Merge pull request 'dev' (#15) from dev into main

Reviewed-on: #15
2026-03-04 11:02:43 +01:00
parent d951212576 179be37a36
commit d9931a6fae
17 changed files with 460 additions and 53 deletions
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -10,11 +10,12 @@ RUN ./gradlew bootJar -x test --no-daemon

 # Stage 2: Runtime Environment
 FROM eclipse-temurin:21-jre-jammy
+ARG ORCA_VERSION=2.3.1
+ARG ORCA_DOWNLOAD_URL

 # Install system dependencies for OrcaSlicer (same as before)
 RUN apt-get update && apt-get install -y \
    wget \
-    p7zip-full \
    assimp-utils \
    libgl1 \
    libglib2.0-0 \
@@ -25,8 +26,35 @@ RUN apt-get update && apt-get install -y \

 # Install OrcaSlicer
 WORKDIR /opt
-RUN wget -q https://github.com/SoftFever/OrcaSlicer/releases/download/v2.2.0/OrcaSlicer_Linux_V2.2.0.AppImage -O OrcaSlicer.AppImage \
-    && 7z x OrcaSlicer.AppImage -o/opt/orcaslicer \
+RUN set -eux; \
+    ORCA_URL="${ORCA_DOWNLOAD_URL:-}"; \
+    if [ -n "${ORCA_URL}" ]; then \
+      wget -q "${ORCA_URL}" -O OrcaSlicer.AppImage; \
+    else \
+      CANDIDATES="\
+https://github.com/OrcaSlicer/OrcaSlicer/releases/download/v${ORCA_VERSION}/OrcaSlicer_Linux_AppImage_Ubuntu2204_V${ORCA_VERSION}.AppImage \
+https://github.com/SoftFever/OrcaSlicer/releases/download/v${ORCA_VERSION}/OrcaSlicer_Linux_AppImage_Ubuntu2204_V${ORCA_VERSION}.AppImage \
+https://github.com/SoftFever/OrcaSlicer/releases/download/v2.2.0/OrcaSlicer_Linux_V2.2.0.AppImage"; \
+      ok=0; \
+      for url in $CANDIDATES; do \
+        if wget -q --spider "$url"; then \
+          echo "Using OrcaSlicer URL: $url"; \
+          wget -q "$url" -O OrcaSlicer.AppImage; \
+          ok=1; \
+          break; \
+        fi; \
+      done; \
+      if [ "$ok" -ne 1 ]; then \
+        echo "Failed to find OrcaSlicer AppImage for version ${ORCA_VERSION}" >&2; \
+        echo "Tried URLs:" >&2; \
+        for url in $CANDIDATES; do echo " - $url" >&2; done; \
+        exit 1; \
+      fi; \
+    fi \
+    && chmod +x OrcaSlicer.AppImage \
+    && rm -rf /opt/orcaslicer /opt/squashfs-root \
+    && ./OrcaSlicer.AppImage --appimage-extract >/dev/null \
+    && mv /opt/squashfs-root /opt/orcaslicer \
    && chmod -R +x /opt/orcaslicer \
    && rm OrcaSlicer.AppImage

--- a/backend/build.gradle
+++ b/backend/build.gradle
@@ -42,6 +42,15 @@ dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
 	implementation 'net.codecrete.qrbill:qrbill-generator:3.4.0'
 	implementation 'org.springframework.boot:spring-boot-starter-mail'
+	implementation platform('org.lwjgl:lwjgl-bom:3.3.4')
+	implementation 'org.lwjgl:lwjgl'
+	implementation 'org.lwjgl:lwjgl-assimp'
+	runtimeOnly 'org.lwjgl:lwjgl::natives-linux'
+	runtimeOnly 'org.lwjgl:lwjgl::natives-macos'
+	runtimeOnly 'org.lwjgl:lwjgl::natives-macos-arm64'
+	runtimeOnly 'org.lwjgl:lwjgl-assimp::natives-linux'
+	runtimeOnly 'org.lwjgl:lwjgl-assimp::natives-macos'
+	runtimeOnly 'org.lwjgl:lwjgl-assimp::natives-macos-arm64'



--- a/backend/src/main/java/com/printcalculator/controller/QuoteSessionController.java
+++ b/backend/src/main/java/com/printcalculator/controller/QuoteSessionController.java
@@ -120,7 +120,7 @@ public class QuoteSessionController {

    // Helper to add item
    private QuoteLineItem addItemToSession(QuoteSession session, MultipartFile file, com.printcalculator.dto.PrintSettingsDto settings) throws IOException {
-        if (file.isEmpty()) throw new IOException("File is empty");
+        if (file.isEmpty()) throw new IllegalArgumentException("File is empty");

        // Scan for virus
        clamAVService.scan(file.getInputStream());
@@ -146,6 +146,7 @@ public class QuoteSessionController {
            Files.copy(inputStream, persistentPath, StandardCopyOption.REPLACE_EXISTING);
        }

+        Path convertedPersistentPath = null;
        try {
            // Apply Basic/Advanced Logic
            applyPrintSettings(settings);
@@ -183,9 +184,20 @@ public class QuoteSessionController {
            if (settings.getInfillDensity() != null) processOverrides.put("sparse_infill_density", settings.getInfillDensity() + "%");
            if (settings.getInfillPattern() != null) processOverrides.put("sparse_infill_pattern", settings.getInfillPattern());

