diff --git a/changes/render3d-height-format.md b/changes/render3d-height-format.md
new file mode 100644
index 00000000..66a91673
--- /dev/null
+++ b/changes/render3d-height-format.md
@@ -0,0 +1,8 @@
+bump: patch
+type: perf
+**The terrain's height field takes half the GPU memory.** The baked height and surface normal
+shared one 4096^2 RGBA32F (256 MB); the height now stays alone in its R32F - the same 32 bits
+every placement, the CPU read-back and physics read - and the normal goes beside it as x and z in
+an RG16F (`ter_normal_tex`, bound as `u_ter_normal`), y rebuilt where it is read: 128 MB. The grass
+cull takes it as a third texture (binding 6). In Maroon Lake's play: 2793 -> 2647 MB; the camp's
+frame differs in 0.066% of pixels by more than 8, single grass blades at the slope gate.
diff --git a/packages/ludic.render3d/env.ludic b/packages/ludic.render3d/env.ludic
index bbeedfdb..9bb094de 100644
--- a/packages/ludic.render3d/env.ludic
+++ b/packages/ludic.render3d/env.ludic
@@ -734,6 +734,7 @@ export state Render3dState {
   ter_force_near: bool = false
   ter_skip: bool = false
   ter_height_tex: int = 0
+  ter_normal_tex: int = 0            # the baked surface normal, x and z in RG16F (y rebuilt when read)
   ter_heights: floats = null         # CPU copy, float bits, TERRAIN_RES^2
   ter_reflect: bool = false          # drawing the reflection: the mid mesh is plenty
   ter_prog: int = 0
diff --git a/packages/ludic.render3d/grass_gpu.ludic b/packages/ludic.render3d/grass_gpu.ludic
index 1c200b1f..da9f026a 100644
--- a/packages/ludic.render3d/grass_gpu.ludic
+++ b/packages/ludic.render3d/grass_gpu.ludic
@@ -30,7 +30,7 @@ function gg_init(render3d_st: mut Render3dState) -> void {
   if not gpu_has_compute(render3d_st) or render3d_st.grass_prog == 0 { return }
   if r3d_env_has(render3d_st, "R3D_GRASS_GPU") and r3d_env(render3d_st, "R3D_GRASS_GPU") == "0" { return }
   render3d_st.gg_reset = gpu_compute(render3d_st, "grass_reset", 1)
-  render3d_st.gg_cull = gpu_compute_tex(render3d_st, "grass_cull", 3, 2)
+  render3d_st.gg_cull = gpu_compute_tex(render3d_st, "grass_cull", 3, 3)
   render3d_st.gg_prog = r3d_program(render3d_st, "grass_inst.vert", "model.frag", "#define FOLIAGE\n#define BLADE\n#define GBLADE\n#define GINST\n")
   if render3d_st.gg_reset == 0 or render3d_st.gg_cull == 0 or render3d_st.gg_prog == 0 { return }
   render3d_st.gg_tiles_buf = new []int
@@ -105,7 +105,7 @@ function gg_cull_frame(render3d_st: mut Render3dState) -> void {
   # made once: a words() a frame is a calloc nothing frees
   if render3d_st.gg_rb == null {
     render3d_st.gg_rb = words(4);  render3d_st.gg_cb = words(1);  render3d_st.gg_bufs = words(3)
-    render3d_st.gg_texs = words(2);  render3d_st.gg_pr = words(48)
+    render3d_st.gg_texs = words(3);  render3d_st.gg_pr = words(48)
   }
   let rb = render3d_st.gg_rb
   rb[0] = GG_BANDS;  rb[1] = 0;  rb[2] = 0;  rb[3] = 0
@@ -120,7 +120,7 @@ function gg_cull_frame(render3d_st: mut Render3dState) -> void {
