Ice rendering

Ice keeps its side faces beside water. The old mesher workaround removed both sides of that interface to hide transparency sorting errors, leaving an open block when the camera went underwater. Water still gives up its coplanar face; ice owns the boundary.

Transparent ice uses ice.gdshader: the ice group, or a blended or fake liquid block whose node name or footstep says ice (Asuna's thin_ice nodes; see materials.md). Opaque ice stays opaque. The body colour now comes from procedural internal structure. The surface retains the accepted normal and roughness maps, tile-derived facets and backlighting. The old tile no longer paints the ice's colour or internal inclusions. Relief changes shading, not the block silhouette. Packed and blue ice retain their opaque node materials.

Procedural interior

Two shared, deterministic 3D noise textures describe fractures and cloudy inclusions. They are generated once by Godot's NoiseTexture3D, using cellular distance differences and Perlin noise respectively. The fracture volume is 128 cubed; the cloud volume is 64 cubed. Their world-space periods differ (12 and 11 nodes), with a slow warp and uneven visibility to break up regular cell outlines. Adjacent nodes sample the same field.

The shader takes 24 samples along a refracted ray through a bounded optical layer. Fractures, cloudy regions and sparse ellipsoidal air pockets scatter light at different depths. Their positions therefore shift relative to the surface as the camera moves. Frost broadens the surface highlights, and coloured absorption removes more red from transmitted light. Fine bubbles fade as their projected size becomes too small.

This remains a material approximation: the sampled layer is 1.15 nodes deep along the face normal, adjusted for refraction angle. It neither traces the actual connected ice volume nor detects its exit face. A one-node lake sheet and a thick formation therefore do not yet have physically distinct optical thicknesses. The retained surface facets also still repeat with the tile.

Transmission and water ordering

Ice writes ordinary opaque depth. ice_transmission.gd renders a half-width, half-height HDR background view with the translucent ice meshes excluded on layer 3. The ice material samples that view as transmitted light. Water therefore finds ice in both its opaque colour and depth buffers, rather than losing it when it samples a scene that excludes transparent objects.

This avoids relying on mapblock alpha sorting or a fixed render priority. The discarded alpha-hash trial produced obvious grain; it is not used. Godot documents the relevant limitation in its screen-reading shader reference.

The capture omits the final grade, bloom, screen-space effects and fog. The main view applies the grade and the fog between the camera and the ice. Capture activation uses the visible ice meshes' bounds and camera frustum. The background is disabled when no ice bounds intersect that frustum, or when Solid ice is enabled. The capture excludes the final light-shaft quad.

Solid ice remains available in Video settings. The new default is off; existing saved preferences are respected, so an older profile may still need that toggle switched off to enable transmission.

Limits

This is a softened, screen-aligned background approximation, not nested refraction through multiple ice volumes. All near translucent ice is excluded from the background, and transmission uses the bounded procedural layer, not a traced thickness through an iceberg. The background omits fog beyond the ice. Distant ice retains its existing coarse representation. The capture has a real graphics cost and needs wider landscape assessment. At y=79.49/79.51 the camera near plane clips the water surface, leaving a bright horizontal band. The sweep records that remaining waterline artifact; the geometry assertions do not claim to fix it.

Procedural material review

See the material comparison for the procedural pass against the previously accepted rough ice. Six pairs swap only the shader in the same frozen scene. Camera, sky, lighting and grading are held still within each pair; water animation continues. The review also has a nine-view orbit and separate captures from a fresh launch. These use the same disposable Mineclonia pool, not a natural landscape.

The first edge-view sample at 1600x900 on an RTX 3090 measured median frame times of 8.73 ms for the accepted material and 8.82 ms for the procedural material. Main-view GPU times were 6.25 and 6.42 ms. Each sample contains 120 uncapped frames after 45 warm-up frames, with transmission enabled in both. Capture GPU times varied between samples; these numbers do not isolate an exact shader cost or predict performance on other hardware.

Earlier geometry review and verification

See the ice comparison. These are live Mineclonia captures from a disposable pool on Luanti 5.17.0, rendered with Godot 4.5.1 Forward+. They are geometry and material diagnostics, not a natural frozen-lake showcase. Paired views share camera and server time; clouds were allowed to evolve between captures, so these are not grading comparisons. The two close-ups show only the revised material.

The submerged sheet edge has 66 triangles spanning its 33-node width. The waterline sweep checks cameras at y=78.8, 79.3, 79.49, 79.51, 79.8 and 80.2 around the surface at y=79.5. It also verifies that facing away disables the background. Native build, Godot import and style checks passed.

In the fixed pool edge view at 1600x900 on an RTX 3090, a 90-frame uncapped sample measured median frame time of 5.5 ms with transmission disabled and 7.8 ms enabled. The extra 800x450 viewport measured about 2.2 ms GPU time. These are fixture measurements, not a frame-rate guarantee for landscapes.

The disposable server fixture and capture script are in tools/test/ice-review. Copy that directory into a test world's worldmods/goanna_ice_review, start Mineclonia and connect a client with GOANNA_CONTROL=30862. The fixture command requires the server privilege and replaces its pool coordinates; use a disposable world. Then run:

python3 tools/test/ice-review/capture.py before --create-fixture
# Rebuild and relaunch the changed client against the same test world.
python3 tools/test/ice-review/capture.py after

The fixture occupies x/z=-17..17 and y=72..89. Baseline and revised clients must use the same texture pack, appearance, weather and camera settings.