diff --git a/android/build_apk.py b/android/build_apk.py
index ca10d6e..288d694 100644
--- a/android/build_apk.py
+++ b/android/build_apk.py
@@ -11,6 +11,7 @@ Signed with ~/.local/share/Nexoniarz/Fry3DX-signing/release.keystore (made the f
 or the key in $FRY_KEYSTORE / $FRY_KEYSTORE_PASS. Keep it safe and keep using it: Android only
 updates an app signed with the key it was installed with.
 """
+import json
 import os
 import secrets
 import shutil
@@ -30,11 +31,8 @@ def run(*cmd, **kw):
 
 
 def app_version():
-    with open(os.path.join(ROOT, "CMakeLists.txt")) as f:
-        for line in f:
-            if line.startswith("project(Fry3DX VERSION "):
-                return line.split()[2]
-    return "0"
+    with open(os.path.join(ROOT, "project.json")) as f:  # (the version and the rest live there)
+        return json.load(f)["version"]
 
 
 def main():
diff --git a/engine/render/renderer.cpp b/engine/render/renderer.cpp
index 9b5c89b..71c91dd 100644
--- a/engine/render/renderer.cpp
+++ b/engine/render/renderer.cpp
@@ -211,10 +211,18 @@ void Renderer::drawSprite(const glm::vec3& at, float size, const glm::vec4& colo
     list.push_back({glm::vec4(at, size * 0.5f), color, glm::vec4(0, 0, 0, rotation), glm::vec4(0, 0, 0, tex)});
 }
 
-void Renderer::drawGrid(const glm::vec3& centre, const glm::vec3& u, const glm::vec3& v, float metre, const glm::vec3& look, float reach) {
+void Renderer::drawGrid(const glm::dvec3& under, const glm::vec3& u, const glm::vec3& v, float metre, bool dark, float reach) {
     if (packet_.sprites.size() >= 8192) return;
+    // Its middle a whole number of kilometres along u and v (so the lines are worked out from
+    // small numbers, sprite.frag): a square round it out to `reach` past the eye.
+    const double km = 1000.0 * double(metre);
+    const glm::dvec3 du(u), dv(v);
+    const double cu = std::round(glm::dot(under, du) / km) * km, cv = std::round(glm::dot(under, dv) / km) * km;
+    const glm::dvec3 centre = du * cu + dv * cv;
+    const glm::vec2 eye(float(glm::dot(under, du) - cu), float(glm::dot(under, dv) - cv));
+    const float half = reach + glm::length(eye);
     // (colour.a < 0 marks it; sprite.vert / sprite.frag)
-    packet_.sprites.push_back({glm::vec4(centre, reach), glm::vec4(look, -1.0f), glm::vec4(u, metre), glm::vec4(v, 0.0f)});
+    packet_.sprites.push_back({glm::vec4(glm::vec3(centre), half), glm::vec4(eye, 0.0f, dark ? -1.0f : -2.0f), glm::vec4(u, metre), glm::vec4(v, reach)});
 }
 
 void Renderer::drawStreak(const glm::vec3& from, const glm::vec3& to, float width, const glm::vec4& color, TextureId texture, bool additive, float widthTo) {
@@ -453,11 +461,13 @@ void Renderer::buildPacket(uint32_t width, uint32_t height) {
             for (const glm::vec3& q : corners) radius = std::max(radius, glm::length(q - center));
             radius = std::ceil(radius / 16.0f) * 16.0f;
             const float texel = 2.0f * radius / cascadeSize;
-            glm::mat4 lightView = glm::lookAt(glm::vec3(0), -sunDir_, up);
-            glm::vec4 lc = lightView * glm::vec4(center, 1);
+            // (in doubles: far from the origin a float's steps are near a texel's, and it'd shimmer)
+            const glm::dmat4 lightView0 = glm::lookAt(glm::dvec3(0), -glm::dvec3(sunDir_), glm::dvec3(up));
+            glm::dvec4 lc = lightView0 * glm::dvec4(glm::dvec3(center), 1);
             lc.x = std::floor(lc.x / texel) * texel;
             lc.y = std::floor(lc.y / texel) * texel;
-            center = glm::vec3(glm::inverse(lightView) * lc);
+            center = glm::vec3(glm::inverse(lightView0) * lc);
+            glm::mat4 lightView;
             lightView = glm::lookAt(center + sunDir_ * 8000.0f, center, up);
             frame.cascades[c] = glm::ortho(-radius, radius, -radius, radius, 1.0f, 16000.0f) * lightView;
             frame.splits[c] = f;
diff --git a/engine/render/renderer.h b/engine/render/renderer.h
index 5f0e9a4..be42d7a 100644
--- a/engine/render/renderer.h
+++ b/engine/render/renderer.h
@@ -101,11 +101,12 @@ public:
     // A sprite stretched from `from` to `to`, `width` across (`widthTo` at `to`: < 0, the same),
     // each end turned to face the eye as much as it can (rain; lines drawn in pieces meet exactly).
