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2660d14565444a0a946359103d85103005d93b2c
maszyna/rendering/terrainclipmap.cpp
maj00r 2660d14565 Stream the scenery: a baked terrain heightfield, a logic container, and prefabs 
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.
2026-09-16 23:18:09 +02:00

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/*
This Source Code Form is subject to the
terms of the Mozilla Public License, v.
2.0. If a copy of the MPL was not
distributed with this file, You can
obtain one at
http://mozilla.org/MPL/2.0/.
*/
module;
#include <algorithm>
#include <cmath>
#include <array>
#include <cstdint>
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>
#include "glad/glad.h"
#include "scene/heightfieldformat.h"
#include "global_include/interfaces/ITexture_macros.h"
#include "scene/heightfieldreader.h"
module eu07.rendering.terrainclipmap;
import eu07.glm;
import eu07.utilities.logs;
import eu07.rendering.renderer;
import eu07.model.material;
namespace {
// NOTE: glTexImage2D rather than glTexStorage2D. Immutable storage arrives with OpenGL
// 4.2 and this renderer holds a 3.3 context, where the entry point is simply not there -
// calling it jumps through a null pointer instead of failing in any visible way
GLuint
create_texture( GLenum const Internalformat, GLenum const Type, GLsizei const Side, void const *Data ) {
GLuint texture { 0 };
::glGenTextures( 1, &texture );
::glBindTexture( GL_TEXTURE_2D, texture );
// integer samples carry the cooker's values, no-data included, so nothing may filter them
::glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
::glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
::glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
::glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
::glTexImage2D( GL_TEXTURE_2D, 0, Internalformat, Side, Side, 0, GL_RED_INTEGER, Type, Data );
return texture;
}
} // namespace
terrain_clipmap::~terrain_clipmap() {
close();
}
bool
terrain_clipmap::open( std::string const &Path ) {
close();
if( ( false == m_reader.open( Path ) )
|| ( false == m_loader.open( Path ) ) ) {
ErrorLog( "Terrain: cannot open heightfield \"" + Path + "\"" );
close();
return false;
}
m_path = Path;
build_indices();
build_palette();
resolve_materials();
try {
gl::shader vertex( "terrainclipmap.vert" );
gl::shader fragment( "terrainclipmap.frag" );
m_shader.emplace( std::vector<std::reference_wrapper<gl::shader const>>( { vertex, fragment } ) );
}
catch( gl::shader_exception const &error ) {
ErrorLog( std::string( "Terrain: shader failed, " ) + error.what() );
close();
return false;
}
m_vao.emplace();
resolve_uniforms();
m_ready = true;
WriteLog(
"Terrain: " + Path + ", " + std::to_string( m_reader.tiles().size() ) + " tiles, "
+ std::to_string( m_reader.levels() ) + " levels, grid "
+ std::to_string( m_reader.gridstep() ) + " m, tile " + std::to_string( m_reader.tilesize() ) + " m" );
return true;
}
// uniform locations do not change once the program is linked, so they are looked up
// here rather than per tile per frame
void
terrain_clipmap::resolve_uniforms() {
auto const program { static_cast<GLuint>( *m_shader ) };
m_uniforms.tileorigin = ::glGetUniformLocation( program, "tileorigin" );
m_uniforms.samplestep = ::glGetUniformLocation( program, "samplestep" );
m_uniforms.heightbias = ::glGetUniformLocation( program, "heightbias" );
m_uniforms.heightscale = ::glGetUniformLocation( program, "heightscale" );
m_uniforms.nodata = ::glGetUniformLocation( program, "nodata" );
m_uniforms.side = ::glGetUniformLocation( program, "side" );
m_uniforms.heights = ::glGetUniformLocation( program, "heights" );
m_uniforms.materials = ::glGetUniformLocation( program, "materials" );
m_uniforms.palette = ::glGetUniformLocation( program, "palette" );
m_uniforms.groundtexture = ::glGetUniformLocation( program, "ground" );