   let bufs = render3d_st.gg_bufs
   bufs[0] = tb;  bufs[1] = render3d_st.gg_out;  bufs[2] = render3d_st.gg_cmds
   let texs = render3d_st.gg_texs
-  texs[0] = render3d_st.ter_height_tex;  texs[1] = render3d_st.ter_ortho_tex
+  texs[0] = render3d_st.ter_height_tex;  texs[1] = render3d_st.ter_ortho_tex;  texs[2] = render3d_st.ter_normal_tex
   gpu_dispatch_tex(render3d_st, render3d_st.gg_cull, data_of(pr), 192, bufs, texs, (render3d_st.gg_max + 63) / 64, render3d_st.gg_n)
 }
 
diff --git a/packages/ludic.render3d/shaders/grass.mesh b/packages/ludic.render3d/shaders/grass.mesh
index b172254d..6f2c6305 100644
--- a/packages/ludic.render3d/shaders/grass.mesh
+++ b/packages/ludic.render3d/shaders/grass.mesh
@@ -17,6 +17,9 @@ uniform mat4 u_vp;
 uniform vec3 u_cam_pos;
 uniform float u_time;
 uniform sampler2D u_ts_height;
+// the baked terrain normal: x and z in RG16F, y rebuilt (a terrain normal always points up)
+uniform sampler2D u_ter_normal;
+vec3 terNormal(vec2 uv) { vec2 xz = textureLod(u_ter_normal, uv, 0.0).rg;  return vec3(xz.x, sqrt(max(1.0 - dot(xz, xz), 0.0)), xz.y); }
 uniform vec2 u_ts_origin;
 uniform float u_ts_half;
 uniform sampler2D u_ortho;
@@ -95,7 +98,7 @@ void main() {
     vec4 ht = textureLod(u_ts_height, huv, 0.0);
     vec4 croot = u_vp * vec4(xz.x, ht.r, xz.y, 1.0);
     if (croot.w < -1.0 || abs(croot.x) > croot.w * 1.25 + 1.5 || abs(croot.y) > croot.w * 1.4 + 1.5) continue;
-    vec3 gn = normalize(ht.gba);
+    vec3 gn = terNormal(huv);
     float h3 = bladeHash(ci, j, 2), h4 = bladeHash(ci, j, 3);
     float wl = u_sea_level;
     if (u_lake.z > 0.0) { vec2 q = (xz - u_lake.xy) / u_lake.zw;  if (dot(q, q) < 1.0) wl = max(wl, u_lake_level); }
diff --git a/packages/ludic.render3d/shaders/grass.vert b/packages/ludic.render3d/shaders/grass.vert
index 32f75c16..e434b24b 100644
--- a/packages/ludic.render3d/shaders/grass.vert
+++ b/packages/ludic.render3d/shaders/grass.vert
@@ -15,6 +15,9 @@ uniform mat4 u_vp;
 uniform vec3 u_cam_pos;
 uniform float u_time;
 uniform sampler2D u_ts_height;
+// the baked terrain normal: x and z in RG16F, y rebuilt (a terrain normal always points up)
+uniform sampler2D u_ter_normal;
+vec3 terNormal(vec2 uv) { vec2 xz = textureLod(u_ter_normal, uv, 0.0).rg;  return vec3(xz.x, sqrt(max(1.0 - dot(xz, xz), 0.0)), xz.y); }
 uniform vec2 u_ts_origin;
 uniform float u_ts_half;
 uniform sampler2D u_ortho;
@@ -133,7 +136,7 @@ void main() {
   vec4 ht = texture(u_ts_height, huv);
   vec4 croot = u_vp * vec4(xz.x, ht.r, xz.y, 1.0);
   if (croot.w < -1.0 || abs(croot.x) > croot.w * 1.25 + 1.5 || abs(croot.y) > croot.w * 1.4 + 1.5) { cull(); return; }
-  vec3 gn = normalize(ht.gba);
+  vec3 gn = terNormal(huv);
   float h3 = bladeHash(ci, j, 2), h4 = bladeHash(ci, j, 3);
   // No blades under water: the sea's line everywhere, and the lake's inside its outline. One
   // line for both left a lake above the sea with grass on its bed or a valley with none.
