Implement runtime UI workflow and editor integration

[Gopmyc]

Description

• Adds runtime UI components: CCanvas, CTransform2D, CImage, CText.
• Adds layout components: CLayoutGroup, CHorizontalLayout, CVerticalLayout.
• Implements stretch anchor presets and effective controlChildrenWidth/Height sizing.
• Integrates UI rendering in Scene/Game descriptors and editor controls.
• Exposes new UI components and enums to Lua + editor actor/component flows.

Related Issue(s)

Fixes #631

Review Guidance

• Verify child sizing behavior in CLayoutGroup (controlChildrenWidth/Height).
• Verify CTransform2D stretch presets and inspector behavior.
• Verify CText/Font material path (EnsureEmbeddedMaterial + color override).
• Intentional behavior: Scene View supports inspectable world/canvas-space UI; toolbar toggle controls Scene View screen-space mode.

Reviewer Notes (Key integration details)

1) Layout behavior (CLayoutGroup)

• controlChildrenWidth/Height now effectively writes computed sizes to supported child UI components (CImage, CText extents, CTransform2D size).
• Update is guarded by epsilon-based checks to avoid redundant writes.

2) Dedicated layout components

• CHorizontalLayout and CVerticalLayout are concrete specializations of CLayoutGroup.
• Direction is locked per component (not editable in inspector for these specialized types).
• Added to actor deserialization + inspector + actor creation menu.

3) Transform2D anchor/stretch presets

• Added presets:
  • HORIZONTAL_STRETCH_TOP/MIDDLE/BOTTOM
  • VERTICAL_STRETCH_LEFT/CENTER/RIGHT
  • STRETCH_BOTH
• Position axis editing is disabled in inspector when that axis is stretch-driven.
• Runtime anchored position ignores manual offset on locked axes.

4) Text/Font material flow

• Font now owns an embedded UI material (EnsureEmbeddedMaterial / GetEmbeddedMaterial).
• CText reuses this embedded material and only overrides dynamic text color.
• Reduces per-text material setup duplication and keeps shader/UI flags centralized.

5) Editor rendering mode behavior

• GameView: always includes UI in screen space.
• SceneView: always includes UI; toolbar toggle switches screen-space mode on/off for Scene View display.
• This keeps Scene View inspectable while preserving screen-space preview mode on demand.

6) Lua exposure

• Added bindings for CHorizontalLayout and CVerticalLayout.
• Added new Transform2D anchor preset enum values.

Screenshots/GIFs

AI Usage Disclosure

Generated new code / Refactored code / Debugging

Build Warnings

The changes generate build warnings, specifically 29 new warnings originating from the Clay library itself.
These correspond to typical internal conversions on MSVC side: pointer to uint32_t (hash), double to float, float/__int64 to int32_t.
These are true narrowing warnings, but not relevant to our current integration as long as we remain within normal layout/UI sizes.

Note

You can find an Overload project on the 631-demo branch of my Overload fork. It includes scenes and scripts used to test the Lua API, as well as the added and modified source code.

Checklist

• My code follows the project's code style guidelines
• When applicable, I have commented my code, particularly in hard-to-understand areas
• When applicable, I have updated the documentation accordingly
• My changes don't generate new warnings or errors (left unchecked intentionally: see "Build Warnings")
• I have reviewed and take responsibility for all code in this PR (including any AI-assisted contributions)

[adriengivry]

Found a bunch of issues that I reported to you directly on Discord.

Didn't dive into the code yet, as it's subject to change.

Some design issues to figure out:

• Transform should be "adaptive", depending on the context (2D/3D).
  • When in 2D mode, width/height/anchor preset/anchor pivot should be displayed
  • When in 3D mode, nothing should change from what was previously shown
  • There should be no need for an extra component, the transform should store 2D-related properties under an std::optional data struct.
• Font rendering: currently fonts are rasterized with a fixed font size, so scaling a font will lead to blurry text. This could be fixed by implemented either SDF or dynamic glyph rendering. Dynamic glyph might be easier for now.
• CText::m_text should be displayed as a multiline string. Right now it's not possible to add line breaks in texts.

Some bugs I found so far:

• Anchor presets not working properly (partially addressed, the bounds in scene view are rendering incorrectly)
• Constant-size/scale with screen size issue, if I set the Canvas to 1920x1080, and add an image of size 1920x1080, it doesn't exactly fit the screen. When using scale with screen size (which should be default), we should be able to choose when the ratio is mismatching, to either match Width or Height, shrink, or expand. (see Unity documentation)
• When using multiple Canvas, composition order should be based on their position in the hierarchy.

[Gopmyc]

After testing I found a lot of bugs that I mentioned previously that weren't addressed. Please test thoroughly before requesting a review.

• Horizontal/Vertical layout issues:

  • Pivot still doesn't work properly
  • Size still doesn't work.
  • Layouts bounds are still not drawn in the scene view
  • Duplicated size property between layout & transform 2D

• Scene view UI screen space mode issues:

  • Gizmos still don't draw properly

• When a UI element (e.g. Text, Image, Layout) is selected, and parented to the root of the scene (or any other Actor that doesn't have a Canvas), the 2D transform is still displayed in the inspector until the user deselect/reselect the actor.

• When a font currently being used in the UI is deleted, the console spams with "Unable to read font: /Path/To/Project/Folder/Assets/?"

• CImage crash when the texture being used is deleted (missing sanity check?)

• Text extents could be removed, and the transform 2D size could be used to serve that purpose instead.

The reported bugs have been fixed. I also took the opportunity to fix a few other issues that hadn't been reported yet and refactored parts of the code to make it cleaner and more maintainable.

I improved the way Clay is used so that more of the 2D element management is handled by the library itself.

A number of other changes were made as well. The commit history should give a good overview of the modifications and additions, so the details can be found there.

Overall, the PR is in much better shape now