Vulkan RTX: r_rtx mode visualization + auto vk_rtx_demo_spirv.inc

[timfox]

Summary

Advances the Vulkan KHR RTX demo path toward the documented r_rtx modes (1=shadows, 2=reflections, 3=full) by visualizing mode in the closest-hit shader, wiring the frame UBO to closest-hit, and automating regeneration of vk_rtx_demo_spirv.inc.

Technical changes

• VkRtxFrameUBO: outputSize.z carries clamped r_rtx (0–3) each frame; documented in struct comment.
• vk_rtx_init: descriptor binding 2 (uniform buffer) stage flags = raygen | closest hit.
• rtx_demo.rchit: reads rtx.outputSize.z; tints base albedo by mode (1 darker, 2 cool blue mix, 3 warm accent). Mode 0 keeps legacy flat grey.
• rtx_demo.rgen: comment only (UBO layout unchanged size-wise).
• scripts/compile_shaders.sh: after compiling RTX stages, writes src/renderers/vulkan/vk_rtx_demo_spirv.inc with correct VK_RTX_DEMO_*_SPV_SIZE macros (PROJECT_ROOT export).
• Regenerated shader_data.c, shader_build_meta.txt, and vk_rtx_demo_spirv.inc via ./scripts/compile_shaders.sh --apply.

Docs

• docs/RENDERERS_FUTURE.md — RTX table row updated.
• CHANGELOG.md — [Unreleased] → Added.

Validation

• ./scripts/compile_engine.sh vulkan (recompiles shaders; smoke path OK)
• ctest -R smoke_test
• Separate configure: cmake -B build-rtx-Release -DUSE_VULKAN_RTX=ON + build idtech3_vulkan_x86 (RTX defines compile)

Notes

This is visualization scaffolding for r_rtx presets on the existing single-hit demo; true shadows/reflections/full RT still require additional pipelines / secondary rays / integration per RENDERERS_FUTURE.md.

  

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Gate vk_rtx_demo_spirv.inc writes behind apply mode

compile_shaders.sh now always rewrites src/renderers/vulkan/vk_rtx_demo_spirv.inc even when called in generation-only mode, so invocations that intentionally avoid touching tracked sources (for example the CMake custom command and scripts/validate_ci_build.sh, both of which run without --apply) will still dirty the working tree and can fail in read-only source checkouts. This bypasses the existing --generated-dir/--apply workflow and should be gated so source-tree updates only happen in an explicit apply step.

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[cursor]

Stale comment

Security review complete: I found no high-confidence medium, high, or critical vulnerabilities introduced by this PR.

I also checked the existing unresolved automation thread; it is a build/workflow issue rather than a security finding, so there is no prior security finding to re-report.

  

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[cursor]

Security review complete for PR #178.

No high-confidence medium, high, or critical vulnerabilities were identified in the added or modified code. I also checked the existing unresolved automation thread and it appears to be a build/workflow concern rather than a security finding, so I did not re-report it as a vulnerability.

  

_{Sent by Cursor Automation: Find vulnerabilities}