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Istvan Matejcsok 071eef5454 feat(3d): gl1 shim M0-M2 — FFP-on-WebGL2 substrate + lighting; 12 scenarios truly green

wasm/gl1: the GL1.x fixed-function emulation layer replacing the
gl_ffp_stub.c no-ops in the 3d-regression harness link. This batch:

- symbol split: 52 FFP-only entry points implemented; 10 Emscripten-owned
  names intercepted via wasm-ld --wrap (sources.txt/wrapped_symbols.txt are
  the shared manifests for both link sites; production hookup lands in M7)
- matrix stacks (MODELVIEW/PROJECTION, glGetFloatv readback), immediate
  mode with all 8 GL1 primitive conversions, GL1-default state mirror
- full GL 1.5 Gouraud lighting uber-shader (eye-space light capture at
  glLightfv time, color-material, two-side, COMBINE evaluator + alpha test
  wired but inert until M3/M5)
- draw routing: FFP traffic identified by GL_VERTEX_ARRAY client state;
  blit/2D-GAL draws pass through untouched
- display lists: correct glGenLists/glIsList existing-empty semantics;
  recorder itself is M3 (recorded commands drop with a one-time warning)

Parity: 20/47 under the 0.02 floor, of which 12 verified genuinely
rendering (bg-gradient x2, bounding-box, half-open-cylinder, segment x2,
material x3, light x3 — eyeballed against baselines); the other 8 are
small-geometry scenarios whose missing GLU/display-list content sits under
the floor (become real in M3/M4).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

2026-07-03 15:45:58 +02:00

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wasm/gl1 — GL 1.x fixed-function pipeline on WebGL2

Emulation layer that lets KiCad's 3D viewer renderer (RENDER_3D_OPENGL, pure GL 1.x fixed-function, compiled unmodified) render in the browser. Supersedes the no-op link stubs of wasm/stubs/gl_ffp_stub.c (git history has the old file): same public surface, real implementations.

TDD harness: tests/3d-regression/ — 47 native-golden scenarios; parity via npm run 3d:check:parity (see that README).

How the symbols resolve

In the WASM build, gl* are plain C functions split between two providers:

Emscripten's WebGL library (-sMAX_WEBGL_VERSION=2) owns every modern/WebGL2 name (glClear, glDrawArrays, glTexImage2D, buffers, shaders, stencil...).
This shim owns the FFP-only names WebGL2 lacks (glBegin, display lists, matrix stack, glLight*/glMaterial*, client-array pointers, glTexEnv*, glAlphaFunc, GLU quadrics) — see src/gl1_entry_ffp.cpp.

The emulator must also observe a few Emscripten-owned calls (FFP glEnable caps, draws over client arrays, matrix readback, state recorded inside display lists). Those are intercepted with wasm-ld --wrap: every name in wrapped_symbols.txt gets a -Wl,--wrap=<sym> flag at both link sites, the interceptors live in src/gl1_entry_wrapped.cpp, and __real_* forwards to the WebGL library. No kicad/wxwidgets sources are touched.

Link sites (both read sources.txt + wrapped_symbols.txt):

tests/3d-regression/wasm/Makefile (the TDD harness)
scripts/kicad/build-kicad-target.sh (GL3D_LINK_FLAGS, production kicad_editor)

Draw routing

A glDrawArrays/glDrawElements call is FFP traffic iff GL_VERTEX_ARRAY client state is enabled: only GL1 code calls glEnableClientState, while the raytracer blit (eda_3d_canvas_wasm.cpp) and the 2D WebGL GAL drive their own GLSL programs and never touch client state — their draws pass through untouched.

Invariants that are easy to break (learned from the native goldens)

Display lists snapshot client arrays at record time. The renderer sets gl*Pointer, records glDrawArrays inside glNewList, then delete[]s the arrays right after glEndList (layer_triangles.cpp) — a recorder that stores pointers reads freed memory. Copy eagerly at record.
Lights live in eye space, captured at glLightfv time. init_lights() runs under an identity modelview → the directional lights are anchored to the camera. Re-deriving light directions at draw time breaks every lit scenario.
Do not "fix" mismatched normal counts. generate_middle_triangles rejecting countersink walls (normals ≠ vertices) is upstream KiCad behavior the goldens document; tolerating it would diverge from native.
Lighting is per-vertex (Gouraud) to match fixed-function output; per-fragment lighting visibly mismatches speculars on coarse meshes.

Layout

sources.txt / wrapped_symbols.txt   single source of truth for both link sites
include/gl1_shim.h                  internal API + the state mirror
src/gl1_entry_ffp.cpp               the 52 FFP-only public entry points
src/gl1_entry_wrapped.cpp           __wrap_* interceptors (mechanism-aware TU)
src/gl1_state.cpp                   state singleton, capability routing
src/gl1_matrix.cpp                  MODELVIEW/PROJECTION stacks (+readback)
src/gl1_immediate.cpp               glBegin/glEnd + primitive conversion
src/gl1_dlist.cpp                   display-list recorder/replayer
src/gl1_draw.cpp                    draw execution (stream VBO, attrib setup)
src/gl1_shaders.cpp                 the FFP uber-program (ES 3.00) + uniforms
src/gl1_glu.cpp                     GLU quadrics (SGI tessellation) + gluPerspective

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