Let a shader declare a color the sprite sets (#298)

A shader could only ask its sprites for numbers. A tint, an outline
colour or a glow colour had to be built from three Property nodes.

- New node Color property next to Property: Name and Default (a
  colour, white unless picked), output `color`. It becomes a colour
  row below the Shader dropdown and a vec3 uniform in the program.
- Number and colour properties share one set of names. A clash is
  the existing "Another property is named" problem.
- Like Color it cannot feed the Vertex output.
- Placed from the palette it is called tint, then tint2.
- The preview in the Shader tab shows a colour field for it. Like
  the sliders it starts at the sprite's value and never writes into
  the project.
- `declaredRows` takes the row builder, so the particle graph keeps
  its number rows unchanged.

Tests:
- Gate: 222 files, 3452 tests (3445 + 7)
- e2e 28: 89 checks (28l-v: default colour drawn, then the colour
  the sprite sets)
- e2e total 1704, counted (1703 + 1)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/editor/graph/paletteEntries.ts

@@ -27,7 +27,12 @@ import {
   PROPERTY_NAME_PARAM as PARTICLE_NAME_PARAM,
   propertyNameOf,
 } from '../../core/properties/particles';
-import { nextPropertyName, PROPERTY_NAME_PARAM, SHADER_PROPERTY } from '../../core/properties/shaders';
+import {
+  nextPropertyName,
+  PROPERTY_NAME_PARAM,
+  SHADER_COLOR_PROPERTY,
+  SHADER_PROPERTY,
+} from '../../core/properties/shaders';
 import { nextParticlePropertyName, PARTICLE_NODES, PARTICLE_OUTPUT } from '../../core/particles/nodes';
 import { SHADER_NODES, SHADER_OUTPUT, SHADER_VERTEX_OUTPUT } from '../../core/shader/nodes';
 
@@ -99,7 +104,11 @@ export function paletteEntries(project: Project, asset: GraphAsset): PaletteEntr
     const once = [SHADER_OUTPUT, SHADER_VERTEX_OUTPUT];
     return SHADER_NODES.filter((def) => !once.includes(def.type) || !placed.has(def.type)).map((def) => {
       const params: PropertyBag =
-        def.type === SHADER_PROPERTY ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph) } : {};
+        def.type === SHADER_PROPERTY
+          ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph) }
+          : def.type === SHADER_COLOR_PROPERTY
+            ? { [PROPERTY_NAME_PARAM]: nextPropertyName(asset.graph, 'tint') }
+            : {};
       return { id: def.type, hint: def.category, def, params };
     });
   }

src/editor/shader/ShaderEditor.ts

@@ -1,8 +1,9 @@
 import type { Asset, ShaderAsset } from '../../core/model/Asset';
 import type { FlatDef } from '../../core/properties/PropertySchema';
-import { shaderParamDefs } from '../../core/properties/shaders';
+import { type ShaderParamDef, shaderParamDefs } from '../../core/properties/shaders';
 import {
   Button,
+  ColorField,
   formatNumber,
   HStack,
   Label,
@@ -56,7 +57,8 @@ export class ShaderEditor extends AssetTabEditor<ShaderAsset, GraphCanvas> {
   private readonly subjectLabel = new Label('', { style: 'small' });
   private readonly params = new VStack({ gap: Theme.gap, padding: Theme.padding });
   private readonly sliders = new Map<string, { slider: Slider; value: Label }>();
-  /** What the sliders are set to – the preview's values, never anyone's rows. */
+  private readonly colors = new Map<string, ColorField>();
+  /** What the sliders and colour fields are set to – the preview's values, never anyone's rows. */
   private values: Record<string, number> = {};
   private subject: PictureSubject | null = null;
   /** Rebuild the sliders only when the declared properties change, not on every edit of the graph. */
@@ -139,6 +141,11 @@ export class ShaderEditor extends AssetTabEditor<ShaderAsset, GraphCanvas> {
     return this.sliders.get(key)?.slider;
   }
 
+  /** The colour field of one colour property, for the check scripts. */
+  colorFieldOf(key: string): ColorField | undefined {
+    return this.colors.get(key);
+  }
+
   override selectedId(): string {
     return this.state.selectedShaderId ?? '';
   }
@@ -178,12 +185,15 @@ export class ShaderEditor extends AssetTabEditor<ShaderAsset, GraphCanvas> {
     this.syncControls();
   }
 
