fix artifacts in 2D and morph

Author: likangning93

Source/Scene/GroundPolylinePrimitive.js

@@ -405,10 +405,10 @@ define([
 
             // Check for use of v_width and v_polylineAngle in material shader
             // to determine whether these varyings should be active in the vertex shader.
-            if (materialShaderSource.search(/varying\s+float\s+v_polylineAngle;/g) === -1) {
+            if (materialShaderSource.search(/varying\s+float\s+v_polylineAngle;/g) !== -1) {
                 vsDefines.push('ANGLE_VARYING');
             }
-            if (materialShaderSource.search(/varying\s+float\s+v_width;/g) === -1) {
+            if (materialShaderSource.search(/varying\s+float\s+v_width;/g) !== -1) {
                 vsDefines.push('WIDTH_VARYING');
             }
         } else {
@@ -455,7 +455,7 @@ define([
         var colorProgramMorph = context.shaderCache.getDerivedShaderProgram(groundPolylinePrimitive._sp, 'MorphColor');
         if (!defined(colorProgramMorph)) {
             var vsColorMorph = new ShaderSource({
-                defines : vsDefines,
+                defines : vsDefines.concat(['MAX_TERRAIN_HEIGHT ' + ApproximateTerrainHeights._defaultMaxTerrainHeight.toFixed(1)]),
                 sources : [vsMorph]
             });
 

Source/Shaders/PolylineShadowVolumeFS.glsl

@@ -10,7 +10,7 @@ varying vec4 v_color;
 
 void main(void)
 {
-    float logDepthOrDepth = czm_unpackDepth(texture2D(czm_globeDepthTexture, gl_FragCoord.xy / czm_viewport.zw));
+    float logDepthOrDepth = czm_branchFreeTernary(czm_sceneMode == czm_sceneMode2D, gl_FragCoord.z, czm_unpackDepth(texture2D(czm_globeDepthTexture, gl_FragCoord.xy / czm_viewport.zw)));
     vec3 ecStart = vec3(v_endEcAndStartEcX.w, v_texcoordNormalizationAndStartEcYZ.zw);
 
     // Discard for sky

Source/Shaders/PolylineShadowVolumeMorphVS.glsl

@@ -42,56 +42,64 @@ void main()
     vec4 posRelativeToEye2D = czm_translateRelativeToEye(vec3(0.0, startHiLo2D.xy), vec3(0.0, startHiLo2D.zw));
     vec4 posRelativeToEye3D = czm_translateRelativeToEye(startHiAndForwardOffsetX.xyz, startLoAndForwardOffsetY.xyz);
     vec4 posRelativeToEye = czm_columbusViewMorph(posRelativeToEye2D, posRelativeToEye3D, czm_morphTime);
-    vec3 ecPos2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;
-    vec3 ecPos3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;
-    vec3 ecStart = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;
+    vec3 posEc2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;
+    vec3 posEc3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;
+    vec3 startEC = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;
 
     // Start plane
     vec4 startPlane2D;
     vec4 startPlane3D;
     startPlane2D.xyz = czm_normal * vec3(0.0, startEndNormals2D.xy);
     startPlane3D.xyz = czm_normal * startNormalAndForwardOffsetZ.xyz;
-    startPlane2D.w = -dot(startPlane2D.xyz, ecPos2D);
-    startPlane3D.w = -dot(startPlane3D.xyz, ecPos3D);
+    startPlane2D.w = -dot(startPlane2D.xyz, posEc2D);
+    startPlane3D.w = -dot(startPlane3D.xyz, posEc3D);
 
     // Right plane
     vec4 rightPlane2D;
     vec4 rightPlane3D;
     rightPlane2D.xyz = czm_normal * vec3(0.0, offsetAndRight2D.zw);
     rightPlane3D.xyz = czm_normal * rightNormalAndTextureCoordinateNormalizationY.xyz;
-    rightPlane2D.w = -dot(rightPlane2D.xyz, ecPos2D);
-    rightPlane3D.w = -dot(rightPlane3D.xyz, ecPos3D);
+    rightPlane2D.w = -dot(rightPlane2D.xyz, posEc2D);
+    rightPlane3D.w = -dot(rightPlane3D.xyz, posEc3D);
 
