feat: option to hide cross section background in 3D slice views

src/data_panel_layout.ts

@@ -100,6 +100,7 @@ export interface ViewerUIState
   inputEventBindings: InputEventBindings;
   crossSectionBackgroundColor: TrackableRGB;
   perspectiveViewBackgroundColor: TrackableRGB;
+  hideCrossSectionBackgroundIn3D: TrackableBoolean;
 }
 
 export interface DataDisplayLayout extends RefCounted {
@@ -180,6 +181,7 @@ export function getCommonViewerState(viewer: ViewerUIState) {
     selectedLayer: viewer.selectedLayer,
     visibility: viewer.visibility,
     scaleBarOptions: viewer.scaleBarOptions,
+    hideCrossSectionBackgroundIn3D: viewer.hideCrossSectionBackgroundIn3D,
   };
 }
 

src/layer_group_viewer.ts

@@ -102,6 +102,7 @@ export interface LayerGroupViewerState {
   visibleLayerRoles: WatchableSet<RenderLayerRole>;
   crossSectionBackgroundColor: TrackableRGB;
   perspectiveViewBackgroundColor: TrackableRGB;
+  hideCrossSectionBackgroundIn3D: TrackableBoolean;
 }
 
 export interface LayerGroupViewerOptions {
@@ -357,6 +358,9 @@ export class LayerGroupViewer extends RefCounted {
   get enableAdaptiveDownsampling() {
     return this.viewerState.enableAdaptiveDownsampling;
   }
+  get hideCrossSectionBackgroundIn3D() {
+    return this.viewerState.hideCrossSectionBackgroundIn3D;
+  }
   get showScaleBar() {
     return this.viewerState.showScaleBar;
   }

src/layer_groups_layout.ts

@@ -420,6 +420,7 @@ function getCommonViewerState(viewer: Viewer) {
     velocity: viewer.velocity.addRef(),
     crossSectionBackgroundColor: viewer.crossSectionBackgroundColor,
     perspectiveViewBackgroundColor: viewer.perspectiveViewBackgroundColor,
+    hideCrossSectionBackgroundIn3D: viewer.hideCrossSectionBackgroundIn3D,
   };
 }
 

src/perspective_view/panel.ts

@@ -95,6 +95,7 @@ export interface PerspectiveViewerState extends RenderedDataViewerState {
   showSliceViewsCheckbox?: boolean;
   crossSectionBackgroundColor: TrackableRGB;
   perspectiveViewBackgroundColor: TrackableRGB;
+  hideCrossSectionBackgroundIn3D: TrackableBoolean;
   rpc: RPC;
 }
 
@@ -270,6 +271,7 @@ class PerspectiveViewState extends PerspectiveViewStateBase {
 
 export class PerspectivePanel extends RenderedDataPanel {
   declare viewer: PerspectiveViewerState;
+  sliceViewRenderHelper: SliceViewRenderHelper;
 
   projectionParameters: Owned<DerivedProjectionParameters>;
 
@@ -321,10 +323,6 @@ export class PerspectivePanel extends RenderedDataPanel {
   );
 
   private axesLineHelper = this.registerDisposer(AxesLineHelper.get(this.gl));
-  sliceViewRenderHelper = this.registerDisposer(
-    SliceViewRenderHelper.get(this.gl, perspectivePanelEmit),
-  );
-
   protected offscreenFramebuffer = this.registerDisposer(
     new FramebufferConfiguration(this.gl, {
       colorBuffers: [
@@ -406,6 +404,15 @@ export class PerspectivePanel extends RenderedDataPanel {
     viewer: PerspectiveViewerState,
   ) {
     super(context, element, viewer);
+    this.sliceViewRenderHelper = this.registerDisposer(
+      SliceViewRenderHelper.get(
+        this.gl,
+        perspectivePanelEmit,
+        this.viewer,
+        true /*perspectivePanel*/,
+      ),
+    );
+
     this.projectionParameters = this.registerDisposer(
       new DerivedProjectionParameters({
         navigationState: this.navigationState,
@@ -580,6 +587,11 @@ export class PerspectivePanel extends RenderedDataPanel {
     this.registerDisposer(
       viewer.wireFrame.changed.add(() => this.scheduleRedraw()),
     );
+    this.registerDisposer(
+      viewer.hideCrossSectionBackgroundIn3D.changed.add(() =>
+        this.scheduleRedraw(),
+      ),
+    );
     this.sliceViews.changed.add(() => this.scheduleRedraw());
   }
 

