Text-to-CAD vs text-to-mesh
Text-to-CAD turns a description into a B-rep solid with exact faces, edges and dimensions that you can export as STEP. Text-to-mesh, often called text-to-3D, turns it into triangles that approximate the shape. QuantCAD is a text-to-CAD tool: it builds B-rep solids on the Open CASCADE kernel and exports STEP and STL.
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What is the difference between text-to-CAD and text-to-mesh?
Both start from a text prompt. The difference is what ends up in the file, and that decides what you can do with it afterwards.
| Aspect | Text-to-CAD (B-rep solid) | Text-to-mesh (triangles) |
|---|---|---|
| What the file stores | Exact surfaces (planes, cylinders, freeform patches) plus topology: which faces meet along which edges. | A list of flat triangles that approximate the surface. |
| Dimensions | A 5 mm hole measures 5 mm. | A 5 mm hole measures 4.96 or 5.02 mm depending on where you probe the facets. |
| Editing in CAD | Select a face or edge, change it, add fillets and chamfers. | No faces or edges in the CAD sense. Changes need mesh tools or remodeling. |
| Typical formats | STEP (ISO 10303), plus STL generated from the solid when you need a mesh. | STL, OBJ and GLB. |
| Good for | Parts that are machined, molded or printed to size, assemblies, drawings, tolerancing and CAM. | Renders, games, concept visuals, sculpted shapes and many one-off prints. |
| Converting to the other | Solid to mesh is one step and always works. | Mesh to solid usually wraps each triangle in a flat face. Real surfaces need remodeling. |
When should you choose a B-rep solid?
- You need exact dimensions, hole sizes and clearances.
- The part will be machined, molded or printed to size, or sent to a supplier.
- You will edit it later in SolidWorks, Fusion, Onshape, FreeCAD or another CAD tool.
- You need a STEP file for a quote, a drawing or a PLM or PDM system.
When is a mesh enough?
- The goal is a render, a game asset or a concept image.
- The shape is sculpted or organic and has no critical dimensions.
- You are printing it once and the exact size of each feature does not matter.
Why should large or complex products start as B-rep solids?
A product with dozens of parts works only if the parts meet where they should: bosses that line up with holes, lids that clear the walls around them. A mesh gets every surface close rather than exact, so each of those interfaces carries a small error. When you need to fix one, there is no real face or edge to dimension, fillet or tolerance.
Converting the finished mesh to STEP does not bring that information back. For anything large, precise or headed to manufacturing, start from solids. QuantCAD builds every part of an assembly as a B-rep solid, and the STEP export carries the same geometry you reviewed on screen.
How can you tell whether a STEP file holds a real solid?
Open it in your CAD tool and click the inside of a round hole. One cylindrical face should highlight, not a strip of flat faces. A simple bracket has a few dozen faces; several thousand means a mesh wrapped in a STEP file. The full five-minute check is in Why B-rep matters, and converting meshes is covered in How to convert an AI-generated mesh to STEP.
Frequently asked questions
When should I use a CAD solid instead of a mesh?
Use a CAD solid when you need exact dimensions, clean edges, later edits in a CAD tool, drawings, or a manufacturing workflow that expects STEP. QuantCAD builds every part as a B-rep solid and exports STEP (AP242) for that handoff.
When is a mesh good enough?
A mesh is enough for visualization, artistic assets, sculpted shapes and many 3D printing jobs where the exact size of each feature does not matter and you will not edit the part in CAD.
Is text-to-3D the same as text-to-CAD?
Usually not. Most text-to-3D tools produce meshes for visuals. Text-to-CAD tools produce solids you can dimension and edit. Check the export: if the tool offers STEP and the file opens as a solid with real cylindrical and planar faces, it is CAD.
Can I convert a mesh to STEP?
You can wrap a mesh in a STEP file, but each triangle becomes a flat face, so a round hole is still hundreds of flat strips. Tools such as Fusion and FreeCAD can merge flat regions into single faces, but curved surfaces usually have to be remodeled.
Does QuantCAD export meshes too?
Yes. QuantCAD exports STL in Draft, Normal or High quality, generated from the B-rep solid, alongside STEP for CAD tools.