Textured meshes in g3d

[FDUTCH]

My project requires rendering textured 3d objects, and currently there is no way to add texture to your mesh...

I'm wondering if anyone is already working on implementing texture support,
and if not, I'd like to hear some thoughts on how it should be implemented.

I'm not very good at gpu/3d stuff, but maybe you guys could recommend some resources on this topic so I can learn and contribute to gogpu ecosystem?

[FDUTCH]

okay, I managed to implement it

it's probably a bad implementation, so I'll wait for other opinions...

if someone interested, here is brunch with my changes: https://github.com/FDUTCH/g3d/tree/textures

[kolkov]

Nice work, @FDUTCH! The textured cube looks great, and I can see you understand the GPU pipeline well — bind groups, sampler, texture view, white-pixel fallback for untextured materials, correct material.color * tex_color multiplication in both shaders. That's solid.

I reviewed your textures branch in detail. The core GPU plumbing is right, but there are a few architecture issues that need to be addressed before this can be merged. I'd love to help you get this into a PR we can ship.

What needs to change

1. Texture belongs on Material, not Mesh

Every 3D engine puts textures on materials: Three.js (material.map), GLTF 2.0 (pbrMetallicRoughness.baseColorTexture), Bevy (StandardMaterial.base_color_texture). This allows sharing a material across meshes with different geometries, and later adding normal/roughness/emissive textures as additional material properties.

Target API:

mat := g3d.NewStandardMaterial(
    g3d.WithColor(g3d.RGB(0.8, 0.8, 0.8)),
    g3d.WithBaseColorTexture(img), // image.Image
)

2. No gogpu dependency in g3d library code

g3d must work without the gogpu application framework (ADR-001: dependencies go DOWN only — wgpu, gpucontext, gputypes, never gogpu/gg/ui). The standalone mode (NewRendererFromDevice) is used for headless rendering, tests, and embedding in other frameworks.

Instead of ctx.Renderer().NewTextureFromImageWithOptions(), create textures with raw wgpu calls: device.CreateTexture() + queue.WriteTexture(). This is the same pattern gg uses in internal/gpu/.

3. Render()/RenderTo() signatures must not change

Adding *gogpu.Context as a parameter breaks all existing users and the standalone mode. Texture data should flow through the Material interface — the renderer reads texture info from the material during draw, no extra parameters needed.

4. Use image.Image instead of file paths

os.Open in library code prevents WASM compatibility. Accept image.Image as input — let the user handle file loading. This is standard Go practice (image/png, image/jpeg decoders return image.Image).

Minor issues

• Sampler not released in releasePersistentResources (GPU resource leak)
• Deleted example go.mod/go.sum files (needed for standalone example builds)
• fullscreen-overlay and viewport3d examples not updated for the new signature

What's good and should stay

• White-pixel fallback texture for untextured materials — common pattern in 3D engines
• Texture + sampler in bind group 1 (binding 2, 3) — correct layout
• material.color * tex_color in both WGSL shaders — correct (GLTF 2.0 defines baseColor = baseColorFactor * baseColorTexture)
• Filter mode selection (nearest vs linear)

If you'd like to work on a PR with these changes, I'm happy to review iterations. This is a high-priority Phase 2 feature — textures are the most requested capability right now.

[FDUTCH]

Thank you very much for the feedback!
In that case, I'll create a pr and start working on fixing the issues.

[FDUTCH]

also @kolkov maybe you're on discord or telegram? I'd like to discuss a few minor details... I won't bother you 🫠