src/sliceview/frontend.ts

@@ -27,6 +27,7 @@ import type {
   DisplayDimensionRenderInfo,
   NavigationState,
 } from "#src/navigation_state.js";
+import type { PerspectiveViewerState } from "#src/perspective_view/panel.js";
 import { updateProjectionParametersFromInverseViewAndProjection } from "#src/projection_parameters.js";
 import type {
   ChunkDisplayTransformParameters,
@@ -60,6 +61,7 @@ import {
   SliceViewProjectionParameters,
 } from "#src/sliceview/base.js";
 import { ChunkLayout } from "#src/sliceview/chunk_layout.js";
+import type { SliceViewerState } from "#src/sliceview/panel.js";
 import { SliceViewRenderLayer } from "#src/sliceview/renderlayer.js";
 import type { WatchableValueInterface } from "#src/trackable_value.js";
 import type { Borrowed, Disposer, Owned } from "#src/util/disposable.js";
@@ -71,6 +73,8 @@ import { getObjectId } from "#src/util/object_id.js";
 import { NullarySignal } from "#src/util/signal.js";
 import { withSharedVisibility } from "#src/visibility_priority/frontend.js";
 import type { GL } from "#src/webgl/context.js";
+import type { ParameterizedContextDependentShaderGetter } from "#src/webgl/dynamic_shader.js";
+import { parameterizedContextDependentShaderGetter } from "#src/webgl/dynamic_shader.js";
 import type { HistogramSpecifications } from "#src/webgl/empirical_cdf.js";
 import { TextureHistogramGenerator } from "#src/webgl/empirical_cdf.js";
 import type { TextureBuffer } from "#src/webgl/offscreen.js";
@@ -79,8 +83,7 @@ import {
   FramebufferConfiguration,
   makeTextureBuffers,
 } from "#src/webgl/offscreen.js";
-import type { ShaderModule, ShaderProgram } from "#src/webgl/shader.js";
-import { ShaderBuilder } from "#src/webgl/shader.js";
+import type { ShaderModule, ShaderBuilder } from "#src/webgl/shader.js";
 import { getSquareCornersBuffer } from "#src/webgl/square_corners_buffer.js";
 import type { RPC } from "#src/worker_rpc.js";
 import { registerSharedObjectOwner } from "#src/worker_rpc.js";
@@ -719,41 +722,83 @@ export class SliceViewChunk extends Chunk {
  */
 export class SliceViewRenderHelper extends RefCounted {
   private copyVertexPositionsBuffer;
-  private shader: ShaderProgram;
 
   private textureCoordinateAdjustment = new Float32Array(4);
+  private shaderGetter: ParameterizedContextDependentShaderGetter<
+    { emitter: ShaderModule; isProjection: boolean },
+    boolean
+  >;
 
