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maszyna/tools/terraincook/meshtest.cpp
maj00r 9408216ae7 Give the terrain its own archive, its normals, and a level per tile
The tiles moved out of the scenery's pak into an archive of their own: a
sorted index of fixed-size entries found by where a tile sits in the
quadtree rather than by a name, each entry compressed on its own so a
tile can be read without touching the rest. A name apiece would have been
seventy megabytes of index to read before the first tile could be drawn.

An entry carries what its tile's ground asks for - how far it departs
from the finest mesh, and how long its triangles are - because which
level to draw has to be settled for tiles that are not on the card yet,
and the index is the only thing about them that is read up front. Until
now the figure came from the tile's level, which is the worst tile in it,
so one steep corner spoke for every tile that shared its level.

The mesh carries a normal per vertex, octahedron-encoded into two bytes,
in place of the face normal the fragment stage worked out from how the
view position changed across a triangle. A face normal makes the ground
read as facets, and a coarser level's facets face differently from the
ones they stand for, so the light over a hillside changed as the level
did. A geometry stage hands the fragment stage the three materials of the
triangle it is in and the barycentric weights, so ground changes over a
triangle rather than along its edge; 3.3 has no gl_BaryCoordEXT.

And the level a tile is drawn at now counts the camera's height. The
distance was measured on the ground plane alone, which puts the tile
underfoot nought metres away from a camera a kilometre above it - and
nought metres asks for the finest level there is, so a view from the air
wanted the whole ground at full detail, more tiles than the buffers hold,
and what would not fit came out as holes.

Archives written under the old rules are refused at the door and baked
again.
2026-09-20 21:22:03 +02:00

