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2660d14565
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
3.8 KiB
GLSL
91 lines
3.8 KiB
GLSL
// Terrain heightfield, vertex stage.
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//
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// There is no vertex buffer: the grid exists only as an index buffer, and a sample's
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// row and column come from gl_VertexID. Heights are read as unsigned integers so that
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// the cooker's no-data value survives unchanged instead of being normalised into a float.
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#include <common>
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uniform usampler2D heights;
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uniform usampler2D materials;
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// tile origin relative to the viewpoint, with the viewpoint height already folded into y
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uniform vec3 tileorigin;
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uniform float samplestep; // metres between samples at the level this tile is drawn at
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uniform float heightbias; // world height of stored value 0
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uniform float heightscale; // metres per stored unit
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uniform uint nodata;
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uniform int side; // samples along a tile side at this level
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uniform vec2 tileworld; // tile origin in world space, for texture coordinates
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out vec4 f_pos;
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out vec3 f_normal;
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out vec2 f_ground;
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out float f_valid;
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flat out uint f_material;
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// height of a neighbouring sample, for the central difference the normal is built from.
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// a neighbour that carries no terrain would otherwise decode as the no-data value and
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// read as a surface a hundred metres up, wrecking the normal and leaving the ground
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// unlit; Fallback keeps the difference at zero there, so the edge of a hole comes out
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// flat rather than black
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// height of the first neighbouring sample that carries terrain, or the lowest height on
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// the map when the sample is surrounded by emptiness
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float borrowed_height( ivec2 Texel )
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{
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const ivec2 offsets[ 4 ] = ivec2[ 4 ]( ivec2( -1, 0 ), ivec2( 1, 0 ), ivec2( 0, -1 ), ivec2( 0, 1 ) );
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for( int index = 0; index < 4; ++index ) {
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ivec2 neighbour = clamp( Texel + offsets[ index ], ivec2( 0 ), ivec2( side - 1 ) );
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uint raw = texelFetch( heights, neighbour, 0 ).r;
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if( raw != nodata ) { return heightbias + float( raw ) * heightscale; }
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}
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return heightbias;
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}
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float sample_height( ivec2 Texel, float Fallback )
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{
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ivec2 clamped = clamp( Texel, ivec2( 0 ), ivec2( side - 1 ) );
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uint raw = texelFetch( heights, clamped, 0 ).r;
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if( raw == nodata ) { return Fallback; }
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return heightbias + float( raw ) * heightscale;
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}
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void main()
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{
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int column = gl_VertexID % side;
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int row = gl_VertexID / side;
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ivec2 texel = ivec2( column, row );
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uint raw = texelFetch( heights, texel, 0 ).r;
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f_valid = ( raw == nodata ) ? 0.0 : 1.0;
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f_material = texelFetch( materials, texel, 0 ).r;
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// a sample outside the cooked ground has no height. decoding the no-data value as
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// one puts the vertex at the top of the map's range, and since f_valid is
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// interpolated, the slivers of triangle nearest the valid corners survive the
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// fragment test and stretch up there. so an empty sample borrows a neighbour's
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// height: the fragments are still dropped, but the geometry stays on the ground
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float height = heightbias + float( raw ) * heightscale;
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if( raw == nodata ) {
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height = borrowed_height( texel );
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}
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vec3 local = tileorigin + vec3( float( column ) * samplestep, height, float( row ) * samplestep );
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// central differences over the neighbouring samples; at a tile edge the clamp repeats
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// the border sample, which is what the neighbouring tile holds there as well
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float west = sample_height( texel - ivec2( 1, 0 ), height );
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float east = sample_height( texel + ivec2( 1, 0 ), height );
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float north = sample_height( texel - ivec2( 0, 1 ), height );
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float south = sample_height( texel + ivec2( 0, 1 ), height );
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vec3 normal = normalize( vec3( west - east, 2.0 * samplestep, north - south ) );
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// world coordinates, so the ground texture stays put as the camera moves and as the
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// tile changes mip level
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f_ground = tileworld + vec2( float( column ), float( row ) ) * samplestep;
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f_pos = modelview * vec4( local, 1.0 );
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f_normal = normalize( modelviewnormal * normal );
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gl_Position = projection * f_pos;
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}
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