     // End position
     posRelativeToEye2D = posRelativeToEye2D + vec4(0.0, offsetAndRight2D.xy, 0.0);
     posRelativeToEye3D = posRelativeToEye3D + vec4(startHiAndForwardOffsetX.w, startLoAndForwardOffsetY.w, startNormalAndForwardOffsetZ.w, 0.0);
     posRelativeToEye = czm_columbusViewMorph(posRelativeToEye2D, posRelativeToEye3D, czm_morphTime);
-    ecPos2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;
-    ecPos3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;
-    vec3 ecEnd = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;
+    posEc2D = (czm_modelViewRelativeToEye * posRelativeToEye2D).xyz;
+    posEc3D = (czm_modelViewRelativeToEye * posRelativeToEye3D).xyz;
+    vec3 endEC = (czm_modelViewRelativeToEye * posRelativeToEye).xyz;
+    vec3 forwardEc3D = czm_normal * normalize(vec3(startHiAndForwardOffsetX.w, startLoAndForwardOffsetY.w, startNormalAndForwardOffsetZ.w));
+    vec3 forwardEc2D = czm_normal * normalize(vec3(0.0, offsetAndRight2D.xy));
 
     // End plane
     vec4 endPlane2D;
     vec4 endPlane3D;
     endPlane2D.xyz = czm_normal * vec3(0.0, startEndNormals2D.zw);
     endPlane3D.xyz = czm_normal * endNormalAndTextureCoordinateNormalizationX.xyz;
-    endPlane2D.w = -dot(endPlane2D.xyz, ecPos2D);
-    endPlane3D.w = -dot(endPlane3D.xyz, ecPos3D);
+    endPlane2D.w = -dot(endPlane2D.xyz, posEc2D);
+    endPlane3D.w = -dot(endPlane3D.xyz, posEc3D);
 
     // Forward direction
-    v_forwardDirectionEC = normalize(ecEnd - ecStart);
+    v_forwardDirectionEC = normalize(endEC - startEC);
 
-    v_texcoordNormalization_and_halfWidth.xy = mix(
-        vec2(abs(texcoordNormalization2D.x), texcoordNormalization2D.y),
-        vec2(abs(endNormalAndTextureCoordinateNormalizationX.w), rightNormalAndTextureCoordinateNormalizationY.w), czm_morphTime);
+    vec2 cleanTexcoordNormalization2D;
+    cleanTexcoordNormalization2D.x = abs(texcoordNormalization2D.x);
+    cleanTexcoordNormalization2D.y = czm_branchFreeTernary(texcoordNormalization2D.y > 1.0, 0.0, abs(texcoordNormalization2D.y));
+    vec2 cleanTexcoordNormalization3D;
+    cleanTexcoordNormalization3D.x = abs(endNormalAndTextureCoordinateNormalizationX.w);
+    cleanTexcoordNormalization3D.y = rightNormalAndTextureCoordinateNormalizationY.w;
+    cleanTexcoordNormalization3D.y = czm_branchFreeTernary(cleanTexcoordNormalization3D.y > 1.0, 0.0, abs(cleanTexcoordNormalization3D.y));
+
+    v_texcoordNormalization_and_halfWidth.xy = mix(cleanTexcoordNormalization2D, cleanTexcoordNormalization3D, czm_morphTime);
 
 #ifdef PER_INSTANCE_COLOR
     v_color = czm_batchTable_color(batchId);
 #else // PER_INSTANCE_COLOR
     // For computing texture coordinates
 
-    v_alignedPlaneDistances.x = -dot(v_forwardDirectionEC, ecStart);
-    v_alignedPlaneDistances.y = -dot(-v_forwardDirectionEC, ecEnd);
+    v_alignedPlaneDistances.x = -dot(v_forwardDirectionEC, startEC);
+    v_alignedPlaneDistances.y = -dot(-v_forwardDirectionEC, endEC);
 #endif // PER_INSTANCE_COLOR
 
 #ifdef WIDTH_VARYING
@@ -111,29 +119,41 @@ void main()
 
     // ****** 3D ******
     // Check distance to the end plane and start plane, pick the plane that is closer
-    vec4 positionEC3D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position3DHigh, position3DLow); // w = 1.0, see czm_computePosition
-    float absStartPlaneDistance = abs(czm_planeDistance(startPlane3D, positionEC3D.xyz));
-    float absEndPlaneDistance = abs(czm_planeDistance(endPlane3D, positionEC3D.xyz));
+    vec4 positionEc3D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position3DHigh, position3DLow); // w = 1.0, see czm_computePosition
+    float absStartPlaneDistance = abs(czm_planeDistance(startPlane3D, positionEc3D.xyz));
+    float absEndPlaneDistance = abs(czm_planeDistance(endPlane3D, positionEc3D.xyz));
     vec3 planeDirection = czm_branchFreeTernary(absStartPlaneDistance < absEndPlaneDistance, startPlane3D.xyz, endPlane3D.xyz);
     vec3 upOrDown = normalize(cross(rightPlane3D.xyz, planeDirection)); // Points "up" for start plane, "down" at end plane.
     vec3 normalEC = normalize(cross(planeDirection, upOrDown));         // In practice, the opposite seems to work too.
 
