add exposure parameter (#751)

* add exposure parameter

* add missing uniform

---------

Co-authored-by: David Sehnal <dsehnal@users.noreply.github.com>

CHANGELOG.md

@@ -13,6 +13,7 @@ Note that since we don't clearly distinguish between a public and private interf
 - Fix occlusion artefact with non-canvas viewport and pixel-ratio > 1
 - Update nodejs-shims conditionals to handle polyfilled document object in NodeJS environment.
 - Ensure marking edges are at least one pixel wide
+- Add exposure parameter to renderer
 - Only trigger marking when mouse is directly over canvas
 - Fix blurry occlusion in screenshots
 

src/mol-gl/renderable/schema.ts

@@ -160,6 +160,7 @@ export const GlobalUniformSchema = {
     uMarkerAverage: UniformSpec('f'),
 
     uXrayEdgeFalloff: UniformSpec('f'),
+    uExposure: UniformSpec('f'),
 
     uRenderMask: UniformSpec('i'),
     uMarkingDepthTest: UniformSpec('b'),

src/mol-gl/renderer.ts

@@ -104,6 +104,7 @@ export const RendererParams = {
     markerPriority: PD.Select(1, [[1, 'Highlight'], [2, 'Select']]),
 
     xrayEdgeFalloff: PD.Numeric(1, { min: 0.0, max: 3.0, step: 0.1 }),
+    exposure: PD.Numeric(1, { min: 0.0, max: 3.0, step: 0.01 }),
 
     light: PD.ObjectList({
         inclination: PD.Numeric(150, { min: 0, max: 180, step: 1 }),
@@ -242,6 +243,7 @@ namespace Renderer {
             uMarkerAverage: ValueCell.create(0),
 
             uXrayEdgeFalloff: ValueCell.create(p.xrayEdgeFalloff),
+            uExposure: ValueCell.create(p.exposure),
         };
         const globalUniformList = Object.entries(globalUniforms);
 
@@ -787,6 +789,10 @@ namespace Renderer {
                     p.xrayEdgeFalloff = props.xrayEdgeFalloff;
                     ValueCell.update(globalUniforms.uXrayEdgeFalloff, p.xrayEdgeFalloff);
                 }
+                if (props.exposure !== undefined && props.exposure !== p.exposure) {
+                    p.exposure = props.exposure;
+                    ValueCell.update(globalUniforms.uExposure, p.exposure);
+                }
 
                 if (props.light !== undefined && !deepEqual(props.light, p.light)) {
                     p.light = props.light;

src/mol-gl/shader/chunks/apply-light-color.glsl.ts

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2017-2022 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2017-2023 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  *
@@ -65,4 +65,6 @@ export const apply_light_color = `
 #ifdef dXrayShaded
     gl_FragColor.a *= 1.0 - pow(abs(dot(normal, vec3(0.0, 0.0, 1.0))), uXrayEdgeFalloff);
 #endif
+
+gl_FragColor.rgb *= uExposure;
 `;

src/mol-gl/shader/chunks/common-frag-params.glsl.ts

@@ -72,6 +72,7 @@ uniform vec3 uInteriorColor;
 bool interior;
 
 uniform float uXrayEdgeFalloff;
+uniform float uExposure;
 
 uniform mat4 uProjection;
 

src/mol-gl/shader/direct-volume.frag.ts

@@ -75,6 +75,7 @@ uniform vec3 uFogColor;
 uniform float uAlpha;
 uniform bool uTransparentBackground;
 uniform float uXrayEdgeFalloff;
+uniform float uExposure;
 
 uniform int uRenderMask;