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Warp: restore the translocation-vortex look + fix texture-scroll precision collapse (task #52)

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The death/respawn "blue whirlwind" (tsphere) now matches the original cabinet
photo (capture.png): a smooth spinning lavender vortex with a bright core.

Root cause of the long-standing "radial spokes" artifact was NOT the warp code
but a general engine bug: L4D3D::SetTextureScrolling computed its texture-matrix
offset as scrollDelta * absolute_time, which grows unbounded and collapses UV
float precision -> a smooth scrolled cloud shatters into grainy radial steps.
Wrapped with fmodf(..., 1.0f) (identical under REPEAT tiling, full precision).
This also cleans the scrolling bexp beam grit and any other SCROLL material.

Visual reconstruction (verified against the real 45-vtx TSPHERE.BGF bicone,
offline-rasterized then ported):
  - view ON-AXIS (eye centred on the throat) + spin in place -> concentric rings
    (decomp FUN_00453dc4 does spin-about-local-Z + submit; the port had stubbed it)
  - bintA cloud through a WIDE lavender ramp at full contrast (drawn as SKY);
    no geometry "bands", no log-polar twist, no off-axis tornado (all discarded)
  - tessellate the 12-facet bicone smooth; isotropic + trilinear; ramp baked into
    the texture and drawn SELECTARG1(TEXTURE) to avoid double-tinting

Env knobs (BT_WARP_*) default to the verified values; BT_WARP_SELFTEST/SELFSHOT
are an off-by-default visual-verification harness (backbuffer frame dump).

Docs: new context/translocation-warp.md (geometry/material/visual/lifecycle/env);
reconstruction-gotchas.md gains the accumulated-time precision-collapse bug class;
rendering.md / multiplayer.md / decomp-reference.md / CLAUDE.md cross-linked.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
arcattack
2026-07-10 14:53:50 -05:00
co-authored by Claude Opus 4.8
parent a35f321ba1
commit 0bfb3d4ab3
10 changed files with 591 additions and 22 deletions
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context/rendering.md
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@@ -61,6 +61,15 @@ The `dpl_*` beam renderable was never ported → beams are drawn by `BTPushBeam`
origin re-anchors to the live muzzle every frame (can't run out from under your own beam). See
[[combat-damage]] for fire-rate/muzzle. [T2]
## Translocation warp (the respawn vortex) — see [[translocation-warp]]
The death/respawn "blue whirlwind" is `tsphere.bgf` (a 12-facet bicone) spun on-axis with the `bintA`
cloud through a wide lavender ramp, drawn as SKY. Full geometry/material/lifecycle/env in
[[translocation-warp]]. ⚠ **Rendering-wide fix that came out of it:** `L4D3D::SetTextureScrolling`
computed its texture-matrix offset as `scrollDelta × absolute_time`, which grew unbounded and collapsed
UV float precision → grainy/spoked scrolled textures the longer a session ran. Wrapped with `fmodf(…,
1.0f)`. This also cleans up the scrolling `bexp` beam grit and any other `SCROLL` material. [T2]
(Bug class: [[reconstruction-gotchas]] §13.)
## Performance — the 10fps→60fps fix (~50-80× render speedup)
The 10fps baseline had THREE stacked causes, all fixed (engine tree): (1) **`D3DCREATE_SOFTWARE_
VERTEXPROCESSING`** — every vertex transformed+lit on the CPU → HARDWARE first; (2) D3DX `DrawSubset`