how to deal transform of insert in insert?

[ghost]

I also want show dxf draws by three, I meet a problem, for example, my code the structure your I don't know how to deal it. Orz

[ghost]

oh, I konw, this is because Base point of block, all of block entities need subtract it.

[vagran]

Hello, I am glad you deal out with it. However, this is actually not an easy topic with lot of pitfalls in real world files. Even Autodesk did not get it fully, their official online viewer does not implement properly blocks handling and I have examples which are not properly displayed there. Most important points:

• Drawings extents is often located far from coordinate system origin. A block may be defined near the CS origin and an insertion point be within the extents, or vice versa, block defined within the extents and insertion point near the origin. Also you should have local canvas CS which origin is near drawing extents, and having geometry representation precision 32-bits floating numbers in WebGL. Considering all these facts, it is easy to lose details during coordinates transformation. Transformations flow and order should be carefully designed for proper implementation, otherwise blocks in a final render may be distorted which happens with Autodesk viewer on some files.
• Add possibility of nested blocks to the point above. Complexity becomes way higher.
• For optimal performance some blocks may be flattenned - i.e. rendered without instancing, coordinates should be transformed accordingly on the preparation stage.
• DXF format also have unexpected pitfalls, e.g. there is an extrusion parameter for most shapes, which may mirror geometry. It may be applied to geometric entity in block definition or to a block instance. Symmetry axis coordinate for mirrorring is not always obvious.

So, you can learn this indeed on simple examples, but implementing correct blocks rendering which will work properly for all real-world files is not an easy task at all. I would advice to learn dxf-viewer code, especially trying to follow all logic behing blocks handling.

[ghost]

Thank you.

[ghost]

As I recall, in addition to dxF-Viewer, we can also learn related specifications in the official DXF documentation. It looks like this: You should download .exe at first. https://knowledge.autodesk.com/zh-hans/support/autocad/learn-explore/caas/downloads/downloads/CHS/content/download-install-autocad-2021-product-help.html

[vagran]

Yes, I used it during dxf- viewer implementation. But it is just file format specification (which has also many tricky areas not fully clear from the specification itself, e.g. trick with the extrusion direction, its influence to 2D render). It will not tell anything about proper implementation of renderer of such files.