layer_flutter(l, v) gives a scatter layer a per-leaf tremble. The vertex stage offsets
each leaf by a phase taken from its own place on the card, so neighbouring leaves are
never in step, and writes the result out as a varying the fragment stage uses to flash
the leaf's pale underside as it turns - which is the part that reads, since a still
frame of a tremble is a still frame of nothing. One uniform, one varying, no extra pass.
And the sway itself was measured in METRES: hgt * hgt * 0.35 is right for a 40 cm
flower and puts ten metres of sideways into a 14 m trunk, so every tall tree in the
valley stood bent over like a fishing rod. It is a fraction of the model's own height
now - the tip moves a few per cent of the tree whatever the tree is, and the base does
not move at all.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The grass had a gust built from two sines; the trees had no gust term AT ALL, only a
per-instance wobble. So the meadow rippled and the canopy above it swayed to an unrelated
rhythm, and nothing ever crossed the valley.
wind.glsl is prepended to every stage (programs.ludic, and shaders.ludic for the SPIR-V
build) so grass, crowns and water read the same field at the same world position. It
declares no uniforms on purpose: u_time and u_wind already exist in several of those
files and redeclaring them is a compile error in whichever stage includes both.
The wavelength is what made it work. At 0.030 the front was 209 m crest to crest -
longer than the meadow you can see - so the whole frame sat in one phase and the gust
read as everything breathing together. At 0.085 it is 74 m and a front crosses a view in
a couple of seconds.
R3D_DEBUG_WIND=1 paints the field on the ground. It is the only honest way to show a gust
in a still image, and two shots 0.3 s apart move by 39/255.
400 frames: GL 6.9 s, VK 7.2 s. Backends agree to 0.68/255.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The renderer's projections are OpenGL's, whose clip-space depth runs from -w to w; Vulkan clips
everything below 0. `ludic-dev shaders` now wraps each vertex stage - its own main runs, then
gl_Position.z = (z + w) / 2 - so every variant's depth lands in [0, w]. The GLSL the OpenGL
renderer compiles is untouched. No y flip is needed: a Vulkan target's row 0 is where OpenGL's is
(NDC y = -1), so render to texture, sampling and gl_FragCoord agree between the two, and only the
present and the screenshot flip.
45 vertex modules regenerated (spirv-val clean, manifest unchanged); ludic-dev test 140 passed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Vulkan cannot compile GLSL when the game starts, so the programs render3d builds are listed
(shaders/variants.list, 45 of them, collected with R3D_PROGRAMS_LOG across the self-tests, the
screens, the viewpoints and the debug switches) and `ludic-dev shaders` compiles each into
shaders/spv/<id>.vert.spv and .frag.spv with a manifest of what the backend needs: each
stage's uniform block and member offsets, the samplers' bindings, the vertex inputs.
The GLSL is the renderer's own, assembled as programs.ludic assembles it, through glslang's
relaxed Vulkan mode, so gpu_uniform / u_* can write the same uniforms into a block on Vulkan.
Bindings are assigned by the tool (glslang's own numbering put several samplers of one stage
on binding 0): the vertex block is 0, the fragment block 1, samplers from 2 in name order,
shared across both stages. Every stage passes spirv-val; `ludic-dev test` rebuilds and compares
wherever the Vulkan SDK is installed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
