Martino Ferrari
6a6915e64e
`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.
75 lines
2.5 KiB
C++
75 lines
2.5 KiB
C++
// SPDX-License-Identifier: MIT
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// SPDX-FileCopyrightText: 2026 Martino Ferrari
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#pragma once
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/// Umbrella header: pulls in every public component of the plot library, in
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/// layer order (`core/math -> gl -> data -> render -> plot -> input`), so a
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/// translation unit can include this one header and use the whole surface.
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///
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/// It deliberately stops at the library: the adapters under `adapters/` are
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/// separate targets -- each one drags in GLFW, Dear ImGui, Qt6 or GTK4 -- and
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/// pulling any of them in here would destroy the core's zero-dependency
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/// property, which is the point of `plot_core`.
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///
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/// The macro-gated instrumentation under `*/detail/` is not here either: those
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/// headers exist for the test suite's counters, define nothing without their
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/// PLOT_*_COUNT/PLOT_RING_STATS macro, and are documented as not part of the
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/// public surface.
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#include <plot/core/color.hpp>
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#include <plot/core/rect.hpp>
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#include <plot/core/span.hpp>
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#include <plot/core/status.hpp>
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#include <plot/core/types.hpp>
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#include <plot/math/mat3.hpp>
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#include <plot/math/transform.hpp>
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#include <plot/math/vec2.hpp>
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#include <plot/gl/api.hpp>
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#include <plot/gl/caps.hpp>
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#include <plot/gl/handle.hpp>
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#include <plot/gl/loader.hpp>
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#include <plot/data/array_series.hpp>
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#include <plot/data/minmax_pyramid.hpp>
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#include <plot/data/ring_buffer.hpp>
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#include <plot/data/series.hpp>
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#include <plot/data/stream_series.hpp>
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#include <plot/data/xy_series.hpp>
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#include <plot/render/embedded_mono_font.hpp>
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#include <plot/render/buffer.hpp>
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#include <plot/render/primitives.hpp>
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#include <plot/render/program.hpp>
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#include <plot/render/renderer.hpp>
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#include <plot/render/shaders.hpp>
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#include <plot/render/style.hpp>
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#include <plot/render/text.hpp>
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#include <plot/render/text_atlas.hpp>
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#include <plot/render/vertex_array.hpp>
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#include <plot/plot/annotation.hpp>
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#include <plot/plot/axis.hpp>
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#include <plot/plot/crosshair.hpp>
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#include <plot/plot/cursor.hpp>
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#include <plot/plot/density.hpp>
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#include <plot/plot/figure.hpp>
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#include <plot/plot/grid.hpp>
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#include <plot/plot/legend.hpp>
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#include <plot/plot/measure.hpp>
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#include <plot/plot/plot.hpp>
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#include <plot/plot/region.hpp>
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#include <plot/plot/ticks.hpp>
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#include <plot/plot/trace.hpp>
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#include <plot/input/controller.hpp>
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#include <plot/input/events.hpp>
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// The library version. The one public header configure_file() generates into
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// the build tree (see include/plot/version.hpp.in), so it is not under the
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// source include/ root with the layers above -- last here so the layer order
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// stays the story of the list.
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#include <plot/version.hpp>
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