visual improvements to the grass

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

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

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);
+      if (VertexGrass.w > 1.5) {
-
+        // One-pixel firefly with a full behaviour loop: a long rest on the
-      // Move each touched tuft rigidly a little to the left or right. The
+        // grass, smooth take-off, an irregular short flight, descent, landing
-      // baked clump centre is identical for all its vertices, preventing
+        // and another pause. The baked phase keeps every insect independent.
-      // stretching, twisting and the ugly crushed-grass silhouette.
+        float cycle = fract(grassWind.y * 0.052 + VertexGrass.x * 0.173);
-      vec2 clump = VertexGrass.yz;
+        float takeoff = smoothstep(0.30, 0.39, cycle);
-      float bodyDist = length(clump - grassPlayer.xy);
+        float landing = 1.0 - smoothstep(0.68, 0.79, cycle);
-      float touch = 1.0 - smoothstep(grassPlayer.z * 0.45,
+        float airborne = takeoff * landing;
-                                     grassPlayer.z, bodyDist);
+        float drift = grassWind.y * 0.83 + VertexGrass.x * 3.7;
-      float side = clump.x < grassPlayer.x ? -1.0 : 1.0;
+        float wander = sin(drift) * 2.8 + sin(drift * 0.37 + 1.3) * 1.5;
-      if (abs(clump.x - grassPlayer.x) < 0.5)
+        float lift = 2.5 + sin(drift * 1.19) * 1.1
-        side = sin(VertexGrass.x) < 0.0 ? -1.0 : 1.0;
+                     + sin(drift * 0.53 + 0.8) * 0.7;
-
+        w.x += airborne * wander;
-      // Preserve the existing wind bend. Player contact is only a small,
+        w.y += airborne * lift;
-      // uniform X translation, just enough to suggest the grass parting.
+        // Mostly dim while resting, visibly brighter in flight, with a soft
-      w.xz += offset * bend;
+        // asynchronous pulse rather than a hard on/off blink.
-      w.x += side * touch * grassPlayer.w;
+        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 })

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