Additional views from ViewerDrawerBGFX and lines depth offset

[alemuntoni]

• ViewerDrawerBGFX provides 4 additional views that can be used by DrawableObjects to render with multiple passes;
• Added a depth offset float setting to Lines class that allows to add a small depth and allow to draw them entirely also when they are colinear with triangles (e.g. wireframe)

[Copilot]

Pull request overview

This PR extends the BGFX rendering pipeline to support multi-pass drawing via additional view IDs provided by ViewerDrawerBGFX, and adds a configurable depth offset for line rendering to reduce z-fighting (e.g., wireframes over filled triangles).

Changes:

• Added a shared u_linesSettings uniform block for line shaders and introduced a depth offset applied in line vertex shaders.
• Extended DrawObjectSettingsBGFX / ViewerDrawerBGFX to provide 4 additional BGFX view IDs for multi-pass rendering.
• Updated mesh rendering to submit wireframe/edge/point passes to additional views, and updated the Qt example to exercise vertex/face colors and wireframe buffers.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vclib/render/shaders/vclib/bgfx/primitives/lines/uniforms.sh	Introduces shared line uniform definitions, including u_depthOffset.
vclib/render/shaders/vclib/bgfx/primitives/lines/primitive_lines/vs_primitive_lines.sc	Applies clip-space depth offset for primitive lines.
vclib/render/shaders/vclib/bgfx/primitives/lines/primitive_lines/fs_primitive_lines.sc	Switches to shared line uniforms include.
vclib/render/shaders/vclib/bgfx/primitives/lines/cpu_generated_lines/vs_cpu_generated_lines.sc	Applies depth offset to CPU-generated line endpoints.
vclib/render/shaders/vclib/bgfx/primitives/lines/cpu_generated_lines/fs_cpu_generated_lines.sc	Switches to shared line uniforms include.
vclib/render/include/vclib/bgfx/settings/draw_object_settings_bgfx.h	Adds additionalViewIds to draw settings for multi-pass submissions.
vclib/render/include/vclib/bgfx/primitives/lines.h	Adds depthOffset setting and packs line settings into u_linesSettings.
vclib/render/include/vclib/bgfx/drawers/viewer_drawer_bgfx.h	Allocates/configures additional BGFX views and propagates them via settings.
vclib/render/include/vclib/bgfx/drawable/mesh/mesh_render_buffers.h	Sets a small default line depth offset for edges/wireframe lines.
vclib/render/include/vclib/bgfx/drawable/drawable_mesh_bgfx.h	Submits wireframe/edges/points using additional views (multi-pass).
examples/render/02-mesh-viewer/qt/main.cpp	Updates example to enable vertex colors and wireframe buffer updates.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.