This was the production checklist for the Metal Path Tracer release: the rendering, acceleration, material, camera, and interface work I wanted resolved before considering the project production-ready.

Critical Features

• Caustics support
  • Target: v2.0 release.
• Automatic HWRT availability detection
  • Use HWRT when available.
  • Automatically fall back to SWRT when hardware acceleration is unavailable.
• Screenshot capture directly from ImGui
  • EXR output.

Improvements & Performance

• Refactor HWRT / SWRT backend selection
  • SWRT should remain the baseline implementation.
  • Use HWRT by default when available.
  • Provide an HWRT toggle when supported.
  • Automatically fall back to SWRT when HWRT is unavailable.
• Fix HWRT acceleration structure issues — Critical
  • Multiple meshes / instances in BLAS.
  • Mesh indexing issues in TLAS.
  • Requires Xcode GPU Capture.
  • Determine whether the remaining problems are renderer-side or an Apple Metal / hardware issue.
• Improve HWRT performance
• Fix camera orbiting stutter
• Review implemented materials
  • Alloys
  • Plastic
  • Glass
  • Marble
  • Car paint / coating
  • Wax

Minor Improvements

• Fix HiDPI scaling
  • Allow high user-facing resolutions such as 1920×1080 without breaking ImGui.
  • Fix UI sizing and responsiveness issues.

ImGui Overlay

• Add environment map selector
• Move environment map and scene selectors to the top
  • Place below sample count.
• Remove Scene collapsible header
• Review whether Debug collapsible header is still necessary

Camera

• Add yaw control
• Add pitch control

Objects / ImGuizmo

• Add Objects collapsible header
• Add object material index
• Add real-time material editing
  • Albedo color picker
  • Metallic
  • Roughness
  • Isotropic
  • Subsurface
  • IOR
  • Additional material-specific properties
• Add transform controls
  • Position X / Y / Z
  • Rotation X / Y / Z
  • Scale X / Y / Z
• Add ImGuizmo viewport controls
  • Translate
  • Rotate
  • Scale
• Add Local / World coordinate toggle
• Display Local → World values
• Display World → Local values