     void drawStreak(const glm::vec3& from, const glm::vec3& to, float width, const glm::vec4& color, TextureId texture, bool additive = false, float widthTo = -1.0f);
-    // A grid of lines on the plane through `centre` along u and v (unit), drawn for each pixel:
+    // A grid of lines on the plane through the origin along u and v (unit), drawn for each pixel:
     // every 10^n metres (`metre`: units in one), each set showing by how far apart its lines are
-    // on the screen, the axes coloured; look: the lines' shade (0 dark, 1 light), how faint, how
-    // strong; fading out `reach` from the centre.
-    void drawGrid(const glm::vec3& centre, const glm::vec3& u, const glm::vec3& v, float metre, const glm::vec3& look, float reach);
+    // on the screen, the axes coloured; dark lines (on the sunny ground) or light ones (in the
+    // grey room); fading out `reach` from `under` (the point under the eye, as a double: far out,
+    // a float's too coarse for lines a pixel wide).
+    void drawGrid(const glm::dvec3& under, const glm::vec3& u, const glm::vec3& v, float metre, bool dark, float reach);
     // skin: one matrix per joint (anim::skinMatrices) for skinned models; ignored otherwise.
     // lighting: probe light for moving things (nullptr = lightmap or simple sun shading).
     void drawModel(ModelId model, const glm::mat4& transform, const glm::vec4& tint = glm::vec4(1.0f),
diff --git a/engine/rhi/gl/gl_legacy.cpp b/engine/rhi/gl/gl_legacy.cpp
index 0b1536a..68ee323 100644
--- a/engine/rhi/gl/gl_legacy.cpp
+++ b/engine/rhi/gl/gl_legacy.cpp
@@ -368,7 +368,7 @@ uniform mat4 u_viewProj;
 uniform vec4 u_posSize, u_right, u_up; // right.w: turn (radians)
 uniform vec4 u_color;
 out vec2 v_uv;
-out vec3 v_world;
+out vec2 v_rel; // (a grid: where on it, from its middle)
 const vec2 kQuad[6] = vec2[](vec2(-1,-1), vec2(1,-1), vec2(1,1), vec2(-1,-1), vec2(1,1), vec2(-1,1));
 void main() {
     vec2 q = kQuad[gl_VertexID];
@@ -381,43 +381,46 @@ void main() {
         world = end + (length(side) > 1e-9 ? normalize(side) : vec3(0.0, 0.0, 1.0)) * q.x * (q.y < 0.0 ? -u_posSize.w : u_right.w);
     }
     v_uv = vec2(q.x * 0.5 + 0.5, 0.5 - q.y * 0.5);
-    v_world = world;
+    v_rel = u_color.a < 0.0 ? q * u_posSize.w : vec2(0.0);
     gl_Position = u_viewProj * vec4(world, 1.0);
     gl_Position.z = gl_Position.z * 2.0 - gl_Position.w;
 }
 )";
 const char* kSpriteFrag = R"(
 in vec2 v_uv;
-in vec3 v_world;
+in vec2 v_rel;
 uniform sampler2D u_albedo;
 uniform vec4 u_color, u_posSize, u_right, u_up;
 out vec4 o_color;
-// A grid (a sprite with colour.a < 0), worked out for each pixel where it lies on its plane:
-// lines every 10^n metres (`metre`: units in one), the four sets from the finest that isn't
-// crowded together here, each showing by how far apart its lines are on the screen (none where
-// they crowd, stronger where they're far apart: nothing jumps as the view moves), about a pixel
-// wide, smooth; the axes through the middle in the colour of the world's axis they run along.
-// look: x the lines' shade (0 dark, 1 light), y how faint, z how strong; reach: it fades out there.
