visual improvements to the grass
Davi D'artemis · 2026-08-07 ·
parent a46f194009
visual improvements to the grass
Changed files
lib/ChunkMesher.lua | 4 +++-
lib/Structures.lua | 32 ++++++++++++++++++++++++++++++++
lib/Voxel3D.lua | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------
lib/VoxelScene.lua | 3 +++
4 files changed, 92 insertions(+), 20 deletions(-)
Diff
diff --git a/lib/ChunkMesher.lua b/lib/ChunkMesher.lua
index 6213260..532c3d4 100644
--- a/lib/ChunkMesher.lua
+++ b/lib/ChunkMesher.lua
@@ -821,7 +821,9 @@ local function quadsMesh(quads, grass)
local uv = q.uv and q.uv[i] or { q.u, q.v }
local v = { c[1], c[2], c[3], uv[1], uv[2], q.shade }
if grass then
- v[7], v[8], v[9] = q.sway or 0, q.cx or 0, q.cz or 0
+ v[7], v[8], v[9], v[10] = q.sway or 0, q.cx or 0,
+ q.cz or 0,
+ q.firefly and 2 or (q.leaf and 1 or 0)
end
verts[#verts + 1] = v
end
diff --git a/lib/Structures.lua b/lib/Structures.lua
index 0f971e0..851de65 100644
--- a/lib/Structures.lua
+++ b/lib/Structures.lua
@@ -3521,6 +3521,38 @@ function Structures.buildGrass(S, map, x0, x1, y0, y1, data)
cx = wx + 4, cz = wz + 4,
}
end
+
+ -- Sparse wind-borne leaf. It reuses one opaque grass texel and is
+ -- animated entirely on the GPU, so no per-frame Lua particles exist.
+ if #tpl > 0 and ((tx * 13 + ty * 7) % 11 == 0) then
+ local src = tpl[1]
+ local uv = src.uv and src.uv[1] or { src.u, src.v }
+ local lx = wx + 2 + ((tx * 5 + ty * 3) % 5)
+ local lz = wz + 4
+ local ly, size = 9 + ((tx + ty) % 3), 1.25
+ quads[#quads + 1] = {
+ { lx - size, ly, lz }, { lx + size, ly, lz },
+ { lx + size, ly + size, lz }, { lx - size, ly + size, lz },
+ uv = { uv, uv, uv, uv }, shade = 1, sway = sway + 0.73,
+ cx = lx, cz = lz, leaf = true,
+ }
+ end
+
+ -- Rarer one-pixel firefly. Geometry exists all day, but the shader
+ -- gives it zero glow outside outdoor night.
+ if #tpl > 0 and ((tx * 17 + ty * 11) % 29 == 0) then
+ local src = tpl[1]
+ local uv = src.uv and src.uv[1] or { src.u, src.v }
+ local fx = wx + 2 + ((tx * 3 + ty * 5) % 5)
+ local fz = wz + 4
+ local fy, half = 9 + ((tx + ty) % 4), 0.5
+ quads[#quads + 1] = {
+ { fx - half, fy, fz }, { fx + half, fy, fz },
+ { fx + half, fy + 1, fz }, { fx - half, fy + 1, fz },
+ uv = { uv, uv, uv, uv }, shade = 1, sway = sway + 1.37,
+ cx = fx, cz = fz, firefly = true,
+ }
+ end
end
end
end
diff --git a/lib/Voxel3D.lua b/lib/Voxel3D.lua
index 8257f0f..58d96c8 100644
--- a/lib/Voxel3D.lua
+++ b/lib/Voxel3D.lua
@@ -55,7 +55,7 @@ Voxel3D.GRASS_FORMAT = {
{ "VertexPosition", "float", 3 },
{ "VertexTexCoord", "float", 2 },
{ "VertexShade", "float", 1 },
- { "VertexGrass", "float", 3 }, -- phase, clump centre x, clump centre z
+ { "VertexGrass", "float", 4 }, -- phase, clump centre x/z, effect kind
}
Voxel3D.GRASS_WIND_PIXELS = 1.15
@@ -88,6 +88,8 @@ local SHADER = [[
varying float vShade;
varying vec3 vSun; // this fragment's place in the sun's view
varying float vFog; // how deep into the map's haze it stands
+ varying float vFirefly; // zero normally, night glow on firefly cards
