FA-10771 / Raster memory layout / Open access
Texture mirror repeat period · case 01
Ordinary repeat wraps instead of reversing every alternate texture copy.
ROOT CAUSE
Ordinary repeat wraps instead of reversing every alternate texture copy.
VERIFIED REPAIR
Use the stage contract: Mirror-repeat integer texel indices with duplicated edge texels and period twice the positive texture size.
Unsuccessful approach: Edge clamping never traverses reflected texels beyond the texture.
Case contract
Mirror-repeat integer texel indices with duplicated edge texels and period twice the positive texture size.
Why this case matters
A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(coordinate, size):
return coordinate%size
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(4, 4)), 3)
check('fixture 2', solve(*(5, 4)), 2)
check('fixture 3', solve(*(-1, 4)), 0)
check('fixture 4', solve(*(8, 4)), 0)
check('fixture 5', solve(*(2, 4)), 2)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| fixture 1 | 0 | 3 | Failed |
| fixture 2 | 1 | 2 | Failed |
| fixture 3 | 3 | 0 | Failed |
| fixture 4 | 0 | 0 | Passed |
| fixture 5 | 2 | 2 | Passed |
SHA-256 / 10ffe12e6cc957962875000d5825b4a9859a130b584bf4a453775abd6cd69e88
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(coordinate, size):
return min(size-1,max(0,coordinate))
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(4, 4)), 3)
check('fixture 2', solve(*(5, 4)), 2)
check('fixture 3', solve(*(-1, 4)), 0)
check('fixture 4', solve(*(8, 4)), 0)
check('fixture 5', solve(*(2, 4)), 2)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| fixture 1 | 3 | 3 | Passed |
| fixture 2 | 3 | 2 | Failed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 3 | 0 | Failed |
| fixture 5 | 2 | 2 | Passed |
SHA-256 / d4dc2ceddd1c6bdd817f5d22eeb7847689cd279bfce6ff0398f5f6cabf7e5735
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(coordinate, size):
return (coordinate%(2*size)) if coordinate%(2*size)<size else 2*size-1-coordinate%(2*size)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(4, 4)), 3)
check('fixture 2', solve(*(5, 4)), 2)
check('fixture 3', solve(*(-1, 4)), 0)
check('fixture 4', solve(*(8, 4)), 0)
check('fixture 5', solve(*(2, 4)), 2)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| fixture 1 | 3 | 3 | Passed |
| fixture 2 | 2 | 2 | Passed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 5 | 2 | 2 | Passed |
SHA-256 / 3b89fe6315df06e494b36c24a211e2393e472357b341f5edf20e44b3ec272d7f
Verification & scope
This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:38:41.970420+00:00.
Case digest / 4e71012f4eeac939d1768ffe828e7b860bbeb8f0370a6b32062871113a81d770