+// A grid (a sprite with colour.a < 0: -1 dark lines, -2 light ones), worked out for each pixel
+// where it lies on its plane: lines every 10^n metres (`metre`: units in one), the four sets from
+// the finest that isn't crowded together here, each showing by how far apart its lines are on the
+// screen (none where they crowd, stronger where they're far apart: nothing jumps as the view
+// moves), about a pixel wide, smooth; the axes through the middle in the colour of the world's
+// axis they run along. All from `rel`, where it is from the square's middle (a whole number of
+// kilometres from the world's: far out, the world's own numbers are too coarse for lines a
+// pixel wide); `eye`: the point under the eye, from the middle; it fades out `reach` from there.
 vec3 gridAxisColor(vec3 d) {
     d = abs(d);
     return d.x > 0.5 ? vec3(0.9, 0.25, 0.25) : d.y > 0.5 ? vec3(0.3, 0.75, 0.25) : vec3(0.25, 0.45, 0.95);
 }
-vec4 gridColor(vec3 w, vec3 centre, vec3 u, vec3 v, float metre, vec3 look, float reach) {
-    vec2 c = vec2(dot(w, u), dot(w, v));
-    vec2 fw = max(fwidth(c), vec2(1e-9));
+vec4 gridColor(vec2 rel, vec3 centre, vec3 u, vec3 v, float metre, float kind, vec2 eye, float reach) {
+    vec2 base = vec2(dot(centre, u), dot(centre, v)); // (the middle: whole kilometres)
+    vec2 fw = max(fwidth(rel), vec2(1e-9));
     float finest = floor(log(min(fw.x, fw.y) * 5.0 / metre) / log(10.0)); // (10^this m: 5 pixels apart or more)
+    vec3 look = kind < -1.5 ? vec3(1.0, 0.05, 0.16) : vec3(0.0, 0.14, 0.4); // (shade, how faint, how strong)
     float lines = 0.0;
     for (int k = 0; k < 4; ++k) {
         float s = metre * pow(10.0, finest + float(k));
         vec2 apart = s / fw; // (pixels between this set's lines, each way)
-        vec2 off = abs(fract(c / s + 0.5) - 0.5) * apart; // (pixels to the nearest of them)
+        vec2 off = abs(fract(fract(base / s) + rel / s + 0.5) - 0.5) * apart; // (pixels to the nearest of them)
         vec2 strong = smoothstep(20.0, 160.0, apart);
         vec2 cover = clamp(0.5 * (1.0 + 0.6 * strong) + 0.5 - off, 0.0, 1.0);
         vec2 a = cover * smoothstep(5.0, 20.0, apart) * mix(vec2(look.y), vec2(look.z), strong);
         lines = max(lines, max(a.x, a.y));
     }
-    vec2 axis = clamp(1.25 - abs(c) / fw, 0.0, 1.0) * 0.9; // (x: the line along v, y: along u)
-    float fade = smoothstep(reach, reach * 0.6, length(w - centre));
+    vec2 axis = clamp(1.25 - abs(base + rel) / fw, 0.0, 1.0) * 0.9; // (x: the line along v, y: along u)
+    float fade = smoothstep(reach, reach * 0.6, length(rel - eye));
     vec3 col = vec3(look.x) * lines;
     float a = lines;
     col = mix(col, gridAxisColor(v), axis.x), a = mix(a, 1.0, axis.x);
@@ -426,7 +429,7 @@ vec4 gridColor(vec3 w, vec3 centre, vec3 u, vec3 v, float metre, vec3 look, floa
 }
 void main() {
     if (u_color.a < 0.0) {
-        o_color = gridColor(v_world, u_posSize.xyz, normalize(u_right.xyz), normalize(u_up.xyz), u_right.w, u_color.rgb, u_posSize.w);
+        o_color = gridColor(v_rel, u_posSize.xyz, normalize(u_right.xyz), normalize(u_up.xyz), u_right.w, u_color.a, u_color.xy, u_up.w);
         return;
     }
     vec4 t = texture(u_albedo, v_uv);
diff --git a/engine/shaders/sprite.frag b/engine/shaders/sprite.frag
index 32d352f..2ba66e4 100644
--- a/engine/shaders/sprite.frag
+++ b/engine/shaders/sprite.frag
@@ -9,33 +9,36 @@ PUSH_BLOCK {
     vec4 up;
 } pc;
 layout(location = 0) in vec2 v_uv;
-layout(location = 1) in vec3 v_world;
-// A grid (a sprite with colour.a < 0), worked out for each pixel where it lies on its plane:
-// lines every 10^n metres (`metre`: units in one), the four sets from the finest that isn't
-// crowded together here, each showing by how far apart its lines are on the screen (none where
-// they crowd, stronger where they're far apart: nothing jumps as the view moves), about a pixel
-// wide, smooth; the axes through the middle in the colour of the world's axis they run along.