+ uniform float fireflyNight; // shared safely by vertex and pixel stages
#ifdef VOXEL_CULL
// where this fragment stands in the FLAT world, for the diorama's
// viewport to measure. Same precision reasoning as vGrid below: a
@@ -115,9 +117,10 @@ local SHADER = [[
uniform vec4 grassPlayer; // world x, world z, radius, push pixels
uniform vec2 grassPrevious; // previous player world xz for swept contact
attribute float VertexShade;
- attribute vec3 VertexGrass;
+ attribute vec4 VertexGrass;
vec4 position(mat4 transform_projection, vec4 vertex_position) {
vShade = VertexShade;
+ vFirefly = 0.0;
#ifdef VOXEL_GRID
// MODEL space, deliberately: every mesh here is built a unit per
// voxel in its own frame, so the seams ride the model however it is
@@ -144,23 +147,51 @@ local SHADER = [[
float bend = clamp(vertex_position.y / 8.0, 0.0, 1.0);
bend *= bend;
float wave = sin(grassWind.y * grassWind.w + VertexGrass.x);
- vec2 offset = vec2(wave * grassWind.z, 0.0);
-
- // Move each touched tuft rigidly a little to the left or right. The
- // baked clump centre is identical for all its vertices, preventing
- // stretching, twisting and the ugly crushed-grass silhouette.
- vec2 clump = VertexGrass.yz;
- float bodyDist = length(clump - grassPlayer.xy);
- float touch = 1.0 - smoothstep(grassPlayer.z * 0.45,
- grassPlayer.z, bodyDist);
- float side = clump.x < grassPlayer.x ? -1.0 : 1.0;
- if (abs(clump.x - grassPlayer.x) < 0.5)
- side = sin(VertexGrass.x) < 0.0 ? -1.0 : 1.0;
-
- // Preserve the existing wind bend. Player contact is only a small,
- // uniform X translation, just enough to suggest the grass parting.
- w.xz += offset * bend;
- w.x += side * touch * grassPlayer.w;
+ if (VertexGrass.w > 1.5) {
+ // One-pixel firefly with a full behaviour loop: a long rest on the
+ // grass, smooth take-off, an irregular short flight, descent, landing
+ // and another pause. The baked phase keeps every insect independent.
+ float cycle = fract(grassWind.y * 0.052 + VertexGrass.x * 0.173);
+ float takeoff = smoothstep(0.30, 0.39, cycle);
+ float landing = 1.0 - smoothstep(0.68, 0.79, cycle);
+ float airborne = takeoff * landing;
+ float drift = grassWind.y * 0.83 + VertexGrass.x * 3.7;
+ float wander = sin(drift) * 2.8 + sin(drift * 0.37 + 1.3) * 1.5;
+ float lift = 2.5 + sin(drift * 1.19) * 1.1
+ + sin(drift * 0.53 + 0.8) * 0.7;
+ w.x += airborne * wander;
+ w.y += airborne * lift;
+ // Mostly dim while resting, visibly brighter in flight, with a soft
+ // asynchronous pulse rather than a hard on/off blink.
+ float blink = 0.68 + 0.32 * (sin(drift * 2.11) * 0.5 + 0.5);
+ vFirefly = fireflyNight * blink * mix(0.14, 0.92, airborne);
+ } else if (VertexGrass.w > 0.5) {
+ // The first 72% of the cycle is airborne. A leaf gets an initial
+ // upward lift, travels with the wind, then gravity accelerates it
+ // down to the ground. It rests there for the remainder before a new
+ // leaf is emitted. Z remains fixed, preserving sprite depth order.
