mesh_view c api by joa-quim · Pull Request #3229 · f3d-app/f3d

joa-quim · 2026-06-10T12:52:54Z

Describe your changes

Issue ticket number and link if any

Checklist for finalizing the PR

I have performed a self-review of my code
I have added tests for new features and bugfixes
I have added documentation for new features
If it is a modifying the libf3d API, I have updated bindings
If it is a modifying the .github/workflows/versions.json, I have updated docker_timestamp

AI Disclosure

I did not use AI to generate any of the content of that pull request
I used AI to generate code in that pull request, if yes please disclose which part of the code was generated and with which model.
Claude Opus 4.8 was used in this work

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Expose the zero-copy f3d::mesh_view path through the C API so bindings can show in-memory meshes (geometry, point/cell scalars, animation) without copying arrays into libf3d: - c/types_c_api.h: enum f3d_mesh_data_type_t; structs f3d_data_array_t, f3d_cell_array_t, f3d_memory_view_t. - c/scene_c_api.{h,cxx}: f3d_scene_add_mesh_view() with to_cpp_* converters and a concrete c_mesh_view keeping the caller's data pointers. Also add an optional in-memory base-color (and optional emissive) texture carried on the mesh_view itself, so a textured/draped mesh needs no temp image file: - library/public/mesh_view.h: texture_t {width,height,components,data, emissive} + texture_t baseColorTexture in memory_view_t. - library/src/scene_impl.cxx: build a vtkImageData+vtkTexture (sRGB) from baseColorTexture and hand it to the importer. - vtkext vtkF3DGenericImporter: SetBaseColorTexture(vtkTexture*, bool emissive), applied per block in CreateActorForBlock. - vtkext vtkF3DRenderer: the rendered coloring actor is a clone of the importer's OriginalActor; propagate albedoTex/emissiveTex from the source actor to the clone when no global texture override is set (RGBA forces translucent). Without this an actor-level texture renders blank. All additive (336 insertions, no deletions).

Smoke test for the zero-copy mesh_view C binding: builds a small in-memory mesh (a triangle with a per-point scalar) via f3d_memory_view_t and adds it to the scene with f3d_scene_add_mesh_view. Gated on the same VTK version as the other zero-copy tests (stride arrays).

github-actions · 2026-06-10T12:53:06Z

You are modifying libf3d public API! ⚠️Please update bindings accordingly⚠️!
You can find them in their respective directories: c, python, java, webassembly.

github-actions · 2026-06-10T13:11:40Z

Style Checks CI failed:

diff --git a/c/scene_c_api.cxx b/c/scene_c_api.cxx
index 4b0a6b1..d792994 100644
--- a/c/scene_c_api.cxx
+++ b/c/scene_c_api.cxx
@@ -179,7 +179,8 @@ f3d::mesh_view::memory_view_t to_cpp_memory_view(const f3d_memory_view_t* c)
     const unsigned int comps = static_cast<unsigned int>(
       c->base_color_texture_components ? c->base_color_texture_components : 3);
     f3d::image img(static_cast<unsigned int>(c->base_color_texture_width),
-      static_cast<unsigned int>(c->base_color_texture_height), comps, f3d::image::ChannelType::BYTE);
+      static_cast<unsigned int>(c->base_color_texture_height), comps,
+      f3d::image::ChannelType::BYTE);
     // setContent deep-copies, so the caller's buffer need not outlive this call
     img.setContent(const_cast<void*>(c->base_color_texture));
     v.baseColorTexture = std::move(img);
diff --git a/c/scene_c_api.h b/c/scene_c_api.h
index 12cf969..0593c7f 100644
--- a/c/scene_c_api.h
+++ b/c/scene_c_api.h
@@ -64,8 +64,8 @@ extern "C"
    * @param t_max Animation time range maximum.
    * @return 1 on success, 0 on failure.
    */
-  F3D_EXPORT int f3d_scene_add_mesh_view(
-    f3d_scene_t* scene, const f3d_memory_view_t* view, const char* name, double t_min, double t_max);
+  F3D_EXPORT int f3d_scene_add_mesh_view(f3d_scene_t* scene, const f3d_memory_view_t* view,
+    const char* name, double t_min, double t_max);
 
   /**
    * @brief Add and load a memory buffer into the scene.
diff --git a/library/src/scene_impl.cxx b/library/src/scene_impl.cxx
index 624c341..b19eb5d 100644
--- a/library/src/scene_impl.cxx
+++ b/library/src/scene_impl.cxx
@@ -19,12 +19,12 @@
 #include <vtkCellArray.h>
 #include <vtkCellData.h>
 #include <vtkFloatArray.h>
+#include <vtkImageData.h>
 #include <vtkLightCollection.h>
 #include <vtkMemoryResourceStream.h>
 #include <vtkPointData.h>
 #include <vtkPoints.h>
 #include <vtkPolyData.h>
-#include <vtkImageData.h>
 #include <vtkProgressBarRepresentation.h>
 #include <vtkProgressBarWidget.h>
 #include <vtkTexture.h>
diff --git a/python/F3DPythonBindings.cxx b/python/F3DPythonBindings.cxx
index b264993..d5200a2 100644
--- a/python/F3DPythonBindings.cxx
+++ b/python/F3DPythonBindings.cxx
@@ -636,8 +636,8 @@ PYBIND11_MODULE(pyf3d, module)
     // base_color_texture_emissive is true the same image is also installed as the emissive map
     // (flat / full-strength display).
     .def_readwrite("base_color_texture", &f3d::mesh_view::memory_view_t::baseColorTexture)
-    .def_readwrite("base_color_texture_emissive",
-                   &f3d::mesh_view::memory_view_t::baseColorTextureEmissive);
+    .def_readwrite(
+      "base_color_texture_emissive", &f3d::mesh_view::memory_view_t::baseColorTextureEmissive);
 
