Replace unused system rotation computation with the one that is actually used

modules/exoplanets/exoplanetshelper.cpp

@@ -24,6 +24,7 @@
 
 #include <modules/exoplanets/exoplanetshelper.h>
 
+#include <openspace/util/spicemanager.h>
 #include <ghoul/filesystem/filesystem.h>
 #include <ghoul/fmt.h>
 #include <ghoul/logging/logmanager.h>
@@ -137,44 +138,41 @@ glm::dmat4 computeOrbitPlaneRotationMatrix(float i, float bigom, float omega) {
     return orbitPlaneRotation;
 }
 
-// Rotate the original coordinate system (where x is pointing to First Point of Aries)
-// so that x is pointing from star to the sun.
-// Modified from "http://www.opengl-tutorial.org/intermediate-tutorials/
-// tutorial-17-quaternions/ #how-do-i-find-the-rotation-between-2-vectors"
-glm::dmat3 exoplanetSystemRotation(glm::dvec3 start, glm::dvec3 end) {
-    glm::quat rotationQuat;
-    glm::dvec3 rotationAxis;
-    const float cosTheta = static_cast<float>(glm::dot(start, end));
-    constexpr float Epsilon = 1E-3f;
+glm::dmat3 computeSystemRotation(glm::dvec3 starPosition) {
+    const glm::dvec3 sunPosition = glm::dvec3(0.0, 0.0, 0.0);
+    const glm::dvec3 starToSunVec = glm::normalize(sunPosition - starPosition);
+    const glm::dvec3 galacticNorth = glm::dvec3(0.0, 0.0, 1.0);
 
-    if (cosTheta < -1.f + Epsilon) {
-        // special case when vectors in opposite directions:
-        // there is no "ideal" rotation axis
-        // So guess one; any will do as long as it's perpendicular to start vector
-        rotationAxis = glm::cross(glm::dvec3(0.0, 0.0, 1.0), start);
-        if (glm::length2(rotationAxis) < 0.01f) {
-            // bad luck, they were parallel, try again!
-            rotationAxis = glm::cross(glm::dvec3(1.0, 0.0, 0.0), start);
-        }
+    const glm::dmat3 galacticToCelestialMatrix =
+        SpiceManager::ref().positionTransformMatrix("GALACTIC", "J2000", 0.0);
 
-        rotationAxis = glm::normalize(rotationAxis);
-        rotationQuat = glm::quat(glm::radians(180.f), rotationAxis);
-        return glm::dmat3(glm::toMat4(rotationQuat));
-    }
-
-    rotationAxis = glm::cross(start, end);
-
-    const float s = sqrt((1.f + cosTheta) * 2.f);
-    const float invs = 1.f / s;
-
-    rotationQuat = glm::quat(
-        s * 0.5f,
-        static_cast<float>(rotationAxis.x * invs),
-        static_cast<float>(rotationAxis.y * invs),
-        static_cast<float>(rotationAxis.z * invs)
+    const glm::dvec3 celestialNorth = glm::normalize(
+        galacticToCelestialMatrix * galacticNorth
     );
 
-    return glm::dmat3(glm::toMat4(rotationQuat));
+    // Earth's north vector projected onto the skyplane, the plane perpendicular to the
+    // viewing vector (starToSunVec)
+    const float celestialAngle = static_cast<float>(glm::dot(
+        celestialNorth,
+        starToSunVec
+    ));
+    glm::dvec3 northProjected = glm::normalize(
+        celestialNorth - (celestialAngle / glm::length(starToSunVec)) * starToSunVec
+    );
+
+    const glm::dvec3 beta = glm::normalize(glm::cross(starToSunVec, northProjected));
+
+    return glm::dmat3(
+        northProjected.x,
+        northProjected.y,
+        northProjected.z,
+        beta.x,
+        beta.y,
+        beta.z,
+        starToSunVec.x,
+        starToSunVec.y,
+        starToSunVec.z
+    );
 }
 
 std::string createIdentifier(std::string name) {

modules/exoplanets/exoplanetshelper.h

@@ -82,7 +82,7 @@ glm::dmat4 computeOrbitPlaneRotationMatrix(float i, float bigom, float omega);
 
 // Rotate the original coordinate system (where x is pointing to First Point of Aries)
 // so that x is pointing from star to the sun.
-glm::dmat3 exoplanetSystemRotation(glm::dvec3 start, glm::dvec3 end);
+glm::dmat3 computeSystemRotation(glm::dvec3 starPosition);
 
 // Create an identifier without whitespaces
 std::string createIdentifier(std::string name);

modules/exoplanets/exoplanetsmodule_lua.inl

@@ -29,7 +29,6 @@
 #include <openspace/scene/scenegraphnode.h>
 #include <openspace/scripting/scriptengine.h>
 #include <openspace/util/distanceconstants.h>
-#include <openspace/util/spicemanager.h>
 #include <openspace/util/timeconversion.h>
 #include <openspace/util/timemanager.h>
 #include <ghoul/filesystem/filesystem.h>
@@ -146,40 +145,7 @@ void createExoplanetSystem(std::string_view starName) {
         p.positionZ * distanceconstants::Parsec
     );
 
-    const glm::dvec3 sunPosition = glm::dvec3(0.0, 0.0, 0.0);
-    const glm::dvec3 starToSunVec = glm::normalize(sunPosition - starPosition);
-    const glm::dvec3 galacticNorth = glm::dvec3(0.0, 0.0, 1.0);
-
-    const glm::dmat3 galaxticToCelestialMatrix =
-        SpiceManager::ref().positionTransformMatrix("GALACTIC", "J2000", 0.0);
-
-    const glm::dvec3 celestialNorth = glm::normalize(
-        galaxticToCelestialMatrix * galacticNorth
-    );
-
-    // Earth's north vector projected onto the skyplane, the plane perpendicular to the
-    // viewing vector (starToSunVec)
-    const float celestialAngle = static_cast<float>(glm::dot(
-        celestialNorth,
-        starToSunVec
-    ));
-    glm::dvec3 northProjected = glm::normalize(
-        celestialNorth - (celestialAngle / glm::length(starToSunVec)) * starToSunVec
-    );
-
-    const glm::dvec3 beta = glm::normalize(glm::cross(starToSunVec, northProjected));
-
-    const glm::dmat3 exoplanetSystemRotation = glm::dmat3(
-        northProjected.x,
-        northProjected.y,
-        northProjected.z,
-        beta.x,
-        beta.y,
-        beta.z,
-        starToSunVec.x,
-        starToSunVec.y,
-        starToSunVec.z
-    );
+    const glm::dmat3 exoplanetSystemRotation = computeSystemRotation(starPosition);
 
     // Star renderable globe, if we have a radius and bv color index
     std::string starGlobeRenderableString;