Globe Lighting

CHANGES.md

@@ -55,6 +55,7 @@ Beta Releases
 * Added prototype equals function to `NearFarScalar`, and `TimeIntervalCollection`.
 * Added `Matrix4.fromTranslationQuaternionRotationScale` and `Matrix4.multiplyByScale`.
 * Added `FrameState.events`.
+* Added `enableLighting`, `lightingFadeOutDistance`, and `lightingFadeInDistance` properties to `CentralBody` to configure lighting.
 * Added `Primitive.allowPicking` to save memory when picking is not needed.
 * Added `debugShowBoundingVolume`, for debugging primitive rendering, to `Primitive`, `Polygon`, `ExtentPrimitive`, `EllipsoidPrimitive`, `BillboardCollection`, `LabelCollection`, and `PolylineCollection`.
 * Added `DebugModelMatrixPrimitive` for debugging primitive's `modelMatrix`.

Source/Scene/CentralBody.js

@@ -213,6 +213,33 @@ define([
          */
         this.tileCacheSize = 100;
 
+        /**
+         * Enable lighting the globe with the sun as a light source.
+         *
+         * @type {Boolean}
+         * @default false
+         */
+        this.enableLighting = false;
+        this._enableLighting = false;
+
+        /**
+         * The distance where everything becomes lit. This only takes effect
+         * when <code>enableLighting</code> is <code>true</code>.
+         *
+         * @type {Number}
+         * @default 7500000.0
+         */
+        this.lightingFadeOutDistance = 7500000.0;
+
+        /**
+         * The distance where lighting resumes. This only takes effect
+         * when <code>enableLighting</code> is <code>true</code>.
+         *
+         * @type {Number}
+         * @default 9000000.0
+         */
+        this.lightingFadeInDistance = 9000000.0;
+
         this._lastOceanNormalMapUrl = undefined;
         this._oceanNormalMap = undefined;
         this._zoomedOutOceanSpecularIntensity = 0.5;
@@ -227,6 +254,12 @@ define([
             },
             u_oceanNormalMap : function() {
                 return that._oceanNormalMap;
+            },
+            u_lightingFadeOutDistance : function() {
+                return that.lightingFadeOutDistance;
+            },
+            u_lightingFadeInDistance : function() {
+                return that.lightingFadeInDistance;
             }
         };
     };
@@ -619,13 +652,15 @@ define([
         var projectionChanged = this._projection !== projection;
         var hasWaterMask = this._surface._terrainProvider.hasWaterMask();
         var hasWaterMaskChanged = this._hasWaterMask !== hasWaterMask;
+        var hasEnableLightingChanged = this._enableLighting !== this.enableLighting;
 
         if (!defined(this._surfaceShaderSet) ||
             !defined(this._northPoleCommand.shaderProgram) ||
             !defined(this._southPoleCommand.shaderProgram) ||
             modeChanged ||
             projectionChanged ||
             hasWaterMaskChanged ||
+            hasEnableLightingChanged ||
             (defined(this._oceanNormalMap)) !== this._showingPrettyOcean) {
 
             var getPosition3DMode = 'vec4 getPosition(vec3 position3DWC) { return getPosition3DMode(position3DWC); }';
@@ -662,7 +697,10 @@ define([
             }
 
             this._surfaceShaderSet.baseVertexShaderString = createShaderSource({
-                defines : [hasWaterMask ? 'SHOW_REFLECTIVE_OCEAN' : ''],
+                defines : [
+                    (hasWaterMask ? 'SHOW_REFLECTIVE_OCEAN' : ''),
+                    (this.enableLighting ? 'ENABLE_LIGHTING' : '')
+                ],
                 sources : [CentralBodyVS, getPositionMode, get2DYPositionFraction]
             });
 
