Merge pull request #187 from ABRG-Models/dev/constexpr_geodesics_vec

Dev/constexpr geodesics vec. constexpr operator+, operator/ and renormalize in morph::vec seem to be safe.

CMakeLists.txt

@@ -175,6 +175,9 @@ if(wxWidgets_FOUND)
   endif()
 endif()
 
+# Make it possible to compile complex constexpr functions
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fconstexpr-ops-limit=5000000000")
+
 # rapidxml is bundled in the source, but its headers will be installed in ${CMAKE_INSTALL_PREFIX}/morph/, and they're symlinked in ${PROJECT_SOURCE_DIR}/morph
 #include_directories("${PROJECT_SOURCE_DIR}/include/rapidxml-1.13")
 

examples/CMakeLists.txt

@@ -195,6 +195,7 @@ if(USE_GLEW)
 endif()
 
 add_executable(scatter scatter.cpp)
+set_property(TARGET scatter PROPERTY CXX_STANDARD 20)
 target_link_libraries(scatter OpenGL::GL glfw Freetype::Freetype)
 if(USE_GLEW)
   target_link_libraries(scatter GLEW::GLEW)
@@ -326,15 +327,25 @@ if(USE_GLEW)
   target_link_libraries(icosahedron GLEW::GLEW)
 endif()
 
+# Need C++20 for the way I use constexpr here so that it is legal to
+# have "a definition of a variable for which no initialization is
+# performed".
 add_executable(testce testce.cpp)
-set_property(TARGET testce PROPERTY CXX_STANDARD 23)
+set_property(TARGET testce PROPERTY CXX_STANDARD 20)
 
 add_executable(geodesic geodesic.cpp)
 target_link_libraries(geodesic OpenGL::GL glfw Freetype::Freetype)
 if(USE_GLEW)
   target_link_libraries(geodesic GLEW::GLEW)
 endif()
 
+add_executable(geodesic_ce geodesic_ce.cpp)
+set_property(TARGET geodesic_ce PROPERTY CXX_STANDARD 20)
+target_link_libraries(geodesic_ce OpenGL::GL glfw Freetype::Freetype)
+if(USE_GLEW)
+  target_link_libraries(geodesic_ce GLEW::GLEW)
+endif()
+
 add_executable(tri tri.cpp)
 target_link_libraries(tri OpenGL::GL glfw Freetype::Freetype)
 if(USE_GLEW)

examples/geodesic.cpp

@@ -16,7 +16,7 @@ int main()
 {
     int rtn = -1;
 
-    morph::Visual v(1024, 768, "Geodesic Polyhedron");
+    morph::Visual v(1024, 768, "Geodesic Polyhedra (ordered vertices/faces)");
     v.showCoordArrows = true;
 
     try {
@@ -31,25 +31,15 @@ int main()
             std::string lbl = std::string("iterations = ") + std::to_string(i);
             gv1->addLabel (lbl, {0, -1, 0}, morph::TextFeatures(0.06f));
             gv1->cm.setType (morph::ColourMapType::Jet);
-            //gv1->colourScale.do_autoscale = false;
-            //gv1->colourScale.compute_autoscale (0.0f, 2.0f);
             gv1->finalize();
-#if 0       // no re-colouring
-            v.addVisualModel (gv1);
-#else       // re-colour after construction
-            auto gv1p = v.addVisualModel (gv1);
 
+            // re-colour after construction
+            auto gv1p = v.addVisualModel (gv1);
             float imax_mult = 1.0f / static_cast<float>(imax);
-# if 0      // Funky pattern colouring
-            for (unsigned int j = 0; j < gv1p->data.size(); ++j) {
-                gv1p->data[j] = j%3 ? 0 : (1+i) * imax_mult;
-            }
-# else      // sequential colouring
+            // sequential colouring:
             size_t sz1 = gv1p->data.size();
             gv1p->data.linspace (0.0f, 1+i * imax_mult, sz1);
-# endif
             gv1p->updateColours();
-#endif
         }
 
         v.keepOpen();

