added a new model-index color theme based off the trajectory index theme but instead using the Model.Index structure property

src/mol-theme/color.ts

@@ -38,6 +38,7 @@ import { EntityIdColorThemeProvider } from './color/entity-id';
 import { Texture, TextureFilter } from '../mol-gl/webgl/texture';
 import { VolumeValueColorThemeProvider } from './color/volume-value';
 import { Vec3, Vec4 } from '../mol-math/linear-algebra';
+import { ModelIndexColorThemeProvider } from './color/model-index';
 
 export type LocationColor = (location: Location, isSecondary: boolean) => Color
 
@@ -132,7 +133,7 @@ namespace ColorTheme {
         'entity-source': EntitySourceColorThemeProvider,
         'hydrophobicity': HydrophobicityColorThemeProvider,
         'illustrative': IllustrativeColorThemeProvider,
-        'trajectory-index': TrajectoryIndexColorThemeProvider,
+        'model-index': ModelIndexColorThemeProvider,
         'molecule-type': MoleculeTypeColorThemeProvider,
         'occupancy': OccupancyColorThemeProvider,
         'operator-hkl': OperatorHklColorThemeProvider,
@@ -144,6 +145,7 @@ namespace ColorTheme {
         'secondary-structure': SecondaryStructureColorThemeProvider,
         'sequence-id': SequenceIdColorThemeProvider,
         'shape-group': ShapeGroupColorThemeProvider,
+        'trajectory-index': TrajectoryIndexColorThemeProvider,
         'uncertainty': UncertaintyColorThemeProvider,
         'unit-index': UnitIndexColorThemeProvider,
         'uniform': UniformColorThemeProvider,

src/mol-theme/color/model-index.ts

@@ -0,0 +1,74 @@
+/**
+ * Copyright (c) 2019-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+
+import { Color } from '../../mol-util/color';
+import { Location } from '../../mol-model/location';
+import { StructureElement, Bond, Model } from '../../mol-model/structure';
+import { ColorTheme, LocationColor } from '../color';
+import { ParamDefinition as PD } from '../../mol-util/param-definition';
+import { ThemeDataContext } from '../../mol-theme/theme';
+import { getPaletteParams, getPalette } from '../../mol-util/color/palette';
+import { TableLegend, ScaleLegend } from '../../mol-util/legend';
+
+const DefaultColor = Color(0xCCCCCC);
+const Description = 'Gives every model a unique color based on the position (index) of the model in the list of models in the structure.';
+
+export const ModelIndexColorThemeParams = {
+    ...getPaletteParams({ type: 'colors', colorList: 'purples' }),
+};
+export type ModelIndexColorThemeParams = typeof ModelIndexColorThemeParams
+export function getModelIndexColorThemeParams(ctx: ThemeDataContext) {
+    return ModelIndexColorThemeParams; // TODO return copy
+}
+
+export function ModelIndexColorTheme(ctx: ThemeDataContext, props: PD.Values<ModelIndexColorThemeParams>): ColorTheme<ModelIndexColorThemeParams> {
+    let color: LocationColor;
+    let legend: ScaleLegend | TableLegend | undefined;
+
+    if (ctx.structure) {
+        const { models } = ctx.structure.root;
+
+        const size = Math.max(...models.map(m => Model.Index.get(m)?.value || 0));
+
+        const palette = getPalette(size, props);
+        legend = palette.legend;
+        const modelColor = new Map<number, Color>();
+        for (let i = 0, il = models.length; i < il; ++i) {
+            const idx = Model.Index.get(models[i])?.value || 0;
+            modelColor.set(idx, palette.color(idx));
+        }
+
+        color = (location: Location): Color => {
+            if (StructureElement.Location.is(location)) {
+                return modelColor.get(Model.Index.get(location.unit.model).value || 0)!;
+            } else if (Bond.isLocation(location)) {
+                return modelColor.get(Model.Index.get(location.aUnit.model).value || 0)!;
+            }
+            return DefaultColor;
+        };
+    } else {
+        color = () => DefaultColor;
+    }
+
+    return {
+        factory: ModelIndexColorTheme,
+        granularity: 'instance',
+        color,
+        props,
+        description: Description,
+        legend
+    };
+}
+
+export const ModelIndexColorThemeProvider: ColorTheme.Provider<ModelIndexColorThemeParams, 'model-index'> = {
+    name: 'model-index',
+    label: 'Model Index',
+    category: ColorTheme.Category.Chain,
+    factory: ModelIndexColorTheme,
+    getParams: getModelIndexColorThemeParams,
+    defaultValues: PD.getDefaultValues(ModelIndexColorThemeParams),
+    isApplicable: (ctx: ThemeDataContext) => !!ctx.structure && ctx.structure.elementCount > 0
+};