stone' generated mesh and the simple cube mesh:

Code: Select all

--minetest.register_node("default:stone", {
--	description = "Stone",
--	tiles = {"default_stone.png"},
--	groups = {cracky = 3, stone = 1},
--	drop = 'default:cobble',
--	legacy_mineral = true,
--	sounds = default.node_sound_stone_defaults(),
--})

-- simple cube mesh stone
minetest.register_node("default:stone", {
  description = "Test mesh stone",
  drawtype = "mesh",
  mesh = "test.obj",
  tiles = {"default_stone.png"},
  is_ground_content = false,
  drop = 'default:cobble',
  groups = {cracky = 3, stone = 1},
  sounds = default.node_sound_stone_defaults(),
})

Code: Select all

# Blender v2.79 (sub 0) OBJ File: 'Stone.blend'
# www.blender.org
mtllib test.mtl
o Cube.000_Cube.002
v -0.500000 -0.500000 0.500000
v -0.500000 0.500000 0.500000
v -0.500000 -0.500000 -0.500000
v -0.500000 0.500000 -0.500000
v 0.500000 -0.500000 0.500000
v 0.500000 0.500000 0.500000
v 0.500000 -0.500000 -0.500000
v 0.500000 0.500000 -0.500000
vt 0.000200 0.999800
vt 0.000200 0.666866
vt 0.333134 0.666866
vt 0.333134 0.999800
vt 0.666866 0.333134
vt 0.666866 0.000200
vt 0.999800 0.000200
vt 0.999800 0.333134
vt 0.333134 0.333533
vt 0.333134 0.666467
vt 0.000200 0.666467
vt 0.000200 0.333533
vt 0.666467 0.333533
vt 0.666467 0.666467
vt 0.333533 0.666467
vt 0.333533 0.333533
vt 0.666467 0.333134
vt 0.333533 0.333134
vt 0.333533 0.000200
vt 0.666467 0.000200
vt 0.333134 0.333134
vt 0.000200 0.333134
vt 0.000200 0.000200
vt 0.333134 0.000200
vn -1.0000 0.0000 0.0000
vn 0.0000 0.0000 -1.0000
vn 1.0000 0.0000 0.0000
vn 0.0000 0.0000 1.0000
vn 0.0000 -1.0000 0.0000
vn 0.0000 1.0000 0.0000
usemtl None
s off
f 1/1/1 2/2/1 4/3/1 3/4/1
f 3/5/2 4/6/2 8/7/2 7/8/2
f 7/9/3 8/10/3 6/11/3 5/12/3
f 5/13/4 6/14/4 2/15/4 1/16/4
f 3/17/5 7/18/5 5/19/5 1/20/5
f 8/21/6 4/22/6 2/23/6 6/24/6

[stu]

I think you may be confusing the term nodebox (a node composed of many smaller boxes) and simple cubic nodes like dirt and stone, apologies if I am mistaken.

In simple terms, the map-block rendering is optimised for simple cubes, whereas complex meshes require more processing and memory, multiply that by the number of stone nodes in your average scene then this does not surprise me. Someone else may be able to provide a more detailed explanation.

However, I you do mean a single cube 'nodebox' is more efficient than a simple mesh cube then that does suggests nodeboxes are handled differently.

[Skulls]

Yup, I couldn't find a term for the meshes that are generated so I just called them 'node boxes'. Whatever the landscape nodes are called.

.. a single cube 'nodebox' is more efficient than a simple mesh cube then that does suggests nodeboxes are handled differently.

Correct! Either the way that the generated simple mesh cubes are handled vs a cube.obj is different or (more likely) I'm doing something weird.

[stu]

Suggestion: Try using the wireframe mode to see the differences between nodes, nodeboxes, and meshes, maybe it can provide some clues :)

[Skulls]

Well, there we go then. It seems to be drawing *all* the obj meshes, even ones behind others.

Default generated map nodes:

mesh_stone0.png (374.7 KiB) Viewed 446 times

Simple blender cube mesh map node:

mesh_stone1.png (322.64 KiB) Viewed 446 times

[stu]

Seems pretty conclusive, though I am not sure you have discovered anything that is not already known but again, I could be mistaken, it does seem a bit silly.

Certainly a good reason to not use meshnodes or nodeboxes for map generation :)

[Skulls]

Seems pretty conclusive, though I am not sure you have discovered anything that is not already known but again, I could be mistaken, it does seem a bit silly.

Certainly a good reason to not use meshnodes or nodeboxes for map generation :)

Very true. So seems as if backface culling is only on the generated meshes?

[stu]

Seems pretty conclusive, though I am not sure you have discovered anything that is not already known but again, I could be mistaken, it does seem a bit silly.

Certainly a good reason to not use meshnodes or nodeboxes for map generation :)

Very true. So seems as if backface culling is only on the generated meshes?

I think the term is occlusion culling but yeah, maybe that too :)

[Skulls]

Look at this crazy! Generated nodes on the left, blender mesh on the right with a tail and a floating on each side.



The surfaces are actually merged per node type. Now that is some clever optimization. Very nice!

[Drachenbauer32]

you should not go only for memory.
There are more differences:
with meshes, you have more freedom for designing your stuff:
-you can add slopes and curves to the shape (not only horizontal and vertical rectangle surfaces)
-you can create more detailed texturing (sample: a fireplace can have a ceramic-tiled outside and a dark inside with wooden logs as fuel in there and also animated flames, all in a single node)

[sirrobzeroone]

I asked a similar question a few months back and Krock gave some awesome info:

http://forum.minetest.net/viewtopic.php?f=47&t=23262