gltf_baker: improve error reporting.

libs/gltfio/src/AssetPipeline.cpp

@@ -1149,6 +1149,13 @@ const cgltf_data* Pipeline::parameterize(const cgltf_data* sourceAsset) {
     utils::slog.i << "Packing charts..." << utils::io::endl;
     xatlas::PackCharts(atlas);
 
+    if (atlas->atlasCount == 0) {
+        // When this occurs, try building in the debug configuration (xatlas has many asserts).
+        utils::slog.e << "Error: unable to generate atlas, mesh is not clean." << utils::io::endl;
+        xatlas::Destroy(atlas);
+        return nullptr;
+    }
+
     utils::slog.i << "Produced "
             << atlas->atlasCount << " atlases, "
             << atlas->chartCount << " charts, "

libs/rays/src/PathTracer.cpp

@@ -270,6 +270,10 @@ static void renderTileToGbuffer(EmbreeContext* context, PixelRectangle rect) {
                         RTC_BUFFER_TYPE_VERTEX_ATTRIBUTE, 0, position, 3);
                 rtcInterpolate0(geo, rayhit.hit.primID, rayhit.hit.u, rayhit.hit.v,
                         RTC_BUFFER_TYPE_VERTEX_ATTRIBUTE, 1, normal, 3);
+
+                // AO won't be computed until the second pass, but we show an instant preview of
+                // the chart shapes by setting a placeholder value in the AO map.
+                image.getPixelRef(col, row)[0] = 0.5f;
             }
         }
     }

samples/gltf_baker.cpp

@@ -84,6 +84,7 @@ struct App {
     std::atomic<bool> requestOverlayUpdate;
     std::atomic<bool> requestStatePop;
     gltfio::AssetPipeline* pipeline;
+    std::string messageBoxText;
 };
 
 struct OverlayVertex {
@@ -333,19 +334,23 @@ static void prepAsset(App& app) {
     gltfio::AssetPipeline::AssetHandle asset = pipeline.load(app.filename);
     if (!asset) {
         std::cerr << "Unable to read " << app.filename << std::endl;
-        exit(1);
+        app.state = LOADED;
+        return;
     }
 
     asset = pipeline.flatten(asset);
     if (!asset) {
         std::cerr << "Unable to flatten " << app.filename << std::endl;
-        exit(1);
+        app.state = LOADED;
+        return;
     }
 
     asset = pipeline.parameterize(asset);
     if (!asset) {
         std::cerr << "Unable to parameterize " << app.filename << std::endl;
-        exit(1);
+        app.state = LOADED;
+        app.messageBoxText = "Unable to parameterize mesh, check terminal output for details.";
+        return;
     }
 
     const utils::Path folder = app.filename.getAbsolutePath().getParent();
@@ -537,6 +542,21 @@ int main(int argc, char** argv) {
             if (app.renderedImage) {
                 ImGui::Checkbox("Show embree result", &app.showOverlay);
             }
+
+            if (!app.messageBoxText.empty()) {
+                ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, {10, 10} );
+                ImGui::OpenPopup("MessageBox");
+                if (ImGui::BeginPopupModal("MessageBox", nullptr,
+                        ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoTitleBar)) {
+                    ImGui::TextUnformatted(app.messageBoxText.c_str());
+                    if (ImGui::Button("OK", ImVec2(120,0))) {
+                        app.messageBoxText.clear();
+                        ImGui::CloseCurrentPopup();
+                    }
+                    ImGui::EndPopup();
+                }
+                ImGui::PopStyleVar();
+            }
         });
 
         // Leave FXAA enabled but we also enable MSAA for a nice result. The wireframe looks