+    // Nudge the top vertex upwards to prevent flickering
+    vec3 geodeticSurfaceNormal = normalize(cross(normalEC, forwardEc3D));
+    geodeticSurfaceNormal *= float(0.0 <= rightNormalAndTextureCoordinateNormalizationY.w && rightNormalAndTextureCoordinateNormalizationY.w <= 1.0);
+    geodeticSurfaceNormal *= MAX_TERRAIN_HEIGHT;
+    positionEc3D.xyz += geodeticSurfaceNormal;
+
     // Determine if this vertex is on the "left" or "right"
     normalEC *= sign(endNormalAndTextureCoordinateNormalizationX.w);
 
     // A "perfect" implementation would push along normals according to the angle against forward.
     // In practice, just pushing the normal out by halfWidth is sufficient for morph views.
-    positionEC3D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEC3D)) * normalEC; // prevent artifacts when czm_metersPerPixel is negative (behind camera)
+    positionEc3D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEc3D)) * normalEC; // prevent artifacts when czm_metersPerPixel is negative (behind camera)
 
     // ****** 2D ******
     // Check distance to the end plane and start plane, pick the plane that is closer
-    vec4 positionEC2D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position2DHigh.zxy, position2DLow.zxy); // w = 1.0, see czm_computePosition
-    absStartPlaneDistance = abs(czm_planeDistance(startPlane2D, positionEC2D.xyz));
-    absEndPlaneDistance = abs(czm_planeDistance(endPlane2D, positionEC2D.xyz));
+    vec4 positionEc2D = czm_modelViewRelativeToEye * czm_translateRelativeToEye(position2DHigh.zxy, position2DLow.zxy); // w = 1.0, see czm_computePosition
+    absStartPlaneDistance = abs(czm_planeDistance(startPlane2D, positionEc2D.xyz));
+    absEndPlaneDistance = abs(czm_planeDistance(endPlane2D, positionEc2D.xyz));
     planeDirection = czm_branchFreeTernary(absStartPlaneDistance < absEndPlaneDistance, startPlane2D.xyz, endPlane2D.xyz);
     upOrDown = normalize(cross(rightPlane2D.xyz, planeDirection)); // Points "up" for start plane, "down" at end plane.
     normalEC = normalize(cross(planeDirection, upOrDown));         // In practice, the opposite seems to work too.
 
+    // Nudge the top vertex upwards to prevent flickering
+    geodeticSurfaceNormal = normalize(cross(normalEC, forwardEc2D));
+    geodeticSurfaceNormal *= float(0.0 <= texcoordNormalization2D.y && texcoordNormalization2D.y <= 1.0);
+    geodeticSurfaceNormal *= MAX_TERRAIN_HEIGHT;
+    positionEc2D.xyz += geodeticSurfaceNormal;
+
     // Determine if this vertex is on the "left" or "right"
     normalEC *= sign(texcoordNormalization2D.x);
 #ifndef PER_INSTANCE_COLOR
@@ -143,11 +163,10 @@ void main()
 
     // A "perfect" implementation would push along normals according to the angle against forward.
     // In practice, just pushing the normal out by halfWidth is sufficient for morph views.
-    positionEC2D.xyz -= normalEC; // undo the unit length push
-    positionEC2D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEC2D)) * normalEC; // prevent artifacts when czm_metersPerPixel is negative (behind camera)
+    positionEc2D.xyz += halfWidth * max(0.0, czm_metersPerPixel(positionEc2D)) * normalEC; // prevent artifacts when czm_metersPerPixel is negative (behind camera)
 
     // Blend for actual position
-    gl_Position = czm_projection * mix(positionEC2D, positionEC3D, czm_morphTime);
+    gl_Position = czm_projection * mix(positionEc2D, positionEc3D, czm_morphTime);
 
 #ifdef ANGLE_VARYING
     // Approximate relative screen space direction of the line.