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d2a5f284e3
Each resident tile had a height texture and a material texture of its own, uploaded with glTexImage2D, and was drawn once per material it held with every other material's fragments discarded, all of them whether in view or not. Thousands of draws a frame. Now the tiles of a level live in one pair of texture arrays (terrain_tile_pool), a layer per tile. A pool starts at sixteen layers and doubles when full, copying what it holds on the gpu, so a level takes only the memory its tiles need; uploads go through a pixel buffer orphaned for each tile. The ground textures of every material are gathered into one sRGB array with mipmaps (terrain_ground) - drawn into it layer by layer by a small shader once the engine has each texture ready, since the scenery's textures are compressed and cannot be blitted - with a table of placeholder colours and measured tiling beside it. Each frame the tiles in range are tested against the frustum by bounding sphere and gathered per level into a buffer texture of instance data, and each level is drawn in one instanced call. The fragment shader reads the four samples around it, drops the cell when any of them carries no ground - exactly the rule the bake already assumed - and blends the ground textures of their materials by distance, so material boundaries follow the samples smoothly instead of stepping along triangle edges. State the copy pass changes is captured and put back, and the texture unit cache is reset after raw binds, so the rest of the renderer finds things as it left them. On baltyk: all 30 materials land in the array, 663 of the 1120 tiles in range are drawn after culling, and a frame is at most six terrain draws. The residency line in the log now says how many tiles in range were drawn.
99 lines
4.3 KiB
C++
99 lines
4.3 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 drawn { 0 }; // of those, the ones inside the frustum in the last draw
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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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