diff --git a/packages/ludic.render3d/shaders/grass_cull.comp b/packages/ludic.render3d/shaders/grass_cull.comp
index 4f4567ad..e8cde392 100644
--- a/packages/ludic.render3d/shaders/grass_cull.comp
+++ b/packages/ludic.render3d/shaders/grass_cull.comp
@@ -25,8 +25,9 @@ layout(set = 0, binding = 0) uniform Params {
 layout(set = 0, binding = 1) readonly buffer Tiles { vec4 tiles[]; };   // corner x/z, indices per cell, cells per side
 layout(set = 0, binding = 2) buffer Out { vec4 outv[]; };               // 4 per blade
 layout(set = 0, binding = 3) buffer Cmds { uint cmds[]; };              // VkDrawIndexedIndirectCommand per band
-layout(set = 0, binding = 4) uniform sampler2D u_height;                // height, normal (terrain's u_ts_height)
+layout(set = 0, binding = 4) uniform sampler2D u_height;                // the height (terrain's u_ts_height)
 layout(set = 0, binding = 5) uniform sampler2D u_ortho;                 // the photograph
+layout(set = 0, binding = 6) uniform sampler2D u_ter_normal;            // the normal: x and z, y rebuilt
 
 const float CELL = 4.0;   // grass.ludic GRASS_CELL
 
@@ -92,7 +93,8 @@ void main() {
   // the frustum, on a sphere round the blade (it stands at most 0.9 m tall)
   vec3 root = vec3(xz.x, ht.r, xz.y);
   for (int k = 0; k < 4; k++) { if (dot(pr.planes[k].xyz, root) + pr.planes[k].w < -1.0) return; }
-  vec3 gn = normalize(ht.gba);
+  vec2 gxz = textureLod(u_ter_normal, huv, 0.0).rg;
+  vec3 gn = vec3(gxz.x, sqrt(max(1.0 - dot(gxz, gxz), 0.0)), gxz.y);
   float h3 = bladeHash(ci, j, 2), h4 = bladeHash(ci, j, 3);
   float wl = pr.lev.y;
   if (pr.lake.z > 0.0) { vec2 q = (xz - pr.lake.xy) / pr.lake.zw;  if (dot(q, q) < 1.0) wl = max(wl, pr.lev.x); }
diff --git a/packages/ludic.render3d/shaders/spv/1f95f31b.frag.spv b/packages/ludic.render3d/shaders/spv/1f95f31b.frag.spv
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index 2a3f5b41..04901728 100644
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diff --git a/packages/ludic.render3d/shaders/spv/b8cff226.vert.spv b/packages/ludic.render3d/shaders/spv/b8cff226.vert.spv
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diff --git a/packages/ludic.render3d/shaders/spv/cb13f3c6.frag.spv b/packages/ludic.render3d/shaders/spv/cb13f3c6.frag.spv
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index 4858c099..85453269 100644
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diff --git a/packages/ludic.render3d/shaders/spv/f2952361.frag.spv b/packages/ludic.render3d/shaders/spv/f2952361.frag.spv
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diff --git a/packages/ludic.render3d/shaders/spv/f4382918.frag.spv b/packages/ludic.render3d/shaders/spv/f4382918.frag.spv
index 9f268a77..194f3f0b 100644
Binary files a/packages/ludic.render3d/shaders/spv/f4382918.frag.spv and b/packages/ludic.render3d/shaders/spv/f4382918.frag.spv differ
diff --git a/packages/ludic.render3d/shaders/spv/grass_cull.comp.spv b/packages/ludic.render3d/shaders/spv/grass_cull.comp.spv
index 4b9c9260..46bcf895 100644
Binary files a/packages/ludic.render3d/shaders/spv/grass_cull.comp.spv and b/packages/ludic.render3d/shaders/spv/grass_cull.comp.spv differ
