Add support configuration options: supportGap, supportDensity, and tree support settings

[Copilot]

Summary

Adds 6 new configurable options for support structure generation. All defaults match the existing hardcoded implementation values so no existing behaviour changes.

New Options

Shared (normal and tree support)

Option	Type	Default	Description
supportGap	Number (mm)	0.2	Air gap between supports and the printed object. Previously hardcoded as nozzleDiameter / 2.

Normal support

Option	Type	Default	Description
supportDensity	Number (0–100)	50	Density percentage of the support grid. Previously hardcoded to spacing equivalent of 50%. Setting to 0 produces no support lines for that region.

Tree support

Option	Type	Default	Description
supportRootsEnabled	Boolean	true	Enable/disable root structures at the base of the trunk.
supportRootCount	Number (1–8)	4	Number of roots spreading radially from the trunk base.
supportBranchAngle	Number (degrees)	45	Angle of branches rising from the trunk (0° = horizontal, 90° = vertical).
supportTwigAngle	Number (degrees)	45	Angle of twigs rising from branch nodes to contact tips.

Changes

• src/polyslice.coffee — new constructor properties; new getter/setter methods delegating to accessors
• src/utils/accessors.coffee — new get* and set* functions with validation
• src/slicer/support/normal/normal.coffee — reads supportGap and supportDensity from slicer instead of hardcoded values
• src/slicer/support/tree/tree.coffee — reads all tree-specific settings from slicer; buildTreeStructure parameters refactored into an opts object
• src/slicer/support/support.test.coffee — 18 new tests for all getter/setter pairs
• src/polyslice.test.coffee — default-value assertions for all new support options
• src/utils/accessors.test.coffee — extended support settings test with getter/setter coverage for all 6 new options including boundary validation checks
• src/slicer/support/normal/normal.test.coffee — new generateRegionSupportPattern tests covering supportDensity=0 early return, supportGap region collapse, and density-vs-line-count relationship
• src/slicer/support/tree/tree.test.coffee — new buildTreeStructure opts tests covering supportGap collapse, gap effect on twig count, and branchAngle/twigAngle geometry effects
• docs/slicer/support/SUPPORT.md — updated with all new options, tree support anatomy, and API reference
• .github/instructions/slicer/support/overview.instructions.md — updated configuration table, tree support structure section, and usage examples

Validation

All 888 tests pass.

[jgphilpott]

Okay this is looking good @copilot, thanks! Could you please also make sure the support instructions (.github/instructions/slicer/support/overview.instructions.md) and support docs (docs/slicer/support/SUPPORT.md) are up-to-date with the current implementation?

[Copilot]

Okay this is looking good @copilot, thanks! Could you please also make sure the support instructions (.github/instructions/slicer/support/overview.instructions.md) and support docs (`docs/slicer/sup...

Done in b10eb84. Both files have been updated:

docs/slicer/support/SUPPORT.md — usage example updated to show all new options; supportType now lists "tree" as implemented; added individual configuration sections for supportGap, supportDensity, supportRootsEnabled, supportRootCount, supportBranchAngle, and supportTwigAngle; tree support generation section added (anatomy diagram, node radii table, angle/root config); API reference and slicer methods table updated; file structure and limitations sections updated.

.github/instructions/slicer/support/overview.instructions.md — configuration parameters table expanded with all 6 new params; tree support sub-module description updated from "placeholder" to real implementation; support types table updated; grid parameters and gap sections updated to show configurable values; new "Tree Support Structure" section added with anatomy, radii, angle formulas, root config, and trunk accessibility details; both usage examples updated; important conventions updated with new items for density, gap, angle constraints, and root count.

[jgphilpott]

Excellent progress @copilot! We are almost ready to merge, before we do can you make sure all the relevant test files have also been updated?

• src/polyslice.test.coffee
• src/utils/accessors.test.coffee
• src/slicer/support/support.test.coffee
• src/slicer/support/normal/normal.test.coffee
• src/slicer/support/tree/tree.test.coffee

Thanks!

[Copilot]

Excellent progress @copilot! We are almost ready to merge, before we do can you make sure all the relevant test files have also been updated?

• src/polyslice.test.coffee
  ...

Done in 34257a6. All five test files have been updated:

• src/polyslice.test.coffee — default-value assertions added for all 7 support options (supportThreshold, supportGap, supportDensity, supportRootsEnabled, supportRootCount, supportBranchAngle, supportTwigAngle)
• src/utils/accessors.test.coffee — the 'should set and get support settings' test extended with 6 new getter/setter pairs including validation boundary checks for each
• src/slicer/support/support.test.coffee — two stale "not yet implemented" comments removed (tree support and everywhere placement are both fully implemented)
• src/slicer/support/normal/normal.test.coffee — new generateRegionSupportPattern describe block with 4 tests: supportDensity=0 early return, supportGap region collapse, valid default case, and density-vs-line-count relationship
• src/slicer/support/tree/tree.test.coffee — 4 new buildTreeStructure opts tests: supportGap collapse, larger gap producing fewer twigs, branchAngle effect on branch Z geometry, and twigAngle effect on twig Z geometry

All 209 tests across the 5 affected files pass.

[Copilot]

Pull request overview

Adds new configuration options to the slicer support-generation system (normal + tree) by extending the Polyslice API (constructor + accessors), wiring the options into support algorithms, and documenting/testing the new behavior.

Changes:

• Introduces 6 new support-related settings (supportGap, supportDensity, and 4 tree-specific knobs) with getters/setters and default-value coverage.
• Updates normal support grid generation to derive spacing from supportDensity and to use configurable supportGap.
• Updates tree support to consume slicer-provided settings and refactors buildTreeStructure to accept an opts object; updates docs and bumps three/prettier.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/utils/accessors.coffee	Adds getters/setters + validation for new support settings.
src/utils/accessors.test.coffee	Adds getter/setter tests for new support settings.
src/polyslice.coffee	Adds new constructor properties and method delegates for support options.
src/polyslice.test.coffee	Asserts default values for newly added support options.
src/slicer/support/normal/normal.coffee	Derives spacing from supportDensity and uses supportGap instead of hardcoded constants.
src/slicer/support/normal/normal.test.coffee	Adds tests for density=0 behavior, gap collapse, and density-vs-output relationship.
src/slicer/support/tree/tree.coffee	Reads new tree settings from slicer and threads them into buildTreeStructure; enables configurable roots/rootCount.
src/slicer/support/tree/tree.test.coffee	Adds tests for supportGap collapse and angle-driven geometry differences.
src/slicer/support/support.test.coffee	Adds tests for new support option defaults and validation behavior.
docs/slicer/support/SUPPORT.md	Documents new support options and adds detailed tree support explanation.
.github/instructions/slicer/support/overview.instructions.md	Updates internal support-module overview with new options and tree support details.
package.json	Bumps three and prettier versions.
package-lock.json	Lockfile updates for the dependency bumps.

[jgphilpott]

@copilot I replied to all your comment, please review my notes and apply changes based on the conversation in this thread. Thanks!

[Copilot]

@copilot I replied to all your comment, please review my notes and apply changes based on the conversation in [this thread](#189 (review)...

All four items from the review thread addressed in ea3adaa — see the individual thread replies for details.