m_uniforms.groundscale = ::glGetUniformLocation( program, "groundscale" );
m_uniforms.drawnmaterial = ::glGetUniformLocation( program, "drawnmaterial" );
m_uniforms.tileworld = ::glGetUniformLocation( program, "tileworld" );
m_uniforms.hastexture = ::glGetUniformLocation( program, "hastexture" );
m_uniforms.fallback = ::glGetUniformLocation( program, "fallback" );
}
void
terrain_clipmap::close() {
// the loader first, so nothing arrives for tiles that are being torn down
m_loader.close();
m_wanted.clear();
m_arrived.clear();
m_inrange.clear();
m_wantedlevel.clear();
m_scanrange = -1.f;
for( auto & [ tilekey, tile ] : m_tiles ) { retire( tile ); }
m_tiles.clear();
m_indices.clear();
m_indexcounts.clear();
m_vao.reset();
m_shader.reset();
m_palette.clear();
m_reader.close();
m_stats = {};
m_ready = false;
}
// index buffers, one per mip level. the grid they describe is the same shape at every
// level, only smaller, and the vertices themselves never exist in memory: the shader
// derives a sample's row and column from gl_VertexID
void
terrain_clipmap::build_indices() {
m_indices.resize( m_reader.levels() );
m_indexcounts.resize( m_reader.levels() );
std::vector<std::uint32_t> indices;
for( std::uint32_t level = 0; level < m_reader.levels(); ++level ) {
auto const side { m_reader.samples_per_side( level ) };
indices.clear();
indices.reserve( static_cast<std::size_t>( side - 1 ) * ( side - 1 ) * 6 );
for( std::uint32_t row = 0; row + 1 < side; ++row ) {
for( std::uint32_t column = 0; column + 1 < side; ++column ) {
auto const topleft { row * side + column };
auto const topright { topleft + 1 };
auto const bottomleft { topleft + side };
auto const bottomright { bottomleft + 1 };
indices.push_back( topleft ); indices.push_back( bottomleft ); indices.push_back( topright );
indices.push_back( topright ); indices.push_back( bottomleft ); indices.push_back( bottomright );
}
}
m_indexcounts[ level ] = static_cast<std::uint32_t>( indices.size() );
m_indices[ level ] = std::make_unique<gl::buffer>();
m_indices[ level ]->allocate(
gl::buffer::ELEMENT_ARRAY_BUFFER, indices.size() * sizeof( std::uint32_t ), GL_STATIC_DRAW );
m_indices[ level ]->upload(
gl::buffer::ELEMENT_ARRAY_BUFFER, indices.data(), 0, indices.size() * sizeof( std::uint32_t ) );
}
}
// placeholder colours, one per cooked material, so that the shape of the terrain and the
// division into surfaces can be judged before the real materials are wired in
void
terrain_clipmap::build_palette() {
m_palette.clear();
m_palette.reserve( std::max<std::size_t>( 1, m_reader.materials().size() ) );
for( std::size_t index = 0; index < m_reader.materials().size(); ++index ) {
auto const hue { static_cast<float>( index ) * 0.61803399f };
auto const phase { ( hue - std::floor( hue ) ) * 6.f };
auto const rising { phase - std::floor( phase ) };
glm::vec3 colour { 0.45f, 0.5f, 0.4f };
switch( static_cast<int>( phase ) ) {
case 0: colour = { 0.55f, 0.45f + 0.2f * rising, 0.3f }; break;
case 1: colour = { 0.55f - 0.2f * rising, 0.6f, 0.3f }; break;
case 2: colour = { 0.35f, 0.6f, 0.3f + 0.2f * rising }; break;
case 3: colour = { 0.35f, 0.6f - 0.15f * rising, 0.5f }; break;
case 4: colour = { 0.35f + 0.2f * rising, 0.45f, 0.5f }; break;
default: colour = { 0.55f, 0.45f, 0.5f - 0.15f * rising }; break;
}
m_palette.push_back( colour );
}
if( true == m_palette.empty() ) { m_palette.push_back( { 0.45f, 0.5f, 0.4f } ); }
}
std::uint32_t
terrain_clipmap::level_for( double const Distance ) const {
if( Distance <= terrain_finest_range ) { return 0; }
auto const steps { static_cast<std::uint32_t>( std::log2( Distance / terrain_finest_range ) ) + 1 };
return std::min( steps, m_reader.levels() - 1 );
}
void
terrain_clipmap::upload( terrain_tile_loader::payload const &Tile ) {
auto const tilekey { key( Tile.tile.x, Tile.tile.z ) };
auto const side { m_reader.samples_per_side( Tile.tile.level ) };
auto const existing { m_tiles.find( tilekey ) };
