Draw the Toolpaths Top-Down When the Camera Looks Down on the Print

The segments come in print order, bottom layer first, which seen from above is back to
front: every hidden fragment is shaded before the one that covers it, and on an integrated
GPU that overdraw is most of the frame. Drawing the instances last to first whenever the
camera looks down lets the depth test reject the hidden fragments instead. Side views and
views from below keep the print order, and the shadow-caster pass is unchanged.

CMakeLists.txt

@@ -70,6 +70,9 @@ if (POLICY CMP0092)
     cmake_policy(SET CMP0092 NEW)
 endif ()
 
+# project() reads this, so set it first.
+set(CMAKE_USER_MAKE_RULES_OVERRIDE "${CMAKE_CURRENT_LIST_DIR}/cmake/modules/ClangClShowIncludes.cmake")
+
 project(OrcaSlicer)
 
 # Backward compatibility for old CMake versions

cmake/modules/ClangClShowIncludes.cmake

@@ -0,0 +1,10 @@
+# ccache does not parse the -clang: arguments CMake uses for clang-cl's gcc-style
+# depfile, so a cache hit writes the object and no depfile, and Ninja then records
+# no headers for that object. ccache reproduces /showIncludes output on a hit.
+foreach (_lang C CXX)
+    if (CMAKE_${_lang}_COMPILER_ID STREQUAL "Clang" AND
+        CMAKE_${_lang}_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
+        set(CMAKE_DEPFILE_FLAGS_${_lang} "/showIncludes")
+        set(CMAKE_${_lang}_DEPFILE_FORMAT msvc)
+    endif ()
+endforeach ()

deps/CMakeLists.txt

@@ -38,6 +38,14 @@ if(POLICY CMP0135) # DOWNLOAD_EXTRACT_TIMESTAMP
     cmake_policy(SET CMP0135 NEW)
 endif()
 
+# project() reads this, so set it first. scripts/flatpak/make_deps_tar.sh packs deps/
+# without cmake/, so the file is missing in a Flatpak build.
+set(_rules_override "${CMAKE_CURRENT_LIST_DIR}/../cmake/modules/ClangClShowIncludes.cmake")
+if (EXISTS "${_rules_override}")
+    set(CMAKE_USER_MAKE_RULES_OVERRIDE "${_rules_override}")
+endif ()
+unset(_rules_override)
+
 project(OrcaSlicer-deps)
 
 # Backward compatibility for old CMake versions
@@ -220,6 +228,7 @@ if (NOT IS_CROSS_COMPILE OR NOT APPLE)
             -DCMAKE_CXX_COMPILER:STRING=${CMAKE_CXX_COMPILER}
             -DCMAKE_C_COMPILER_LAUNCHER:STRING=${CMAKE_C_COMPILER_LAUNCHER}
             -DCMAKE_CXX_COMPILER_LAUNCHER:STRING=${CMAKE_CXX_COMPILER_LAUNCHER}
+            -DCMAKE_USER_MAKE_RULES_OVERRIDE:STRING=${CMAKE_USER_MAKE_RULES_OVERRIDE}
             -DCMAKE_TOOLCHAIN_FILE:STRING=${CMAKE_TOOLCHAIN_FILE}
             -DCMAKE_EXE_LINKER_FLAGS:STRING=${CMAKE_EXE_LINKER_FLAGS}
             -DCMAKE_SHARED_LINKER_FLAGS:STRING=${CMAKE_SHARED_LINKER_FLAGS}
@@ -267,6 +276,7 @@ else()
             -DCMAKE_IGNORE_PREFIX_PATH:STRING=${CMAKE_IGNORE_PREFIX_PATH}
             -DCMAKE_C_COMPILER_LAUNCHER:STRING=${CMAKE_C_COMPILER_LAUNCHER}
             -DCMAKE_CXX_COMPILER_LAUNCHER:STRING=${CMAKE_CXX_COMPILER_LAUNCHER}
+            -DCMAKE_USER_MAKE_RULES_OVERRIDE:STRING=${CMAKE_USER_MAKE_RULES_OVERRIDE}
             -DBUILD_SHARED_LIBS:BOOL=OFF
             ${_cmake_osx_arch}
             "${_configs_line}"

