Add boilerplate for shader based csg

sandboxes/opencsg/ShaderCSGDisplay.cpp

@@ -0,0 +1,81 @@
+#include "ShaderCSGDisplay.hpp"
+#include "libslic3r/SLAPrint.hpp"
+#include <GL/glew.h>
+
+namespace Slic3r { namespace GL {
+
+void ShaderCSGDisplay::add_mesh(const TriangleMesh &mesh)
+{
+    auto v = std::make_shared<CSGVolume>();
+    v->load_mesh(mesh);
+    m_volumes.emplace_back(v);
+}
+
+void ShaderCSGDisplay::render_scene()
+{
+    GLfloat color[] = {1.f, 1.f, 0.f, 0.f};
+    glColor4fv(color);
+    glDepthFunc(GL_LESS);
+    for (auto &v : m_volumes) v->render();
+    glFlush();
+}
+
+void ShaderCSGDisplay::on_scene_updated(const Scene &scene)
+{
+    // TriangleMesh mesh = print->objects().front()->hollowed_interior_mesh();
+    // Look at CSGDisplay::on_scene_updated to see how its done there.
+    
+    const SLAPrint *print = scene.get_print();
+    if (!print) return;
+    
+    m_volumes.clear();
+    
+    for (const SLAPrintObject *po : print->objects()) {
+        const ModelObject *mo = po->model_object();
+        TriangleMesh msh = mo->raw_mesh();
+        
+        sla::DrainHoles holedata = mo->sla_drain_holes;
+        
+        for (const ModelInstance *mi : mo->instances) {
+            
+            TriangleMesh mshinst = msh;
+            auto interior = po->hollowed_interior_mesh();
+            interior.transform(po->trafo().inverse());
+            
+            mshinst.merge(interior);
+            mshinst.require_shared_vertices();
+            
+            mi->transform_mesh(&mshinst);
+            
+            auto bb = mshinst.bounding_box();
+            auto center = bb.center().cast<float>();
+            mshinst.translate(-center);
+            
+            mshinst.require_shared_vertices();
+            add_mesh(mshinst);
+            
+            auto tr = Transform3f::Identity();
+            tr.translate(-center);
+            
+            transform_pts(holedata.begin(), holedata.end(), tr,
+                          [](const sla::DrainHole &dh) {
+                              return dh.pos;
+                          });
+            
+            transform_pts(holedata.begin(), holedata.end(), tr,
+                          [](const sla::DrainHole &dh) {
+                              return dh.normal;
+                          });
+        }
+        
+        for (const sla::DrainHole &holept : holedata) {
+            TriangleMesh holemesh = sla::to_triangle_mesh(holept.to_mesh());
+            holemesh.require_shared_vertices();
+            add_mesh(holemesh);
+        }
+    }
+    
+    repaint();
+}
+
+}} // namespace Slic3r::GL