if( existing != m_tiles.end() ) {
// a level change means new textures: the sample count differs
retire( existing->second );
m_tiles.erase( existing );
}
resident_tile tile;
tile.x = Tile.tile.x;
tile.z = Tile.tile.z;
tile.level = Tile.tile.level;
tile.side = side;
tile.lastused = m_frame;
tile.heighttexture = create_texture(
GL_R16UI, GL_UNSIGNED_SHORT, static_cast<GLsizei>( side ), Tile.heights.data() );
tile.materialtexture = create_texture(
GL_R8UI, GL_UNSIGNED_BYTE, static_cast<GLsizei>( side ), Tile.materials.data() );
// the tile is drawn once per material it contains, so the set is worked out here
// rather than rescanned every frame
std::array<bool, 256> present {};
for( auto const material : Tile.materials ) { present[ material ] = true; }
for( std::size_t material = 0; material < present.size(); ++material ) {
if( true == present[ material ] ) { tile.materials.push_back( static_cast<std::uint8_t>( material ) ); }
}
if( auto const *description { m_reader.find( Tile.tile.x, Tile.tile.z ) } ) {
tile.minheight = description->minheight;
tile.maxheight = description->maxheight;
}
m_stats.texturebytes += static_cast<std::size_t>( side ) * side * 3u;
++m_stats.uploaded;
m_tiles.emplace( tilekey, std::move( tile ) );
}
void
terrain_clipmap::retire( resident_tile &Tile ) {
if( Tile.heighttexture != 0 ) { ::glDeleteTextures( 1, &Tile.heighttexture ); Tile.heighttexture = 0; }
if( Tile.materialtexture != 0 ) { ::glDeleteTextures( 1, &Tile.materialtexture ); Tile.materialtexture = 0; }
auto const bytes { static_cast<std::size_t>( Tile.side ) * Tile.side * 3u };
m_stats.texturebytes -= std::min( m_stats.texturebytes, bytes );
}
void
terrain_clipmap::scan( glm::dvec3 const &Viewpoint ) {
m_scanpoint = Viewpoint;
m_scanrange = m_range;
m_inrange.clear();
m_wantedlevel.clear();
auto const tilesize { static_cast<double>( m_reader.tilesize() ) };
auto const reach { std::max( 1, static_cast<std::int32_t>( m_range / tilesize ) + 1 ) };
auto const centrex { m_reader.tile_x( Viewpoint.x ) };
auto const centrez { m_reader.tile_z( Viewpoint.z ) };
std::vector<std::pair<double, terrain_tile_loader::request>> wishes;
for( std::int32_t z = centrez - reach; z <= centrez + reach; ++z ) {
for( std::int32_t x = centrex - reach; x <= centrex + reach; ++x ) {
if( false == m_reader.contains( x, z ) ) { continue; }
// distance to the nearest point of the tile, not to its centre. a regional
// field has tiles kilometres across, and a tile the camera is standing on
// can have its centre far outside the draw range
auto const west { x * tilesize };
auto const north { z * tilesize };
auto const nearestx { std::clamp( Viewpoint.x, west, west + tilesize ) };
auto const nearestz { std::clamp( Viewpoint.z, north, north + tilesize ) };
auto const distance {
glm::length( glm::dvec2 { nearestx - Viewpoint.x, nearestz - Viewpoint.z } ) };
if( distance > m_range ) { continue; }
auto const tilekey { key( x, z ) };
auto const level { level_for( distance ) };
m_inrange.push_back( { tilekey, level } );
m_wantedlevel.emplace( tilekey, level );
auto const resident { m_tiles.find( tilekey ) };
if( ( resident == m_tiles.end() ) || ( resident->second.level != level ) ) {
wishes.push_back( { distance, { x, z, level } } );
}
}
}
// nearest first, so the ground under the camera is never waiting behind the horizon
std::sort( wishes.begin(), wishes.end(),
[]( auto const &Left, auto const &Right ) { return Left.first < Right.first; } );
m_wanted.clear();
for( auto const &wish : wishes ) { m_wanted.push_back( wish.second ); }
m_loader.want( m_wanted );
}
void
terrain_clipmap::update( glm::dvec3 const &Viewpoint ) {
if( false == m_ready ) { return; }
++m_frame;
auto const moved {
glm::length( glm::dvec2 { Viewpoint.x - m_scanpoint.x, Viewpoint.z - m_scanpoint.z } ) };
if( ( m_range != m_scanrange )
|| ( moved > m_reader.tilesize() * 0.25 ) ) {
scan( Viewpoint );
}
