Usage — Block Reality

The creative tab

Everything is in one creative tab, Block Reality.

Item	Id	What it is
Structural Steel	`steel_rect_200x400`	a 6-DOF beam, 200 × 400 mm section
Concrete Slab	`concrete_slab_200`	a MITC4 shell facet, 200 mm thick
Stress Glasses	—	the lens: hold it to see anything at all

The two blocks are two different element types, not one type in two colours. Steel is solved as a line element carrying axial force, shear, moment and torsion. A slab is solved as a plate.

What counts as grounded

A structural block is grounded when the block directly below it is a solid, non-structural block. Stone, dirt, anything ordinary.

Nothing else grounds anything. A beam butted sideways against a wall is not held by it, and the analysis will correctly call the result a mechanism. That trips people up, but it is the same answer any real frame analysis would give.

Your first structure

Build something small

Stack a few Structural Steel blocks on the ground. Start small: with a short column you already know what the answer should be, so it is easy to tell whether you are reading the HUD right.

A short column of Structural Steel blocks standing on snow, with the Block Reality items in the hotbar — Four Structural Steel blocks on the ground. The bottom one rests on a solid block, so the whole run is grounded.

Hold the Stress Glasses and look at it

The HUD only shows while you are holding the glasses. Look at a member and its section diagram appears in the corner.

The Stress lens reading a single steel member, with a section diagram showing top and bottom fibres both in compression — The Stress lens on that column. Both extreme fibres read `COMPRESSION −0.15 MPa`: a column carrying only its own weight is in uniform compression, with no bending to make the two faces differ.

Put a load on it

Sneak-right-click a block with the glasses in hand to apply a 20 kN test load. The same click removes it again.

A cantilever is worth building next. It is the first case where the numbers are not obvious:

Build a stone wall five blocks high.
Put one Structural Steel block on top of the wall, then four more in a line out from it, into the air. The first rests on stone, so it is grounded; the other four hang off it.
Hold the Stress Glasses.
Sneak-right-click the far end to apply the test load.

Reading the HUD

The top block of text describes the whole structure. The lines under it describe the member you are looking at.

Line	What it means
`max D/C`	worst demand-to-capacity ratio anywhere in the structure. Below 1 it holds, at or above 1 it does not.
`n members`	how many members the solver found, after merging collinear blocks into single runs.
`buckling λ_cr`	linear buckling load factor. Multiply the current load by this and it buckles. Below 1 means it buckles under what is already on it.
`contour full scale`	the stress range the colour ramp covers right now. It rescales, so the same red will not mean the same number in two different shots.
`member #n`	the member under your crosshair, with its section name.
`governing fibre`	which face of the section is the critical one. `section at x = …` is how far along the member that station sits.

The diagram itself is the stress profile through the depth of the section, with the neutral axis and the extreme fibre values written out.

Whether the top fibre is in tension or compression depends on the structural form, not on the beam. A cantilever hogs, so its top fibre is in tension. A beam supported at both ends sags, so its top fibre is in compression. Both readings are correct, which is why the HUD states them in words rather than leaving them to be inferred from colour.

The three lenses

Right-click the air to cycle through them:

Utilisation → Stress → Material

Utilisation is the one to leave on. It colours every member by how close it is to capacity:

safe
approaching limit
at or over capacity

Utilisation lens across two portal frames, one coloured red at or over capacity, reporting max D/C 2.652 — Two portal frames. The near one is red at `max D/C 2.652`, well past capacity; the far one is still teal. The HUD also reports `1 of 2 structures are unrestrained`.

Cases worth trying

Nothing supporting it: Reported as a mechanism rather than a structure. Nothing is holding it up, so there are no stresses.
Overloaded: Max D/C rises above 1 and the member turns red.
A tall slender column: Stress D/C stays low while the buckling load factor drops below 1. Strength and stability are different questions.

Commands

Command	What it does
`/br status`	engine state, every path searched, last result
`/br members`	per member: D/C, governing fibre, governing section, peak
`/br section <id>`	per station, in text
`/br scan [radius]`	re-read the chunks around you (default radius 4, so 9×9), for blocks placed by command or WorldEdit
`/br resolve`	force re-analysis
`/br reset`	restart the engine after it has been disabled (OP only)

Scope

Implemented: 6-DOF beams; MITC4 shells including floors and shear walls; linear buckling with geometric stiffness for both beams and shells; per-member and per-shell D/C; surface stress contours.

Not implemented:

The shell D/C is an elastic surface screen only. Transverse shear is recovered and reported but not screened, and there is no per-plate buckling check and no plate ultimate strength.
No composite reinforced-concrete sections. The section catalogue is solid rectangles and circles, named so.
No nonlinear post-buckling. The buckling factor is the linear onset, an upper bound on the real critical load.

Every solve returns a global equilibrium residual computed independently from geometry and density rather than read back from the assembled load vector. The verification record for this build — engine identity, every benchmark against its closed form, cross-platform determinism and timing — is in the repository.

Read the verification record