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feat(render3d): the lake answers to a body standing in it

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water.frag takes u_wade - a point and a strength - and puts spreading rings and a
patch of churn into the surface normals there, so a wader marks the water and a
swimmer works the whole of it. It is one uniform in a fragment stage that was
already running, applied after the distance flattening so a disturbance close to
the camera survives it, and it measures no frame cost at all.

Also records the two renderer features that shipped without a changeset.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Orkun ÇAKILKAYA 2026-09-19 20:23:27 +03:00
parent 5ca14eeaec
commit 4975c60ac1
6 changed files with 62 additions and 7 deletions
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17
packages/ludic.render3d/water.ludic
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@ -13,6 +13,11 @@ var water_cz: int = 0
var water_ex: int = 0
var water_ez: int = 0
var water_on: bool = false
# Where a body is standing in the water and how hard it is disturbing it. The game sets it;
# strength 0 means nobody is in the water and the whole term is skipped.
var wt_wade_x: int = 0
var wt_wade_z: int = 0
var wt_wade_s: int = 0
var water_refl: Target = null # the world mirrored in the surface, half resolution
var water_refl_div: int = 2 # R3D_REFLDIV overrides: 2 = half res, 4 = quarter
var water_saved: words = null # the real camera's matrices, restored after the pass
@ -330,6 +335,18 @@ function water_draw(depth_tex: int) -> void {
# the window's size sent the refraction and depth reads into the wrong corner of the
# frame, and the lake showed a squashed copy of it instead of its own bed.
u_f2(gpu_uniform(p, "u_screen"), fi(post_w), fi(post_h))
# Read into locals first. Passing these three globals straight into the call gives the
# shader wrong values - the whole lake churns instead of a patch of it - and a single dead
# `let junk = wt_wade_x` above the same unchanged call is enough to make it correct again.
# It is a codegen fault, not a fact about this shader: the values print identically either
# way at the line above, and it is not the position in the function (it does the same bound
# right after gpu_use_program) nor the nested gpu_uniform call (hoisting that changes
# nothing). Verified by picture, both backends. Read a global into a local before handing it
# to a uniform call.
let wx = wt_wade_x
let wz = wt_wade_z
let ws = wt_wade_s
u_f3(gpu_uniform(p, "u_wade"), wx, wz, ws)
var ron = F_ZERO
if water_refl != null and wb_primary >= 0 {
# bind on its own unit first: generating the mip chain re-binds the texture on the active unit,