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https://github.com/MaSzyna-EU07/maszyna.git
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be4d691ae2
Levels changed at fixed distances - 512 m, 1 km, 2 km and on - whatever the window, the field of view or the zoom. Now a level is used out to the distance where one of its sample spacings covers terraindetail pixels on screen, 3 by default, which follows from the viewport height and the vertical field of view with the zoom applied; each level doubles the spacing, so each doubles the distance. Zooming in or a taller window pushes detail further, a coarser setting pulls it in. The finest range never drops below four tile sides, which the morphing needs to close the seams. Levels and morphing both follow the finest range the last scan used, so they always agree, and a change of more than a percent - a zoom, a resize - triggers a rescan. tools/terraincook/seamcheck.py now also tries finest ranges of 5.7 and 11.3 tiles, and finds no gap in any of them. terraindetail is in the ini and on a slider in the debug panel; the panel's level table and the residency line in the log show the resulting ranges. On baltyk the current window works out to 484 m, so the 512 m minimum applies and nothing changes by default; a scenery setting terraindetail 1 got 1349 m, and the samples on the gpu went from 3 MB to 10 MB with it.
98 lines
4.2 KiB
C++
98 lines
4.2 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 <algorithm>
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#include <array>
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#include <cmath>
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#include <cstddef>
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#include <cstdint>
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#include <string>
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#include <vector>
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export module eu07.rendering.terrainstatus;
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export {
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// Which level a tile is drawn at follows from what its samples look like on screen: a level is
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// used out to the distance where one of its sample spacings covers the detail setting in
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// pixels. Each level doubles the spacing, so each doubles that distance too. Pixelsperunit is
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// the viewport height over twice the tangent of half the vertical field of view - what a
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// metre at a metre's distance spans - so zooming in or a taller window pushes detail further.
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//
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// The finest range never drops below four tile sides, whatever the screen: the morphing below
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// only closes the seams when a level's range is several tiles long.
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inline constexpr double terrain_finest_tiles { 4.0 };
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inline double
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terrain_finest_range( double const Gridstep, double const Tilesize, double const Pixelsperunit, double const Detail ) {
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return std::max( terrain_finest_tiles * Tilesize, Gridstep * Pixelsperunit / std::max( 0.1, Detail ) );
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}
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// how far the camera may move before the tiles in range and their levels are worked out
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// again, in tile sides
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inline constexpr double terrain_rescan_tiles { 0.25 };
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// the distance up to which a level is used, given the finest level's range
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inline double
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terrain_level_distance( std::uint32_t const Level, double const Finest ) {
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return Finest * std::pow( 2.0, Level );
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}
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// A tile morphs into the next level over a band at the far end of its level's range. Two
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// neighbours at levels L and L+1 then meet exactly when, all along their shared edge, the
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// finer tile has finished morphing and the coarser one has not started. The band ends a
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// rescan's worth of travel short of the range, because levels are chosen where the camera
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// was at the last rescan while the morph follows the camera every frame; and it is a fifth
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// of the range wide, which keeps the coarser tile's band, a whole range further out, clear of
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// any edge a finer tile can reach. Both were settled by a geometric test over random camera
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// positions, three tile sizes and several finest ranges (tools/terraincook/seamcheck.py),
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// which finds no gap with these values and finds them at every level boundary with a band
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// ending at the range itself.
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inline constexpr double terrain_morph_band { 0.2 };
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// the distances, from the camera, over which a level L tile morphs into level L+1
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inline double
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terrain_morph_end( std::uint32_t const Level, double const Finest, double const Tilesize ) {
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return terrain_level_distance( Level, Finest ) - terrain_rescan_tiles * Tilesize;
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}
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inline double
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terrain_morph_begin( std::uint32_t const Level, double const Finest, double const Tilesize ) {
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return terrain_morph_end( Level, Finest, Tilesize ) - terrain_morph_band * terrain_level_distance( Level, Finest );
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}
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// what one terrain field's streamer is doing, kept by the field and read by the debug panel
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struct terrain_statistics {
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std::size_t resident { 0 }; // tiles holding gl textures
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std::size_t inview { 0 }; // resident tiles within range in the last update
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std::size_t wanted { 0 }; // tiles in range missing, or at the wrong level
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std::size_t uploaded { 0 }; // uploads since opening
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std::size_t dropped { 0 }; // arrivals discarded as stale since opening
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std::size_t texturebytes { 0 };
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std::array<std::size_t, 8> perlevel {}; // tiles in view at each level
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};
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// one field as the debug panel shows it. the renderer writes it once a frame from the main
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// view, the panel reads it; neither needs to know the other's types
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struct terrain_field_status {
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std::string path;
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float gridstep { 0.f };
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float tilesize { 0.f };
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float range { 0.f };
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float finest { 0.f }; // range of the finest level, from the screen
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std::uint32_t levels { 0 };
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std::size_t backlog { 0 }; // tiles the loader has queued or finished and not handed over
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terrain_statistics stats;
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};
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inline std::vector<terrain_field_status> TerrainStatus;
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}
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