diff --git a/assets/shaders/render_params.wgsl b/assets/shaders/render_params.wgsl
index f51dfa0c..b56a3085 100644
--- a/assets/shaders/render_params.wgsl
+++ b/assets/shaders/render_params.wgsl
@@ -11,7 +11,9 @@ struct RenderParams {
     sand_col: vec4<f32>,
     sea_col: vec4<f32>,
     viewport: vec2<f32>,
+    unproj_pos: vec2<f32>,
     time: f32,
     time_always: f32,
     shadow_mapping_resolution: i32,
+    terraforming_mode_radius: f32,
 }
\ No newline at end of file
diff --git a/assets/shaders/terrain/terrain.frag.wgsl b/assets/shaders/terrain/terrain.frag.wgsl
index ab1fba92..14e3ee5d 100644
--- a/assets/shaders/terrain/terrain.frag.wgsl
+++ b/assets/shaders/terrain/terrain.frag.wgsl
@@ -143,7 +143,7 @@ fn frag(@builtin(position) position: vec4<f32>,
     let V_denorm: vec3<f32> = params.cam_pos.xyz - in_wpos;
     let depth: f32 = length(V_denorm);
     let V: vec3<f32> = V_denorm / depth;
-    let F0: vec3<f32> = vec3(0.00);
+    let F0: vec3<f32> = vec3(0.01);
     let roughness: f32 = 1.3; // avoid specular highlights which look weird on terrain
     let normal: vec3<f32> = normalize(in_normal);
     let F_spec: vec3<f32> = F0; // simplified with constant folding: fresnelSchlickRoughness(max(dot(normal, V), 0.0), F0, roughness);
@@ -152,6 +152,21 @@ fn frag(@builtin(position) position: vec4<f32>,
     c = 0.05 * vec3(0.0, 0.0, debug);
     #endif
 
+    if (params.terraforming_mode_radius > 0.0) {
+        let dist = length(params.unproj_pos - in_wpos.xy);
+        let alpha = smoothstep(params.terraforming_mode_radius, 0.0, dist) * 0.1;
+        let alpha2 = smoothstep(params.terraforming_mode_radius * 0.5, 0.0, dist) * 0.3;
+        let alpha3 = smoothstep(params.terraforming_mode_radius * 0.25, 0.0, dist) * 0.3;
+        var fw = fwidth(in_wpos.z) * 2.5;
+        let alpha4 = smoothstep(fw, 0.0, abs((in_wpos.z % 10.0) - 5.0)) * 0.1;
+        let alpha5 = smoothstep(fw, 0.0, abs((in_wpos.z % 50.0) - 25.0)) * 0.1;
+
+        c = mix(c, vec3(1.0, 0.5, 0.5), alpha);
+        c = mix(c, vec3(0.5, 1.0, 0.5), alpha2);
+        c = mix(c, vec3(0.5, 0.5, 1.0), alpha3);
+        c = mix(c, vec3(0.0, 0.0, 0.0), alpha4 + alpha5);
+    }
+
     let final_rgb: vec3<f32> = render(params.sun,
                                       V,
                                       position.xy,
diff --git a/engine/src/gfx.rs b/engine/src/gfx.rs
index c9ce6222..14832d4e 100644
--- a/engine/src/gfx.rs
+++ b/engine/src/gfx.rs
@@ -159,7 +159,7 @@ pub struct RenderParams {
     pub sun_shadow_proj: [Matrix4; N_CASCADES],
     pub cam_pos: Vec3,
     pub _pad: f32,
-    pub cam_dir: Vec3,
+    pub cam_dir: Vec3, // Vec3s need to be 16 aligned
     pub _pad4: f32,
     pub sun: Vec3,
     pub _pad2: f32,
@@ -168,10 +168,21 @@ pub struct RenderParams {
     pub sand_col: LinearColor,
     pub sea_col: LinearColor,
     pub viewport: Vec2,
+    pub unproj_pos: Vec2,
     pub time: f32,
     pub time_always: f32,
     pub shadow_mapping_resolution: i32,
-    pub _pad5: [f32; 3],
+    pub terraforming_mode_radius: f32,
+}
+
+#[cfg(test)]
+#[test]
+fn test_renderparam_size() {
+    println!(
+        "size of RenderParams: {}",
+        std::mem::size_of::<RenderParams>()
+    );
+    assert!(std::mem::size_of::<RenderParams>() < 1024);
 }
 
