fix(ishdr): gate bloom for legacy weather mods

[SkrubbySkrubInAShrub]

Fixes old weather mods looking blown out in SDR. Merge when verified by users on discord.

Summary by CodeRabbit

• Bug Fixes
  • Improved bloom effect rendering to properly distinguish between HDR and standard dynamic range displays, ensuring consistent visual quality across different display configurations.

[github-actions]

No actionable suggestions for changed features.

[coderabbitai]

📝 Walkthrough

Walkthrough

The BLEND shader path now branches its bloom addition logic based on HDR mode. For HDR, it applies a soft-saturation mask using exponential decay; for SDR, it applies a hard-cutoff mask. Both paths multiply the resulting bloomMask by bloomColor before adding to the blended result.

Changes

HDR-dependent bloom masking

Layer / File(s)	Summary
HDR-dependent bloom mask calculation package/Shaders/ISHDR.hlsl	Bloom masking branches on isHDR: HDR uses saturate(Param.x - (1.0 - exp2(-blendedColor))) while SDR uses saturate(Param.x - blendedColor). Both multiply the resulting mask by bloomColor and add to blendedColor.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• community-shaders/skyrim-community-shaders#1516: Both PRs modify ISHDR.hlsl's bloom/BLEND color path—changing how bloom is computed and applied (masking/tonemap interplay and use of blendedColor).
• community-shaders/skyrim-community-shaders#1445: Both PRs modify the BLEND path in package/Shaders/ISHDR.hlsl and change how bloom is computed/applied (HDR-dependent bloom mask vs. hdrColor += max(0, Param.x - hdrColor) \* bloomColor).
• community-shaders/skyrim-community-shaders#1458: Both PRs edit the bloom addition calculation in package/Shaders/ISHDR.hlsl, changing how the bloom mask/intensity is computed (different approaches to the same bloom contribution code).

Suggested reviewers

• alandtse
• doodlum

Poem

🐰 A bloom so bright, now split in two—
One path for HDR's softer hue,
One sharp and clear for SDR's tone,
The shader's heart now fully known! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix(ishdr): gate bloom for legacy weather mods' clearly and accurately describes the main change: gating bloom in the ISHDR shader to address legacy weather mods appearing blown out in SDR.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

package/Shaders/ISHDR.hlsl (1)

171-176: Consider adding an issue-closing keyword in the PR description (if this maps to a tracked bug).

Using Fixes #<id> / Closes #<id> will improve traceability and auto-close behavior after merge.

As per coding guidelines "Suggest adding appropriate GitHub keywords: 'Fixes #123' or 'Closes #123' for bug fixes".

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@package/Shaders/ISHDR.hlsl` around lines 171 - 176, The PR lacks an
issue-closing keyword for traceability; update the pull request description to
include a GitHub keyword like "Fixes #<id>" or "Closes #<id>" that references
the tracked bug this change addresses (e.g., the HDR/SDR bloom behavior code
around bloomMask, isHDR, Param.x, blendedColor and bloomColor in ISHDR.hlsl) so
the issue is auto-closed on merge.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@package/Shaders/ISHDR.hlsl`:
- Around line 171-176: The PR lacks an issue-closing keyword for traceability;
update the pull request description to include a GitHub keyword like "Fixes
#<id>" or "Closes #<id>" that references the tracked bug this change addresses
(e.g., the HDR/SDR bloom behavior code around bloomMask, isHDR, Param.x,
blendedColor and bloomColor in ISHDR.hlsl) so the issue is auto-closed on merge.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 86075eed-9b90-497b-afca-05db9bed5e29

📥 Commits

Reviewing files that changed from the base of the PR and between 4294716 and 131756e.

📒 Files selected for processing (1)

• package/Shaders/ISHDR.hlsl