Fix: SPIR-V Validation Rejects Loop With Unbounded Iterations

Quick answer: SPIR-V validation rejecting a shader loop with 'cannot bound iteration count'? Validators require explicit iteration bounds for safety - use a compile-time max or LoopHint.

Raymarch loop has data-dependent termination. Validation: cannot determine iteration count.

Add explicit max bound

for (int i = 0; i < MAX_STEPS; i++) {
  if (hit) break;
}

Compile-time max bound satisfies validators while preserving the early-exit behavior.

Use loop_hint

HLSL: [loop][allow_uav_condition]. Tells the compiler the loop is intentional; bypasses some validators.

Profile loop max

MAX_STEPS = 64 may be too low for landscape shots, too high for close-ups. Tune per-content; not just compile.

“Shader loops are bounded by hardware. The bound has to be visible to validators.”

Build a small shader test that hits the max-step bound. If it's not visible (no shimmer), MAX_STEPS is fine; if it shimmers, raise it.