-// look: x the lines' shade (0 dark, 1 light), y how faint, z how strong; reach: it fades out there.
+layout(location = 1) in vec2 v_rel;
+// A grid (a sprite with colour.a < 0: -1 dark lines, -2 light ones), worked out for each pixel
+// where it lies on its plane: lines every 10^n metres (`metre`: units in one), the four sets from
+// the finest that isn't crowded together here, each showing by how far apart its lines are on the
+// screen (none where they crowd, stronger where they're far apart: nothing jumps as the view
+// moves), about a pixel wide, smooth; the axes through the middle in the colour of the world's
+// axis they run along. All from `rel`, where it is from the square's middle (a whole number of
+// kilometres from the world's: far out, the world's own numbers are too coarse for lines a
+// pixel wide); `eye`: the point under the eye, from the middle; it fades out `reach` from there.
 vec3 gridAxisColor(vec3 d) {
     d = abs(d);
     return d.x > 0.5 ? vec3(0.9, 0.25, 0.25) : d.y > 0.5 ? vec3(0.3, 0.75, 0.25) : vec3(0.25, 0.45, 0.95);
 }
-vec4 gridColor(vec3 w, vec3 centre, vec3 u, vec3 v, float metre, vec3 look, float reach) {
-    vec2 c = vec2(dot(w, u), dot(w, v));
-    vec2 fw = max(fwidth(c), vec2(1e-9));
+vec4 gridColor(vec2 rel, vec3 centre, vec3 u, vec3 v, float metre, float kind, vec2 eye, float reach) {
+    vec2 base = vec2(dot(centre, u), dot(centre, v)); // (the middle: whole kilometres)
+    vec2 fw = max(fwidth(rel), vec2(1e-9));
     float finest = floor(log(min(fw.x, fw.y) * 5.0 / metre) / log(10.0)); // (10^this m: 5 pixels apart or more)
+    vec3 look = kind < -1.5 ? vec3(1.0, 0.05, 0.16) : vec3(0.0, 0.14, 0.4); // (shade, how faint, how strong)
     float lines = 0.0;
     for (int k = 0; k < 4; ++k) {
         float s = metre * pow(10.0, finest + float(k));
         vec2 apart = s / fw; // (pixels between this set's lines, each way)
-        vec2 off = abs(fract(c / s + 0.5) - 0.5) * apart; // (pixels to the nearest of them)
+        vec2 off = abs(fract(fract(base / s) + rel / s + 0.5) - 0.5) * apart; // (pixels to the nearest of them)
         vec2 strong = smoothstep(20.0, 160.0, apart);
         vec2 cover = clamp(0.5 * (1.0 + 0.6 * strong) + 0.5 - off, 0.0, 1.0);
         vec2 a = cover * smoothstep(5.0, 20.0, apart) * mix(vec2(look.y), vec2(look.z), strong);
         lines = max(lines, max(a.x, a.y));
     }
-    vec2 axis = clamp(1.25 - abs(c) / fw, 0.0, 1.0) * 0.9; // (x: the line along v, y: along u)
-    float fade = smoothstep(reach, reach * 0.6, length(w - centre));
+    vec2 axis = clamp(1.25 - abs(base + rel) / fw, 0.0, 1.0) * 0.9; // (x: the line along v, y: along u)
+    float fade = smoothstep(reach, reach * 0.6, length(rel - eye));
     vec3 col = vec3(look.x) * lines;
     float a = lines;
     col = mix(col, gridAxisColor(v), axis.x), a = mix(a, 1.0, axis.x);
@@ -45,8 +48,8 @@ vec4 gridColor(vec3 w, vec3 centre, vec3 u, vec3 v, float metre, vec3 look, floa
 
 layout(location = 0) out vec4 o_color;
 void main() {
-    if (pc.color.a < 0.0) { // a grid: right.w the units in a metre, color.rgb its look, posSize.w how far it reaches
-        o_color = gridColor(v_world, pc.posSize.xyz, normalize(pc.right.xyz), normalize(pc.up.xyz), pc.right.w, pc.color.rgb, pc.posSize.w);