+            Path slicerInputPath = persistentPath;
+            if ("3mf".equals(ext)) {
+                String convertedFilename = UUID.randomUUID() + "-converted.stl";
+                convertedPersistentPath = sessionStorageDir.resolve(convertedFilename).normalize();
+                if (!convertedPersistentPath.startsWith(sessionStorageDir)) {
+                    throw new IOException("Invalid converted STL storage path");
+                }
+                slicerService.convert3mfToPersistentStl(persistentPath.toFile(), convertedPersistentPath);
+                slicerInputPath = convertedPersistentPath;
+            }
+            
            // 3. Slice (Use persistent path)
            PrintStats stats = slicerService.slice(
-                persistentPath.toFile(), 
+                slicerInputPath.toFile(),
                machineProfile, 
                filamentProfile, 
                processProfile, 
@@ -193,7 +205,7 @@ public class QuoteSessionController {
                processOverrides
            );

-            Optional<ModelDimensions> modelDimensions = slicerService.inspectModelDimensions(persistentPath.toFile());
+            Optional<ModelDimensions> modelDimensions = slicerService.inspectModelDimensions(slicerInputPath.toFile());
            
            // 4. Calculate Quote
            QuoteResult result = quoteCalculator.calculate(stats, machine.getPrinterDisplayName(), selectedVariant);
@@ -216,6 +228,9 @@ public class QuoteSessionController {
            Map<String, Object> breakdown = new HashMap<>();
            breakdown.put("machine_cost", result.getTotalPrice()); // Excludes setup fee which is at session level
            breakdown.put("setup_fee", 0);
+            if (convertedPersistentPath != null) {
+                breakdown.put("convertedStoredPath", QUOTE_STORAGE_ROOT.relativize(convertedPersistentPath).toString());
+            }
            item.setPricingBreakdown(breakdown);
            
            // Dimensions for shipping/package checks are computed server-side from the uploaded model.
@@ -237,6 +252,9 @@ public class QuoteSessionController {
        } catch (Exception e) {
            // Cleanup if failed
            Files.deleteIfExists(persistentPath);
+            if (convertedPersistentPath != null) {
+                Files.deleteIfExists(convertedPersistentPath);
+            }
            throw e;
        }
    }
@@ -408,6 +426,7 @@ public class QuoteSessionController {
            dto.put("colorCode", item.getColorCode());
            dto.put("filamentVariantId", item.getFilamentVariant() != null ? item.getFilamentVariant().getId() : null);
            dto.put("status", item.getStatus());
+            dto.put("convertedStoredPath", extractConvertedStoredPath(item));
            
            BigDecimal unitPrice = item.getUnitPriceChf();
            if (totalSeconds.compareTo(BigDecimal.ZERO) > 0 && item.getPrintTimeSeconds() != null) {
@@ -468,7 +487,8 @@ public class QuoteSessionController {
    @GetMapping(value = "/{sessionId}/line-items/{lineItemId}/content")
    public ResponseEntity<org.springframework.core.io.Resource> downloadLineItemContent(
            @PathVariable UUID sessionId,
-            @PathVariable UUID lineItemId
+            @PathVariable UUID lineItemId,
+            @RequestParam(name = "preview", required = false, defaultValue = "false") boolean preview
    ) throws IOException {
        QuoteLineItem item = lineItemRepo.findById(lineItemId)
                .orElseThrow(() -> new RuntimeException("Item not found"));
@@ -477,20 +497,32 @@ public class QuoteSessionController {
            return ResponseEntity.badRequest().build();
        }

-        if (item.getStoredPath() == null) {
+        String targetStoredPath = item.getStoredPath();
+        if (preview) {
+            String convertedPath = extractConvertedStoredPath(item);
+            if (convertedPath != null && !convertedPath.isBlank()) {
+                targetStoredPath = convertedPath;
+            }
+        }
+
+        if (targetStoredPath == null) {
            return ResponseEntity.notFound().build();
        }

-        Path path = resolveStoredQuotePath(item.getStoredPath(), sessionId);
+        Path path = resolveStoredQuotePath(targetStoredPath, sessionId);
        if (path == null || !Files.exists(path)) {
            return ResponseEntity.notFound().build();
        }

        org.springframework.core.io.Resource resource = new UrlResource(path.toUri());
+        String downloadName = item.getOriginalFilename();
+        if (preview) {
+            downloadName = path.getFileName().toString();
+        }

        return ResponseEntity.ok()
                .contentType(MediaType.APPLICATION_OCTET_STREAM)
-                .header(org.springframework.http.HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + item.getOriginalFilename() + "\"")
+                .header(org.springframework.http.HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + downloadName + "\"")
                .body(resource);
    }

@@ -531,4 +563,17 @@ public class QuoteSessionController {
            return null;
        }
    }
+
+    private String extractConvertedStoredPath(QuoteLineItem item) {
+        Map<String, Object> breakdown = item.getPricingBreakdown();
+        if (breakdown == null) {
+            return null;
+        }
+        Object converted = breakdown.get("convertedStoredPath");
+        if (converted == null) {
+            return null;
+        }
+        String path = String.valueOf(converted).trim();
+        return path.isEmpty() ? null : path;
+    }
 }
--- a/backend/src/main/java/com/printcalculator/exception/GlobalExceptionHandler.java
+++ b/backend/src/main/java/com/printcalculator/exception/GlobalExceptionHandler.java
@@ -17,6 +17,20 @@ import java.util.Map;
@ControllerAdvice
 public class GlobalExceptionHandler {