diff --git a/packages/ludic.render3d/shaders/spv/manifest.txt b/packages/ludic.render3d/shaders/spv/manifest.txt
index 78000865..3d92618e 100644
--- a/packages/ludic.render3d/shaders/spv/manifest.txt
+++ b/packages/ludic.render3d/shaders/spv/manifest.txt
@@ -918,8 +918,9 @@ T d48d6a48 u_nrm 7
 T d48d6a48 u_ortho 8
 T d48d6a48 u_prefilter 9
 T d48d6a48 u_shadow 10
-T d48d6a48 u_tershadow 11
-T d48d6a48 u_ts_height 12
+T d48d6a48 u_ter_normal 11
+T d48d6a48 u_tershadow 12
+T d48d6a48 u_ts_height 13
 P cb13f3c6 grass.vert model.frag #define FOLIAGE;#define BLADE;#define GBLADE;
 B cb13f3c6 vert 0 324
 U cb13f3c6 vert u_view 0 mat4 1 0
@@ -1000,8 +1001,9 @@ T cb13f3c6 u_nrm 7
 T cb13f3c6 u_ortho 8
 T cb13f3c6 u_prefilter 9
 T cb13f3c6 u_shadow 10
-T cb13f3c6 u_tershadow 11
-T cb13f3c6 u_ts_height 12
+T cb13f3c6 u_ter_normal 11
+T cb13f3c6 u_tershadow 12
+T cb13f3c6 u_ts_height 13
 P b8cff226 grass.vert model.frag #define FOLIAGE;#define BLADE;#define GBLADE;#define TILES;
 B b8cff226 vert 0 4420
 U b8cff226 vert u_view 0 mat4 1 0
@@ -1083,8 +1085,9 @@ T b8cff226 u_nrm 7
 T b8cff226 u_ortho 8
 T b8cff226 u_prefilter 9
 T b8cff226 u_shadow 10
-T b8cff226 u_tershadow 11
-T b8cff226 u_ts_height 12
+T b8cff226 u_ter_normal 11
+T b8cff226 u_tershadow 12
+T b8cff226 u_ts_height 13
 P 3733fc38 impostor.vert impostor.frag 
 B 3733fc38 vert 0 232
 U 3733fc38 vert u_view 0 mat4 1 0
@@ -3020,8 +3023,9 @@ T 2e2908c8 u_rock_n 13
 T 2e2908c8 u_shadow 14
 T 2e2908c8 u_snow_d 15
 T 2e2908c8 u_sunshadow 16
-T 2e2908c8 u_tershadow 17
-T 2e2908c8 u_ts_height 18
+T 2e2908c8 u_ter_normal 17
+T 2e2908c8 u_tershadow 18
+T 2e2908c8 u_ts_height 19
 P 1f95f31b terrain.vert terrain.frag #define FAR_ONLY;
 B 1f95f31b vert 0 204
 U 1f95f31b vert u_half 0 float 1 0
@@ -3097,8 +3101,9 @@ T 1f95f31b u_rock_n 13
 T 1f95f31b u_shadow 14
 T 1f95f31b u_snow_d 15
 T 1f95f31b u_sunshadow 16
-T 1f95f31b u_tershadow 17
-T 1f95f31b u_ts_height 18
+T 1f95f31b u_ter_normal 17
+T 1f95f31b u_tershadow 18
+T 1f95f31b u_ts_height 19
 P f4382918 terrain.vert terrain.frag #define NEAR_ONLY;
 B f4382918 vert 0 204
 U f4382918 vert u_half 0 float 1 0
@@ -3174,8 +3179,9 @@ T f4382918 u_rock_n 13
 T f4382918 u_shadow 14
 T f4382918 u_snow_d 15
 T f4382918 u_sunshadow 16
-T f4382918 u_tershadow 17
-T f4382918 u_ts_height 18
+T f4382918 u_ter_normal 17
+T f4382918 u_tershadow 18
+T f4382918 u_ts_height 19
 P f2952361 terrain.vert terrain.frag #define SUN_INLINE;
 B f2952361 vert 0 204
 U f2952361 vert u_half 0 float 1 0
@@ -3251,8 +3257,9 @@ T f2952361 u_rock_n 13
 T f2952361 u_shadow 14
 T f2952361 u_snow_d 15
 T f2952361 u_sunshadow 16
-T f2952361 u_tershadow 17
-T f2952361 u_ts_height 18
+T f2952361 u_ter_normal 17
+T f2952361 u_tershadow 18
+T f2952361 u_ts_height 19
 P a0f2dbac terrain.vert terrain.frag #define SUN_INLINE;#define FAR_ONLY;
 B a0f2dbac vert 0 204
 U a0f2dbac vert u_half 0 float 1 0
@@ -3328,8 +3335,9 @@ T a0f2dbac u_rock_n 13
 T a0f2dbac u_shadow 14
 T a0f2dbac u_snow_d 15
 T a0f2dbac u_sunshadow 16
-T a0f2dbac u_tershadow 17
-T a0f2dbac u_ts_height 18
+T a0f2dbac u_ter_normal 17
+T a0f2dbac u_tershadow 18
+T a0f2dbac u_ts_height 19
 P 5e4589a1 terrain.vert terrain.frag #define SUN_INLINE;#define NEAR_ONLY;
 B 5e4589a1 vert 0 204
