mirror of
https://github.com/OpenSpace/OpenSpace.git
synced 2026-04-22 19:29:04 -05:00
Kalle Bladin
106 lines
4.1 KiB
Plaintext
106 lines
4.1 KiB
Plaintext
/*****************************************************************************************
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* *
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* OpenSpace *
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* *
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* Copyright (c) 2014 *
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* *
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this *
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* software and associated documentation files (the "Software"), to deal in the Software *
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* without restriction, including without limitation the rights to use, copy, modify, *
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* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to *
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* permit persons to whom the Software is furnished to do so, subject to the following *
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* conditions: *
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* *
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* The above copyright notice and this permission notice shall be included in all copies *
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* or substantial portions of the Software. *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, *
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* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A *
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* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT *
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF *
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE *
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* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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****************************************************************************************/
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#ifndef ELLIPSOID_HGLSL
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#define ELLIPSOID_HGLSL
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struct PositionNormalPair {
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vec3 position;
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vec3 normal;
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};
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struct Intersection {
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bool intersects;
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float nearParameter;// Along ray
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float farParameter; // Along ray
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};
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vec3 geodeticSurfaceNormal(float latitude, float longitude)
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{
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float cosLat = cos(latitude);
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return vec3(
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cosLat * cos(longitude),
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cosLat * sin(longitude),
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sin(latitude));
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}
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PositionNormalPair geodetic3ToCartesian(
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float latitude,
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float longitude,
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float height,
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vec3 radiiSquared)
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{
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vec3 normal = geodeticSurfaceNormal(latitude, longitude);
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vec3 k = radiiSquared * normal;
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float gamma = sqrt(dot(k, normal));
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vec3 rSurface = k / gamma;
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PositionNormalPair toReturn;
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toReturn.position = rSurface + height * normal;
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toReturn.normal = normal;
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return toReturn;
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}
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PositionNormalPair geodetic2ToCartesian(float latitude, float longitude, vec3 radiiSquared)
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{
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// Position on surface : height = 0
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return geodetic3ToCartesian(latitude, longitude, 0, radiiSquared);
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}
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vec3 latLonToCartesian(float latitude, float longitude, float radius) {
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return radius * vec3(
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cos(latitude) * cos(longitude),
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cos(latitude) * sin(longitude),
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sin(latitude));
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}
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//
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// Assumes ellipsoid is at (0, 0, 0)
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//
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Intersection rayIntersectEllipsoid(
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vec3 rayOrigin,
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vec3 rayOriginSquared,
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vec3 rayDirection,
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vec3 oneOverEllipsoidRadiiSquared)
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{
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float a = dot(rayDirection * rayDirection, oneOverEllipsoidRadiiSquared);
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float b = 2.0 * dot(rayOrigin * rayDirection, oneOverEllipsoidRadiiSquared);
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float c = dot(rayOriginSquared, oneOverEllipsoidRadiiSquared) - 1.0;
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float discriminant = b * b - 4.0 * a * c;
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if (discriminant < 0.0) {
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return Intersection(false, 0.0, 0.0);
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}
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else if (discriminant == 0.0) {
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float time = -0.5 * b / a;
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return Intersection(true, time, time);
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}
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float t = -0.5 * (b + (b > 0.0 ? 1.0 : -1.0) * sqrt(discriminant));
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float root1 = t / a;
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float root2 = c / t;
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return Intersection(true, min(root1, root2), max(root1, root2));
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}
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#endif // ELLIPSOID_HGLSL |