fix: Segment shader.

[freezy]

Fixes compilation errors on latest Unity version, as well as the emission intensity issue.

[Copilot]

Pull Request Overview

This PR refactors the segment display shader to improve maintainability by replacing global shader parameters with a structured context approach. The key change is eliminating global variables and parameter passing in favor of a centralized SegContext structure that encapsulates all segment display parameters.

• Introduces a SegContext struct to encapsulate all segment display parameters
• Removes global shader variables and replaces them with context-based parameter passing
• Updates all segment display functions to accept and use the context structure

Reviewed Changes

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

File	Description
SegmentDisplayShader.hlsl	Main shader refactoring: removes global variables, adds SegContext struct, updates all functions to use context parameters
SegmentDisplayGraph.shadergraph	Updates shader graph configuration to support the new context-based approach and removes deprecated HDRP emission node

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