84 lines
4.3 KiB
JavaScript
84 lines
4.3 KiB
JavaScript
//This file is automatically rebuilt by the Cesium build process.
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export default "float interpolateByDistance(vec4 nearFarScalar, float distance)\n\
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{\n\
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float startDistance = nearFarScalar.x;\n\
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float startValue = nearFarScalar.y;\n\
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float endDistance = nearFarScalar.z;\n\
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float endValue = nearFarScalar.w;\n\
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float t = clamp((distance - startDistance) / (endDistance - startDistance), 0.0, 1.0);\n\
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return mix(startValue, endValue, t);\n\
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}\n\
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\n\
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void computeAtmosphereScattering(vec3 positionWC, vec3 lightDirection, out vec3 rayleighColor, out vec3 mieColor, out float opacity, out float underTranslucentGlobe)\n\
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{\n\
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float ellipsoidRadiiDifference = czm_ellipsoidRadii.x - czm_ellipsoidRadii.z;\n\
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\n\
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// Adjustment to the atmosphere radius applied based on the camera height.\n\
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float distanceAdjustMin = czm_ellipsoidRadii.x / 4.0;\n\
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float distanceAdjustMax = czm_ellipsoidRadii.x;\n\
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float distanceAdjustModifier = ellipsoidRadiiDifference / 2.0;\n\
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float distanceAdjust = distanceAdjustModifier * clamp((czm_eyeHeight - distanceAdjustMin) / (distanceAdjustMax - distanceAdjustMin), 0.0, 1.0);\n\
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\n\
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// Since atmosphere scattering assumes the atmosphere is a spherical shell, we compute an inner radius of the atmosphere best fit\n\
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// for the position on the ellipsoid.\n\
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float radiusAdjust = (ellipsoidRadiiDifference / 4.0) + distanceAdjust;\n\
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float atmosphereInnerRadius = (length(czm_viewerPositionWC) - czm_eyeHeight) - radiusAdjust;\n\
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\n\
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// Setup the primary ray: from the camera position to the vertex position.\n\
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vec3 cameraToPositionWC = positionWC - czm_viewerPositionWC;\n\
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vec3 cameraToPositionWCDirection = normalize(cameraToPositionWC);\n\
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czm_ray primaryRay = czm_ray(czm_viewerPositionWC, cameraToPositionWCDirection);\n\
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\n\
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underTranslucentGlobe = 0.0;\n\
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\n\
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// Brighten the sky atmosphere under the Earth's atmosphere when translucency is enabled.\n\
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#if defined(GLOBE_TRANSLUCENT)\n\
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\n\
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// Check for intersection with the inner radius of the atmopshere.\n\
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czm_raySegment primaryRayEarthIntersect = czm_raySphereIntersectionInterval(primaryRay, vec3(0.0), atmosphereInnerRadius + radiusAdjust);\n\
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if (primaryRayEarthIntersect.start > 0.0 && primaryRayEarthIntersect.stop > 0.0) {\n\
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\n\
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// Compute position on globe.\n\
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vec3 direction = normalize(positionWC);\n\
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czm_ray ellipsoidRay = czm_ray(positionWC, -direction);\n\
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czm_raySegment ellipsoidIntersection = czm_rayEllipsoidIntersectionInterval(ellipsoidRay, vec3(0.0), czm_ellipsoidInverseRadii);\n\
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vec3 onEarth = positionWC - (direction * ellipsoidIntersection.start);\n\
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\n\
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// Control the color using the camera angle.\n\
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float angle = dot(normalize(czm_viewerPositionWC), normalize(onEarth));\n\
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\n\
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// Control the opacity using the distance from Earth.\n\
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opacity = interpolateByDistance(vec4(0.0, 1.0, czm_ellipsoidRadii.x, 0.0), length(czm_viewerPositionWC - onEarth));\n\
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vec3 horizonColor = vec3(0.1, 0.2, 0.3);\n\
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vec3 nearColor = vec3(0.0);\n\
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\n\
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rayleighColor = mix(nearColor, horizonColor, exp(-angle) * opacity);\n\
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\n\
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// Set the traslucent flag to avoid alpha adjustment in computeFinalColor funciton.\n\
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underTranslucentGlobe = 1.0;\n\
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return;\n\
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}\n\
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#endif\n\
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\n\
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computeScattering(\n\
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primaryRay,\n\
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length(cameraToPositionWC),\n\
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lightDirection,\n\
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atmosphereInnerRadius,\n\
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rayleighColor,\n\
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mieColor,\n\
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opacity\n\
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);\n\
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\n\
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// Alter the opacity based on how close the viewer is to the ground.\n\
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// (0.0 = At edge of atmosphere, 1.0 = On ground)\n\
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float cameraHeight = czm_eyeHeight + atmosphereInnerRadius;\n\
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float atmosphereOuterRadius = atmosphereInnerRadius + ATMOSPHERE_THICKNESS;\n\
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opacity = clamp((atmosphereOuterRadius - cameraHeight) / (atmosphereOuterRadius - atmosphereInnerRadius), 0.0, 1.0);\n\
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\n\
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// Alter alpha based on time of day (0.0 = night , 1.0 = day)\n\
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float nightAlpha = (u_radiiAndDynamicAtmosphereColor.z != 0.0) ? clamp(dot(normalize(positionWC), lightDirection), 0.0, 1.0) : 1.0;\n\
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opacity *= pow(nightAlpha, 0.5);\n\
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}\n\
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";
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