   class PyMesh
     : public f3d::mesh_view
diff --git a/vtkext/private/module/vtkF3DRenderer.cxx b/vtkext/private/module/vtkF3DRenderer.cxx
index 1553ff1..0b067f4 100644
--- a/vtkext/private/module/vtkF3DRenderer.cxx
+++ b/vtkext/private/module/vtkF3DRenderer.cxx
@@ -2599,7 +2599,8 @@ void vtkF3DRenderer::ConfigureActorsProperties()
         coloring.OriginalActor->ForceTranslucentOn();
       }
     }
-    else if (vtkTexture* origAlbedo = coloring.OriginalActor->GetProperty()->GetTexture("albedoTex"))
+    else if (vtkTexture* origAlbedo =
+               coloring.OriginalActor->GetProperty()->GetTexture("albedoTex"))
     {
       // No global override: honour a base-color texture carried by the source actor (e.g.
       // f3d::mesh_view::memory_view_t::baseColorTexture), propagating it to the rendered
@@ -2626,7 +2627,8 @@ void vtkF3DRenderer::ConfigureActorsProperties()
       coloring.Actor->GetProperty()->SetEmissiveTexture(emissTex);
       coloring.OriginalActor->GetProperty()->SetEmissiveTexture(emissTex);
     }
-    else if (vtkTexture* origEmis = coloring.OriginalActor->GetProperty()->GetTexture("emissiveTex"))
+    else if (vtkTexture* origEmis =
+               coloring.OriginalActor->GetProperty()->GetTexture("emissiveTex"))
     {
       // No global override: honour an emissive texture carried by the source actor (e.g.
       // f3d::mesh_view::memory_view_t::baseColorTexture with emissive=true).

mwestphal · 2026-06-11T05:40:34Z

    std::vector<data_array_t> pointScalars;
    std::vector<data_array_t> cellScalars;
+
+    // optional in-memory base-color texture (sampled via textureCoordinates)


what makes this optional ?

The PR update has now a longer comments about this

Meakk

Overall it makes sense now, but some improvements needed.
Also I don't think it will pass the coverage requirement.

Meakk · 2026-06-11T06:37:24Z

+   * must remain valid until the mesh is removed from the scene. When `emissive` is true the
+   * same image is additionally installed as the emissive texture (for unlit/flat display).
+   */
+  struct texture_t


as pointed in Discord, I still think we should use f3d::image here and add support for non-owning buffers in f3d::image later.
Since it's public API, it's important to make sure the design is future proof.

Meakk · 2026-06-11T06:39:08Z

+    size_t height = 0;
+    size_t components = 3;
+    const void* data = nullptr;
+    bool emissive = false;


Why emissive is needed here?
Are you using it? I think what you want is unlit option https://f3d.app/docs/libf3d/OPTIONS#model.unlit

Meakk · 2026-06-11T06:44:16Z

+   * same image is additionally installed as the emissive texture (for unlit/flat display).
+   */
+  struct texture_t
+  {


texture_t C/Python bindings missing and not tested

Addressed in the PR update

Co-authored-by: Mathieu Westphal <mwestphal.f3d@protonmail.com>

…/f3d into feature/mesh-view-c-api

joa-quim · 2026-06-11T11:45:03Z

I am so sorry but somehow the changes involving the using of f3d::image had not left my local copy of the fork and hence had not made it into the PR. Now they do.

…ture tests

joa-quim added 2 commits June 8, 2026 19:05

joa-quim requested a review from a team as a code owner June 10, 2026 12:52

Meakk added the ci:fast label Jun 10, 2026

Meakk changed the title ~~Feature/mesh view c api \ci fast~~ Feature/mesh view c api Jun 10, 2026

Meakk changed the title ~~Feature/mesh view c api~~ mesh_view c api Jun 10, 2026

Meakk self-requested a review June 10, 2026 13:11

mwestphal reviewed Jun 11, 2026

View reviewed changes

Comment thread c/testing/CMakeLists.txt Outdated

mwestphal reviewed Jun 11, 2026

View reviewed changes

Comment thread c/scene_c_api.cxx

mwestphal requested changes Jun 11, 2026

View reviewed changes

Meakk requested changes Jun 11, 2026

View reviewed changes

joa-quim and others added 3 commits June 11, 2026 11:37

Update c/testing/CMakeLists.txt

9e71d98

Co-authored-by: Mathieu Westphal <mwestphal.f3d@protonmail.com>

Address review: use f3d::image for the in-memory base-color texture

3391c89

Merge branch 'feature/mesh-view-c-api' of https://github.com/joa-quim…

8f97173

…/f3d into feature/mesh-view-c-api

mesh_view C API: handle exceptions, expose texture to Python, add tex…

e815de6

…ture tests

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joa-quim commented Jun 10, 2026

Describe your changes

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Checklist for finalizing the PR

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