examples/geodesic_ce.cpp

@@ -0,0 +1,64 @@
+/*
+ * Visualize an Icosahedron using the Geodesic Visual that co-ops the unordered
+ * constexpr geodesic function.
+ */
+#include <morph/Visual.h>
+#include <morph/ColourMap.h>
+#include <morph/GeodesicVisualCE.h>
+#include <morph/vec.h>
+#include <iostream>
+#include <fstream>
+#include <cmath>
+#include <array>
+#include <stdexcept>
+#include <string>
+
+int main()
+{
+    int rtn = -1;
+
+    morph::Visual v(1024, 768, "(constexpr) Geodesic Polyhedra");
+    v.showCoordArrows = true;
+    v.lightingEffects (true);
+
+    try {
+        morph::vec<float, 3> offset = { 0.0, 0.0, 0.0 };
+        morph::vec<float, 3> step = { 2.2, 0.0, 0.0 };
+
+        auto gv1 = std::make_unique<morph::GeodesicVisualCE<float, 0>> (offset + step * 0, 0.9f);
+        v.bindmodel (gv1);
+        std::string lbl = std::string("iterations = 0");
+        gv1->addLabel (lbl, {0, -1, 0}, morph::TextFeatures(0.06f));
+        gv1->finalize();
+        v.addVisualModel (gv1);
+
+        auto gv2 = std::make_unique<morph::GeodesicVisualCE<float, 1>> (offset + step * 1, 0.9f);
+        v.bindmodel (gv2);
+        lbl = std::string("iterations = 1");
+        gv2->addLabel (lbl, {0, -1, 0}, morph::TextFeatures(0.06f));
+        gv2->finalize();
+        v.addVisualModel (gv2);
+
+        auto gv3 = std::make_unique<morph::GeodesicVisualCE<float, 2>> (offset + step * 2, 0.9f);
+        v.bindmodel (gv3);
+        lbl = std::string("iterations = 2");
+        gv3->addLabel (lbl, {0, -1, 0}, morph::TextFeatures(0.06f));
+        gv3->finalize();
+        v.addVisualModel (gv3);
+
+        auto gv4 = std::make_unique<morph::GeodesicVisualCE<float, 3>> (offset + step * 3, 0.9f);
+        v.bindmodel (gv4);
+        lbl = std::string("iterations = 4");
+        gv4->addLabel (lbl, {0, -1, 0}, morph::TextFeatures(0.06f));
+        gv4->finalize();
+        v.addVisualModel (gv4);
+
+        v.keepOpen();
+
+    } catch (const std::exception& e) {
+        std::cerr << "Caught exception: " << e.what() << std::endl;
+        rtn = -1;
+    }
+
+    return rtn;
+}

examples/scatter.cpp

@@ -64,6 +64,7 @@ int main()
         while (v.readyToFinish == false) {
             v.waitevents (0.018);
             v.render();
+            v.readyToFinish = true; // debug/profile
         }
 
     } catch (const std::exception& e) {

examples/testce.cpp

@@ -5,6 +5,10 @@ int main()
 {
     // Note that we force the compile time evaluation of geometry_ce::icosahedron by returning a constexpr object
     constexpr morph::geometry_ce::polyhedron<double, 12, 20> ico = morph::geometry_ce::icosahedron<double>();
-    std::cout << "constexpr vertices:\n" << ico.vertices.str() << std::endl;
+    std::cout << "constexpr 1st vertices:\n" << static_cast<morph::vec<double, 3>>(ico.vertices[0]) << std::endl;
+
+    constexpr
+    auto geo = morph::geometry_ce::make_icosahedral_geodesic<double, 3>();
+    std::cout << "constexpr geo.vertices: " << static_cast<morph::vec<double, 3>>(geo.poly.vertices[0]).str() << std::endl;
     return 0;
 }

morph/GeodesicVisualCE.h

@@ -0,0 +1,68 @@
+#pragma once
+
+#include <morph/vec.h>
+#include <morph/VisualModel.h>
+#include <morph/mathconst.h>
+#include <morph/Scale.h>
+#include <morph/ColourMap.h>
+#include <array>
+
+namespace morph {
+
+    /*!
+     * This class creates the vertices for an geodesic polyhedron in a 3D scene using
+     * the constexpr function.
+     *
+     * \tparam T the type for the data to be visualized as face (or maybe vertex) colours
+     *
+     * \tparam glver The usual OpenGL version code; match this to everything else in
+     * your program.
+     */
+    template<typename T, int iterations, int glver = morph::gl::version_4_1>
+    class GeodesicVisualCE : public VisualModel<glver>
+    {
+    public:
+        GeodesicVisualCE() { this->init ({0.0, 0.0, 0.0}, 1.0f); }
+
+        //! Initialise with offset, start and end coordinates, radius and a single colour.
+        GeodesicVisualCE(const vec<float, 3> _offset, const float _radius)
+        {
+            this->init (_offset, _radius);
+        }
+
+        ~GeodesicVisualCE () {}
+
+        void init (const vec<float, 3> _offset, const float _radius)
+        {
+            // Set up...
+            this->mv_offset = _offset;
+            this->viewmatrix.translate (this->mv_offset);
+            this->radius = _radius;
+        }
+
+        //! Initialize vertex buffer objects and vertex array object.
+        void initializeVertices()
+        {
+            this->vertexPositions.clear();
+            this->vertexNormals.clear();
+            this->vertexColors.clear();
+            this->indices.clear();
+
+            if (iterations > 5) {
+                // Note odd necessity to stick in the 'template' keyword after this->
+                this->template computeSphereGeoFast<double, iterations> (this->idx, morph::vec<float, 3>({0,0,0}),
+                                                                         this->colour, this->radius);
+            } else {
+                // computeSphereGeo F defaults to float
+                this->template computeSphereGeoFast<float, iterations> (this->idx, morph::vec<float, 3>({0,0,0}),
+                                                                        this->colour, this->radius);
+            }
+        }
+
+        //! The radius of the geodesic
+        float radius = 1.0f;
+        //! Fixed colour.
+        std::array<float, 3> colour = { 0.2f, 0.1f, 0.7f };
+    };
+
+} // namespace morph