+    @ExceptionHandler(ModelProcessingException.class)
+    public ResponseEntity<Object> handleModelProcessingException(
+            ModelProcessingException ex, WebRequest request) {
+        Map<String, Object> body = new LinkedHashMap<>();
+        body.put("timestamp", LocalDateTime.now());
+        body.put("status", HttpStatus.UNPROCESSABLE_ENTITY.value());
+        body.put("error", "Unprocessable Entity");
+        body.put("code", ex.getCode());
+        body.put("message", ex.getMessage());
+        body.put("path", extractPath(request));
+
+        return new ResponseEntity<>(body, HttpStatus.UNPROCESSABLE_ENTITY);
+    }
+
    @ExceptionHandler(VirusDetectedException.class)
    public ResponseEntity<Object> handleVirusDetectedException(
            VirusDetectedException ex, WebRequest request) {
@@ -58,4 +72,12 @@ public class GlobalExceptionHandler {

        return new ResponseEntity<>(body, HttpStatus.BAD_REQUEST);
    }
+
+    private String extractPath(WebRequest request) {
+        String raw = request.getDescription(false);
+        if (raw == null) {
+            return "";
+        }
+        return raw.startsWith("uri=") ? raw.substring(4) : raw;
+    }
 }
--- a/backend/src/main/java/com/printcalculator/exception/ModelProcessingException.java
+++ b/backend/src/main/java/com/printcalculator/exception/ModelProcessingException.java
@@ -0,0 +1,21 @@
+package com.printcalculator.exception;
+
+import java.io.IOException;
+
+public class ModelProcessingException extends IOException {
+    private final String code;
+
+    public ModelProcessingException(String code, String message) {
+        super(message);
+        this.code = code;
+    }
+
+    public ModelProcessingException(String code, String message, Throwable cause) {
+        super(message, cause);
+        this.code = code;
+    }
+
+    public String getCode() {
+        return code;
+    }
+}
--- a/backend/src/main/java/com/printcalculator/service/SlicerService.java
+++ b/backend/src/main/java/com/printcalculator/service/SlicerService.java
@@ -2,8 +2,14 @@ package com.printcalculator.service;

 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.printcalculator.exception.ModelProcessingException;
 import com.printcalculator.model.ModelDimensions;
 import com.printcalculator.model.PrintStats;
+import org.lwjgl.PointerBuffer;
+import org.lwjgl.assimp.AIFace;
+import org.lwjgl.assimp.AIMesh;
+import org.lwjgl.assimp.AIScene;
+import org.lwjgl.assimp.AIVector3D;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
 import org.w3c.dom.Document;
@@ -11,7 +17,6 @@ import org.w3c.dom.Element;
 import org.w3c.dom.NamedNodeMap;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
-import org.xml.sax.InputSource;

 import javax.xml.XMLConstants;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -19,7 +24,7 @@ import java.io.BufferedWriter;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.StringReader;
+import java.nio.IntBuffer;
 import java.nio.file.Files;
 import java.nio.file.InvalidPathException;
 import java.nio.file.Path;
@@ -38,6 +43,14 @@ import java.util.regex.Pattern;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;

+import static org.lwjgl.assimp.Assimp.aiGetErrorString;
+import static org.lwjgl.assimp.Assimp.aiImportFile;
+import static org.lwjgl.assimp.Assimp.aiProcess_JoinIdenticalVertices;
+import static org.lwjgl.assimp.Assimp.aiProcess_PreTransformVertices;
+import static org.lwjgl.assimp.Assimp.aiProcess_SortByPType;
+import static org.lwjgl.assimp.Assimp.aiProcess_Triangulate;
+import static org.lwjgl.assimp.Assimp.aiReleaseImport;
+
@Service
 public class SlicerService {

@@ -144,7 +157,10 @@ public class SlicerService {

                if (!finished) {
                    process.destroyForcibly();
-                    throw new IOException("Slicer timed out");
+                    throw new ModelProcessingException(
+                            "SLICER_TIMEOUT",
+                            "Model processing timed out. Try another format or contact us directly via Request Consultation."
+                    );
                }

                if (process.exitValue() != 0) {
@@ -156,7 +172,11 @@ public class SlicerService {
                        logger.warning("Slicer reported model out of printable area, retrying with arrange.");
                        continue;
                    }
-                    throw new IOException("Slicer failed with exit code " + process.exitValue() + ": " + error);
+                    logger.warning("Slicer failed with exit code " + process.exitValue() + ". Log: " + error);
+                    throw new ModelProcessingException(
+                            "SLICER_EXECUTION_FAILED",
+                            "Unable to process this model. Try another format or contact us directly via Request Consultation."
+                    );
                }

