Solve struct ellipsoid caused the model to dark

CHANGES.md

@@ -16,6 +16,7 @@ Change Log
 * Fixed polyline colors when `scene.highDynamicRange` is enabled. [#7924](https://github.com/AnalyticalGraphicsInc/cesium/pull/7924)
 * Fixed a bug in the inspector where the min/max height values of a picked tile were undefined. [#7904](https://github.com/AnalyticalGraphicsInc/cesium/pull/7904)
 * Fixed `Math.factorial` to return the correct values. (https://github.com/AnalyticalGraphicsInc/cesium/pull/7969)
+* Fixed a bug that caused 3D models to appear darker on Android devices. [#7944](https://github.com/AnalyticalGraphicsInc/cesium/pull/7944)
 
 ### 1.58.1 - 2018-06-03
 _This is an npm-only release to fix a publishing issue_.

CONTRIBUTORS.md

@@ -214,3 +214,4 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to Cesiu
 * [Trubie Turner](https://github.com/flexei)
 * [Merijn Wijngaard](https://github.com/mwijngaard)
 * [Dennis Adams](https://github.com/dennisadams)
+* [Hai Zhou](https://github.com/verybigzhouhai)

Source/Scene/processPbrMaterials.js

@@ -740,9 +740,8 @@ define([
 
             fragmentShader += '    vec3 r = normalize(czm_inverseViewRotation * normalize(reflect(v, n)));\n';
             // Figure out if the reflection vector hits the ellipsoid
-            fragmentShader += '    czm_ellipsoid ellipsoid = czm_getWgs84EllipsoidEC();\n';
             fragmentShader += '    float vertexRadius = length(positionWC);\n';
-            fragmentShader += '    float horizonDotNadir = 1.0 - min(1.0, ellipsoid.radii.x / vertexRadius);\n';
+            fragmentShader += '    float horizonDotNadir = 1.0 - min(1.0, czm_ellipsoidRadii.x / vertexRadius);\n';
             fragmentShader += '    float reflectionDotNadir = dot(r, normalize(positionWC));\n';
             // Flipping the X vector is a cheap way to get the inverse of czm_temeToPseudoFixed, since that's a rotation about Z.
             fragmentShader += '    r.x = -r.x;\n';

Source/Shaders/Builtin/Constants/ellipsoidInverseRadii.glsl

@@ -0,0 +1,7 @@
+/**
+ * The reciprocal of the radius of the WGS84 ellipsoid.
+ *
+ * @name czm_ellipsoidInverseRadii
+ * @glslConstant
+ */
+const vec3 czm_ellipsoidInverseRadii = vec3(1.0 / 6378137.0, 1.0 / 6378137.0, 1.0 / 6356752.314245);

Source/Shaders/Builtin/Constants/ellipsoidRadii.glsl

@@ -0,0 +1,7 @@
+/**
+ * The radius of the WGS84 ellipsoid.
+ *
+ * @name czm_ellipsoidRadii
+ * @glslConstant
+ */
+const vec3 czm_ellipsoidRadii = vec3(6378137.0, 6378137.0, 6356752.314245);

Source/Shaders/Builtin/Functions/ellipsoidContainsPoint.glsl

@@ -5,8 +5,8 @@
  * @glslFunction
  *
  */
-bool czm_ellipsoidContainsPoint(czm_ellipsoid ellipsoid, vec3 point)
+bool czm_ellipsoidContainsPoint(vec3 ellipsoid_inverseRadii, vec3 point)
 {
-    vec3 scaled = ellipsoid.inverseRadii * (czm_inverseModelView * vec4(point, 1.0)).xyz;
+    vec3 scaled = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(point, 1.0)).xyz;
     return (dot(scaled, scaled) <= 1.0);
 }

Source/Shaders/Builtin/Functions/rayEllipsoidIntersectionInterval.glsl

@@ -4,17 +4,17 @@
  * @name czm_rayEllipsoidIntersectionInterval
  * @glslFunction
  */
-czm_raySegment czm_rayEllipsoidIntersectionInterval(czm_ray ray, czm_ellipsoid ellipsoid)
+czm_raySegment czm_rayEllipsoidIntersectionInterval(czm_ray ray, vec3 ellipsoid_center, vec3 ellipsoid_inverseRadii)
 {
    // ray and ellipsoid center in eye coordinates.  radii in model coordinates.
-    vec3 q = ellipsoid.inverseRadii * (czm_inverseModelView * vec4(ray.origin, 1.0)).xyz;
-    vec3 w = ellipsoid.inverseRadii * (czm_inverseModelView * vec4(ray.direction, 0.0)).xyz;
-   
-    q = q - ellipsoid.inverseRadii * (czm_inverseModelView * vec4(ellipsoid.center, 1.0)).xyz;
-    
+    vec3 q = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ray.origin, 1.0)).xyz;
+    vec3 w = ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ray.direction, 0.0)).xyz;
+
+    q = q - ellipsoid_inverseRadii * (czm_inverseModelView * vec4(ellipsoid_center, 1.0)).xyz;
+
     float q2 = dot(q, q);
     float qw = dot(q, w);
-    
+
     if (q2 > 1.0) // Outside ellipsoid.
     {
         if (qw >= 0.0) // Looking outward or tangent (0 intersections).
@@ -27,11 +27,11 @@ czm_raySegment czm_rayEllipsoidIntersectionInterval(czm_ray ray, czm_ellipsoid e
             float difference = q2 - 1.0; // Positively valued.
             float w2 = dot(w, w);
             float product = w2 * difference;
-            
+
             if (qw2 < product) // Imaginary roots (0 intersections).
             {
-                return czm_emptyRaySegment;     
-            }   
+                return czm_emptyRaySegment;
+            }
             else if (qw2 > product) // Distinct roots (2 intersections).
             {
                 float discriminant = qw * qw - product;