morph/ScatterVisual.h

@@ -114,14 +114,14 @@ namespace morph {
                 if (this->sizeFactor == Flt{0}) {
                     if constexpr (draw_spheres_as_geodesics) {
                         // Slower than regular computeSphere(). 2 iterations gives 320 faces
-                        this->computeSphereGeo (this->idx, (*this->dataCoords)[i], clr, this->radiusFixed, 2);
+                        this->template computeSphereGeoFast<float, 3> (this->idx, (*this->dataCoords)[i], clr, this->radiusFixed);
                     } else {
                         // (16+2) * 20 gives 360 faces
                         this->computeSphere (this->idx, (*this->dataCoords)[i], clr, this->radiusFixed, 16, 20);
                     }
                 } else {
                     if constexpr (draw_spheres_as_geodesics) {
-                        this->computeSphereGeo (this->idx, (*this->dataCoords)[i], clr, dcopy[i]*this->sizeFactor, 2);
+                        this->template computeSphereGeoFast<float, 3> (this->idx, (*this->dataCoords)[i], clr, dcopy[i]*this->sizeFactor);
                     } else {
                         this->computeSphere (this->idx, (*this->dataCoords)[i], clr, dcopy[i]*this->sizeFactor, 16, 20);
                     }
@@ -134,13 +134,9 @@ namespace morph {
             }
         }
 
-        // I've tested geodesic sphere drawing code, but it probably isn't yet suitable
-        // for use where many spheres are repeatedly computed (the base geodesic is
-        // repeatedly computed, which is a waste of cycles). In fact, the overall
-        // approach here, where each sphere model is repeatedly re-computed for each
-        // point is probably about the least performant way you could draw a bunch of
-        // spheres in OpenGL! However, using geodesic code is noticably slower even than
-        // the regular VisualModel::computeSphere()
+        // The constexpr, unordered geodesic code is no slower than the regular
+        // VisualModel::computeSphere(), but leave this off for now (if true, C++-20 is
+        // required)
         static constexpr bool draw_spheres_as_geodesics = false;
 
         //! Set this->radiusFixed, then re-compute vertices.

morph/VisualModel.h

@@ -1395,6 +1395,40 @@ namespace morph {
             return gi.n_faces;
         }
 
+        //! Fast computeSphereGeo, which uses constexpr make_icosahedral_geodesic. The
+        //! resulting vertices and faces are NOT in any kind of order, but ok for
+        //! plotting, e.g. scatter graph spheres.
+        template<typename F=float, int iterations = 2>
+        int computeSphereGeoFast (GLuint& idx, vec<float> so, std::array<float, 3> sc,
+                                  float r = 1.0f)
+        {
+            // test if type F is float
+            if constexpr (std::is_same<std::decay_t<F>, float>::value == true) {
+                static_assert (iterations <= 5, "computeSphereGeoFast: For iterations > 5, F needs to be double precision");
+            } else {
+                static_assert (iterations <= 10, "computeSphereGeoFast: This is an abitrary iterations limit (10 gives 20971520 faces)");
+            }
+            // Note that we need double precision to compute higher iterations of the geodesic (iterations > 5)
+            constexpr morph::geometry_ce::icosahedral_geodesic<F, iterations>  geo = morph::geometry_ce::make_icosahedral_geodesic<F, iterations>();
+
+            // Now essentially copy geo into vertex buffers
+            for (auto v : geo.poly.vertices) {
+                this->vertex_push (v.as_float() * r + so, this->vertexPositions);
+                this->vertex_push (v.as_float(), this->vertexNormals);
+                this->vertex_push (sc, this->vertexColors);
+            }
+            for (auto f : geo.poly.faces) {
+                this->indices.push_back (idx + f[0]);
+                this->indices.push_back (idx + f[1]);
+                this->indices.push_back (idx + f[2]);
+            }
+            // idx is the *vertex index* and should be incremented by the number of vertices in the polyhedron
+            int n_verts = static_cast<int>(geo.poly.vertices.size());
+            idx += n_verts;
+
+            return n_verts;
+        }
+
         /*!
          * Sphere, 1 colour version.
          *