1b8b55d3ee37d13a9d8533784a343ac1755b4153
10
Commits
| Author | SHA1 | Message | Date | |
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 Martino Ferrari
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1b8b55d3ee |
feat: a phosphor density is the trace, one grid per trace in its own colour
A user looked at the display and reported three things at once: "there is clearly a gain offset between latest acquisition and persistent image", "persistent instead of being brighter + opaque is just gray/white", and "last acquisition does not seem to be affected, it looks like persistent image + last acquisition (so for example last acquisition never fade in time mode)". What they add up to is that this was not a phosphor yet: it was a **density with a solid trace drawn over it**. Four changes, and the first is the one the others follow from: - **The current acquisition is deposited like every other, and no solid trace is drawn over the image.** `Renderer::draw_traces()` returns at once while a density is on: the trace ink *is* the image, so the newest acquisition is a sweep inside it and fades with it. Drawing the polyline as well put a solid, unfading stroke over its own faint ghost -- the reported "persistent image + last acquisition", where the last acquisition never faded in time mode. - **One grid per trace, in that trace's own colour.** `Plot::density_grid(trace)` is one screen-sized `f32` grid per trace, deposited from that trace and drawn in `Trace::color`, because a density that had one hue for the plot could not say *which* trace put the ink there -- two signals agreeing in a cell would be one blended pixel. The display's memory is therefore `traces * columns * rows * 4` bytes rather than one plot's worth (a trace with no series, an unbound slot, holds no grid), which is the one cost this change adds: four signals in one 800x480 row are four grids, 6 MB. - **The ceiling is the trace's own brightness, not the fade's steady state.** `full_scale` now defaults to **one sweep**: a cell with one acquisition's ink is drawn in its trace's colour at that colour's own alpha, and a signal crossing the same place every acquisition settles *at* the colour its trace would have drawn (the ceiling clamps) rather than a fraction of a brighter steady state -- the gain offset the user reported. `Style::density`'s near-white 0.85 tint is gone with it, because there is no one tint any more. A caller that wants the fade's ramp on screen instead still sets `full_scale` to the sum the fade settles at and accepts the offset; that is a legitimate choice, just not the one a phosphor makes. The reading is a **framebuffer** one, because neither `ink`/`peak` nor a tint can make a colour or a fade: `a_phosphor_density_is_the_trace_in_its_own_colour` deposits one sweep, checks the saturated cell is *exactly* the trace's colour (`full=224`, the trace's `0xE0` green, against `bg=25` -- the old monochrome tint read ~190 red), then fades it one time constant and checks the same pixel is dimmer (`faded=115`) and still the trace's hue -- which a stroke over the density could not do. It moves the trace and draws without depositing to prove no polyline is drawn (`moved` equals the no-density frame at the moved row), and reads a steady state against a quarter of it (`steady=224`, `quarter=138`), in the signal's colour throughout. `a_density_holds_one_grid_per_trace` reads two traces' grids apart (`267 472 cells each, ink 584/584`, in two rows). The grid's own cases are unchanged where they should be (`a_density_halves_per_acquisition_and_keeps_the_newest_brightest` `peak_steady=2.000`, `a_density_fades_by_its_time_constant` `exp(-dt/tau)`). Suite: **397 cases, 0 failed**, 4/4 ctest entries. |
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Martino Ferrari
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738205293e |
fix: the density's brightness ceiling is the fade's steady state, and the ramp is linear
A user looked at the display and reported "the colour fading is not applied, it looks white or full color, no opacity gradient" -- and the *numbers* were right: ink decayed, `step-time` was 1/e, `step-acquisitions` was 1 + 0.5 x 1. It was the mapping from a cell's value to a pixel. **Neither the shader nor the blend was wrong** (the answer to the question that was asked): the fragment write is already the weighted one (`vec4(u_color.rgb, u_color.a * ink)`) with the frame's straight-alpha blend, and a cell at half ink over a grid line rendered 160 where the arithmetic predicts 160. What was wrong was the **scale**: - `full_scale` defaulted to **1.0**, so the *newest* acquisition already sat at the ceiling and everything above it clamped to the same pixel -- a display of one sweep and a display of five were one white. It is now **1/(1 - 0.5) = 2.0**, the steady state of the default per-acquisition fade, so one sweep reads half ink and white is reached only where acquisitions agree. A caller whose fade settles elsewhere states its own sum (udpscope's is `1/(1 - factor)`, in its commit). - `gamma` defaulted to **0.45**, the