@@ -671,7 +709,8 @@ define([
             this._surfaceShaderSet.baseFragmentShaderString = createShaderSource({
                 defines : [
                     (hasWaterMask ? 'SHOW_REFLECTIVE_OCEAN' : ''),
-                    (showPrettyOcean ? 'SHOW_OCEAN_WAVES' : '')
+                    (showPrettyOcean ? 'SHOW_OCEAN_WAVES' : ''),
+                    (this.enableLighting ? 'ENABLE_LIGHTING' : '')
                 ],
                 sources : [CentralBodyFS]
             });

Source/Shaders/CentralBodyFS.glsl

@@ -41,6 +41,11 @@ uniform float u_zoomedOutOceanSpecularIntensity;
 uniform sampler2D u_oceanNormalMap;
 #endif
 
+#ifdef ENABLE_LIGHTING
+uniform float u_lightingFadeOutDistance;
+uniform float u_lightingFadeInDistance;
+#endif
+
 varying vec3 v_positionMC;
 varying vec3 v_positionEC;
 varying vec2 v_textureCoordinates;
@@ -122,6 +127,11 @@ void main()
 #endif
 
     vec4 color = vec4(startDayColor, 1.0);
+
+#if defined(SHOW_REFLECTIVE_OCEAN) || defined(ENABLE_LIGHTING)
+    vec3 normalMC = normalize(czm_geodeticSurfaceNormal(v_positionMC, vec3(0.0), vec3(1.0)));   // normalized surface normal in model coordinates
+    vec3 normalEC = normalize(czm_normal3D * normalMC);                                         // normalized surface normal in eye coordiantes
+#endif
 
 #ifdef SHOW_REFLECTIVE_OCEAN
     vec2 waterMaskTranslation = u_waterMaskTranslationAndScale.xy;
@@ -132,10 +142,8 @@ void main()
 
     if (mask > 0.0)
     {
-        vec3 normalMC = normalize(czm_geodeticSurfaceNormal(v_positionMC, vec3(0.0), vec3(1.0)));   // normalized surface normal in model coordinates
-        vec3 normalEC = normalize(czm_normal3D * normalMC);                                           // normalized surface normal in eye coordiantes
         mat3 enuToEye = czm_eastNorthUpToEyeCoordinates(v_positionMC, normalEC);
-
+        
         vec2 ellipsoidTextureCoordinates = czm_ellipsoidWgs84TextureCoordinates(normalMC);
         vec2 ellipsoidFlippedTextureCoordinates = czm_ellipsoidWgs84TextureCoordinates(normalMC.zyx);
 
@@ -144,8 +152,16 @@ void main()
         color = computeWaterColor(v_positionEC, textureCoordinates, enuToEye, startDayColor, mask);
     }
 #endif
-
+
+#ifdef ENABLE_LIGHTING
+    float diffuseIntensity = clamp(czm_getLambertDiffuse(czm_sunDirectionEC, normalEC) * 5.0 + 0.3, 0.0, 1.0);
+    float cameraDist = length(czm_view[3]);
+    float t = clamp((cameraDist - u_lightingFadeOutDistance) / (u_lightingFadeInDistance - u_lightingFadeOutDistance), 0.0, 1.0);
+    diffuseIntensity = mix(1.0, diffuseIntensity, t);
+    gl_FragColor = vec4(color.rgb * diffuseIntensity, color.a);
+#else
     gl_FragColor = color;
+#endif
 }
 
 #ifdef SHOW_REFLECTIVE_OCEAN

Source/Shaders/CentralBodyVS.glsl

@@ -84,8 +84,8 @@ void main()
     vec3 position3DWC = position3DAndHeight.xyz + u_center3D;
 
     gl_Position = getPosition(position3DWC);
-    
-#ifdef SHOW_REFLECTIVE_OCEAN
+
+#if defined(SHOW_REFLECTIVE_OCEAN) || defined(ENABLE_LIGHTING)
     v_positionEC = (czm_modelView3D * vec4(position3DWC, 1.0)).xyz;
     v_positionMC = position3DWC;                                 // position in model coordinates
 #endif