// the tiles in range are touched every frame, which is what render() draws and what
// eviction spares
m_stats.inview = 0;
m_stats.wanted = 0;
m_stats.perlevel.fill( 0 );
for( auto const &tile : m_inrange ) {
auto const resident { m_tiles.find( tile.key ) };
if( resident == m_tiles.end() ) {
++m_stats.wanted;
continue;
}
// still wanted, at whatever level it has until the right one arrives
resident->second.lastused = m_frame;
++m_stats.inview;
++m_stats.perlevel[ std::min<std::size_t>( resident->second.level, m_stats.perlevel.size() - 1 ) ];
if( resident->second.level != tile.level ) { ++m_stats.wanted; }
}
m_arrived.clear();
m_loader.collect( m_arrived, m_uploadsperframe );
for( auto const &tile : m_arrived ) {
if( false == tile.valid ) { continue; }
// a tile read for where the camera was is put up only if nothing of it is on the gpu
// yet - some level is better than a hole. otherwise it is dropped, and the level
// wanted now is already queued
auto const tilekey { key( tile.tile.x, tile.tile.z ) };
auto const wanted { m_wantedlevel.find( tilekey ) };
auto const stillwanted { ( wanted != m_wantedlevel.end() ) && ( wanted->second == tile.tile.level ) };
if( stillwanted || ( false == m_tiles.contains( tilekey ) ) ) {
upload( tile );
// put up this frame, so drawn this frame
m_tiles.find( tilekey )->second.lastused = m_frame;
}
else {
++m_stats.dropped;
}
}
if( ( m_tiles.size() > m_budget ) && ( m_tiles.size() > m_stats.inview ) ) {
// over budget, and not everything is in view: drop whatever has gone longest without
// being asked for
std::vector<std::pair<std::uint64_t, std::int64_t>> aged;
for( auto const & [ tilekey, tile ] : m_tiles ) {
if( tile.lastused != m_frame ) { aged.emplace_back( tile.lastused, tilekey ); }
}
auto const excess { std::min( aged.size(), m_tiles.size() - m_budget ) };
std::partial_sort( aged.begin(), aged.begin() + excess, aged.end() );
for( std::size_t index = 0; index < excess; ++index ) {
auto const victim { m_tiles.find( aged[ index ].second ) };
retire( victim->second );
m_tiles.erase( victim );
}
}
m_stats.resident = m_tiles.size();
report_residency();
}
// the cooked material names are the ones the scenery used, so the engine resolves them
// exactly as it does for any other geometry. only the diffuse texture is taken: the
// terrain has its own shader and none of the rest of a material applies to it
void
terrain_clipmap::resolve_materials() {
m_materials.clear();
auto const &names { m_reader.materials() };
auto const &scales { m_reader.material_scales() };
m_materials.reserve( names.size() );
std::size_t resolved { 0 };
std::string unresolved;
for( std::size_t index = 0; index < names.size(); ++index ) {
material_binding binding;
binding.scale = ( index < scales.size() ? scales[ index ] : 4.f );
if( binding.scale < 0.01f ) { binding.scale = 4.f; }
auto const material { GfxRenderer->Fetch_Material( names[ index ] ) };
if( material != null_handle ) {
binding.texture = GfxRenderer->Material( material )->GetTexture( 0 );
}
if( binding.texture != null_handle ) {
++resolved;
}
else {
// drawn in its placeholder colour instead, so a missing texture shows up as
// an obvious flat patch rather than as black ground
unresolved += ( unresolved.empty() ? "" : ", " ) + names[ index ];
}
m_materials.push_back( binding );
}
WriteLog(
"Terrain: " + std::to_string( resolved ) + " of " + std::to_string( names.size() )
+ " materials resolved to textures" );
if( false == unresolved.empty() ) {
WriteLog( "Terrain: no texture for " + unresolved );
}
}
// residency settles within a second of the camera stopping and then barely moves, so a
// line is written when it shifts by a noticeable amount rather than every frame. that
// makes the warm figure - what the terrain actually costs - readable from the log
void
terrain_clipmap::report_residency() {
auto const difference {
m_stats.resident > m_reportedresidency ?