value `Style::intensity_gamma` wants where the measure is a *dwell fraction*; on a *count* it spends most of the ramp on the last sweep (a quarter of the scale mapped to 0.54). It is now **1.0 -- linear in sweeps**, because half as many sweeps must read as half the ink. The case that would have caught this is a **framebuffer** reading, not the grid's, and `a_phosphor_density_is_drawn_under_the_traces` now makes it: it fades the grid to a quarter through the time rule (`dt = tau ln 4`, asserted at 0.25 off the ink) and reads the same pixel back, so the ramp is asserted where the eye sees it -- **`empty=21 full=83 quarter=54`** (red channel), against the 199 / 199 the ceiling and a single sweep both read at the old defaults. A full cell must be measurably above the background and above a quarter cell, and a quarter cell above the background: three assertions on pixels, none of which the grid's own numbers can make. Suite: **396 cases, 0 failed**, 4/4 ctest entries. |
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Martino Ferrari
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6a6915e64e |
feat: a plot can carry a phosphor density, one image for every acquisition
`Plot::set_density()` gives a plot a **phosphor density**: a screen-sized intensity image behind its traces, into which each acquisition is deposited and which fades by a time constant or by a per-acquisition factor. It is the library's and not a host's because the library is the side that knows a trace's device geometry -- a host would be re-rasterising traces the renderer has already staged, at a second derivation of the same mapping. It is an **image and not a set of retained traces**, and that is the whole of its cost: one `f32` cell per device pixel of the axes rect (`DensityGrid`), a cell's value a *number of sweeps*, so a display of a thousand acquisitions costs what one costs and there is no depth to get wrong. Measured on a 640x360 viewport's axes: **573x313 = 179 349 cells, 717 396 bytes** of grid, and one byte per cell uploaded on the frame the grid moved. - `Plot::accumulate_density()` deposits the acquisition on screen: every visible trace's window is mapped to sample indices and gathered exactly as `Renderer::draw_traces()` maps it, then walked column by column -- so the deposit is bounded by the axes' columns and not by the samples behind them -- and a cell takes **1.0 once per trace per sweep**, however many of that trace's own samples crossed it. Counting the hits instead put a single dense sweep at the ceiling of the brightness scale and hid the sweeps behind it, and it made a cell mean "how much the beam moved here" rather than "how many acquisitions were here"; the dedupe is a stamp per grid *row* (one `u64`, keyed by trace and column) so two sweeps agreeing on a cell still count twice. Dwell is a different question the library already answers (`Style::intensity_grading`). - `decay_density(dt_s)` fades by the clock, `clear_density()` and switching the density off drop the image at once. `DensityConfig` carries `full_scale` and `gamma`, applied on the CPU when the grid changed: the value a host reads back through `ink()`/`peak()` and the picture it sees are one derivation, and a frame whose grid did not move skips the conversion and the upload entirely (`FrameStats::density_cells`/`density_upload_bytes`, the latter the *frame's* total over every row, which one row's assignment used to overwrite). - The renderer draws it as one attribute-less quad over the axes rect (`kDensityVS`/`kDensityFS`, `DensityProgram`), over the grid and the invalid-span bands and **under the traces**, inside the axes' clip: it reserves no layout space and nothing on it can be picked, exactly as `Plot::set_invalid_spans()` does. `Style::density` is its tint. - The two fades are the two questions a persistence display can be asked -- "still visible a second later" and "the N-th back is gone" -- so the choice is the caller's. Six cases, all in the suite: four plot-level ones (the grid's resolution and memory, the per-acquisition schedule **584 -> 876 -> 1022** ink with `peak_steady=2.000`, `exp(-dt/tau)` off the ink, and the deposit's own geometry including a NaN as a gap) and one on the real driver (`a_phosphor_density_is_drawn_under_the_traces`: `cells=179349 uploaded=179349` on the moved frame and `uploaded=0` on the identical one after it, with the trace's stroke keeping its own colour over the ink). The suite is **396 cases, 0 failed** and all four ctest entries pass. |
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Martino FerrariandClaude Opus 4.6
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37e414bcc5 |
feat: grade a sparse window's polyline by slope, so phosphor does not switch off on zoom