                File gcodeFile = tempDir.resolve(basename + ".gcode").toFile();
@@ -165,14 +185,20 @@ public class SlicerService {
                    if (alt.exists()) {
                        gcodeFile = alt;
                    } else {
-                        throw new IOException("GCode output not found in " + tempDir);
+                        throw new ModelProcessingException(
+                                "SLICER_OUTPUT_MISSING",
+                                "Unable to generate slicing output for this model. Try another format or contact us directly via Request Consultation."
+                        );
                    }
                }

                return gCodeParser.parse(gcodeFile);
            }

-            throw new IOException("Slicer failed after retry");
+            throw new ModelProcessingException(
+                    "SLICER_FAILED_AFTER_RETRY",
+                    "Unable to process this model. Try another format or contact us directly via Request Consultation."
+            );

        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
@@ -305,6 +331,31 @@ public class SlicerService {
        return convertedStlPaths;
    }

+    public Path convert3mfToPersistentStl(File input3mf, Path destinationStl) throws IOException {
+        Path tempDir = Files.createTempDirectory("slicer_convert_");
+        try {
+            List<String> convertedPaths = convert3mfToStlInputPaths(input3mf, tempDir);
+            if (convertedPaths.isEmpty()) {
+                throw new ModelProcessingException(
+                        "MODEL_CONVERSION_FAILED",
+                        "Unable to process this 3MF file. Try another format or contact us directly via Request Consultation."
+                );
+            }
+            Path source = Path.of(convertedPaths.get(0));
+            Path parent = destinationStl.toAbsolutePath().normalize().getParent();
+            if (parent != null) {
+                Files.createDirectories(parent);
+            }
+            Files.copy(source, destinationStl, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+            return destinationStl;
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new IOException("Interrupted during 3MF conversion", e);
+        } finally {
+            deleteRecursively(tempDir);
+        }
+    }
+
    private List<String> convert3mfToStlInputPaths(File input3mf, Path tempDir) throws IOException, InterruptedException {
        Path conversionOutputDir = tempDir.resolve("converted-from-3mf");
        Files.createDirectories(conversionOutputDir);
@@ -319,30 +370,145 @@ public class SlicerService {
        );
        String input3mfPath = requireSafeArgument(input3mf.getAbsolutePath(), "input 3MF path");

-        Path convertedStl = Path.of(conversionOutputStlPath);
-        String stlLog = runAssimpExport(input3mfPath, conversionOutputStlPath, tempDir.resolve("assimp-convert-stl.log"));
-        if (hasRenderableGeometry(convertedStl)) {
-            return List.of(convertedStl.toString());
+        String stlLog = "";
+        String objLog = "";
+
+        Path lwjglConvertedStl = conversionOutputDir.resolve("converted-lwjgl.stl");
+        try {
+            long lwjglTriangles = convert3mfToStlWithLwjglAssimp(input3mf.toPath(), lwjglConvertedStl);
+            if (lwjglTriangles > 0 && hasRenderableGeometry(lwjglConvertedStl)) {
+                logger.info("Converted 3MF to STL via LWJGL Assimp. Triangles: " + lwjglTriangles);
+                return List.of(lwjglConvertedStl.toString());
+            }
+            logger.warning("LWJGL Assimp conversion produced no renderable geometry.");
+        } catch (Exception | LinkageError e) {
+            logger.warning("LWJGL Assimp conversion failed, falling back to assimp CLI: " + e.getMessage());
        }

-        logger.warning("Assimp STL conversion produced empty geometry. Retrying conversion to OBJ.");
+        Path convertedStl = Path.of(conversionOutputStlPath);
+        try {
+            stlLog = runAssimpExport(input3mfPath, conversionOutputStlPath, tempDir.resolve("assimp-convert-stl.log"));
+            if (hasRenderableGeometry(convertedStl)) {
+                return List.of(convertedStl.toString());
+            }
+            logger.warning("Assimp STL conversion produced empty geometry.");
+        } catch (IOException e) {
+            stlLog = e.getMessage() != null ? e.getMessage() : "";
+            logger.warning("Assimp STL conversion failed, trying alternate conversion paths: " + stlLog);
+        }
+
+        logger.warning("Retrying 3MF conversion to OBJ.");

        Path convertedObj = Path.of(conversionOutputObjPath);
-        String objLog = runAssimpExport(input3mfPath, conversionOutputObjPath, tempDir.resolve("assimp-convert-obj.log"));
-        if (hasRenderableGeometry(convertedObj)) {
-            return List.of(convertedObj.toString());
+        try {
+            objLog = runAssimpExport(input3mfPath, conversionOutputObjPath, tempDir.resolve("assimp-convert-obj.log"));
+            if (hasRenderableGeometry(convertedObj)) {
+                Path stlFromObj = conversionOutputDir.resolve("converted-from-obj.stl");
+                runAssimpExport(
+                        convertedObj.toString(),
+                        stlFromObj.toString(),
+                        tempDir.resolve("assimp-convert-obj-to-stl.log")
+                );
+                if (hasRenderableGeometry(stlFromObj)) {
+                    return List.of(stlFromObj.toString());
+                }
+                logger.warning("Assimp OBJ->STL conversion produced empty geometry.");
+            }
+            logger.warning("Assimp OBJ conversion produced empty geometry.");
+        } catch (IOException e) {
+            objLog = e.getMessage() != null ? e.getMessage() : "";
+            logger.warning("Assimp OBJ conversion failed: " + objLog);
        }

