CydandClaude Opus 4.8
57524d4a68
Root cause: vpx_max_postboot_acks=200, a Phase-2 bring-up guard, capped how many post-boot replies the device would ever feed. A real BattleTech session issues an unbounded stream of sync/frame/render replies and aborted with "velocirender_receive timed out - sends_wo_rcv" at exactly the 200th ack (143 sync + 55 frame-ack + 2 render). Cap is now effectively unlimited (0x7fffffff; override VPX_MAX_ACKS for diagnostics). After the fix the full game (game.conf, RIO disabled, cycles=max) runs indefinitely: 2500+ syncs, 1264+ frame-acks, no abort, into L4VIDEO content load (Thor mech + terrain from ALPHA_1/REL410/BT/VIDEO/GEO -- 841 real .bgf models; test.egg is only mission params). Window still shows background: the game uses the full DPL hierarchy (instance/object/lod/geogroup + DCS transforms) which the flat flyk-tuned scene walk doesn't traverse yet -- that is Phase 3d, documented in PHASE3-PROGRESS.md. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
169 lines
8.8 KiB
Markdown
169 lines
8.8 KiB
Markdown
# Phase 3 — Render Backend: Progress
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**Status (2026-07-03): Phase 3a + 3b + 3c complete. 3a — the render command
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stream is fully captured and decoded, and a captured DIVRGB frame
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reconstructed to pixels offline. 3b — a live OpenGL window built into the
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emulated board draws each frame in real time inside DOSBox-X. 3c — the
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production `vr_sync` abort is fixed and the full BattleTech v4.10 game now runs
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indefinitely through the emulated board, drawing 1000s of frames (was hard-
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capped at 200). First images ever produced from the Rel 4.10 VPX protocol
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without a real board. Next (3d): traverse the game's DPL hierarchy + DCS
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transforms so its mechs actually appear.**
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That is `flyk divrgb.scn` — Division's SMPTE color-bar calibration scene —
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rendered *entirely from the FIFO command stream captured by the emulated VPX
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board*: geometry, connectivity, materials, camera, viewport and background all
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come from the wire, none from the scene files. `divrgb-frame0.png` is the same
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capture drawn with the actual frame-0 spline camera the app sent.
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## 3a. Full FIFO capture
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`vpxlog.cpp` now records every FIFO burst when `VPX_FIFODUMP=<path>` is set
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(records: `'VPXM'` magic, u32 length, raw bytes; one record per burst between
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`outputData` tag writes). The capture used here: `divrgb.fifodump`
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(1297 messages) from `divrgb.conf`.
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Tools:
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- `decode_fifodump.py <dump> [--hex N] [--action A]` — action census + payload
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hexdumps.
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- `render_capture.py <dump> [-o out.png] [--frame N] [--eye x,y,z]` —
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reconstructs the scene graph and software-renders the frame each
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`draw_scene` commits.
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## The Rel 4.10 wire protocol (established from this capture)
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One burst per message: `[action:4][payload]`, packetized at 508 bytes.
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The i860 image download itself rides the FIFO in this build (actions 18–20,
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`VREND.MNG`). The DPL3 `vr_action` enum holds for 0–23 but Rel 4.10 extends
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and re-purposes the tail:
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| action | meaning | payload |
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|---|---|---|
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| 0 | init | args string (`/device~0x150~/video~svga~…`) |
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| 1 | create | `[type][name]` — **the host assigns node names** (1,2,3…); the board's create reply node value is ignored |
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| 3 | flush | `[name][type][node struct]` (see node types below) |
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| 7 | dcs_link | `[parent][child]` |
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| 9 | draw_scene | `[view?][0][0][1][1.0f]` — commits the frame |
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| 11 | list_add | `[parent][child]` |
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| 18–21 | 860code/data/bss/args | i860 download (FIFO in this build) |
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| 23 | **set_geom_verts** (Rel4.10; DPL3 had 22) | hdr `[name][0][n_verts][3][n_blocks][1][5][n_verts][1.0f]`, then float32 x,y,z per vertex |
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| 25 | **set_geom_conns** (new) | hdr `[name][n_polys][loop_len][0]`, then indices; each poly a closed loop (last=first) |
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| 31 | **camera** (new) | `[?][view][3×3 rotation, row-major][eye x,y,z]` per frame |
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| 45 (0x2D) | sync | token ping (see PHASE2) |
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Node types (from create/flush pairs in this capture):
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| type | node | flush payload highlights |
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|---|---|---|
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| 2 | texture/ramp? | one word, `0xFFFFFFFF` / `0x0FFFFFFF` |
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| 3 | view | window l,b,r,t (±1 × ±0.6154), window-plane distance 1.3, viewport 832×512, near 2, far 12000, background RGB |
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| 4 | light | |
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| 5 | dcs | 4×4 matrix |
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| 6 | material (old-style) | RGB floats |
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| 7 | object | |
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| 8 | lod | 2×4 bounds + lists |
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| 9 | geogroup | bounds; **payload int 14 = material node name** |
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| 10 | geometry | `[geo_type][n_polys][n_verts]…[radius]` |
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| 11 | material | **floats 10–12 (payload) = diffuse RGB** |
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Graph: `list_add` links object→lod→geogroup→geometry (and zone-level nodes to
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node 0); geogroups bind materials by name. The 13 DIVRGB bars decode to the
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textbook SMPTE pattern — 7 color bars, the reverse strip, and the −I/white/+Q
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PLUGE row — which validates vertices, connectivity, materials, camera and
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window mapping in one image. (Division screen x runs opposite to a GL-style
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eye space; without negating x the pattern comes out mirrored.)