+ float life = fract(grassWind.y * 0.085 + VertexGrass.x * 0.159);
+ float fall = min(life / 0.72, 1.0);
+ float travel = fall * 44.0 - 6.0;
+ float flutter = grassWind.y * 3.0 + VertexGrass.x * 4.7;
+ float lift = sin(fall * 3.14159265) * 5.0;
+ float gravity = 9.0 * fall * fall;
+ float flutterFade = 1.0 - smoothstep(0.62, 1.0, fall);
+ w.x += travel + sin(flutter) * 1.2 * flutterFade;
+ w.y += lift - gravity
+ + sin(flutter * 0.61) * 0.8 * flutterFade;
+ } else {
+ vec2 offset = vec2(wave * grassWind.z, 0.0);
+ vec2 clump = VertexGrass.yz;
+ float bodyDist = length(clump - grassPlayer.xy);
+ float touch = 1.0 - smoothstep(grassPlayer.z * 0.45,
+ grassPlayer.z, bodyDist);
+ float side = clump.x < grassPlayer.x ? -1.0 : 1.0;
+ if (abs(clump.x - grassPlayer.x) < 0.5)
+ side = sin(VertexGrass.x) < 0.0 ? -1.0 : 1.0;
+ w.xz += offset * bend;
+ w.x += side * touch * grassPlayer.w;
+ }
}
// THE MAP'S HAZE (see ForestAtmos): how much fog stands between the
// eye and this vertex -- distance dissolves into it, altitude climbs
@@ -389,6 +420,9 @@ local SHADER = [[
// solid silhouette. Last in the chain, so neither the sun nor a voxel
// seam can mottle it.
rgb = mix(rgb, ghostColor, ghost);
+ // Emissive but still coloured: increasingly visible as Lua raises the
+ // night factor, without adding more insects or washing the scene white.
+ rgb = mix(rgb, vec3(0.82, 1.00, 0.22), vFirefly);
// the viewport's rim is an ALPHA, so the last of the model blends into
// whatever the frame opened with -- the sky, or the chroma key. 1
// everywhere without the cut compiled in, which is every flat frame.
@@ -1116,6 +1150,7 @@ function Voxel3D.beginScene(w, h, cx, cy, vw, vh, sky, slot)
pcall(sh.send, sh, "ghostColor", Voxel3D.GHOST_COLOR)
-- the hour's light, as the caller last set it (see Voxel3D.tint)
pcall(sh.send, sh, "dayTint", Voxel3D.tint or { 1, 1, 1 })
+ pcall(sh.send, sh, "fireflyNight", Voxel3D.fireflyNight or 0)
-- and the map's haze (see Voxel3D.fog), density 0 when there is none
local fog = Voxel3D.fog
pcall(sh.send, sh, "fogColor", (fog and fog.color) or { 0, 0, 0 })
diff --git a/lib/VoxelScene.lua b/lib/VoxelScene.lua
index 95cfb92..53459b1 100644
--- a/lib/VoxelScene.lua
+++ b/lib/VoxelScene.lua
@@ -913,6 +913,9 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
local GlassMask = V.require("GlassMask")
Voxel3D.glassMask = outdoor and GlassMask.texture(state.map.tileset) or nil
Voxel3D.glassNight = outdoor and DayNight.windowLight() or 0
+ -- The existing day/night ramp is also a darkness factor. Fireflies fade
+ -- in naturally at dusk and reach full contrast only at deepest night.
+ Voxel3D.fireflyNight = outdoor and DayNight.windowLight() or 0
local g = VoxelScene.glintStep(glint, cx, cy)
Voxel3D.glassPhase, Voxel3D.glassGlint = g.phase, g.amp
-- and the map's atmosphere, if it has one (see ForestAtmos): the haze