src/libvgcode/src/Shaders.hpp

@@ -34,6 +34,10 @@ static const char* Segments_Vertex_Shader =
 // ORCA: 0 during the shadow caster pass - the bias below shifts eye_position but not
 // world_position, so the caster would write a depth the receiver never looks up.
 "uniform float bias_scale;\n"
+// draw the instances last to first, top layers before the ones they hide, so that early depth
+// rejection discards most of the hidden fragments; set when the camera looks down on the print
+"uniform int reverse_order;\n"
+"uniform int instance_count;\n"
 "in int vertex_id;\n"
 "out vec3 color;\n"
 "// ORCA: realistic view - the light the shadow map is able to block, kept apart from the\n"
@@ -59,7 +63,8 @@ static const char* Segments_Vertex_Shader =
 "  return top_diffuse + front_diffuse + top_specular;\n"
 "}\n"
 "void main() {\n"
-"  int id_a = int(texelFetch(segment_index_tex, gl_InstanceID).r);\n"
+"  int instance = (reverse_order != 0) ? instance_count - 1 - gl_InstanceID : gl_InstanceID;\n"
+"  int id_a = int(texelFetch(segment_index_tex, instance).r);\n"
 "  int id_b = id_a + 1;\n"
 "  vec3 pos_a = texelFetch(position_tex, id_a).xyz;\n"
 "  vec3 pos_b = texelFetch(position_tex, id_b).xyz;\n"

src/libvgcode/src/ViewerImpl.cpp

@@ -763,6 +763,8 @@ void ViewerImpl::init(const std::string& opengl_context_version)
     m_uni_segments_height_width_angle_tex_id = glGetUniformLocation(m_segments_shader_id, "height_width_angle_tex");
     m_uni_segments_colors_tex_id             = glGetUniformLocation(m_segments_shader_id, "color_tex");
     m_uni_segments_segment_index_tex_id      = glGetUniformLocation(m_segments_shader_id, "segment_index_tex");
+    m_uni_segments_reverse_order_id          = glGetUniformLocation(m_segments_shader_id, "reverse_order");
+    m_uni_segments_instance_count_id         = glGetUniformLocation(m_segments_shader_id, "instance_count");
     // ORCA: realistic view
     m_uni_segments_shadow_map_id             = glGetUniformLocation(m_segments_shader_id, "shadow_map");
     m_uni_segments_shadow_light_vp_id        = glGetUniformLocation(m_segments_shader_id, "shadow_light_vp");
@@ -2090,6 +2092,15 @@ void ViewerImpl::render_segments(const Mat4x4& view_matrix, const Mat4x4& projec
     glsafe(glUniformMatrix4fv(m_uni_segments_view_matrix_id, 1, GL_FALSE, view_matrix.data()));
     glsafe(glUniformMatrix4fv(m_uni_segments_projection_matrix_id, 1, GL_FALSE, projection_matrix.data()));
     glsafe(glUniform3fv(m_uni_segments_camera_position_id, 1, camera_position.data()));
+    // The segments come in print order, bottom layer first. Seen from above, that is back to front,
+    // and every hidden fragment is shaded before the one that covers it. Drawing them last to first
+    // lets the depth test reject the hidden ones instead. The camera looks down when the world's
+    // up axis points towards it, which is the view matrix's (2, 2) entry being positive.
+    const bool top_down = !m_rendering_shadow_casters && view_matrix[10] > 0.0f;
+    glsafe(glUniform1i(m_uni_segments_reverse_order_id, top_down ? 1 : 0));
+#ifndef ENABLE_OPENGL_ES
+    glsafe(glUniform1i(m_uni_segments_instance_count_id, static_cast<int>(m_enabled_segments_count)));
+#endif // ENABLE_OPENGL_ES
     // ORCA: realistic view. The depth pass writes the map it would otherwise read, so it shades
     // with the lookup off.
     glsafe(glUniform1i(m_uni_segments_shadow_map_id, m_shadow_map_texture_unit));

src/libvgcode/src/ViewerImpl.hpp

@@ -362,6 +362,8 @@ private:
     int m_uni_segments_height_width_angle_tex_id{ -1 };
     int m_uni_segments_colors_tex_id{ -1 };
     int m_uni_segments_segment_index_tex_id{ -1 };
+    int m_uni_segments_reverse_order_id{ -1 };
+    int m_uni_segments_instance_count_id{ -1 };
     int m_uni_segments_shadow_map_id{ -1 };
     int m_uni_segments_shadow_light_vp_id{ -1 };
     int m_uni_segments_shadow_intensity_id{ -1 };

src/slic3r/GUI/GLCanvas3D.cpp

@@ -2354,6 +2354,13 @@ void GLCanvas3D::render_thumbnail(ThumbnailData &         thumbnail_data,
     render_thumbnail(thumbnail_data, w, h, thumbnail_params, model_objects, m_volumes, camera_type, camera_view_angle_type, for_picking, ban_light);
 }
 
