Use map projection with geo line

scwx-qt/source/scwx/qt/gl/draw/draw_item.cpp

@@ -6,6 +6,7 @@
 #include <glm/glm.hpp>
 #include <glm/gtc/matrix_transform.hpp>
 #include <glm/gtc/type_ptr.hpp>
+#include <mbgl/util/constants.hpp>
 #pragma warning(pop)
 
 namespace scwx
@@ -46,6 +47,49 @@ void DrawItem::UseDefaultProjection(
       uMVPMatrixLocation, 1, GL_FALSE, glm::value_ptr(projection));
 }
 
+// TODO: Refactor to utility class
+static glm::vec2
+LatLongToScreenCoordinate(const QMapbox::Coordinate& coordinate)
+{
+   double latitude = std::clamp(
+      coordinate.first, -mbgl::util::LATITUDE_MAX, mbgl::util::LATITUDE_MAX);
+   glm::vec2 screen {
+      mbgl::util::LONGITUDE_MAX + coordinate.second,
+      -(mbgl::util::LONGITUDE_MAX -
+        mbgl::util::RAD2DEG *
+           std::log(std::tan(M_PI / 4.0 +
+                             latitude * M_PI / mbgl::util::DEGREES_MAX)))};
+   return screen;
+}
+
+void DrawItem::UseMapProjection(
+   const QMapbox::CustomLayerRenderParameters& params,
+   GLint                                       uMVPMatrixLocation,
+   GLint                                       uMapScreenCoordLocation)
+{
+   OpenGLFunctions& gl = p->gl_;
+
+   // TODO: Refactor to utility class
+   const float scale = std::pow(2.0, params.zoom) * 2.0f *
+                       mbgl::util::tileSize / mbgl::util::DEGREES_MAX;
+   const float xScale = scale / params.width;
+   const float yScale = scale / params.height;
+
+   glm::mat4 uMVPMatrix(1.0f);
+   uMVPMatrix = glm::scale(uMVPMatrix, glm::vec3(xScale, yScale, 1.0f));
+   uMVPMatrix = glm::rotate(uMVPMatrix,
+                            glm::radians<float>(params.bearing),
+                            glm::vec3(0.0f, 0.0f, 1.0f));
+
+   gl.glUniform2fv(uMapScreenCoordLocation,
+                   1,
+                   glm::value_ptr(LatLongToScreenCoordinate(
+                      {params.latitude, params.longitude})));
+
+   gl.glUniformMatrix4fv(
+      uMVPMatrixLocation, 1, GL_FALSE, glm::value_ptr(uMVPMatrix));
+}
+
 } // namespace draw
 } // namespace gl
 } // namespace qt