-  private syncParams(defs: readonly FlatDef<'number'>[]): void {
-    const key = JSON.stringify(defs.map((d) => [d.key, d.min, d.max, d.default]));
+  private syncParams(defs: readonly ShaderParamDef[]): void {
+    const key = JSON.stringify(
+      defs.map((d) => (d.kind === 'color' ? [d.key, d.kind] : [d.key, d.min, d.max, d.default])),
+    );
     if (key !== this.paramsKey) {
       this.paramsKey = key;
       for (const row of this.params.removeChildren()) row.destroy({ children: true });
       this.sliders.clear();
+      this.colors.clear();
       for (const def of defs) this.params.add(this.paramRow(def));
       // Neither the column nor, with as many rows as before, the stack of rows changes its size,
       // and a resize that changes nothing lays nothing out: both lay out anew, outside in.
@@ -191,14 +201,36 @@ export class ShaderEditor extends AssetTabEditor<ShaderAsset, GraphCanvas> {
       this.params.relayout();
     }
     for (const def of defs) {
-      const row = this.sliders.get(def.key);
       const value = this.values[def.key] ?? def.default;
+      this.colors.get(def.key)?.setValue(value);
+      const row = this.sliders.get(def.key);
       row?.slider.setValue(value);
       row?.value.setText(formatNumber(value));
     }
   }
 
-  private paramRow(def: FlatDef<'number'>): Widget {
+  private paramRow(def: ShaderParamDef): Widget {
+    const row = new HStack({ gap: Theme.gap, align: 'center' });
+    row.minHeight = Theme.controlHeight;
+    const name = new Label(def.label, { style: 'small' });
+    name.minWidth = PARAM_NAME_WIDTH;
+    row.add(name);
+    if (def.kind === 'color') {
+      const show = (color: number) => {
+        this.values[def.key] = color;
+        this.preview.invalidate();
+      };
+      const field = new ColorField(this.values[def.key] ?? def.default, { onInput: show, onChange: show });
+      this.colors.set(def.key, field);
+      row.add(field, 1);
+      return row;
+    }
+    row.add(this.slider(def), 1);
+    row.add(this.sliders.get(def.key)!.value);
+    return row;
+  }
+
+  private slider(def: FlatDef<'number'>): Slider {
     const { min, max } = sliderRange(def);
     const slider = new Slider(this.values[def.key] ?? def.default, min, max, 80);
     const value = new Label('', { style: 'small', align: 'right' });
@@ -210,14 +242,7 @@ export class ShaderEditor extends AssetTabEditor<ShaderAsset, GraphCanvas> {
       this.preview.invalidate();
     };
     this.sliders.set(def.key, { slider, value });
-    const row = new HStack({ gap: Theme.gap, align: 'center' });
-    row.minHeight = Theme.controlHeight;
-    const name = new Label(def.label, { style: 'small' });
-    name.minWidth = PARAM_NAME_WIDTH;
-    row.add(name);
-    row.add(slider, 1);
-    row.add(value);
-    return row;
+    return slider;
   }
 
   /** Stands the preview at a second, or lets it run again with `null` – what Hold and Run do. */

src/editor/shader/previewPicture.ts

@@ -1,12 +1,12 @@
 import { findObject } from '../../core/model/hierarchy';
 import { resolvedHolder } from '../../core/model/instance';
-import type { PropertyBag } from '../../core/model/Properties';
+import { colorOf, type PropertyBag } from '../../core/model/Properties';
 import { findAsset, findObjectHolder, type Project } from '../../core/model/Project';
 import { objectName } from '../../core/model/SceneObject';
 import { findFrame, resolvePicture, resolveTexture, type TextureRef } from '../../core/model/texture';
 import type { FlatDef } from '../../core/properties/PropertySchema';
 import { resolveAssetProps, resolveSceneObjectProps } from '../../core/properties/resolve';
-import { shaderOf } from '../../core/properties/shaders';
+import { type ShaderParamDef, shaderOf } from '../../core/properties/shaders';
 import type { Selection } from '../state';
 
 /** Something the Shader tab's preview can show: a sprite, placed or not, a texture or one of its frames (#168). */
@@ -85,15 +85,17 @@ function texturePicture(name: string, ref: TextureRef): PreviewPicture {
 
 /** Where a slider starts: the subject's own value when it wears this shader, the declared default otherwise. */
 export function startValues(
-  defs: readonly FlatDef<'number'>[],
+  defs: readonly ShaderParamDef[],
   props: PropertyBag,
   shaderId: string,
 ): Record<string, number> {
   const wears = shaderOf(props) === shaderId;
   const values: Record<string, number> = {};
   for (const def of defs) {
-    const own = Number(props[def.key]);
-    values[def.key] = wears && Number.isFinite(own) ? own : def.default;
+    const own = props[def.key];
+    if (def.kind === 'color')
+      values[def.key] = wears && own !== undefined ? colorOf(own, def.default) : def.default;
+    else values[def.key] = wears && Number.isFinite(Number(own)) ? Number(own) : def.default;
   }
   return values;
 }