1.0.4: flower/bush/statue/trash-can billboards, in-place mesh refresh

Flowers stand as 1px animated cutouts on their own pulled mesh (own-cell
flowers hide behind the walker, the cell south still overdraws feet).
Cuttable bushes, gym statues (single-block plinth) and Lt. Surge's trash
cans stand as 5-voxel prop cutouts; prop_ground names the tile painted
beneath. Block edits refresh meshes in place instead of blinking to 2D.

lib/VoxelScene.lua

@@ -460,6 +460,14 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
     ShadowMap.draw(nbMesh[i], atlasFor(nb.map),
                    Mat4.translate(nb.ox, 0, nb.oy))
   end
+  -- flower billboards live outside the terrain mesh (they draw after the
+  -- characters, pulled -- see render), but the sun still sees them: a
+  -- handful of cutouts per meadow, unlike the grass left out below
+  ShadowMap.draw(ChunkMesher.flowers(state.map), atlasFor(state.map), nil)
+  for _, nb in ipairs(state.neighbors or {}) do
+    ShadowMap.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy))
+  end
   for _, p in ipairs(posed) do
     local def = p.sprite.def
     local frame, mirror = frameFor(def, p.facing, p.phase, p.flip)
@@ -559,6 +567,23 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor)
     Voxel3D.draw(ChunkMesher.grass(nb.map), atlasFor(nb.map),
                  Mat4.translate(nb.ox, 0, nb.oy), pull)
   end
+  -- flower billboards: pulled like the characters and the grass, MINUS
+  -- the depth of 8 world pixels along the view (8 sin a -- the camera
+  -- looks along (0, -cos a, -sin a), so that is exactly one tile row of
+  -- northness). A pure depth handicap with zero screen drift: every
+  -- flower is judged as if it stood one tile row further north. The
+  -- character card's feet plane sits at its cell's MIDDLE (py + 8), so
+  -- a flower on the walker's own cell (z +4 or +12 across the cell)
+  -- lands behind the card and the player obscures the patch they stand
+  -- ON, while the nearest flower of the cell south (+20) stays in front
+  -- and keeps overdrawing their feet.
+  local fpull = math.max(0, pull - 8 * math.sin(math.max(Voxel.angle, 0.05)))
+  Voxel3D.draw(ChunkMesher.flowers(state.map), atlasFor(state.map), nil,
+               fpull)
+  for _, nb in ipairs(state.neighbors or {}) do
+    Voxel3D.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                 Mat4.translate(nb.ox, 0, nb.oy), fpull)
+  end
 
   return Voxel3D.endScene()
 end