        Path fallbackStl = conversionOutputDir.resolve("converted-fallback.stl");
-        long fallbackTriangles = convert3mfArchiveToAsciiStl(input3mf.toPath(), fallbackStl);
-        if (fallbackTriangles > 0 && hasRenderableGeometry(fallbackStl)) {
-            logger.warning("Assimp conversion produced empty geometry. Fallback 3MF XML extractor generated "
-                    + fallbackTriangles + " triangles.");
-            return List.of(fallbackStl.toString());
+        try {
+            long fallbackTriangles = convert3mfArchiveToAsciiStl(input3mf.toPath(), fallbackStl);
+            if (fallbackTriangles > 0 && hasRenderableGeometry(fallbackStl)) {
+                logger.warning("Assimp conversion produced empty geometry. Fallback 3MF XML extractor generated "
+                        + fallbackTriangles + " triangles.");
+                return List.of(fallbackStl.toString());
+            }
+            logger.warning("3MF XML fallback completed but produced no renderable triangles.");
+        } catch (IOException e) {
+            logger.warning("3MF XML fallback conversion failed: " + e.getMessage());
        }

-        throw new IOException("3MF conversion produced no renderable geometry (STL+OBJ). STL log: "
-                + stlLog + " OBJ log: " + objLog);
+        throw new ModelProcessingException(
+                "MODEL_CONVERSION_FAILED",
+                "Unable to process this 3MF file. Try another format or contact us directly via Request Consultation."
+        );
+    }
+
+    private long convert3mfToStlWithLwjglAssimp(Path input3mf, Path outputStl) throws IOException {
+        int flags = aiProcess_Triangulate
+                | aiProcess_JoinIdenticalVertices
+                | aiProcess_PreTransformVertices
+                | aiProcess_SortByPType;
+        AIScene scene = aiImportFile(input3mf.toString(), flags);
+        if (scene == null) {
+            throw new IOException("LWJGL Assimp import failed: " + aiGetErrorString());
+        }
+
+        long triangleCount = 0L;
+        try (BufferedWriter writer = Files.newBufferedWriter(outputStl, StandardCharsets.UTF_8)) {
+            writer.write("solid converted\n");
+
+            int meshCount = scene.mNumMeshes();
+            PointerBuffer meshPointers = scene.mMeshes();
+            if (meshCount <= 0 || meshPointers == null) {
+                throw new IOException("LWJGL Assimp import contains no meshes");
+            }
+
+            for (int meshIndex = 0; meshIndex < meshCount; meshIndex++) {
+                long meshPtr = meshPointers.get(meshIndex);
+                if (meshPtr == 0L) {
+                    continue;
+                }
+                AIMesh mesh = AIMesh.create(meshPtr);
+                AIVector3D.Buffer vertices = mesh.mVertices();
+                AIFace.Buffer faces = mesh.mFaces();
+                if (vertices == null || faces == null) {
+                    continue;
+                }
+
+                int vertexCount = mesh.mNumVertices();
+                int faceCount = mesh.mNumFaces();
+                for (int faceIndex = 0; faceIndex < faceCount; faceIndex++) {
+                    AIFace face = faces.get(faceIndex);
+                    if (face.mNumIndices() != 3) {
+                        continue;
+                    }
+                    IntBuffer indices = face.mIndices();
+                    if (indices == null || indices.remaining() < 3) {
+                        continue;
+                    }
+                    int i0 = indices.get(0);
+                    int i1 = indices.get(1);
+                    int i2 = indices.get(2);
+                    if (i0 < 0 || i1 < 0 || i2 < 0
+                            || i0 >= vertexCount
+                            || i1 >= vertexCount
+                            || i2 >= vertexCount) {
+                        continue;
+                    }
+
+                    Vec3 p1 = toVec3(vertices.get(i0));
+                    Vec3 p2 = toVec3(vertices.get(i1));
+                    Vec3 p3 = toVec3(vertices.get(i2));
+                    writeAsciiFacet(writer, p1, p2, p3);
+                    triangleCount++;
+                }
+            }
+
+            writer.write("endsolid converted\n");
+        } finally {
+            aiReleaseImport(scene);
+        }
+
+        if (triangleCount <= 0) {
+            throw new IOException("LWJGL Assimp conversion produced no triangles");
+        }
+        return triangleCount;
    }

    private String runAssimpExport(String input3mfPath, String outputModelPath, Path conversionLogPath)
@@ -583,6 +749,10 @@ public class SlicerService {
        writer.write("endfacet\n");
    }

+    private Vec3 toVec3(AIVector3D v) {
+        return new Vec3(v.x(), v.y(), v.z());
+    }
+
    private Vec3 computeNormal(Vec3 a, Vec3 b, Vec3 c) {
        double ux = b.x() - a.x();
        double uy = b.y() - a.y();
--- a/backend/src/main/resources/application.properties
+++ b/backend/src/main/resources/application.properties
@@ -4,7 +4,7 @@ server.port=8000
 # Database Configuration
 spring.datasource.url=${DB_URL:jdbc:postgresql://localhost:5432/printcalc}
 spring.datasource.username=${DB_USERNAME:printcalc}
-spring.datasource.password=${DB_PASSWORD:}
+spring.datasource.password=${DB_PASSWORD:printcalc_secret}
 spring.jpa.hibernate.ddl-auto=update
 spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
 spring.jpa.open-in-view=false
@@ -13,6 +13,7 @@ spring.jpa.open-in-view=false
 # Slicer Configuration
 # Map SLICER_PATH env var if present (default to /opt/orcaslicer/AppRun or Mac path)
 slicer.path=${SLICER_PATH:/Applications/OrcaSlicer.app/Contents/MacOS/OrcaSlicer}
+assimp.path=${ASSIMP_PATH:assimp}
 profiles.root=${PROFILES_DIR:profiles}


