G-buffer: terrain-free static shader + terrain pipeline; slim G-buffer VS #813

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opened 2026-10-17 18:10:01 +00:00 by sky_line · 1 comment

sky_line commented

2026-10-17 18:10:01 +00:00

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Merged (be625ce523, 2c14225fd0). The G-buffer fragment shader used 112 registers because PBR terrain (mostly hex tiling) was compiled into every draw; non-terrain draws now use a 48-register shader and terrain its own (72, 112 with hex as a specialisation constant). G-buffer static pass 2.79-2.95 -> 1.92-2.18 ms (Firestorm-equivalent settings) and 4.48 -> 3.14 ms (high settings) on the GTX 1080 at 4K. Settings RenderVKGbufTerrainSplit / RenderVKGbufSlimVS (both default on).

Still to check before closing: image A/B (terrain with and without hex, coplanar terrain/prim seams), occlusion paths on, ship.

Context: measured on a GTX 1080 (Pascal) at 4K with the test-control channel and the shader clock (RenderVKShaderClockLighting) / pipeline stats (RenderVKPipelineStats). The frame is GPU-bound but not bandwidth-bound (memory controller ~36% busy on the 1080, ~14% on a 5090): it is latency / occupancy bound, so trading a little memory traffic for fewer registers and fewer dependent loads should help every GPU generation.

Merged (be625ce523, 2c14225fd0). The G-buffer fragment shader used 112 registers because PBR terrain (mostly hex tiling) was compiled into every draw; non-terrain draws now use a 48-register shader and terrain its own (72, 112 with hex as a specialisation constant). G-buffer static pass 2.79-2.95 -> 1.92-2.18 ms (Firestorm-equivalent settings) and 4.48 -> 3.14 ms (high settings) on the GTX 1080 at 4K. Settings RenderVKGbufTerrainSplit / RenderVKGbufSlimVS (both default on). Still to check before closing: image A/B (terrain with and without hex, coplanar terrain/prim seams), occlusion paths on, ship. Context: measured on a GTX 1080 (Pascal) at 4K with the test-control channel and the shader clock (RenderVKShaderClockLighting) / pipeline stats (RenderVKPipelineStats). The frame is GPU-bound but not bandwidth-bound (memory controller ~36% busy on the 1080, ~14% on a 5090): it is latency / occupancy bound, so trading a little memory traffic for fewer registers and fewer dependent loads should help every GPU generation.

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2026-10-17 18:10:01 +00:00

sky_line added this to the Slipstream project

2026-10-17 18:10:01 +00:00

sky_line referenced this issue

2026-10-17 21:14:16 +00:00

Probe captures: capture-only forward shader (no RT/SSR/mirror/debug) + light grid #829

sky_line referenced this issue

2026-10-17 22:16:24 +00:00

Probe captures: deferred opaque path (G-buffer + base lighting at probe resolution) #833

sky_line commented

2026-10-18 22:26:31 +00:00

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Fixed in Slipstream 1.3.0 (stable): https://git.slipstreamviewer.org/sky_line/Slipstream/releases/tag/v1.3.0

If you still see this on 1.3.0, reply here and we'll reopen it.

Fixed in **Slipstream 1.3.0** (stable): https://git.slipstreamviewer.org/sky_line/Slipstream/releases/tag/v1.3.0 If you still see this on 1.3.0, reply here and we'll reopen it.

sky_line closed this issue

2026-10-18 22:26:31 +00:00

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