 U 5e4589a1 vert u_half 0 float 1 0
@@ -3405,8 +3413,9 @@ T 5e4589a1 u_rock_n 13
 T 5e4589a1 u_shadow 14
 T 5e4589a1 u_snow_d 15
 T 5e4589a1 u_sunshadow 16
-T 5e4589a1 u_tershadow 17
-T 5e4589a1 u_ts_height 18
+T 5e4589a1 u_ter_normal 17
+T 5e4589a1 u_tershadow 18
+T 5e4589a1 u_ts_height 19
 P bf3151c8 terrain.vert tersun.frag 
 B bf3151c8 vert 0 204
 U bf3151c8 vert u_half 0 float 1 0
@@ -3462,8 +3471,9 @@ T bf3151c8 u_height 3
 T bf3151c8 u_irradiance 4
 T bf3151c8 u_prefilter 5
 T bf3151c8 u_shadow 6
-T bf3151c8 u_tershadow 7
-T bf3151c8 u_ts_height 8
+T bf3151c8 u_ter_normal 7
+T bf3151c8 u_tershadow 8
+T bf3151c8 u_ts_height 9
 P 46e2325c water.vert water.frag 
 B 46e2325c vert 0 152
 U 46e2325c vert u_view 0 mat4 1 0
diff --git a/packages/ludic.render3d/shaders/ternormal.frag b/packages/ludic.render3d/shaders/ternormal.frag
index 25355982..583fd3a7 100644
--- a/packages/ludic.render3d/shaders/ternormal.frag
+++ b/packages/ludic.render3d/shaders/ternormal.frag
@@ -1,5 +1,5 @@
-// Second generation pass: copy the height into R and bake the B-spline surface normal into
-// GBA, once, at texel resolution. terrain.frag used to differentiate the bicubic height
+// Second generation pass: bake the B-spline surface normal, once, at texel resolution: x and z
+// into an RG16F beside the R32F height (y is rebuilt where it is read). terrain.frag used to differentiate the bicubic height
 // per pixel — four bicubic reads, sixteen taps — for a quantity that never changes.
 in vec2 v_uv;
 out vec4 o;
@@ -28,5 +28,5 @@ void main() {
   float hd = heightSmooth(u_src, v_uv - vec2(0, step));
   float hu = heightSmooth(u_src, v_uv + vec2(0, step));
   vec3 n = normalize(vec3(hl - hr, 2.0 * world, hd - hu));
-  o = vec4(texture(u_src, v_uv).r, n);
+  o = vec4(n.x, n.z, 0.0, 0.0);      // into RG16F: x and z, y rebuilt when read (always up)
 }
diff --git a/packages/ludic.render3d/shaders/terrain.frag b/packages/ludic.render3d/shaders/terrain.frag
index a2d2cb2a..e6816fe9 100644
--- a/packages/ludic.render3d/shaders/terrain.frag
+++ b/packages/ludic.render3d/shaders/terrain.frag
@@ -7,6 +7,9 @@ out vec4 o_color;
 #define gnoise(p) 0.1
 #endif
 uniform sampler2D u_height;
+// the baked terrain normal: x and z in RG16F, y rebuilt (a terrain normal always points up)
+uniform sampler2D u_ter_normal;
+vec3 terNormal(vec2 uv) { vec2 xz = texture(u_ter_normal, uv).rg;  return vec3(xz.x, sqrt(max(1.0 - dot(xz, xz), 0.0)), xz.y); }
 uniform float u_half;
 uniform float u_texel;               // height-map texel size in uv
 uniform sampler2D u_grass_d; uniform sampler2D u_grass_n; uniform sampler2D u_grass_a;
@@ -76,7 +79,7 @@ float heightSmooth(sampler2D tex, vec2 uv) {
 }
 // baked at generation (ternormal.frag) into the height texture's GBA
 vec3 terrainNormal(vec2 uv) {
-  return normalize(texture(u_height, uv).gba);
+  return terNormal(uv);
 }
 
 // stochastic (triangle-grid) sampling: three randomly offset / rotated taps blended by
@@ -223,7 +226,7 @@ void triC(bool cheap, sampler2D d, sampler2D nm, sampler2D am, vec3 p, vec3 dpx,
 uniform float u_far_split;
 uniform float u_far_band;
 float sunInline(vec3 p, float dist, float viewDepth) {
-  vec3 Ng = normalize(texture(u_height, v_huv).gba);