+bool GLCanvas3D::_set_shown_canvas_current()
+{
+    // Thumbnails also render outside render(), where another library's GL context (e.g. WebKitGTK's) can be current.
+    // Inside render(), the shown canvas is the one already bound.
+    return wxGetApp().plater()->get_current_canvas3D()->_set_current();
+}
+
 void GLCanvas3D::render_thumbnail(ThumbnailData &           thumbnail_data,
                                   unsigned int              w,
                                   unsigned int              h,
@@ -2365,6 +2372,9 @@ void GLCanvas3D::render_thumbnail(ThumbnailData &           thumbnail_data,
                                   bool                      for_picking,
                                   bool                      ban_light)
 {
+    if (!_set_shown_canvas_current())
+        return;
+
     GLShaderProgram* shader = nullptr;
     if (for_picking)
         shader = wxGetApp().get_shader("flat");
@@ -2403,6 +2413,9 @@ void GLCanvas3D::render_thumbnail(ThumbnailData &                    thumbnail_d
                                   bool                               for_picking,
                                   bool                               ban_light)
 {
+    if (!_set_shown_canvas_current())
+        return;
+
     GLShaderProgram *shader = wxGetApp().get_shader("thumbnail");
     switch (OpenGLManager::get_framebuffers_type()) {
         case OpenGLManager::EFramebufferType::Arb: {

src/slic3r/GUI/GLCanvas3D.hpp

@@ -1320,6 +1320,7 @@ private:
     bool _init_collapse_toolbar();
 
     bool _set_current();
+    bool _set_shown_canvas_current();
     void _resize(unsigned int w, unsigned int h);
 
     //BBS: add part plate related logic

src/slic3r/Utils/PresetUpdater.cpp

@@ -1098,35 +1098,32 @@ void PresetUpdater::priv::check_installed_vendor_profiles() const
     const auto enabled_vendors = app_config->vendors();
 
     std::set<std::string> bundles;
-    // Orca: always install filament library
-    bundles.insert(PresetBundle::ORCA_FILAMENT_LIBRARY);
     // A vendor is named by its profile or, where the build ships preset caches
     // instead of the raw profile JSONs, by its cache alone.
     for (const std::string &vendor_name : vendor_names_in(rsrc_path)) {
-        if (bundles.find(vendor_name) != bundles.end())continue;
-
-        const auto is_vendor_enabled = (vendor_name == PresetBundle::ORCA_DEFAULT_BUNDLE) // always update configs from resource to vendor for ORCA_DEFAULT_BUNDLE
+        // enabled_vendors lists the vendors whose printer models the user picked, and
+        // neither of these two is ever in it.
+        const auto is_vendor_enabled = (vendor_name == PresetBundle::ORCA_DEFAULT_BUNDLE)
+                                       || (vendor_name == PresetBundle::ORCA_FILAMENT_LIBRARY)
                                        || (enabled_vendors.find(vendor_name) != enabled_vendors.end());
         if (is_vendor_installed(vendor_name)) {
-            if (enabled_config_update) {
-                if (is_vendor_enabled) {
-                    // Orca: whichever form of the vendor resources ships at the newer
-                    // version is the one installing lays down, and the one to judge
-                    // what is installed against.
-                    Semver resource_ver = resource_vendor_version(vendor_name);
-                    // Orca: a vendor installed as a preset cache has no profile
-                    // beside it; the version it was installed at is in the cache.
-                    Semver vendor_ver = installed_vendor_version(vendor_name);
+            if (is_vendor_enabled) {
+                // Orca: whichever form of the vendor resources ships at the newer
+                // version is the one installing lays down, and the one to judge
+                // what is installed against.
+                Semver resource_ver = resource_vendor_version(vendor_name);
+                // Orca: a vendor installed as a preset cache has no profile
+                // beside it; the version it was installed at is in the cache.
+                Semver vendor_ver = installed_vendor_version(vendor_name);
 
-                    if (vendor_ver < resource_ver) {
-                        BOOST_LOG_TRIVIAL(info) << "[Orca Updater]:found vendor " << vendor_name << " newer version "
-                                                << resource_ver.to_string() << " from resource, old version " << vendor_ver.to_string();
-                        bundles.insert(vendor_name);
-                    }
-                } else {
-                    // need to be removed because not installed
-                    remove_installed_vendor(vendor_name);
+                if (vendor_ver < resource_ver) {
+                    BOOST_LOG_TRIVIAL(info) << "[Orca Updater]:found vendor " << vendor_name << " newer version "
+                                            << resource_ver.to_string() << " from resource, old version " << vendor_ver.to_string();
+                    bundles.insert(vendor_name);
                 }
+            } else {
+                // need to be removed because not installed
+                remove_installed_vendor(vendor_name);
             }
         } else if (is_vendor_enabled) {
             bundles.insert(vendor_name);