-  constructor(
-    public gl: GL,
+  defineShader(
+    builder: ShaderBuilder,
+    hideTransparent: boolean,
+    isProjection: boolean,
     emitter: ShaderModule,
   ) {
-    super();
-    this.copyVertexPositionsBuffer = getSquareCornersBuffer(this.gl);
-
-    const builder = new ShaderBuilder(gl);
     builder.addVarying("vec2", "vTexCoord");
     builder.addUniform("sampler2D", "uSampler");
     builder.addInitializer((shader) => {
-      gl.uniform1i(shader.uniform("uSampler"), 0);
+      this.gl.uniform1i(shader.uniform("uSampler"), 0);
     });
     builder.addUniform("vec4", "uColorFactor");
     builder.addUniform("vec4", "uBackgroundColor");
     builder.addUniform("mat4", "uProjectionMatrix");
     builder.addUniform("vec4", "uTextureCoordinateAdjustment");
     builder.require(emitter);
-    builder.setFragmentMain(`
+    const glsl_fragmentMainStart = `
 vec4 sampledColor = texture(uSampler, vTexCoord);
-if (sampledColor.a == 0.0) {
+if (sampledColor.a == 0.0) {`;
+    let glsl_fragmentMainEnd: string;
+    if (hideTransparent && isProjection) {
+      glsl_fragmentMainEnd = `
+  discard;
+}
+else {
+  emit(sampledColor * uColorFactor, 0u);
+}
+`;
+    } else {
+      glsl_fragmentMainEnd = `
   sampledColor = uBackgroundColor;
 }
 emit(sampledColor * uColorFactor, 0u);
-`);
+`;
+    }
+    builder.setFragmentMain(`${glsl_fragmentMainStart}${glsl_fragmentMainEnd}`);
     builder.addAttribute("vec4", "aVertexPosition");
     builder.setVertexMain(`
 vTexCoord = uTextureCoordinateAdjustment.xy + 0.5 * (aVertexPosition.xy + 1.0) * uTextureCoordinateAdjustment.zw;
 gl_Position = uProjectionMatrix * aVertexPosition;
 `);
-    this.shader = this.registerDisposer(builder.build());
+  }
+
+  constructor(
+    public gl: GL,
+    private emitter: ShaderModule,
+    private viewer: SliceViewerState | PerspectiveViewerState,
+    private isProjection: boolean,
+  ) {
+    super();
+
+    this.copyVertexPositionsBuffer = getSquareCornersBuffer(this.gl);
+    this.shaderGetter = parameterizedContextDependentShaderGetter(
+      this,
+      this.gl,
+      {
+        memoizeKey: "sliceview/SliceViewRenderHelper",
+        parameters: this.viewer.hideCrossSectionBackgroundIn3D,
+        getContextKey: ({ emitter, isProjection }) =>
+          `${getObjectId(emitter)}${isProjection}`,
+        defineShader: (builder, context, hideTransparent) => {
+          this.defineShader(
+            builder,
+            hideTransparent,
+            context.isProjection,
+            context.emitter,
+          );
+        },
+      },
+    );
   }
 
   draw(
@@ -766,11 +811,19 @@ gl_Position = uProjectionMatrix * aVertexPosition;
     xEnd: number,
     yEnd: number,
   ) {
-    const { gl, shader, textureCoordinateAdjustment } = this;
+    const { gl, textureCoordinateAdjustment } = this;
     textureCoordinateAdjustment[0] = xStart;
     textureCoordinateAdjustment[1] = yStart;
     textureCoordinateAdjustment[2] = xEnd - xStart;
     textureCoordinateAdjustment[3] = yEnd - yStart;
+    const shaderResult = this.shaderGetter({
+      emitter: this.emitter,
+      isProjection: this.isProjection,
+    });
+    const shader = shaderResult.shader;
+    if (shader === null) {
+      throw new Error("Shader compilation failed in SliceViewRenderHelper.");
+    }
     shader.bind();
     gl.activeTexture(gl.TEXTURE0);
     gl.bindTexture(gl.TEXTURE_2D, texture);
@@ -799,10 +852,15 @@ gl_Position = uProjectionMatrix * aVertexPosition;
     gl.bindTexture(gl.TEXTURE_2D, null);
   }
 
-  static get(gl: GL, emitter: ShaderModule) {
+  static get(
+    gl: GL,
+    emitter: ShaderModule,
+    viewer: SliceViewerState | PerspectiveViewerState,
+    isProjection: boolean,
+  ) {
     return gl.memoize.get(
       `sliceview/SliceViewRenderHelper:${getObjectId(emitter)}`,
-      () => new SliceViewRenderHelper(gl, emitter),
+      () => new SliceViewRenderHelper(gl, emitter, viewer, isProjection),
     );
   }
 }

src/sliceview/panel.ts

@@ -66,6 +66,7 @@ export interface SliceViewerState extends RenderedDataViewerState {
   wireFrame: TrackableBoolean;
   scaleBarOptions: TrackableScaleBarOptions;
   crossSectionBackgroundColor: TrackableRGB;
+  hideCrossSectionBackgroundIn3D: TrackableBoolean;
 }
 