--- a/frontend/src/app/features/calculator/calculator-page.component.html
+++ b/frontend/src/app/features/calculator/calculator-page.component.html
@@ -65,6 +65,16 @@
          (proceed)="onProceed()"
          (itemChange)="onItemChange($event)"
        ></app-quote-result>
+      } @else if (isZeroQuoteError()) {
+        <app-card class="zero-result-card">
+          <h3>{{ "CALC.ZERO_RESULT_TITLE" | translate }}</h3>
+          <p>{{ "CALC.ZERO_RESULT_HELP" | translate }}</p>
+          <div class="zero-result-action">
+            <app-button variant="outline" (click)="onConsult()">
+              {{ "QUOTE.CONSULT" | translate }}
+            </app-button>
+          </div>
+        </app-card>
      } @else {
        <app-card>
          <h3>{{ "CALC.BENEFITS_TITLE" | translate }}</h3>
--- a/frontend/src/app/features/calculator/calculator-page.component.scss
+++ b/frontend/src/app/features/calculator/calculator-page.component.scss
@@ -9,6 +9,12 @@
  margin: 0 auto;
 }

+.error-action {
+  display: flex;
+  justify-content: center;
+  margin-top: calc(var(--space-4) * -1);
+}
+
 .content-grid {
  display: grid;
  grid-template-columns: 1fr;
@@ -82,6 +88,15 @@
  line-height: 2;
 }

+.zero-result-card p {
+  color: var(--color-text-muted);
+  line-height: 1.6;
+}
+
+.zero-result-action {
+  margin-top: var(--space-4);
+}
+
 .loader-content {
  text-align: center;
  max-width: 300px;
--- a/frontend/src/app/features/calculator/calculator-page.component.ts
+++ b/frontend/src/app/features/calculator/calculator-page.component.ts
@@ -1,5 +1,6 @@
 import {
  Component,
+  computed,
  signal,
  ViewChild,
  ElementRef,
@@ -7,11 +8,12 @@ import {
 } from '@angular/core';
 import { CommonModule } from '@angular/common';
 import { TranslateModule } from '@ngx-translate/core';
-import { forkJoin } from 'rxjs';
-import { map } from 'rxjs/operators';
+import { forkJoin, of } from 'rxjs';
+import { catchError, map } from 'rxjs/operators';

 import { AppCardComponent } from '../../shared/components/app-card/app-card.component';
 import { AppAlertComponent } from '../../shared/components/app-alert/app-alert.component';
+import { AppButtonComponent } from '../../shared/components/app-button/app-button.component';
 import { UploadFormComponent } from './components/upload-form/upload-form.component';
 import { QuoteResultComponent } from './components/quote-result/quote-result.component';
 import {
@@ -31,6 +33,7 @@ import { LanguageService } from '../../core/services/language.service';
    TranslateModule,
    AppCardComponent,
    AppAlertComponent,
+    AppButtonComponent,
    UploadFormComponent,
    QuoteResultComponent,
    SuccessStateComponent,
@@ -47,6 +50,9 @@ export class CalculatorPageComponent implements OnInit {
  result = signal<QuoteResult | null>(null);
  error = signal<boolean>(false);
  errorKey = signal<string>('CALC.ERROR_GENERIC');
+  isZeroQuoteError = computed(
+    () => this.error() && this.errorKey() === 'CALC.ERROR_ZERO_PRICE',
+  );

  orderSuccess = signal(false);

@@ -122,15 +128,18 @@ export class CalculatorPageComponent implements OnInit {

    // Download all files
    const downloads = items.map((item) =>
-      this.estimator.getLineItemContent(session.id, item.id).pipe(
-        map((blob: Blob) => {
+      forkJoin({
+        originalBlob: this.estimator.getLineItemContent(session.id, item.id),
+        previewBlob: this.estimator
+          .getLineItemContent(session.id, item.id, true)
+          .pipe(catchError(() => of(null))),
+      }).pipe(
+        map(({ originalBlob, previewBlob }) => {
          return {
-            blob,
+            originalBlob,
+            previewBlob,
            fileName: item.originalFilename,
-            // We need to match the file object to the item so we can set colors ideally.
-            // UploadForm.setFiles takes File[].
-            // We might need to handle matching but UploadForm just pushes them.
-            // If order is preserved, we are good. items from backend are list.
+            hasConvertedPreview: !!item.convertedStoredPath,
          };
        }),
      ),
@@ -140,13 +149,25 @@ export class CalculatorPageComponent implements OnInit {
      next: (results: any[]) => {
        const files = results.map(
          (res) =>
-            new File([res.blob], res.fileName, {
+            new File([res.originalBlob], res.fileName, {
              type: 'application/octet-stream',
            }),
        );

        if (this.uploadForm) {
          this.uploadForm.setFiles(files);
+          results.forEach((res, index) => {
+            if (!res.hasConvertedPreview || !res.previewBlob) {
+              return;
+            }
+            const previewName = res.fileName
+              .replace(/\.[^.]+$/, '')
+              .concat('.stl');
+            const previewFile = new File([res.previewBlob], previewName, {
+              type: 'model/stl',
+            });
+            this.uploadForm.setPreviewFileByIndex(index, previewFile);
+          });
          this.uploadForm.patchSettings(session);

