Add utility files

modules/skybrowser/include/utility.h

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+#include <openspace/interaction/navigationhandler.h>
+#include <openspace/engine/globals.h>
+#include <openspace/util/camera.h>
+#include <cmath> // For atan2
+#include <glm/gtx/string_cast.hpp> // For printing glm data
+#define _USE_MATH_DEFINES
+#include <math.h>
+
+
+namespace openspace::skybrowser {
+    const double SCREENSPACE_Z = -2.1;
+    const double RAD_TO_DEG = 180.0 / M_PI;
+    const double DEG_TO_RAD = M_PI / 180.0;
+
+    // Conversion matrix from this paper: https://arxiv.org/abs/1010.3773v1
+    const glm::dmat3 conversionMatrix = glm::dmat3({
+               -0.054875539390,  0.494109453633, -0.867666135681, // col 0
+               -0.873437104725, -0.444829594298, -0.198076389622, // col 1
+               -0.483834991775,  0.746982248696,  0.455983794523 // col 2
+        });
+
+    // J2000 to galactic conversion and vice versa
+    glm::dvec2 cartesianToSpherical(glm::dvec3 cartesianCoords);
+    glm::dvec3 sphericalToCartesian(glm::dvec2 sphericalCoords);
+    glm::dvec2 galacticCartesianToJ2000(glm::dvec3 rGal);
+    glm::dvec3 J2000ToGalacticCartesian(double ra, double dec, double distance);
+    glm::dvec2 J2000ToScreenSpace(double ra, double dec);
+    
+    glm::dvec2 galacticToScreenSpace(glm::dvec3 galacticCoord);
+}
+    
+    
+

modules/skybrowser/src/utility.cpp

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+
+#include <openspace/interaction/navigationhandler.h>
+#include <openspace/engine/globals.h>
+#include <openspace/util/camera.h>
+#include <modules/skybrowser/include/utility.h>
+#include <cmath> // For atan2
+#include <glm/gtx/string_cast.hpp> // For printing glm data
+#define _USE_MATH_DEFINES
+#include <cmath>
+
+
+
+namespace openspace::skybrowser {
+
+        glm::dvec3 sphericalToCartesian(glm::dvec2 sphericalCoords) {
+
+            glm::dvec3 cartesian = glm::dvec3(
+                cos(sphericalCoords.x * DEG_TO_RAD) * cos(sphericalCoords.y * DEG_TO_RAD),
+                sin(sphericalCoords.x * DEG_TO_RAD) * cos(sphericalCoords.y * DEG_TO_RAD),
+                sin(sphericalCoords.y * DEG_TO_RAD)
+            );
+
+            return cartesian;
+        }
+
+        glm::dvec2 cartesianToSpherical(glm::dvec3 cartesianCoords) {
+
+            double ra = atan2(cartesianCoords[1], cartesianCoords[0]);
+            double dec = atan2(cartesianCoords[2], glm::sqrt((cartesianCoords[0] * cartesianCoords[0]) + (cartesianCoords[1] * cartesianCoords[1])));
+
+            ra = ra > 0 ? ra : ra + (2 * M_PI);
+
+            return glm::dvec2(RAD_TO_DEG * ra, RAD_TO_DEG * dec);
+        }
+
+        glm::dvec2 galacticCartesianToJ2000(glm::dvec3 rGal) {
+            glm::dvec3 J2000 = glm::transpose(conversionMatrix) * rGal;
+            return cartesianToSpherical(J2000);
+        }
+
+        glm::dvec3 J2000ToGalacticCartesian(double ra, double dec, double distance) {
+            glm::dvec3 rGalactic = conversionMatrix * sphericalToCartesian(glm::dvec2(ra, dec)); // on the unit sphere
+            return distance * rGalactic;
+        }
+        
+        glm::dvec2 galacticToScreenSpace(glm::dvec3 imageCoordsGalacticCartesian) {
+
+            // Transform vector to camera's local coordinate system
+            glm::dvec3 camPos = global::navigationHandler->camera()->positionVec3();
+            glm::dvec3 camToCoordsDir = glm::normalize(imageCoordsGalacticCartesian - camPos);
+            glm::dmat4 camMat = global::navigationHandler->camera()->viewRotationMatrix();
+            glm::dvec3 viewDirectionLocal = camMat * glm::dvec4(camToCoordsDir, 1.0);
+            viewDirectionLocal = glm::normalize(viewDirectionLocal);
+
+            // Calculate screen space coords x and y
+            long double tan_x = viewDirectionLocal.x / viewDirectionLocal.z;
+            long double tan_y = viewDirectionLocal.y / viewDirectionLocal.z;
+
+            glm::dvec2 angleCoordsLocal = glm::dvec2(std::atanl(tan_x), std::atanl(tan_y));
+            glm::dvec2 imageCoordsScreenSpace = glm::dvec2(SCREENSPACE_Z * static_cast<double>(std::tanl(angleCoordsLocal.x)), SCREENSPACE_Z * static_cast<double>(std::tanl(angleCoordsLocal.y)));
+            
+            return imageCoordsScreenSpace;
+        }
+
+        glm::dvec2 J2000ToScreenSpace(double ra, double dec) {
+            // Transform equatorial J2000 to galactic coord with infinite radius
+            constexpr double infinity = std::numeric_limits<float>::max();
+            glm::dvec3 imageCoordsGalacticCartesian = J2000ToGalacticCartesian(ra, dec, infinity);
+            // Transform galactic coord to screen space
+            glm::dvec2 imageCoordsScreenSpace = galacticToScreenSpace(imageCoordsGalacticCartesian);
+            return imageCoordsScreenSpace;
+        }
+
+    }
+    
+    
+