 export enum OffscreenTextures {
@@ -101,11 +102,10 @@ const tempVec4 = vec4.create();
 
 export class SliceViewPanel extends RenderedDataPanel {
   declare viewer: SliceViewerState;
+  private sliceViewRenderHelper;
 
   private axesLineHelper = this.registerDisposer(AxesLineHelper.get(this.gl));
-  private sliceViewRenderHelper = this.registerDisposer(
-    SliceViewRenderHelper.get(this.gl, sliceViewPanelEmitColor),
-  );
+
   private colorFactor = vec4.fromValues(1, 1, 1, 1);
   private pickIDs = new PickIDManager();
 
@@ -167,7 +167,20 @@ export class SliceViewPanel extends RenderedDataPanel {
     viewer: SliceViewerState,
   ) {
     super(context, element, viewer);
+
+    this.sliceViewRenderHelper = this.registerDisposer(
+      SliceViewRenderHelper.get(
+        this.gl,
+        sliceViewPanelEmitColor,
+        this.viewer,
+        false /*sliceViewPanel*/,
+      ),
+    );
+
     viewer.wireFrame.changed.add(() => this.scheduleRedraw());
+    viewer.hideCrossSectionBackgroundIn3D.changed.add(() =>
+      this.scheduleRedraw(),
+    );
     registerActionListener(
       element,
       "rotate-via-mouse-drag",

src/ui/default_input_event_bindings.ts

@@ -29,6 +29,7 @@ export function getDefaultGlobalBindings() {
     map.set("keyv", "toggle-default-annotations");
     map.set("keya", "toggle-axis-lines");
     map.set("keyo", "toggle-orthographic-projection");
+    map.set("keyt", "toggle-hide-cross-section-background-3d");
 
     for (let i = 1; i <= 9; ++i) {
       map.set("digit" + i, "toggle-layer-" + i);

src/ui/viewer_settings.ts

@@ -118,6 +118,10 @@ export class ViewerSettingsPanel extends SidePanel {
     addCheckbox("Show axis lines", viewer.showAxisLines);
     addCheckbox("Show scale bar", viewer.showScaleBar);
     addCheckbox("Show cross sections in 3-d", viewer.showPerspectiveSliceViews);
+    addCheckbox(
+      "Hide sections background 3-d",
+      viewer.hideCrossSectionBackgroundIn3D,
+    );
     addCheckbox("Show default annotations", viewer.showDefaultAnnotations);
     addCheckbox(
       "Show chunk statistics",

src/viewer.ts

@@ -306,6 +306,10 @@ class TrackableViewerState extends CompoundTrackable {
     this.add("showDefaultAnnotations", viewer.showDefaultAnnotations);
 
     this.add("showSlices", viewer.showPerspectiveSliceViews);
+    this.add(
+      "hideCrossSectionBackgroundIn3D",
+      viewer.hideCrossSectionBackgroundIn3D,
+    );
     this.add(
       "gpuMemoryLimit",
       viewer.dataContext.chunkQueueManager.capacities.gpuMemory.sizeLimit,
@@ -469,6 +473,7 @@ export class Viewer extends RefCounted implements ViewerState {
   enableAdaptiveDownsampling = new TrackableBoolean(true, true);
   showScaleBar = new TrackableBoolean(true, true);
   showPerspectiveSliceViews = new TrackableBoolean(true, true);
+  hideCrossSectionBackgroundIn3D = new TrackableBoolean(true, true);
   visibleLayerRoles = allRenderLayerRoles();
   showDefaultAnnotations = new TrackableBoolean(true, true);
   crossSectionBackgroundColor = new TrackableRGB(
@@ -1119,6 +1124,9 @@ export class Viewer extends RefCounted implements ViewerState {
       this.showPerspectiveSliceViews.toggle(),
     );
     this.bindAction("toggle-show-statistics", () => this.showStatistics());
+    this.bindAction("toggle-hide-cross-section-background-3d", () =>
+      this.hideCrossSectionBackgroundIn3D.toggle(),
+    );
   }
 
   toggleHelpPanel() {