src/app.rs

@@ -205,6 +205,13 @@ impl OpenVistaProApp {
 
         ui.separator();
         ui.label("Hydrology");
+        ui.horizontal(|ui| {
+            if ui.button("Reset hydrology").clicked() {
+                self.data.apply(AppAction::ResetHydrology);
+                changed = true;
+            }
+            ui.label("Lake and river overlays are clean-room defaults");
+        });
         let mut river_level = self.data.scene.hydrology.river_level;
         let mut lake_level = self.data.scene.hydrology.lake_level;
         let mut drainage = self.data.scene.hydrology.drainage;
@@ -217,39 +224,59 @@ impl OpenVistaProApp {
         changed |= ui
             .add(egui::Slider::new(&mut drainage, 0.0..=5.0).text("Drainage"))
             .changed();
+        ui.label("Lake placement");
+        let mut lake_center_x = self.data.scene.hydrology.lake_center_x;
+        let mut lake_center_z = self.data.scene.hydrology.lake_center_z;
+        let mut lake_radius = self.data.scene.hydrology.lake_radius;
+        ui.horizontal(|ui| {
+            ui.label("Center X/Z");
+            changed |= ui
+                .add(
+                    egui::DragValue::new(&mut lake_center_x)
+                        .speed(0.01)
+                        .range(0.0..=1.0),
+                )
+                .changed();
+            changed |= ui
+                .add(
+                    egui::DragValue::new(&mut lake_center_z)
+                        .speed(0.01)
+                        .range(0.0..=1.0),
+                )
+                .changed();
+        });
+        changed |= ui
+            .add(egui::Slider::new(&mut lake_radius, 0.0..=0.5).text("Radius"))
+            .changed();
+        ui.label("River placement");
+        let mut river_center_x = self.data.scene.hydrology.river_center_x;
+        let mut river_width = self.data.scene.hydrology.river_width;
+        let mut river_bend = self.data.scene.hydrology.river_bend;
+        changed |= ui
+            .add(egui::Slider::new(&mut river_center_x, 0.0..=1.0).text("Center X"))
+            .changed();
+        changed |= ui
+            .add(egui::Slider::new(&mut river_width, 0.0..=0.25).text("Width"))
+            .changed();
+        changed |= ui
+            .add(egui::Slider::new(&mut river_bend, 0.0..=0.35).text("Bend"))
+            .changed();
         self.data.apply(AppAction::SetHydrology {
             river_level,
             lake_level,
             drainage,
+            lake_center_x,
+            lake_center_z,
+            lake_radius,
+            river_center_x,
+            river_width,
+            river_bend,
         });
 
         ui.separator();
         ui.label("Color map");
         ui.label("Core elevation bands");
         let mut palette = self.data.scene.palette;
-        changed |= ui
-            .add(egui::Slider::new(&mut palette.water_level, -5.0..=15.0).text("Water level"))
-            .changed();
-        changed |= ui
-            .add(egui::Slider::new(&mut palette.tree_line, -5.0..=15.0).text("Tree line"))
-            .changed();
-        changed |= ui
-            .add(egui::Slider::new(&mut palette.snow_line, -5.0..=15.0).text("Snow line"))
-            .changed();
-        if palette.tree_line < palette.water_level + 0.1 {
-            palette.tree_line = palette.water_level + 0.1;
-            changed = true;
-        }
-        if palette.snow_line < palette.tree_line + 0.1 {
-            palette.snow_line = palette.tree_line + 0.1;
-            changed = true;
-        }
-        if palette.water_level > palette.tree_line - 0.1 {
-            palette.water_level = palette.tree_line - 0.1;
-            changed = true;
-        }
-        ui.separator();
-        ui.label("Band colors");
         ui.horizontal(|ui| {
             ui.label("Water");
             changed |= ui.color_edit_button_srgb(&mut palette.water).changed();

src/app_state.rs

@@ -4,7 +4,7 @@ use image::RgbImage;
 
 use crate::path::{CameraPath, build_demo_path};
 use crate::render::{
-    render_perspective_with_quality, render_top_down_with_quality, RenderQualityPreset,
+    RenderQualityPreset, render_perspective_with_quality, render_top_down_with_quality,
 };
 use crate::scene::{Scene, Vec3};
 use crate::scene_file::{self, SceneFileError};

src/cli.rs

@@ -3,7 +3,9 @@ use std::path::PathBuf;
 use clap::{Args, Parser, Subcommand, ValueEnum};
 use image::ImageError;
 