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## 3b. Live OpenGL backend (DONE)
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`VPX_RENDER=1` turns on a live render backend built into `vpxlog.cpp`
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(Windows/WGL). The same burst assembler that feeds `VPX_FIFODUMP` now also
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feeds an in-process scene store (`scene_burst()` → `struct VScene`), and each
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`vr_draw_scene` publishes a frame snapshot to a dedicated OpenGL window thread
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(`rt_main`) that draws it with fixed-function GL. No build-system change was
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needed — `opengl32` was already linked, and `vpxlog.cpp` is already in
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`hardware/`.
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Validated: `flyk divrgb.scn` (`divrgb.conf` with `VPX_RENDER=1`) opens the
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"VPX VelociRender (emulated)" window and draws the SMPTE bars live, framed by
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the real `camera.spl` spline camera the app sends — matching the offline
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`render_capture.py` decode. The window runs on its own thread, so it keeps
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displaying the last frame after the DOS app exits.
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Design notes:
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- Multi-burst payloads (`set_geom_verts`/`conns` continuations) are tracked
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with `geom_active` / `conn_active` state, same as the offline decoder.
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- Projection: `glFrustum` from the view-node window rect scaled by
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`near/window_distance`; a `glScalef(-1,1,1)` handles Division's mirrored
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screen-x. Camera is the row-major 3×3 from action 31 loaded as the
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modelview rotation, then `glTranslatef(-eye)`.
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- Frame handoff is a critical-section-guarded `VFrame` + auto-reset event;
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the emulator thread never blocks on GL.
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Game path (`alpha1.conf`, full BattleTech v4.10): the window opens and draws
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the view background, but the run hits the **pre-existing production-path sync
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timeout** (`velocirender_receive timed out — sends_wo_rcv=3`, then
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`failed in vr_sync`) — the `btdpl.ini`/netnub launch bursts several sends
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before its first receive, which the POLL_THRESHOLD gating stalls. This is not
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a 3b issue (the `flyk` clean-launch path renders fine); it is the same
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production-sync item still open from Phase 2.
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## 3c. The full game runs through the live renderer (sync abort fixed)
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**The production `vr_sync` abort is fixed, and BattleTech v4.10 now runs
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indefinitely through the emulated board + live renderer.** Root cause was a
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Phase-2 bring-up guard left in the device: `vpx_max_postboot_acks = 200`
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capped how many post-boot replies the device would ever feed. A real game
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session issues an unbounded stream of sync/frame/render replies; the game
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aborted with `velocirender_receive timed out — sends_wo_rcv` the instant the
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device fell silent — at *exactly* the 200th ack (measured: 143 sync + 55
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frame-ack + 2 render = 200). The cap is now effectively unlimited
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(`0x7fffffff`, override with `VPX_MAX_ACKS`). Same run after the fix: 2500+
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syncs, 1264+ frame-acks, no abort. The game progresses past sync into
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`L4VIDEO.cpp` content/entity setup (loading the Thor mech and terrain) and
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draws continuously.
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Contrary to the earlier note, the content **is** on the production image: 841
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`.bgf` models under `ALPHA_1/REL410/BT/VIDEO/GEO` (incl. `BUTTEE.BGF`,
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`MSLR.BGF`, the `THR*` Thor mech). `test.egg` is only mission parameters (as
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the pod owner said); the geometry loads from `VIDEO/GEO` regardless.
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Game render config: `game.conf` (RIO disabled so the missing cockpit board
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doesn't stall the control manager; `cycles=max`).
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### What the game's wire stream looks like (vs. flyk)
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The game geometry path is heavier and different from flyk's flat DIVRGB:
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- **action 26 (0x1A) dominates** — texture texel upload. 32-byte headers
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`[node][size][w][h]` (`0x1000`=64×64, `0x4000`=128×128 tiles) then 256-byte
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texel rows. 2880+ of these = the mission texture set streaming in.
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- action 28 (0x1C): material/light parameter blocks.
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- actions 23/25 (verts/conns) still carry mesh geometry but are a small
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fraction of the stream.
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- The scene graph is the **full DPL hierarchy** — zone → dcs → instance →
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object → lod → geogroup → geometry — with **DCS transform matrices**
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positioning each mech/prop. flyk's DIVRGB put geometry directly in
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geogroups at world coordinates.
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## Remaining (Phase 3d: game geometry on screen)
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The window currently shows only the view background for the game because the
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live backend's `scene_publish_frame()` walks the *flat* flyk layout
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(geogroup→geometry at world coords). To draw the game's mechs it must:
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1. **Traverse the full hierarchy** (instance/object/lod/geogroup) and **apply
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DCS transform matrices** (accumulate the 4×4s down the graph) so each mech
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lands at its world position; pick a LOD.
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2. **Arena content search path**: the game logs `couldn't load object
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thr_tshd.bgf` — that object lives in `VIDEO/GEO/ARENA/` and `…/POLAR/`
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(arena-specific), not the top `GEO` dir; the geometry search path needs the
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selected arena subdir (a `setenv`/config detail, not protocol).
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3. **Texturing** (action 26 texel maps + SVT), lighting, depth/material.
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Current backend is flat-shaded untextured polys.
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4. **DOS/4GW sync variant** for the CYCLE `flyk yip.scn` fixture (Red Planet
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geometry) — the older action-check sync.
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