244 lines
13 KiB
C++

// What the cook promises, checked on a terrain made up for the purpose: a tile reads back as it was
// written, two tiles sharing a border agree on it whatever level each is drawn at, a hole the scenery
// left stays a hole, a wall is ground and is laid exactly once, and the tiling of a material is
// measured off the source rather than guessed.
//
// Run it with no arguments; it writes its files to a temporary directory and removes them.
#include <cmath>
#include <cstdio>
#include <filesystem>
#include <set>
#include <cstdlib>
#include <system_error>
#include <map>
#include <tuple>
#include <set>
#include <vector>
#include "scene/quantizedmesharchive.h"
#include "scene/quantizedmeshcooker.h"
#include "scene/quantizedmeshreader.h"
namespace qm = quantizedmesh;
int failures = 0;
void check( bool ok, char const *what ) {
if( !ok ) { std::printf( "FAIL: %s\n", what ); ++failures; }
}
int main() {
auto const directory = std::filesystem::temp_directory_path() / "eu07-meshtest";
std::error_code ignored;
std::filesystem::create_directories( directory, ignored );
std::string const scratch = ( directory / "terrain.cook" ).string();
std::string const archive = ( directory / "terrain.pak" ).string();
qm::cooker cooker;
cooker.quiet();
check( cooker.begin( scratch, 2000 ), "begin" );
auto const height = []( double x, double z ) {
return 20.0 * std::sin( x / 300.0 ) * std::cos( z / 250.0 ) + 0.01 * x;
};
// a 1200 x 1200 m field on a 10 m grid, with a square hole and one big triangle
double const step = 10.0;
int const cells = 120;
for( int ix = 0; ix < cells; ++ix ) {
for( int iz = 0; iz < cells; ++iz ) {
double const x0 = -600.0 + ix * step, x1 = x0 + step;
double const z0 = -600.0 + iz * step, z1 = z0 + step;
// a hole in the middle, as a scenery leaves where water or a building is
if( ( x0 >= -100.0 ) && ( x1 <= 100.0 ) && ( z0 >= -100.0 ) && ( z1 <= 100.0 ) ) { continue; }
char const *material = ( x0 < 0.0 ) ? "grass" : "gravel";
auto const corner = [&]( double x, double z ) {
return qm::cooker::corner{ x, height( x, z ), z,
static_cast<float>( x / 25.0 ), static_cast<float>( z / 25.0 ) };
};
cooker.add( corner( x0, z0 ), corner( x1, z0 ), corner( x1, z1 ), material );
cooker.add( corner( x0, z0 ), corner( x1, z1 ), corner( x0, z1 ), material );
}
}
// an upright wall, as the side of an embankment is. it is ground too, and must be laid - once,
// although it lies exactly along the border between two tiles (z = -512)
for( int piece = 0; piece < 4; ++piece ) {
double const xa = 100.0 + piece * 20.0, xb = xa + 20.0;
cooker.add( { xa, 0.0, -512.0, 0.f, 0.f }, { xb, 0.0, -512.0, 1.f, 0.f }, { xb, 8.0, -512.0, 1.f, 1.f }, "wall" );
cooker.add( { xa, 0.0, -512.0, 0.f, 0.f }, { xb, 8.0, -512.0, 1.f, 1.f }, { xa, 8.0, -512.0, 0.f, 1.f }, "wall" );
}
// one big triangle spanning many tiles, as 3ds Max terrain has
cooker.add( { -600.0, -5.0, 700.0, 0.f, 0.f }, { 600.0, -5.0, 700.0, 24.f, 0.f }, { 0.0, -5.0, 1100.0, 12.f, 16.f }, "grass" );
qm::archive_writer writer;
check( writer.open( archive, qm::cook_rules ), "archive opened for writing" );
qm::terrain_table table;
std::map<std::int64_t, qm::tile_address> written;
auto const sink = [&]( qm::tile_address const &tile, std::vector<std::uint8_t> const &bytes,
qm::tile_measure const &measure ) {
written.emplace( qm::tile_key( tile ), tile );
check( writer.add( tile, bytes, measure ), "tile written" );
};
check( cooker.finish( sink, table ), "finish" );
auto const tabletext = qm::write_table( table );
check( writer.table( tabletext ), "table written" );
check( writer.close(), "archive closed" );
auto const &report = cooker.result();
std::printf( "added %zu, laid %zu triangles in %zu tiles, %u levels, %zu vertices, %zu kB, refused %zu\n",
cooker.added(), report.triangles, report.tiles, report.levels, report.vertices,
report.bytes / 1024, report.refused );
check( cooker.refusals().empty(), "nothing refused: a wall is ground too" );
check( report.levels >= 3, "quadtree deeper than the root" );
qm::reader reader;
check( reader.open( archive ), "reader open" );
check( reader.table().materials.size() == 3, "grass, gravel and the wall" );
for( auto const &material : reader.table().materials ) {
std::printf( " material %s, one repeat every %.2f m\n", material.name.c_str(), material.repeat );
}
for( auto const &material : reader.table().materials ) {
if( material.name != "wall" ) { check( std::abs( material.repeat - 25.0 ) < 0.5, "the tiling was measured off the source" ); }
}
check( reader.table().levels == report.levels, "levels agree" );
for( std::uint32_t level = 0; level < reader.table().levels; ++level ) {
std::printf( " level %u error %.3f m, tile %.0f m\n", level,
reader.table().error( level ), reader.table().tilesize( level ) );
}
// the finest level is let go of only where it says the same thing twice, so it is off by
// centimetres rather than by nothing
check( reader.table().error( reader.table().levels - 1 ) < 0.05f, "the finest level is off by centimetres" );
// every level is at least as far off as the one below it, and the coarsest is further off than
// the finest - which is what makes the ladder worth walking down
for( std::uint32_t level = 0; level + 1 < reader.table().levels; ++level ) {
check( reader.table().error( level ) >= reader.table().error( level + 1 ) - 1e-4f,
"a coarser level is at least as far off as the one below it" );
}
check( reader.table().error( 0 ) > reader.table().error( reader.table().levels - 1 ),
"the coarsest level is further off than the finest" );
// A coordinate is quantized to fifteen bits across its tile, so how closely a position comes back
// follows the tile's size: a thousand-metre tile holds it to a few centimetres. Everything below
// compares against that rather than against a fixed figure.
auto const quantum = [ & ]( std::uint32_t level ) { return reader.table().tilesize( level ) / 32767.0; };