+  vec3 Ng = terNormal(v_huv);
   if (dist > u_far_split + u_far_band) return sunShadowCheap(p, Ng, viewDepth);
   if (dist < u_far_split - u_far_band) return sunShadow(p, Ng, viewDepth);
   return mix(sunShadow(p, Ng, viewDepth), sunShadowCheap(p, Ng, viewDepth),
diff --git a/packages/ludic.render3d/shaders/tersun.frag b/packages/ludic.render3d/shaders/tersun.frag
index 7a72c6bf..f11c851b 100644
--- a/packages/ludic.render3d/shaders/tersun.frag
+++ b/packages/ludic.render3d/shaders/tersun.frag
@@ -12,13 +12,16 @@ in vec3 v_wpos;
 in vec2 v_huv;
 out float o_sh;
 uniform sampler2D u_height;
+// the baked terrain normal: x and z in RG16F, y rebuilt (a terrain normal always points up)
+uniform sampler2D u_ter_normal;
+vec3 terNormal(vec2 uv) { vec2 xz = texture(u_ter_normal, uv).rg;  return vec3(xz.x, sqrt(max(1.0 - dot(xz, xz), 0.0)), xz.y); }
 uniform mat4 u_view;
 uniform float u_far_split;
 uniform float u_far_band;
 void main() {
   vec3 p = v_wpos;
   if (p.y < u_clip_y) discard;
-  vec3 N = normalize(texture(u_height, v_huv).gba);
+  vec3 N = terNormal(v_huv);
   float dist = length(p - u_cam_pos);
   float viewDepth = -(u_view * vec4(p, 1.0)).z;
   // The same tier choice the ground makes, cross-faded over the same band: the near tier
diff --git a/packages/ludic.render3d/terrain.ludic b/packages/ludic.render3d/terrain.ludic
index 433ee665..863ac4c8 100644
--- a/packages/ludic.render3d/terrain.ludic
+++ b/packages/ludic.render3d/terrain.ludic
@@ -199,16 +199,19 @@ function terrain_generate(render3d_st: mut Render3dState) -> void {
   }
   mesh_draw(render3d_st, render3d_st.sky_fullscreen)
   # second pass: R = height, GBA = the smooth surface normal, baked once (ternormal.frag)
+  # the height stays in its own R32F (physics and every placement read it at full precision); the
+  # baked normal goes beside it as x and z in RG16F, y rebuilt where it is read - 128 MB where one
+  # RGBA32F carrying both was 256 (plan 23 of maroon-lake)
   let raw = render3d_st.ter_height_tex
-  render3d_st.ter_height_tex = tex_target(render3d_st, TERRAIN_RES, TERRAIN_RES, GL_RGBA32F, GL_RGBA, GL_FLOAT, GL_LINEAR)
-  gpu_fb_color(render3d_st, 0, render3d_st.ter_height_tex)
+  if render3d_st.ter_normal_tex != 0 { gpu_tex_free(render3d_st, render3d_st.ter_normal_tex) }
+  render3d_st.ter_normal_tex = tex_target(render3d_st, TERRAIN_RES, TERRAIN_RES, GL_RG16F, GL_RG, GL_FLOAT, GL_LINEAR)
+  gpu_fb_color(render3d_st, 0, render3d_st.ter_normal_tex)
   let pn = r3d_program(render3d_st, "fullscreen.vert", "ternormal.frag", "")
   gpu_use_program(render3d_st, pn)
   r3d_bind_2d(render3d_st, pn, "u_src", 0, raw)
   u_f(render3d_st, gpu_uniform(render3d_st, pn, "u_half"), float(render3d_st.TERRAIN_HALF))
   mesh_draw(render3d_st, render3d_st.sky_fullscreen)
   gpu_program_free(render3d_st, pn)
-  gpu_tex_free(render3d_st, raw)
   # read the heights back for placement, into the array a previous map had: always the same size,
   # and made anew on every build it was 64 MB lost per world swap
   if render3d_st.ter_heights == null { render3d_st.ter_heights = floats(TERRAIN_RES * TERRAIN_RES) }
@@ -224,6 +227,7 @@ function terrain_generate(render3d_st: mut Render3dState) -> void {