 impl Default for RenderParams {
@@ -187,13 +198,14 @@ impl Default for RenderParams {
             cam_dir: Default::default(),
             sun: Default::default(),
             viewport: vec2(1000.0, 1000.0),
+            unproj_pos: Default::default(),
             time: 0.0,
             time_always: 0.0,
             shadow_mapping_resolution: 2048,
+            terraforming_mode_radius: 0.0,
             _pad: 0.0,
             _pad2: 0.0,
             _pad4: 0.0,
-            _pad5: Default::default(),
         }
     }
 }
diff --git a/native_app/src/game_loop.rs b/native_app/src/game_loop.rs
index 6311bcf8..6ef5cfd4 100644
--- a/native_app/src/game_loop.rs
+++ b/native_app/src/game_loop.rs
@@ -10,6 +10,7 @@ use simulation::utils::time::GameTime;
 use simulation::Simulation;
 
 use crate::audio::GameAudio;
+use crate::gui::terraforming::TerraformingResource;
 use crate::gui::windows::debug::DebugObjs;
 use crate::gui::windows::settings::{manage_settings, Settings};
 use crate::gui::{ExitState, FollowEntity, Gui, Tool, UiTextures};
@@ -262,6 +263,15 @@ impl State {
             )
             .try_into()
             .unwrap();
+        params.unproj_pos = self
+            .uiw
+            .read::<InputMap>()
+            .unprojected
+            .unwrap_or_default()
+            .xy();
+        params.terraforming_mode_radius = matches!(*self.uiw.read::<Tool>(), Tool::Terraforming)
+            .then(|| self.uiw.read::<TerraformingResource>().radius)
+            .unwrap_or_default();
         drop(camera);
         let c = simulation::config();
         params.grass_col = c.grass_col.into();
diff --git a/native_app/src/gui/terraforming.rs b/native_app/src/gui/terraforming.rs
index 498e5913..ca9470aa 100644
--- a/native_app/src/gui/terraforming.rs
+++ b/native_app/src/gui/terraforming.rs
@@ -3,7 +3,7 @@ use crate::inputmap::{InputAction, InputMap};
 use crate::rendering::immediate::ImmediateDraw;
 use crate::uiworld::UiWorld;
 use egui_inspect::Inspect;
-use geom::{LinearColor, Vec3};
+use geom::Vec3;
 use simulation::map::TerraformKind;
 use simulation::world_command::WorldCommand;
 use simulation::Simulation;
@@ -26,7 +26,7 @@ pub fn terraforming(sim: &Simulation, uiworld: &mut UiWorld) {
     let res = uiworld.write::<TerraformingResource>();
     let tool = *uiworld.read::<Tool>();
     let inp = uiworld.read::<InputMap>();
-    let mut draw = uiworld.write::<ImmediateDraw>();
+    let _draw = uiworld.write::<ImmediateDraw>();
     let _map = sim.map();
     let commands = &mut *uiworld.commands();
 
@@ -35,8 +35,6 @@ pub fn terraforming(sim: &Simulation, uiworld: &mut UiWorld) {
     }
 
     let mpos = unwrap_ret!(inp.unprojected);
-    draw.circle(mpos.up(0.8), res.radius)
-        .color(LinearColor::GREEN.a(0.1));
 
     if inp.act.contains(&InputAction::Select) {
         commands.push(WorldCommand::Terraform {