Resources Numerical accuracy
Calculations
Every calculation under our calculation policies: what it works out, its formula and the precision it runs at. Open one to see its code as it is in the released app.
Calculations
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Where on the sheet
Names the part of the sheet a point is in, on a 3 × 3 grid (upper left, center, lower right and so on).
column = ⌊(x − x₀) ÷ w × 3⌋; row = ⌊(y₁ − y) ÷ h × 3⌋, each clamped to 0…2
Drawing comparison by vector paths changes.js64-bit- MarkupCraft
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Amount of change in an area
How many points of line were removed and added inside one changed area, and whether it counts as added, removed or modified.
removed = Σ hypot over removed pieces in the box; modified when both ≥ 6 pt
Drawing comparison by vector paths changes.js64-bit- MarkupCraft
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Segments clipped to a region
The parts of a sheet's segments that lie inside a task's region.
Liang–Barsky: r = q ÷ p per box side; keep when t₁ − t₀ > 1e-9
Drawing comparison by vector paths tasks.js64-bit- MarkupCraft
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Region snapshot
What a task's region link stores when it is made: the sheet's lines inside the region.
keep the 300 longest clipped segments; each coordinate rounded to 0.1 pt
Drawing comparison by vector paths tasks.js64-bit- MarkupCraft
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Has the region changed
Decides whether the drawing inside a task's region changed between the snapshot and the new revision.
changed when removed + added ≥ 4 pt and (removed + added) ÷ stored length ≥ 0.02
Drawing comparison by vector paths tasks.js64-bit- MarkupCraft
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Has a model element changed
Compares the stored state of a linked model element with its state now, number by number.
same when |x − y| ≤ tol
Drawing comparison by vector paths tasks.js64-bit- MarkupCraft
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Removed and added line reported
The amount of removed and added line shown after comparing two sheets by their lines.
amount = round(Σ hypot(Δx, Δy)) in points
Drawing comparison by vector paths markupcraft.js64-bit- MarkupCraft
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Sheets ranked by change
Ranks the sheet pairs of two sets by how much line changed and marks the ones that changed.
len = round(Σ hypot over removed and added); changed when len ≥ 6
Drawing comparison by vector paths markupcraft.js64-bit- MarkupCraft
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Clouds round the changes
Adds a cloud rectangle markup round each group of changes on every changed sheet.
cloud box = cluster box grown by 8 pt on each side
Drawing comparison by vector paths markupcraft.js64-bit- MarkupCraft
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Product of two transforms
Combines two affine transforms into one.
p′ = p × M (row vectors); (m × n) applies m first
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Inverse of a transform
The inverse of the matrix an object is painted with.
det = a·d − b·c; inverse = adjugate ÷ det
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Path coordinates rewritten
The new numbers of one path-building operator after a move, scale or turn.
U = C × T × C⁻¹; (x′, y′) = (x, y) × U, written with at most 4 decimals
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Matrix round a moved picture or form
The cm matrix written before a picture or form XObject that was moved, scaled or turned.
U = C × T × C⁻¹, six entries with at most 4 decimals
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Is this a move at all
Decides whether an edit's matrix changes anything.
|M − identity| < 1e-9 on all six entries
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Line width in the path's own units
Converts a line width given in page units to the units of the path's own space.
w = page width ÷ √|a·d − b·c|
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Replacement picture fitted into the old one's box
Scales a replacement picture to fit, centered, inside the box of the picture it replaces, keeping its own proportions.
ia = W ÷ H; ba = box w ÷ box h; (sx, sy) = ia > ba ? (1, ba ÷ ia) : (ia ÷ ba, 1)
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Advance of a text run as read
How far each text-showing operator moves the text position when a page's content is read, kept so a later edit can leave the rest of the line in place.
string: Σ (width ÷ 1000 × size + char spacing + word spacing on a single-byte space) × horizontal scale; number in TJ: −v ÷ 1000 × size × horizontal scale
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Advance of a text run
How far a string moves the text position, in unscaled text space.