Intensity grading was gated on the column reduction, which is gated on a density whose only job is killing the moire beat. Dwell has nothing to do with that, so narrowing a window past the threshold turned the whole phosphor model off and a discontinuity went from a third of a flat top's ink to all of it in one pixel of zoom. stage_trace_slopes() grades each segment by its own slope instead, with a measure that agrees with the dense path at the boundary, and reports itself as FrameStats::slope_traces -- disjoint from column_traces, so a host asserting graded_traces == column_traces reads the same as before. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> |
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Martino FerrariandClaude Opus 4.6
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cc908efa36 |
feat(render): a reduced column can be graded by dwell, not drawn as one flat band
A pixel column reduced from a dense envelope is honest about where the signal went and silent about how long it was there: its min and max are identical whether its samples fill the span or pile at its two ends, so a ramp and a pulse are one band. Style::intensity_grading grades it instead -- bright where the signal sits, faint where it only passes through -- by asking the gather for a level finer than the pixel grid and reading the distribution from those sub-buckets. Off by default: a change of look, not a correction of one. The measure is dwell per row, each segment depositing one unit spread over the rows it spans; counting +1 per row instead grades a sine's fast middle as brightly as its rails, which is the pattern inverted. The accumulator is one column wide (a full w*h density image is 33 MB at 4K) with each span written as two delta writes, and normalisation is against the column's own peak -- a frame-wide scale fades the trace out exactly where it moves fastest. Alpha is quantised into tiers, one LineBatch and one draw call each, because the line pipeline's colour is a uniform and a per-segment alpha is inexpressible. The finer ask is floored at level 1 whenever the flat path would have used the pyramid: level_for() answers 0 -- raw samples -- as soon as a sub-column falls under one bucket, so an unfloored ask turns a moderately dense frame into an O(visible) gather (measured at 172 samples a pixel: raw=1154 lod=0 and 6.4 ms a frame against raw=710 lod=453 and 2.3 ms). Grading is a way of drawing a reduction and may not undo it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> |
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Martino FerrariandClaude Opus 4.6
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e81e84645f |
fix(render): a dense trace is drawn one column at a time, not as a polyline
An LOD envelope staged as a polyline moirés. level_for() sizes a bucket at one to two pixel columns and Envelope emits two points per bucket, so a column carries three or four near-vertical hairlines at as many sub-pixel phases; under src-alpha compositing its brightness is then a non-linear function of those phases, the pattern repeats at the beat between the bucket pitch and the pixel pitch, and a pan sweeps the beat so the banding crawls. draw_traces now reduces such a window onto the pixel grid: one exactly vertical segment per integer column of the axes, from the lowest to the highest screen y any gathered point put in it, flushed in framebuffer pixels with the snap on. One phase for the whole trace, so there is nothing left to beat -- and the geometry becomes O(axes.w) rather than O(buckets). Gated on the gathered density rather than on the level (the raw path beats the same way), and on Envelope alone. A hole stays a hole, disjoint neighbours are joined so a fast edge keeps it, and a span under the stroke is drawn as the stroke since the shader caps nothing. It is the one carve-out in u_snap's data/chrome rule: a column is a pixel column, and the y bounds it reports are untouched. Measured by the new test as the number of distinct coverage levels in the ink -- 4 against the polyline's 126, with 627 segments against 60 054. A count of partially covered pixels was tried first and separates nothing (577 against 652): a 1.5 px stroke's fringe always spills into the next column. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> |
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Martino Ferrari
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c960decaea |
feat(plot): the readout marker snaps to the sample it quotes, and the value mode is a choice
The mark was placed at the *pointer's* x with the quoted sample's y, so with the nearest-sample readout it sat off the datum horizontally -- and further off the deeper the zoom. `CrosshairRow` now carries the data `x` the value belongs to and the marker is placed from it, so in `NearestSample` the mark lands on the sample the panel is quoting. `Style::crosshair_marker_px` (9) and `crosshair_marker_width` (1.5) replace the renderer's hard-coded 3 px arm and 1 px stroke: a snapped mark lands among a trace's own sample dots (`marker_px`, 3) and at that size would read as one more sample rather than as the answer to the question the hover asks. `CrosshairValue` makes the previous behaviour reachable rather than deleted. The two modes answer different questions -- `NearestSample` "which datum is under the pointer", `Interpolated` "what is the signal at this instant" -- and only the caller knows which it is asking, so the plot offers both with the sample as the default. `crosshair_interpolate()` is restored for it. `Plot::crosshair_point()` is the lookup with both coordinates, public because a host that draws instruments of its own needs the same snap and a second rule for it would drift from this one; `crosshair_value()` delegates to it. |
