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Today's work on the binary scene format plan (binary-scene-format-plan.md), from the first measurement to a terrain that bakes itself on first run and streams from a thread. The step-by-step history is kept on backup/scene-streaming-format-presquash-0916. Measuring first. -loadprofile times a scenery load by stage and by node kind and reports node counts and resident memory. On l204 terrain is 95% of the bytes and 99.8% of the nodes; on quarkmce2007 vehicles, not models, dominate what is left. The terrain turned out to be a heightfield in all but name, a ribbon covering 12% of its bounding box. The heightfield. scene/heightfieldformat.h is the .ehf layout: Morton-ordered tiles of 128 samples with one shared edge sample, a point-sampled mip chain, zstd per tile, a nodata sentinel, a material palette with a measured tiling per material, and a stamp of the rules that decided what counted as terrain. scene/heightfieldreader.h reads it for the tool, the renderer and the loader alike, and scene/terraincooker.h writes it, shared by the terraincook tool and the engine so a first-run bake is the file the tool would have made. The cooker rasterises every triangle where it is drawn (through scene::place_in_world, the placement the region applies too), keeps an upper surface laid within half a metre over another and the lower of two further apart, and then asks each triangle whether the heightfield shows it: laid, reaching a sample, keeping nearly all it claimed, and with the ground around it drawn at every level out to 2 km. Baking on first run. simulation/terrainbake bakes <scenario>.ehf the first time a scenery is opened, choosing the grid step from the first 200,000 vertices, and on later loads leaves out the triangles its node table says the heightfield shows. Everything else - trees, grass tufts, gantries, bridge decks - is drawn as written, so a bad bake can at worst draw something twice, and the heightfield sits 2 cm under the triangles so the original wins there. Nodes are keyed by file, line, include parameters and placement; an edited file changes its keys and those nodes are drawn again. A bake under older rules, or without its table, is thrown away and redone. A launcher copy named $scenario shares the scenario's files. -nobaketerrain shows the triangles as written. A scenery can still name hand-cooked fields, several at different steps. Drawing and streaming. rendering/terrainclipmap draws resident tiles at the mip level their distance earns, deriving the grid from gl_VertexID and texturing in world space with the scenery's own materials. rendering/terraintileloader reads and decodes tiles on a thread of its own; the renderer rescans what is in range only after moving a quarter of a tile, asks for what is missing nearest first, uploads at most 32 tiles a frame, drops arrivals the camera has moved past, and keeps drawing a tile at the level it has until the right one arrives. The terrain has its own range, terrainrange in the ini and a slider in the debug panel, 20 km by default and independent of basedrawrange; the far plane of an ordinary view is pushed out to it. The debug panel shows the range, tiles in view, on the gpu, wanted and queued, and how many sit at each level. Events. The event queue moved out of the events into a binary heap with a deterministic tie-break, and an event is handed its activator instead of storing it, so basic_event is a definition and nothing else. The logic container. scene/logicformat.h and scene/logiccontainer write a scenery's events, their targets and sibling chains as flat, deterministic arrays with a schema hash that refuses a mismatched build. simulation/logiccook cooks it from the loaded state whenever it is missing, stale or unreadable, reads it straight back to check it, and resolves each target to a position in the registry its event kind searches. -cooklogic forces a cook, -verifylogic only checks. Nothing reads it at load yet. Prefabs. scene/prefab describes a signal by the aspects it can show - lights, speeds, animation channels, a sound - instead of pasting an .inc per variant, and expands an instance to ordinary scenery text. Tried on a light signal and a shape signal. Screenshots without a person present: -shot x,y,z[,yaw[,pitch]], -shotsettle, -shotstay.
91 lines
3.0 KiB
C++
91 lines
3.0 KiB
C++
/*
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This Source Code Form is subject to the
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terms of the Mozilla Public License, v.
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2.0. If a copy of the MPL was not
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distributed with this file, You can
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obtain one at
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http://mozilla.org/MPL/2.0/.
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*/
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module;
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#include <condition_variable>
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#include <cstddef>
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#include <cstdint>
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#include <deque>
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#include <mutex>
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#include <optional>
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#include <string>
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#include <thread>
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#include <vector>
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#include "scene/heightfieldreader.h"
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export module eu07.rendering.terraintileloader;
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export {
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// Reads and decodes heightfield tiles on a thread of its own.
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//
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// Reading a tile means a seek, a read and a zstd decode, which is too much to do on the render
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// thread for the dozens of tiles a moving camera asks for at once. This does that part and
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// nothing else: it knows no gl, keeps its own file handle, and hands back plain sample arrays
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// for the renderer to upload at a pace it chooses.
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//
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// The renderer says each frame what it wants, nearest first, and that list replaces whatever
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// was asked for before and has not been started. A tile the camera has already left is never
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// read, and the nearest tile is always the next one read.
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class terrain_tile_loader {
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public:
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struct request {
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std::int32_t x { 0 }, z { 0 };
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std::uint32_t level { 0 };
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bool operator==( request const & ) const = default;
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};
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struct payload {
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request tile;
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bool valid { false };
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std::vector<std::uint16_t> heights;
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std::vector<std::uint8_t> materials;
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};
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terrain_tile_loader() = default;
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~terrain_tile_loader();
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terrain_tile_loader( terrain_tile_loader const & ) = delete;
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terrain_tile_loader &operator=( terrain_tile_loader const & ) = delete;
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// opens the file on the loader's own handle and starts the thread
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bool open( std::string const &Path );
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// stops the thread; anything not collected is dropped
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void close();
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// replaces the list of wanted tiles, nearest first. tiles being read or already read and
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// not yet collected are left out of it, so asking again every frame costs nothing
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void want( std::vector<request> const &Requests );
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// moves up to Count finished tiles into Out, returning how many
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std::size_t collect( std::vector<payload> &Out, std::size_t const Count );
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// tiles queued or finished and not yet collected
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std::size_t backlog() const;
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private:
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void work();
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// whether the tile is being read or waits to be collected. caller holds the lock
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bool underway( request const &Tile ) const;
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heightfield::reader m_reader;
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std::thread m_thread;
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mutable std::mutex m_mutex;
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std::condition_variable m_wake;
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std::deque<request> m_pending;
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std::optional<request> m_running;
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std::deque<payload> m_done;
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bool m_stop { false };
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// finished tiles allowed to wait for collection. past this the thread stops reading:
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// the renderer uploads at its own pace, and a backlog read for where the camera was a
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// second ago is work spent on tiles nobody wants any more
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static constexpr std::size_t donelimit { 32 };
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};
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}
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