Σ (glyph width ÷ 1000 × size + char spacing + word spacing on a space) × horizontal scale
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Padding after reworded text
The adjustment written after a reworded run so the text that follows on the line does not move.
k = −(old advance − new advance) × 1000 ÷ (size × horizontal scale)
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Matrix of a moved text run
The text matrix written before a text run that was moved.
Tm′ = (Tm × C) × T × C⁻¹
Edits to a page's own content base-content.js64-bit- MarkupCraft
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Line position put back after a moved run
Restores where the text line continues after a run on it was moved.
Tm = line matrix; then advance by −(start + advance) × 1000 ÷ (size × horizontal scale)
Edits to a page's own content base-content.js64-bit- MarkupCraft
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A move added to an object's edits
Adds a move, scale or turn to what an object already had.
T′ = T_old × T_new
Edits to a page's own content base-edit.js64-bit- MarkupCraft
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A moved path point
The new numbers of a path when one of its points or handles is dragged to a place on the page.
u = p_page × (C × T)⁻¹; attached handles shift by u − u_old
Edits to a page's own content base-edit.js64-bit- MarkupCraft
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Drawn-in paths written to the page
Writes paths that were drawn into the page, and the matrix of pasted content, as content stream text.
Edits to a page's own content base-edit.js64-bit- MarkupCraft
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A stored matrix accepted
Checks a move matrix read from a file or autosave before it is used.
|a·d − b·c| > 1e-9 and every |number| < 1e7
Edits to a page's own content base-edit.js64-bit- MarkupCraft
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Box of part of a text item
The box on the sheet round some characters of one piece of the drawing's text.
s = width × i ÷ n; box corners = origin + u·s + v·t, t from −0.22 to 0.9 of the size
Text positions: search hits and the OCR text layer textsearch.js64-bit- MarkupCraft
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Cloud round a search hit
The box of the cloud markup placed round a found word.
box = hit box grown by pad on each side
Text positions: search hits and the OCR text layer textsearch.js64-bit- MarkupCraft
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Picture scale for reading text
The scale at which a scanned page is drawn before its text is read.
s = min(dpi ÷ 72, maxSide ÷ max(w, h), √(maxPixels ÷ (w·h))), at least 0.05
Text positions: search hits and the OCR text layer ocr.js64-bit- MarkupCraft
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Matrix that places the text layer
The matrix that puts the recognizer's text-only page onto the sheet, written into the saved PDF.
M = viewport⁻¹ ∘ [W_px ÷ W_pt, 0, 0, −H_px ÷ H_pt, 0, H_px]
Text positions: search hits and the OCR text layer ocr.js64-bit- MarkupCraft
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Words placed on the sheet
The position, direction and size of each word read from a scan, for Find and Select text.
baseline y at x by linear interpolation along the line's baseline; size = height above the baseline ÷ 0.9
Text positions: search hits and the OCR text layer ocr.js64-bit- MarkupCraft
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Word count and mean confidence
The number of words read on a page and their mean confidence, for the status line.
conf = round(Σ confidence ÷ n)
Text positions: search hits and the OCR text layer ocr.js64-bit- MarkupCraft
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Rounding to 0.1 mm
The rounding applied to every stored mesh coordinate, plan polygon point and item size.
r1(v) = round(v × 10) ÷ 10
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Mesh point
Adds one point to a part's mesh.
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Ring loft
Trunks, pots, limbs and conifer tiers: rings of points round an axis joined into a capped solid.
a = 2π·i ÷ seg; p = [cx + rx·cos a, cy + ry·sin a, z]
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Crown and head blobs
Tree crowns, shrubs, rocks and heads: an icosphere scaled to an ellipsoid with a seeded bump.
t = (1 + √5) ÷ 2; unit point p; k = 1 + bump × (2·rand − 1); point = c + p × [rx, ry, rz] × k
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Wheel
A car wheel: a 14-sided cylinder along y.
a = 2π·i ÷ seg − π ÷ 2; p = [x + r·cos a, y, z + r·sin a]
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Canopy plan symbol
The plan outline of a tree: a 14-point irregular ring, a trunk circle and a cross.
a = 2π·i ÷ 14; k = r × (0.86 + 0.18·rand); p = [k·cos a, k·sin a]
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Library item sizes
The width, depth and height written into the library item.