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Martino FerrariandClaude Opus 4.6
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c028f48fa0 |
fix(plot): a crosshair readout quotes a sample, never a value between two
The readout's y was a linear interpolation between the two samples adjacent to the pointer, which answers "what is the signal at this instant" -- a number the series does not contain. On a source whose samples are already averaged or decimated at ingest that is a value nothing measured, and at a zoom past the sample spacing it is visibly not the datum under the pointer. `crosshair_span()`'s `t` becomes a selector rather than a blend factor: the nearer end wins, a tie reading the earlier sample (the bias the span already takes for a degenerate pair). `t` is measured on the samples' own x through `neighbours()`/`x_at()`, so "nearer" is exact on a non-uniform clock too, and the lookup still reads level 0, so the value is a stored sample and never an LOD bucket's aggregate. `crosshair_interpolate()` had no other caller and is gone. `CrosshairRow::marker` is placed from the same y, so the dot follows the reported sample: past the sample spacing it sits beside the polyline rather than on it, deliberately -- one y feeding both keeps the mark and the number from ever disagreeing. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> |
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Martino Ferrari
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38ef459897 |
feat(plot)!: harden pipeline, XY series, dash/markers, touch, packaging
Breaking: Series::gather emits x relative to x0() and takes a GatherMode; consumers reconstruct absolute x in f64 before mapping (series.hpp documents the contract). Bugs, each pinned by a fail-before regression test: - render: f32 staging quantised epoch-time x into 128 px columns; every data-space draw now stages to_space(x) - to_space(origin) with the origin folded into the offset uniform in f64 (epoch/zero-origin twins rasterise identically) - ticks: major test was ULP-fragile and blanked epoch axes; majors are an integer-index test and are never truncated by the minor cap - gather: LOD envelope emitted buckets straddling [begin,end); ceil/floor bucket edges + raw lead/trail spans - live follow: log x axes held a linear span and zoomed every frame; span and offset now live in axis space (plot + both figure link-group paths) - input: a zero-notch wheel disarmed auto_scale on every axis; dy==0 pans x, factor == 1 / inf refused in wheel and drag zoom - render: the single text flush painted legend names over the crosshair readout panel; two batches, under flushed before the panel - data: NaN dropped from min/max unless it seeded the fold; non-finite samples are now excluded from every aggregate and from cached bounds Robustness: viewport normalisation (no clamp UB), non-finite range refusal, pyramid level cap at 57 (no shift/div UB through public gather), rounded ring capacity documented + pre-sized, GL blend func and UNPACK_ALIGNMENT save/restore, Renderer::release_gl() teardown, u64 buffer epochs, annotation captions clamped, button-aware GLFW row capture, cached figure row rects (no per-event layout), ruler-pair measurement refused, span-nonfinite guards in axis_ends. Features: XY series (sorted x, binary-search neighbours/snap, LOD over sample index); StreamSeries::freeze(); ArraySeries::push(); per-trace dash and markers (scatter at width 0) with auto or literal stride; GatherMode Envelope/Nearest/Mean via bucket_sum/sumsq; Style::line_aa_px; per-glyph text colour (readout values in trace colour); wheel-dx x pan; arrow-key pan; Escape cancels a drag and restores captured ranges; modifier-masked box zoom (Shift both, Ctrl x, Alt y); double-click reset via PointerEvent::time_s; ImGui key repeat unified; pinch gestures on Qt and GTK; pixelDelta wheel path and DevicePixelRatioChange handling; GNUInstallDirs, SOVERSION, SameMinorVersion, generated plot/version.hpp, relocatable plot.pc, licence install, FILES_MATCHING, GitHub Actions CI (debug/coverage/asan). Suite 283 -> 350 cases, 0 failed; coverage 93.9% (3730/3971) over 24 files, floor 80/90 held; ASAN preset suite green; all four demos run headless (the GTK scripted-resize check needs a window manager and fails identically on the parent commit); readme_main.cpp committed and compiles with the README command; pkg-config and find_package consumption verified from a relocated install prefix. |
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Martino Ferrari
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b7d0f901cc | docs: a user guide covering getting started, architecture, embedding, data, interaction, styling and testing |