 # The height field for shaders that place things on the ground (model.vert's u_ground)
 function terrain_bind_height(render3d_st: mut Render3dState, p: int) -> void {
   r3d_bind_2d(render3d_st, p, "u_ts_height", 5, render3d_st.ter_height_tex)
+  r3d_bind_2d(render3d_st, p, "u_ter_normal", 6, render3d_st.ter_normal_tex)
   u_f(render3d_st, gpu_uniform(render3d_st, p, "u_ts_half"), float(render3d_st.TERRAIN_HALF))
   u_f2(render3d_st, gpu_uniform(render3d_st, p, "u_ts_origin"), render3d_st.ter_ox, render3d_st.ter_oz)
 }
@@ -243,6 +247,7 @@ function terrain_bake_shadow(render3d_st: mut Render3dState) -> void {
   gpu_blend(render3d_st, false)
   gpu_use_program(render3d_st, p)
   r3d_bind_2d(render3d_st, p, "u_height", 0, render3d_st.ter_height_tex)
+  r3d_bind_2d(render3d_st, p, "u_ter_normal", 7, render3d_st.ter_normal_tex)
   u_f(render3d_st, gpu_uniform(render3d_st, p, "u_half"), float(render3d_st.TERRAIN_HALF))
   u_v3(render3d_st, gpu_uniform(render3d_st, p, "u_sun"), render3d_st.sun_dir)
   mesh_draw(render3d_st, render3d_st.sky_fullscreen)
@@ -408,6 +413,7 @@ function terrain_draw_shadow(light_vp: floats) -> void {
 function terrain_bind_prog(render3d_st: mut Render3dState, p: int) -> void {
   gpu_use_program(render3d_st, p)
   r3d_bind_2d(render3d_st, p, "u_height", 0, render3d_st.ter_height_tex)
+  r3d_bind_2d(render3d_st, p, "u_ter_normal", 7, render3d_st.ter_normal_tex)
   r3d_bind_2d(render3d_st, p, "u_grass_d", 1, render3d_st.ter_tex[0]);  r3d_bind_2d(render3d_st, p, "u_grass_n", 2, render3d_st.ter_tex[1]);  r3d_bind_2d(render3d_st, p, "u_grass_a", 3, render3d_st.ter_tex[2])
   # The cliff maps went with the dead cliff sample. Binding textures for uniforms the
   # shader no longer declares leaves those units pointing at nothing, which the driver
@@ -516,6 +522,7 @@ function terrain_sun_pass(render3d_st: mut Render3dState, w: int, h: int, depth:
   let p = render3d_st.ter_sun_prog
   gpu_use_program(render3d_st, p)
   r3d_bind_2d(render3d_st, p, "u_height", 0, render3d_st.ter_height_tex)
+  r3d_bind_2d(render3d_st, p, "u_ter_normal", 7, render3d_st.ter_normal_tex)
   u_f(render3d_st, gpu_uniform(render3d_st, p, "u_half"), float(render3d_st.TERRAIN_HALF))
   u_mat4(render3d_st, gpu_uniform(render3d_st, p, "u_view"), render3d_st.cam_view)
   u_mat4(render3d_st, gpu_uniform(render3d_st, p, "u_proj"), render3d_st.cam_proj)
@@ -748,6 +755,7 @@ function cdlod_select(render3d_st: mut Render3dState, level: int, ix: int, iz: i
 # frame-sized targets and the shadow texture, whose size does not depend on the map.
 function terrain_unload(render3d_st: mut Render3dState) -> void {
   if render3d_st.ter_height_tex != 0 { gpu_tex_free(render3d_st, render3d_st.ter_height_tex);  render3d_st.ter_height_tex = 0 }
+  if render3d_st.ter_normal_tex != 0 { gpu_tex_free(render3d_st, render3d_st.ter_normal_tex);  render3d_st.ter_normal_tex = 0 }
   if render3d_st.ter_dem_tex != 0 { gpu_tex_free(render3d_st, render3d_st.ter_dem_tex);  render3d_st.ter_dem_tex = 0 }
   if render3d_st.ter_ortho_tex != 0 { gpu_tex_free(render3d_st, render3d_st.ter_ortho_tex);  render3d_st.ter_ortho_tex = 0 }
   if render3d_st.ter_heights != null { free(render3d_st.ter_heights);  render3d_st.ter_heights = null }