-use crate::render::{demo_camera_for, render_perspective_to_path, render_top_down_to_path};
+use crate::render::{
+    RenderQualityPreset, demo_camera_for, render_perspective_to_path, render_top_down_to_path,
+};
 use crate::scene::Scene;
 use crate::scene_file::{self, SceneFileError};
 use crate::script_exec::{self, ScriptError};
@@ -55,6 +57,9 @@ pub struct RenderArgs {
     /// the top-down preview.
     #[arg(long, default_value_t = false)]
     pub camera_demo: bool,
+    /// Render-quality preset for the CPU spike.
+    #[arg(long, value_enum, default_value_t = RenderQualityPreset::Preview)]
+    pub quality: RenderQualityPreset,
 }
 
 #[derive(Debug, Clone, Args)]
@@ -146,10 +151,23 @@ impl From<ScriptError> for CliError {
     }
 }
 
+impl Preset {
+    pub fn slug(self) -> &'static str {
+        match self {
+            Preset::Plane => "plane",
+            Preset::Hill => "hill",
+        }
+    }
+}
+
 pub fn supported_presets() -> &'static [&'static str] {
     &["plane", "hill"]
 }
 
+pub fn supported_quality_presets() -> &'static [&'static str] {
+    &["preview", "balanced", "final"]
+}
+
 pub fn supported_importers() -> &'static [&'static str] {
     #[cfg(all(
         feature = "hgt",
@@ -223,6 +241,7 @@ pub fn info_text() -> String {
     let mut text = String::new();
     writeln!(&mut text, "openvistapro {}", env!("CARGO_PKG_VERSION")).unwrap();
     writeln!(&mut text, "presets: {}", supported_presets().join(", ")).unwrap();
+    writeln!(&mut text, "quality: {}", supported_quality_presets().join(", ")).unwrap();
     let importers = supported_importers();
     if importers.is_empty() {
         writeln!(&mut text, "importers: (none)").unwrap();

src/render.rs

@@ -184,7 +184,11 @@ fn hydrology_overlay_color(scene: &Scene, nx: f32, nz: f32) -> Option<[u8; 3]> {
     };
     let colored = mix_color(scene.palette.water, tint, coverage);
     Some(if coverage > 0.72 {
-        mix_color(colored, [245, 250, 255], (coverage - 0.72).clamp(0.0, 0.28) * 3.0)
+        mix_color(
+            colored,
+            [245, 250, 255],
+            (coverage - 0.72).clamp(0.0, 0.28) * 3.0,
+        )
     } else {
         colored
     })
@@ -321,13 +325,7 @@ pub fn demo_camera_for(grid: &HeightGrid) -> Camera {
 /// Coordinate convention: world X and Z map onto the grid's `(x, y)` indices,
 /// world Y is elevation, up = +Y.
 pub fn render_perspective(grid: &HeightGrid, scene: &Scene, width: u32, height: u32) -> RgbImage {
-    render_perspective_with_quality(
-        grid,
-        scene,
-        width,
-        height,
-        RenderQualityPreset::Preview,
-    )
+    render_perspective_with_quality(grid, scene, width, height, RenderQualityPreset::Preview)
 }
 
 pub fn render_perspective_with_quality(

src/scene_file.rs

@@ -88,7 +88,11 @@ impl From<toml::de::Error> for SceneFileError {
 
 /// Serialize `scene` into a TOML string with schema and version headers.
 pub fn to_toml_string(scene: &Scene) -> Result<String, SceneFileError> {
-    let file = SceneFile::new(*scene);
+    let mut scene = *scene;
+    scene
+        .palette
+        .sync_thresholds_from_scene(scene.water_level, scene.tree_line, scene.snow_line);
+    let file = SceneFile::new(scene);
     Ok(toml::to_string_pretty(&file)?)
 }
 
@@ -101,7 +105,11 @@ pub fn from_toml_str(text: &str) -> Result<Scene, SceneFileError> {
     if file.version != SCENE_VERSION {
         return Err(SceneFileError::UnsupportedVersion(file.version));
     }
-    Ok(file.scene)
+    let mut scene = file.scene;
+    scene
+        .palette
+        .sync_thresholds_from_scene(scene.water_level, scene.tree_line, scene.snow_line);
+    Ok(scene)
 }
 
 /// Write `scene` to `path` as an OpenVistaPro `.ovp.toml` scene file.
@@ -150,6 +158,12 @@ mod tests {
                 river_level: 0.8,
                 lake_level: 1.1,
                 drainage: 0.2,
+                lake_center_x: 0.42,
+                lake_center_z: 0.58,
+                lake_radius: 0.11,
+                river_center_x: 0.6,
+                river_width: 0.09,
+                river_bend: 0.04,
             },
             palette: Palette {
                 water_level: 0.5,