          // Also restore colors?
@@ -225,6 +246,17 @@ export class CalculatorPageComponent implements OnInit {
              queryParamsHandling: 'merge', // merge with existing params like 'mode' if any
              replaceUrl: true, // prevent cluttering history, or false if we want back button to work. replaceUrl seems safer for "state update"
            });
+            this.estimator.getQuoteSession(res.sessionId).subscribe({
+              next: (sessionData) => {
+                this.restoreFilesAndSettings(
+                  sessionData.session,
+                  sessionData.items || [],
+                );
+              },
+              error: (err) => {
+                console.warn('Failed to refresh files for preview', err);
+              },
+            });
          }
        }
      },
@@ -318,7 +350,14 @@ export class CalculatorPageComponent implements OnInit {
  private currentRequest: QuoteRequest | null = null;

  onConsult() {
-    if (!this.currentRequest) return;
+    if (!this.currentRequest) {
+      this.router.navigate([
+        '/',
+        this.languageService.selectedLang(),
+        'contact',
+      ]);
+      return;
+    }

    const req = this.currentRequest;
    let details = `Richiesta Preventivo:\n`;
@@ -349,7 +388,16 @@ export class CalculatorPageComponent implements OnInit {
  }

  private isInvalidQuote(result: QuoteResult): boolean {
-    return !Number.isFinite(result.totalPrice) || result.totalPrice <= 0;
+    const invalidPrice =
+      !Number.isFinite(result.totalPrice) || result.totalPrice <= 0;
+    const invalidWeight =
+      !Number.isFinite(result.totalWeight) || result.totalWeight <= 0;
+    const invalidTime =
+      !Number.isFinite(result.totalTimeHours) ||
+      !Number.isFinite(result.totalTimeMinutes) ||
+      (result.totalTimeHours <= 0 && result.totalTimeMinutes <= 0);
+
+    return invalidPrice || invalidWeight || invalidTime;
  }

  private setQuoteError(key: string): void {
--- a/frontend/src/app/features/calculator/components/upload-form/upload-form.component.html
+++ b/frontend/src/app/features/calculator/components/upload-form/upload-form.component.html
@@ -2,13 +2,13 @@
  <div class="section">
    @if (selectedFile()) {
      <div class="viewer-wrapper">
-        @if (!isStepFile(selectedFile())) {
+        @if (!canPreviewSelectedFile()) {
          <div class="step-warning">
            <p>{{ "CALC.STEP_WARNING" | translate }}</p>
          </div>
        } @else {
          <app-stl-viewer
-            [file]="selectedFile()"
+            [file]="getSelectedPreviewFile()"
            [color]="getSelectedFileColor()"
          >
          </app-stl-viewer>
--- a/frontend/src/app/features/calculator/components/upload-form/upload-form.component.ts
+++ b/frontend/src/app/features/calculator/components/upload-form/upload-form.component.ts
@@ -32,6 +32,7 @@ import { getColorHex } from '../../../../core/constants/colors.const';

 interface FormItem {
  file: File;
+  previewFile?: File;
  quantity: number;
  color: string;
  filamentVariantId?: number;
@@ -96,12 +97,24 @@ export class UploadFormComponent implements OnInit {

  acceptedFormats = '.stl,.3mf,.step,.stp';

-  isStepFile(file: File | null): boolean {
+  isStlFile(file: File | null): boolean {
    if (!file) return false;
    const name = file.name.toLowerCase();
    return name.endsWith('.stl');
  }

+  canPreviewSelectedFile(): boolean {
+    return this.isStlFile(this.getSelectedPreviewFile());
+  }
+
+  getSelectedPreviewFile(): File | null {
+    const selected = this.selectedFile();
+    if (!selected) return null;
+    const item = this.items().find((i) => i.file === selected);
+    if (!item) return null;
+    return item.previewFile ?? item.file;
+  }
+
  constructor() {
    this.form = this.fb.group({
      itemsTouched: [false], // Hack to track touched state for custom items list
@@ -262,6 +275,7 @@ export class UploadFormComponent implements OnInit {
        const defaultSelection = this.getDefaultVariantSelection();
        validItems.push({
          file,
+          previewFile: this.isStlFile(file) ? file : undefined,
          quantity: 1,
          color: defaultSelection.colorName,
          filamentVariantId: defaultSelection.filamentVariantId,
@@ -390,6 +404,7 @@ export class UploadFormComponent implements OnInit {
    for (const file of files) {
      validItems.push({
        file,
+        previewFile: this.isStlFile(file) ? file : undefined,
        quantity: 1,
        color: defaultSelection.colorName,
        filamentVariantId: defaultSelection.filamentVariantId,
@@ -404,6 +419,16 @@ export class UploadFormComponent implements OnInit {
    }
  }

