spaceship/tests/profile_shader.sh

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Make the lunar backdrop cheap: 3x3 field, then bake and tile it (#68) The crater shader ran on every pixel of a fullscreen rect every frame and was by far the most expensive thing in the surface scene. Nothing else came close: RockField keeps 14 rocks alive, Rock/Ship/Enemy already avoid per-frame queue_redraw() for transform-only changes, and LunarBackground.gd is a handful of scalar ops. Three reductions to the field itself: - 5x5 -> 3x3 neighbour scan. That width was never the geometric answer; it was insurance against craters seen clipping at cell boundaries on-device, i.e. a crater reaching past its nominal radius because a hash returned a value outside [0,1] and extrapolated mix(). Clamping the crater CENTRE into its own cell, alongside the radius clamp already there, bounds the reach whatever the hash returns - so a crater two cells out is >= 1.0 cells away, a normalized distance of >= 2.63, past every threshold the shading reacts to (the last saturates at 1.15). The outer ring provably cannot change a pixel. This removes the clipping bug's cause instead of hiding it behind 16 extra samples. - One hash42 per cell instead of hash21 twice plus hash22, decorrelating on output lanes rather than input offsets. - Squared distances in the loop, square-rooted twice at the end rather than once per sample. Measured with the new tests/profile_shader.sh, above softpipe's own ~657ms fullscreen floor: 9482ms -> 405ms of shader work, a 23x reduction. Then the larger change: the field is a fixed function of world position, so every frame recomputed an identical answer. It is now made periodic (the cell index is wrapped before hashing, which makes a Worley field tile exactly rather than merely blend), baked once at load into one tile, and scrolled with repeat wrapping by lunar_tiled.gdshader - one texture fetch per pixel. Two honest costs: the field repeats every 7040 world units, and a fixed-resolution tile softens when zoomed past 1:1. Lunar regolith is forgiving of both, having no landmarks and being smooth gradients already. The bake waits a frame and asks the material whether it actually samples a field_texture, so a gas giant - which swaps in its own background shader (#51) - does not pay for a 2048-square tile it will never read. Headless runs skip it entirely, having nothing to rasterize. tests/test_lunar_field.gd guards the reasoning, since a fragment shader cannot be asserted on directly: the premises are still in the source, the worst-case ring-2 geometry stays clear of every threshold independent of the hash, a 3x3 and a 5x5 scan render identically over 4000 sampled points, the field repeats exactly in both axes, and the miss sentinel still cannot overflow mediump into +Inf and then NaN. test_surface_profiles.gd asserted "a rocky landing leaves the background alone" by naming lunar_surface.gdshader; it now reads the shader from the scene, which is the property it actually cares about. PlanetSurface.tscn's edit also carries the planet-name relocation described in the HUD commit - same scene file, so the two cannot be split. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-17 23:20:14 +02:00
#!/data/data/com.termux/files/usr/bin/bash
# Times a fullscreen background shader's per-pixel cost. Same Xvfb + Mesa
# softpipe rig as screenshot.sh (see the long note there about llvmpipe
# crashing with SIGILL in this environment), because a fragment shader can
# only be timed if something actually rasterizes it - --headless renders
# nothing at all.
#
# Softpipe is a CPU rasterizer, so treat the numbers as RELATIVE only:
# comparing two versions of the same shader is meaningful, comparing against
# a phone's frame budget is not.
#
# Usage: bash tests/profile_shader.sh <shader_res_path> [timed_frames] [warmup] [WxH]
# Example: bash tests/profile_shader.sh res://lunar_surface.gdshader 30 10 720x1280
set -e
PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
GODOT_BIN="/root/Godot_v4.7.1-stable_linux.arm64"
SHADER_PATH="${1:?usage: profile_shader.sh <shader_res_path> [timed_frames] [warmup] [WxH]}"
TIMED_FRAMES="${2:-30}"
WARMUP_FRAMES="${3:-10}"
RESOLUTION="${4:-720x1280}"
proot-distro login ubuntu -- bash -c "
pkill -x Xvfb >/dev/null 2>&1 || true
rm -f /tmp/.X99-lock /tmp/.X11-unix/X99
Xvfb :99 -screen 0 ${RESOLUTION}x24 &
XVFB_PID=\$!
trap 'kill \$XVFB_PID >/dev/null 2>&1 || true' EXIT
sleep 2
mkdir -p /tmp/xdgrt && chmod 700 /tmp/xdgrt
cd '$PROJECT_DIR'
DISPLAY=:99 XDG_RUNTIME_DIR=/tmp/xdgrt GALLIUM_DRIVER=softpipe '$GODOT_BIN' --audio-driver Dummy --rendering-driver opengl3 --rendering-method gl_compatibility --resolution '$RESOLUTION' -s res://tests/_profile_surface_shader.gd -- '$SHADER_PATH' '$TIMED_FRAMES' '$WARMUP_FRAMES'
"