daffodil · magmacrunch media

A C99 heightfield terrain engine by magmacrunch media. daffodil draws real ground: it reads a heightfield built offline from LiDAR elevation data, reprojected, tiled and written as raw float32 meters, then renders it faithfully and lets you walk on it. The landscape is surveyed, not sculpted.

There's no procedural generation and no terrain sculpting: the shape of the ground comes from the survey, and the engine's job is to reproduce it rather than reshape it. It was built for Block Island Simulator, which is the island below.

daffodil has two C99 siblings. magnolia runs the Wii games. hologram makes the opposite trade: it traces light exactly, dispersion and polarization included, across a few dozen analytic surfaces, where daffodil rasterizes millions of triangles of ground and gets the light approximately right.

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what it draws

Every frame below is a regression baseline, not a promotional render. Eight fixed views are photographed headless under software GL and compared pixel for pixel with the committed copy, and what each view drew is compared with a triangle budget, so these are reproducible by construction rather than posed. The counts are that budget, read off the same frame. Flat shading is the renderer, not a placeholder.

Green rolling island seen from a height, scattered trees and a pond inland, the sea closing the horizon on both sides

the island at range

Chunked level of detail across the whole island at 1:1. 110,440 trees stand where the lidar measured them, drawn instanced in a single draw call and tinted onto the ground itself once they're too far away to draw. LOD is a tenfold triangle reduction overall: 1.87 M in the worst measured view against 18.7 M with every tile at full resolution. 761,344 terrain triangles · 1,395 trees · 2,988 shrub clumps

Old Harbor

The town as one paved sheet with streets cut through it. 612 buildings stand solid, with real openings into their rooms rather than windows painted on, and the walker collides with them. Roads carry their own surface rather than being stripes on grass. 1,020,416 terrain triangles · 602,418 paving · 574 trees

A sheltered pond with a marina of finger docks reaching into it, sandy shore to the left, open sea beyond the far bank

water, and where it meets land

The sheltered shores, the marina and the sea's edge in one frame. Water depth, the tide and the shoreline are the hardest thing in the engine to get right, which is why this view is one of the eight: it's a place something once went wrong, and it's photographed every build so it cannot go wrong again unnoticed. 1,048,832 terrain triangles · 190,194 paving · 650 trees

The same town after dark, a line of lit windows and street lamps along the shore under a near-black sky with faint stars

22:00, and properly dark

Lit by the real sun for a given date and time, going properly dark after it sets, with moonlight from the real moon and 8,404 stars from a real catalog in their actual places. Two lighthouses flash their published characteristics; street lamps light the road under them. Some windows are lit and some are not, and none of them flickers. 963,328 terrain triangles · 634,082 paving · 489 trees

what's in it

terrain Chunked heightfield at 2 m posts, LOD by distance, seams provably invisible rather than approximately so

solar & lunar Real sun and moon positions for a date, time and place; the night is as dark as it actually is

stars 8,404 stars from a real catalog, drawn where they actually are for the hour on the clock

shadows Cascaded shadow maps, with an atlas that defaults smaller on GLES3 than the floor allows

structures Buildings with interiors you can enter, walls that stop you, doors that are openings

vegetation Trees, shrub clumps and grass tufts from measured positions, instanced and impostored by range

water Sea and ponds, tide, current, shoreline and the swim transition at its edge

walker Walks, swims and rides; a bicycle and a moped, each with its own handling

environment Sky, weather, rain, birds, boats and the ferry working its real crossing

audio Mixer, sample bank, WAV loading and a small synth, in-engine rather than bolted on

capture Reads a frame back on every backend, which is what makes a visual claim checkable at all

gles_budget Audits the whole scene against GLES3's guaranteed minimums, with no GPU and no display

the terrain contract

daffodil does not produce heightfield data; it reads it. The producing pipeline lives in the consuming game's repository, in Python, and the two halves agree through a manifest file rather than through shared code. A tile is raw little-endian float32, row-major, and its sample values are meters above local mean sea level.

DAFFODIL_TILE_SAMPLES   257     // 512/2 + 1
DAFFODIL_TILE_METRES    512.0f
DAFFODIL_POST_METRES    2.0f

There's no height scale constant and no decode step: reading a tile is one fread into a float*. A scale constant is a thing two languages can disagree about, and this way they cannot. The +1 in the sample count is load-bearing too, because it makes adjacent tiles share their edge row exactly.

measured against the specification, not against a box

The engine's demands are checked against OpenGL ES 3.0's guaranteed minimums rather than against whatever GPU is to hand. Fitting inside the floor means fitting on any conformant device, so a failure on real hardware is a driver problem rather than a design one. The audit runs with no GPU and no display, which means it runs over ssh.

It says nothing about speed. Not one of those limits is a rate, and the island reported ok on every line while drawing at three frames a second on the one GLES3 GPU it has met. Fits is not plays, and the two are worth keeping apart.

targets

Windows / D3D11 · Linux / OpenGL · macOS / Metal · Raspberry Pi 4 and 5 / GLES3. One rasterizer, four backends, and a frame can be read back on all of them.

the name

After the Daffodil cabin at Twin Maples on Block Island, which is the first ground it renders, and after Juanito Thompson's “Daffodil & Sweet Pea”.

PolyForm Noncommercial 1.0.0 · Copyright 2026 magmacrunch media. Any noncommercial purpose is permitted, and commercial use is reserved to magmacrunch media. Vendored sokol headers, by Andre Weissflog, keep their zlib license.