+  setPreviewFileByIndex(index: number, previewFile: File) {
+    if (!Number.isInteger(index) || index < 0) return;
+    this.items.update((current) => {
+      if (index >= current.length) return current;
+      const updated = [...current];
+      updated[index] = { ...updated[index], previewFile };
+      return updated;
+    });
+  }
+
  private getDefaultVariantSelection(): {
    colorName: string;
    filamentVariantId?: number;
--- a/frontend/src/app/features/calculator/services/quote-estimator.service.ts
+++ b/frontend/src/app/features/calculator/services/quote-estimator.service.ts
@@ -416,10 +416,15 @@ export class QuoteEstimatorService {
  }

  // Session File Retrieval
-  getLineItemContent(sessionId: string, lineItemId: string): Observable<Blob> {
+  getLineItemContent(
+    sessionId: string,
+    lineItemId: string,
+    preview = false,
+  ): Observable<Blob> {
    const headers: any = {};
+    const previewQuery = preview ? '?preview=true' : '';
    return this.http.get(
-      `${environment.apiUrl}/api/quote-sessions/${sessionId}/line-items/${lineItemId}/content`,
+      `${environment.apiUrl}/api/quote-sessions/${sessionId}/line-items/${lineItemId}/content${previewQuery}`,
      {
        headers,
        responseType: 'blob',
--- a/frontend/src/assets/i18n/de.json
+++ b/frontend/src/assets/i18n/de.json
@@ -91,7 +91,9 @@
    "NOTES_PLACEHOLDER": "Spezifische Anweisungen...",
    "SETUP_NOTE": "* Beinhaltet {{cost}} als Einrichtungskosten",
    "SHIPPING_NOTE": "** Versandkosten ausgeschlossen, werden im nächsten Schritt berechnet",
-    "ERROR_ZERO_PRICE": "Etwas ist schiefgelaufen. Versuche ein anderes Format oder kontaktiere uns."
+    "ERROR_ZERO_PRICE": "Bei der Berechnung ist etwas schiefgelaufen. Versuche ein anderes Format oder kontaktiere uns direkt über \"Beratung anfragen\".",
+    "ZERO_RESULT_TITLE": "Ungültiges Ergebnis",
+    "ZERO_RESULT_HELP": "Die Berechnung hat ungültige Werte (0) geliefert. Versuche ein anderes Dateiformat oder kontaktiere uns direkt über \"Beratung anfragen\"."
  },
  "SHOP": {
    "TITLE": "Technische Lösungen",
--- a/frontend/src/assets/i18n/en.json
+++ b/frontend/src/assets/i18n/en.json
@@ -91,7 +91,9 @@
    "NOTES_PLACEHOLDER": "Specific instructions...",
    "SETUP_NOTE": "* Includes {{cost}} as setup cost",
    "SHIPPING_NOTE": "** Shipping costs excluded, calculated at the next step",
-    "ERROR_ZERO_PRICE": "Something went wrong. Try another format or contact us."
+    "ERROR_ZERO_PRICE": "Something went wrong during the calculation. Try another format or contact us directly via Request Consultation.",
+    "ZERO_RESULT_TITLE": "Invalid Result",
+    "ZERO_RESULT_HELP": "The calculation returned invalid zero values. Try another file format or contact us directly via Request Consultation."
  },
  "SHOP": {
    "TITLE": "Technical solutions",
--- a/frontend/src/assets/i18n/fr.json
+++ b/frontend/src/assets/i18n/fr.json
@@ -116,7 +116,9 @@
    "FALLBACK_MATERIAL": "PLA (fallback)",
    "FALLBACK_QUALITY_STANDARD": "Standard",
    "ERR_FILE_TOO_LARGE": "Certains fichiers dépassent la limite de 200MB et n'ont pas été ajoutés.",
-    "ERROR_ZERO_PRICE": "Quelque chose s'est mal passé. Essayez un autre format ou contactez-nous."
+    "ERROR_ZERO_PRICE": "Un problème est survenu pendant le calcul. Essayez un autre format ou contactez-nous directement via Demander une consultation.",
+    "ZERO_RESULT_TITLE": "Résultat invalide",
+    "ZERO_RESULT_HELP": "Le calcul a renvoyé des valeurs nulles invalides. Essayez un autre format de fichier ou contactez-nous directement via Demander une consultation."
  },
  "QUOTE": {
    "PROCEED_ORDER": "Procéder à la commande",
--- a/frontend/src/assets/i18n/it.json
+++ b/frontend/src/assets/i18n/it.json
@@ -116,7 +116,9 @@
    "FALLBACK_MATERIAL": "PLA (fallback)",
    "FALLBACK_QUALITY_STANDARD": "Standard",
    "ERR_FILE_TOO_LARGE": "Alcuni file superano il limite di 200MB e non sono stati aggiunti.",
-    "ERROR_ZERO_PRICE": "Qualcosa è andato storto. Prova con un altro formato oppure contattaci."
+    "ERROR_ZERO_PRICE": "Qualcosa è andato storto nel calcolo. Prova un altro formato o contattaci direttamente con Richiedi Consulenza.",
+    "ZERO_RESULT_TITLE": "Risultato non valido",
+    "ZERO_RESULT_HELP": "Il calcolo ha restituito valori non validi (0). Prova con un altro formato file oppure contattaci direttamente con Richiedi Consulenza."
  },
  "QUOTE": {
    "PROCEED_ORDER": "Procedi con l'ordine",