Source/Shaders/DepthPlaneFS.glsl

@@ -2,13 +2,12 @@ varying vec4 positionEC;
 
 void main()
 {
-    // TODO: make arbitrary ellipsoid
-    czm_ellipsoid ellipsoid = czm_getWgs84EllipsoidEC();
-
     vec3 direction = normalize(positionEC.xyz);
     czm_ray ray = czm_ray(vec3(0.0), direction);
 
-    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid);
+    vec3 ellipsoid_center = czm_view[3].xyz;
+
+    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid_center, czm_ellipsoidInverseRadii);
     if (!czm_isEmpty(intersection))
     {
         gl_FragColor = vec4(1.0, 1.0, 0.0, 1.0);

Source/Shaders/EllipsoidFS.glsl

@@ -72,10 +72,11 @@ void main()
     }
 
     // March ray forward to intersection with larger sphere and find
-    // actual intersection point with ellipsoid.
-    czm_ellipsoid ellipsoid = czm_ellipsoidNew(ellipsoidCenter, u_radii);
     czm_ray ray = czm_ray(t * direction, direction);
-    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid);
+
+    vec3 ellipsoid_inverseRadii = vec3(1.0 / u_radii.x, 1.0 / u_radii.y, 1.0 / u_radii.z);
+
+    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoidCenter, ellipsoid_inverseRadii);
 
     if (czm_isEmpty(intersection))
     {

Source/Shaders/GlobeFS.glsl

@@ -278,7 +278,7 @@ void main()
     float fadeOutDist = u_lightingFadeDistance.x;
     float fadeInDist = u_lightingFadeDistance.y;
     if (czm_sceneMode != czm_sceneMode3D) {
-        vec3 radii = czm_getWgs84EllipsoidEC().radii;
+        vec3 radii = czm_ellipsoidRadii;
         float maxRadii = max(radii.x, max(radii.y, radii.z));
         fadeOutDist -= maxRadii;
         fadeInDist -= maxRadii;
@@ -376,16 +376,16 @@ void main()
     }
 
 #if defined(PER_FRAGMENT_GROUND_ATMOSPHERE) && (defined(ENABLE_DAYNIGHT_SHADING) || defined(ENABLE_VERTEX_LIGHTING))
-    czm_ellipsoid ellipsoid = czm_getWgs84EllipsoidEC();
-
     float mpp = czm_metersPerPixel(vec4(0.0, 0.0, -czm_currentFrustum.x, 1.0));
     vec2 xy = gl_FragCoord.xy / czm_viewport.zw * 2.0 - vec2(1.0);
     xy *= czm_viewport.zw * mpp * 0.5;
 
     vec3 direction = normalize(vec3(xy, -czm_currentFrustum.x));
     czm_ray ray = czm_ray(vec3(0.0), direction);
 
-    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid);
+    vec3 ellipsoid_center = czm_view[3].xyz;
+
+    czm_raySegment intersection = czm_rayEllipsoidIntersectionInterval(ray, ellipsoid_center, czm_ellipsoidInverseRadii);
 
     vec3 ellipsoidPosition = czm_pointAlongRay(ray, intersection.start);
     ellipsoidPosition = (czm_inverseView * vec4(ellipsoidPosition, 1.0)).xyz;

Source/Shaders/GlobeVS.glsl

@@ -176,7 +176,7 @@ void main()
 #endif
 
 #ifdef APPLY_MATERIAL
-    float northPoleZ = czm_getWgs84EllipsoidEC().radii.z;
+    float northPoleZ = czm_ellipsoidRadii.z;
     vec3 northPolePositionMC = vec3(0.0, 0.0, northPoleZ);
     vec3 ellipsoidNormal = normalize(v_positionMC); // For a sphere this is correct, but not generally for an ellipsoid.
     vec3 vectorEastMC = normalize(cross(northPolePositionMC - v_positionMC, ellipsoidNormal));