m_stats.resident - m_reportedresidency :
m_reportedresidency - m_stats.resident };
if( ( m_reported == true ) && ( difference < 16 ) ) { return; }
m_reported = true;
m_reportedresidency = m_stats.resident;
WriteLog(
"Terrain: " + std::to_string( m_stats.resident ) + " tiles resident, "
+ std::to_string( m_stats.texturebytes / 1048576 ) + " MB of samples, "
+ std::to_string( m_stats.uploaded ) + " uploads so far" );
}
void
terrain_clipmap::render( glm::dvec3 const &Viewpoint ) {
if( ( false == m_ready ) || ( true == m_tiles.empty() ) ) { return; }
m_shader->bind();
m_vao->bind();
::glUniform1f( m_uniforms.heightbias, m_reader.height( 0 ) );
::glUniform1f( m_uniforms.heightscale, m_reader.height( 1 ) - m_reader.height( 0 ) );
::glUniform1ui( m_uniforms.nodata, heightfield::nodata );
::glUniform1i( m_uniforms.heights, 0 );
::glUniform1i( m_uniforms.materials, 1 );
::glUniform1i( m_uniforms.groundtexture, 2 );
::glUniform3fv(
m_uniforms.palette, static_cast<GLsizei>( m_palette.size() ), &m_palette.front().x );
auto const tilesize { static_cast<double>( m_reader.tilesize() ) };
auto const gridstep { m_reader.gridstep() };
for( auto const & [ tilekey, tile ] : m_tiles ) {
if( tile.lastused != m_frame ) { continue; }
// tile position relative to the viewpoint, so that the shader never sees a
// coordinate large enough for single precision to matter
glm::vec3 const origin {
static_cast<float>( tile.x * tilesize - Viewpoint.x ),
static_cast<float>( -Viewpoint.y ) - m_depthbias,
static_cast<float>( tile.z * tilesize - Viewpoint.z ) };
::glUniform3fv( m_uniforms.tileorigin, 1, &origin.x );
::glUniform1f( m_uniforms.samplestep, gridstep * static_cast<float>( 1u << tile.level ) );
::glUniform1i( m_uniforms.side, static_cast<GLint>( tile.side ) );
::glUniform2f(
m_uniforms.tileworld,
static_cast<float>( tile.x * tilesize ), static_cast<float>( tile.z * tilesize ) );
::glActiveTexture( GL_TEXTURE0 );
::glBindTexture( GL_TEXTURE_2D, tile.heighttexture );
::glActiveTexture( GL_TEXTURE1 );
::glBindTexture( GL_TEXTURE_2D, tile.materialtexture );
m_indices[ tile.level ]->bind( gl::buffer::ELEMENT_ARRAY_BUFFER );
// one pass per material in the tile: each wants a different texture bound, and
// a fragment belonging to any other material is dropped
for( auto const material : tile.materials ) {
auto const &binding {
material < m_materials.size() ? m_materials[ material ] : material_binding {} };
GfxRenderer->Bind_Texture( 2, binding.texture );
::glUniform1f( m_uniforms.groundscale, binding.scale );
::glUniform1ui( m_uniforms.drawnmaterial, material );
::glUniform1i( m_uniforms.hastexture, binding.texture != null_handle ? 1 : 0 );
auto const &fallback {
m_palette[ std::min<std::size_t>( material, m_palette.size() - 1 ) ] };
::glUniform3fv( m_uniforms.fallback, 1, &fallback.x );
::glDrawElements(
GL_TRIANGLES, static_cast<GLsizei>( m_indexcounts[ tile.level ] ), GL_UNSIGNED_INT, nullptr );
}
}
::glActiveTexture( GL_TEXTURE0 );
m_vao->unbind();
gl::program::bind( 0 );
}
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