Trees, people and cars from numbers entourage.js64-bit- ModelCraft
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Overhanging faces and their area
Which triangles need support, and their total area.
overhang if n_z < −cos((90 − angle)·π ÷ 180) and not on the bed; area = Σ triangle areas
Supports preview and material estimate print-supports.js64-bit- ModelCraft
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Support points under the overhangs
Grid points in plan that fall inside an overhanging triangle, with their height on it.
s = max(spacing, √(overhang area ÷ maxPoints)); (x, y) = ((i + ½)·s, (j + ½)·s); z = λ₁z_a + λ₂z_b + λ₃z_c
Supports preview and material estimate print-supports.js64-bit- ModelCraft
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Where a support lands
The height below each support point where a straight line down meets the model, or the bed.
bottom = z − eps − distance down to the first face, else bed z
Supports preview and material estimate print-supports.js64-bit- ModelCraft
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Column volume
The material one column adds to the estimate.
columns: V = s² × density × h; tree style: V = π × tip² × h; drawn radius = s × √(density ÷ π)
Supports preview and material estimate print-supports.js64-bit- ModelCraft
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Tree supports
Joins nearby support points to one trunk and adds the branches' and trunk's volume.
joint z = min(zᵢ − horizontal distanceᵢ ÷ tan(branch)); trunk radius = tip × √k; V = Σ π·tip²·lengthᵢ + π·r²·(joint z − base z)
Supports preview and material estimate print-supports.js64-bit- ModelCraft
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Sunrise, sunset and solar noon
The clock hours of sunrise, sunset and solar noon and the sun's highest altitude on a day.
hᵢ = min(0.05·i, 23.99), i = 0 … 480; rise = first hᵢ with altitude > 0 after one ≤ 0; noon = hᵢ of the highest altitude
Time of day, date and exposure from plain words scene-say.js64-bit- ModelCraft
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Clock hour for a named time
The hour that stands for dawn, morning, noon, afternoon, golden hour, dusk or night on a given day.
dawn = rise + 0.3; morning = rise + 0.45·(noon − rise); afternoon = noon + 0.55·(set − noon); dusk = set − 0.1; night = set + 2; hour = round to 0.01
Time of day, date and exposure from plain words scene-say.js64-bit- ModelCraft
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The look for the choices made
Combines time, date or season and weather into the sun's date and hour and the render's exposure.
month, day = round(given); exposure = round((weather + time of day) × 100) ÷ 100
Time of day, date and exposure from plain words scene-say.js64-bit- ModelCraft
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Places things can stand on
Top-level placements and large flat faces with their box, top height, height and area.
placement area = Δx × Δy of its box; face area from the model kernel; every number rounded to 0.001
Placing scene trees and people scene-entourage.js64-bit- ModelCraft
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Point inside a face outline
Whether a plan point lies inside a polygon.
count edges with (y_a > y) ≠ (y_b > y) and x < (x_b − x_a)·(y − y_a) ÷ (y_b − y_a) + x_a; inside if odd
Placing scene trees and people scene-entourage.js64-bit- ModelCraft
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The ground a request names
The region to scatter over, the height things stand at, and the boxes to keep clear.
on a placement: its box in plan, z = top of the box; on a face: its outline, z = first point's z; avoid boxes with top > z + 0.3 and bottom < z + 2.5
Placing scene trees and people scene-entourage.js64-bit- ModelCraft
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Planting trees
Places a number of trees over the region, each with a random turn and a size within 10% of the library's.
minimum distance = max(0.5, 0.9 × crown width); yaw = rand × 2π; scale = 0.9 + 0.2 × rand
Placing scene trees and people scene-entourage.js64-bit- ModelCraft
A calculation is added only after its source was read. Each statement can be checked in the code shown on its policy's page; the app repositories are public. When a release changes a calculation, its page says so until it has been read again.