[atomchild411]

iris-hostgl: what SGI's own IRIS GL needs from the guest library (generator hooks), and IMPACT's last two extensions

On IMPACT, SGI's IRIS GL (libgl.so, "IGLOO") is built on OpenGL. The guest tools (v20261017-proto2) can now run it on host GL: hostgl program keeps SGI's libgl.so and gives it the host-GL libGL.so. Most of that work is in the guest library. This PR has the IRIS side: the generator (tools/glshim.py) hooks the guest library's generated encoders call, and two extension names.

The change

• Two extension names. GL_SGIS_texture_border_clamp and GL_SGIX_texture_multi_buffer join the extension list.

  • The first's GL_CLAMP_TO_BORDER_SGIS is core GL_CLAMP_TO_BORDER.
  • The second is a hint the guest library takes itself.

  Every extension IMPACT's libGL names is now there except GL_SGIX_list_priority.

• Guest hooks in the generator (GUEST_HOOKS, GUEST_AFTER):

  • glReadPixels and glDrawPixels with GL_COLOR_INDEX in colour-index contexts are encoded by the guest library itself. The host's RGBA GL would turn them into index 0 through its pixel maps.
  • The texture multi-buffer hint is taken by the guest library.
  • lmcolor(LMC_COLOR): a glBegin is held until its first vertex, and lighting is put back at glEnd. IGLOO says itself which of a colour and a normal came last (glIglooInterfaceSGIX 0x81A1), as IMPACT's libGL uses it, so no hook watches glColor or glNormal.
  • swaptmesh: IGLOO draws a mesh as a GL_TRIANGLE_STRIP and asks libGL for each swap. Inside a mesh, the hooks keep each vertex with its normal, colour and texture coordinate, so the library can send the older of the last two vertices again.

The host's encoders and decoder are unchanged: calls.rs regenerates identically. The guest glshim_gen.c this generator writes is byte-for-byte the one in the guest tools release.

Tests

• cargo test --manifest-path iris-hostgl/Cargo.toml: 32 passed on macOS and on Linux (Debian 12 arm64, Mesa).
• tools/glshim.py output: calls.rs unchanged; the guest glshim_gen.c identical to guest-tools 89253f8's.
• IRIX 6.5.22m, Max IMPACT, macOS host, hostgl against sgigl on the same machine. These are the results of these hooks with the guest library:
  • UroMan: 99.9% of pixels within 8 levels (its organs need iris-hostgl: switch lighting after a clip plane goes off (macOS) #244 on macOS).
  • flight: cockpit complete in 0.55 s.
  • A 79-demo side-by-side sweep matched, apart from emulated-board gaps on the SGI side and two macOS GL issues fixed in iris-hostgl: switch lighting after a clip plane goes off (macOS) #244 and iris-hostgl: a texture's internal format is answered as the program gave it #245.

🤖 Generated with Claude Code