+    if (pc.color.a < 0.0) { // a grid: right.w the units in a metre, up.w how far it reaches, color.xy where the eye is over it
+        o_color = gridColor(v_rel, pc.posSize.xyz, normalize(pc.right.xyz), normalize(pc.up.xyz), pc.right.w, pc.color.a, pc.color.xy, pc.up.w);
         return;
     }
     vec4 t = sampleTex(floatBitsToUint(pc.up.w), v_uv);
diff --git a/engine/shaders/sprite.vert b/engine/shaders/sprite.vert
index bc96d4d..8b9cfc1 100644
--- a/engine/shaders/sprite.vert
+++ b/engine/shaders/sprite.vert
@@ -9,7 +9,7 @@ PUSH_BLOCK {
     vec4 up;      // camera up, w = texture index (bits)
 } pc;
 layout(location = 0) out vec2 v_uv;
-layout(location = 1) out vec3 v_world;
+layout(location = 1) out vec2 v_rel; // (a grid: where on it, from its middle)
 const vec2 kQuad[6] = vec2[](vec2(-1,-1), vec2(1,-1), vec2(1,1), vec2(-1,-1), vec2(1,1), vec2(-1,1));
 void main() {
     vec2 q = kQuad[VERTEX_ID];
@@ -23,6 +23,6 @@ void main() {
     }
     v_uv = q * 0.5 + 0.5;
     v_uv.y = 1.0 - v_uv.y;
-    v_world = world;
+    v_rel = pc.color.a < 0.0 ? q * pc.posSize.w : vec2(0.0);
     gl_Position = pc.viewProj * vec4(world, 1.0);
 }
diff --git a/src/app_view.cpp b/src/app_view.cpp
index 81b727c..150f768 100644
--- a/src/app_view.cpp
+++ b/src/app_view.cpp
@@ -1412,9 +1412,8 @@ auto App::draw3D(keel::Renderer& r) -> void {
         const glm::vec3 u = n.z > 0.5f ? glm::vec3(1, 0, 0) : n.x > 0.5f ? glm::vec3(0, 1, 0) : glm::vec3(1, 0, 0);
         const glm::vec3 v = glm::cross(n, u);
         const float reach = nearFar_.y / kUnits * 0.9f;
-        const glm::vec3 under = eye_ - n * glm::dot(eye_, n); // (the grid's plane goes through the origin)
-        const glm::vec3 look = rendered ? glm::vec3(0.0f, 0.14f, 0.4f) : glm::vec3(1.0f, 0.05f, 0.16f); // (dark lines on the sunny ground, light ones in the grey room)
-        r.drawGrid(under * kUnits, u, v, kUnits, look, reach * kUnits);
+        const glm::dvec3 eye(eye_), dn(n), under = (eye - dn * glm::dot(eye, dn)) * double(kUnits); // (the grid's plane goes through the origin)
+        r.drawGrid(under, u, v, kUnits, rendered, reach * kUnits); // (dark lines on the sunny ground, light ones in the grey room)
     }
     if (tab_ == Tab::Print) drawPrintBed(r, light);
 }
diff --git a/tools/package.py b/tools/package.py
index 2ba8401..4fcb9e6 100644
--- a/tools/package.py
+++ b/tools/package.py
@@ -12,6 +12,7 @@
 Each unpacks to one Fry3DX/ folder: the program, its content (engine/, Fry3DX/; on a Mac inside
 the app), LICENSE and a README.txt. (The Android APK: android/build_apk.py.)
 """
+import json
 import os
 import shutil
 import subprocess
@@ -36,11 +37,8 @@ Open source under the Apache License 2.0 (LICENSE). Sky pictures: Poly Haven, CC
 
 
 def version():
-    with open(os.path.join(ROOT, "CMakeLists.txt")) as f:
-        for line in f:
-            if line.startswith("project(Fry3DX VERSION "):
-                return line.split()[2]
-    return "0"
+    with open(os.path.join(ROOT, "project.json")) as f:  # (the version and the rest live there)
+        return json.load(f)["version"]
 
 
 PC_NEEDS = "a graphics card with Vulkan (or OpenGL 4.6)"