// every tile reads back, and its vertices lie inside its own square
// per level and border point, the heights each tile put there. with walls in the mesh one
// point can carry several heights, so every height of one tile has to find a match in the
// other rather than the lists being compared one to one
std::map<std::tuple<std::uint32_t,long long,long long>, std::map<std::int64_t, std::vector<double>>> bordery;
std::size_t read = 0, trianglesread = 0;
std::map<std::uint32_t, std::size_t> perlevel;
for( auto const &[ key, tile ] : written ) {
qm::reader::tile_data data;
if( !reader.read_tile( tile, data, 0.0, 0.0, 0.0 ) ) { std::printf( "FAIL: read %s\n", qm::tile_name( tile ).c_str() ); ++failures; continue; }
++read;
trianglesread += data.indices.size() / 3;
perlevel[ tile.level ] += data.indices.size() / 3;
auto const side = reader.table().tilesize( tile.level );
auto const west = reader.table().west + tile.x * side;
auto const north = reader.table().north + tile.z * side;
for( auto const &v : data.vertices ) {
double const x = data.originx + v.x, z = data.originz + v.z, y = data.originy + v.y;
auto const slack = 2.0 * quantum( tile.level );
check( x >= west - slack && x <= west + side + slack, "vertex inside its tile in x" );
check( z >= north - slack && z <= north + side + slack, "vertex inside its tile in z" );
check( y >= data.lowest - slack && y <= data.highest + slack, "vertex inside its height range" );
// remember heights on tile borders, to compare with the neighbour later
auto const close = 2.0 * quantum( tile.level );
auto const onborder = std::abs( x - west ) < close || std::abs( x - west - side ) < close
|| std::abs( z - north ) < close || std::abs( z - north - side ) < close;
if( onborder ) {
auto const gx = static_cast<long long>( std::llround( x * 100.0 ) );
auto const gz = static_cast<long long>( std::llround( z * 100.0 ) );
bordery[ { tile.level, gx, gz } ][ key ].push_back( y );
}
}
}
std::printf( "read %zu tiles, %zu triangles\n", read, trianglesread );
for( auto const &[ level, count ] : perlevel ) { std::printf( " level %u: %zu triangles\n", level, count ); }
// a vertex two tiles of the same level share must decode to the same height in both
// where two tiles meet, a point on the border can carry more than one height - a wall standing
// on the ground is two surfaces at one place - and only one of them belongs to the neighbour.
// What has to agree, and is what keeps the ground from cracking, is the single-surface case
double worst = 0.0;
std::size_t shared = 0, manysurfaced = 0;
for( auto const &[ where, pertile ] : bordery ) {
if( pertile.size() < 2 ) { continue; }
++shared;
auto simple = true;
for( auto const &[ which, heights ] : pertile ) { if( heights.size() != 1 ) { simple = false; } }
if( false == simple ) { ++manysurfaced; continue; }
auto const first = pertile.begin()->second.front();
for( auto const &[ which, heights ] : pertile ) {
worst = std::max( worst, std::abs( heights.front() - first ) );
}
}
std::printf( "%zu of %zu shared border points carry more than one surface\n", manysurfaced, shared );
std::printf( "%zu border points shared by two tiles\n", shared );
std::printf( "worst height disagreement on a shared border: %.1f mm\n", worst * 1000.0 );
// heights are quantized against each tile's own range, as the format has it, so two tiles round a
// shared vertex a fraction of a quantum apart
check( worst < 2.0 * quantum( reader.table().levels - 1 ), "shared border vertices agree to a quantum" );
// the coarse levels must actually be coarser
if( perlevel.size() >= 2 ) {
auto const finest = perlevel.rbegin()->second;
auto const next = std::next( perlevel.rbegin() )->second;
check( next < finest, "a coarser level has fewer triangles" );
}
// the wall along the tile border must be there, and exactly once
{
std::size_t wallpieces = 0;
std::set<std::pair<long long,long long>> wallcentres;
for( auto const &[ key, tile ] : written ) {
if( tile.level + 1 != reader.table().levels ) { continue; }
qm::reader::tile_data data;
if( !reader.read_tile( tile, data, 0.0, 0.0, 0.0 ) ) { continue; }
for( std::size_t i = 0; i + 2 < data.indices.size(); i += 3 ) {
bool wall = true;
for( int c = 0; c < 3; ++c ) {
auto const &v = data.vertices[ data.indices[ i + c ] ];
if( std::abs( data.originz + v.z + 512.0 ) > 2.0 * quantum( tile.level ) ) { wall = false; }
}
if( wall ) {
++wallpieces;
double cx = 0.0, cy = 0.0;
for( int c = 0; c < 3; ++c ) {
cx += data.originx + data.vertices[ data.indices[ i + c ] ].x;
cy += data.originy + data.vertices[ data.indices[ i + c ] ].y;
}
wallcentres.insert( { std::llround( cx * 100.0 ), std::llround( cy * 100.0 ) } );
}
}
}
std::printf( "wall triangles on the tile border: %zu (%zu distinct)\n", wallpieces, wallcentres.size() );
check( wallpieces > 0, "the wall on the border was laid" );
check( wallcentres.size() == wallpieces, "no piece of the wall was laid twice" );
}
// a hole stays a hole: nothing may be drawn in the middle of the map at the finest level
std::size_t inhole = 0;
for( auto const &[ key, tile ] : written ) {
if( tile.level + 1 != reader.table().levels ) { continue; }
qm::reader::tile_data data;
if( !reader.read_tile( tile, data, 0.0, 0.0, 0.0 ) ) { continue; }
for( std::size_t i = 0; i + 2 < data.indices.size(); i += 3 ) {
double cx = 0.0, cz = 0.0;
for( int c = 0; c < 3; ++c ) {
cx += data.originx + data.vertices[ data.indices[ i + c ] ].x;
cz += data.originz + data.vertices[ data.indices[ i + c ] ].z;
}
cx /= 3.0; cz /= 3.0;
if( cx > -95.0 && cx < 95.0 && cz > -95.0 && cz < 95.0 ) { ++inhole; }
}
}
std::printf( "triangles inside the hole: %zu\n", inhole );
check( inhole == 0, "the hole was not filled in" );
if( nullptr == getenv( "KEEP" ) ) { std::filesystem::remove_all( directory, ignored ); }
std::printf( failures ? "\n%d checks failed\n" : "\nall checks passed\n", failures );
return failures ? 1 : 0;
}