FA-10651 / Raster clipping / Open access

Scissor intersection empty · case 01

Combining scissor bounds as a union enlarges the drawable region.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Combining scissor bounds as a union enlarges the drawable region.

VERIFIED REPAIR

Use the stage contract: Intersect two valid integer half-open scissor rectangles [left,top,right,bottom]. Clamp negative overlap width/height to zero at the maximum start coordinate.

Unsuccessful approach: Raw intersection can return inverted bounds that a raster backend interprets as huge unsigned extents.

Case contract

Intersect two valid integer half-open scissor rectangles [left,top,right,bottom]. Clamp negative overlap width/height to zero at the maximum start coordinate.

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(a, b):
    return [min(a[0],b[0]),min(a[1],b[1]),max(a[2],b[2]),max(a[3],b[3])]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([0, 0, 4, 4], [2, 1, 6, 3])), [2, 1, 4, 3])
check('fixture 2', solve(*([0, 0, 1, 1], [3, 3, 4, 4])), [3, 3, 3, 3])
check('fixture 3', solve(*([0, 0, 2, 2], [2, 0, 3, 2])), [2, 0, 2, 2])
check('fixture 4', solve(*([0, 0, 4, 4], [1, 1, 2, 2])), [1, 1, 2, 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, 0, 6, 4]`	`[2, 1, 4, 3]`	Failed
fixture 2	`[0, 0, 4, 4]`	`[3, 3, 3, 3]`	Failed
fixture 3	`[0, 0, 3, 2]`	`[2, 0, 2, 2]`	Failed
fixture 4	`[0, 0, 4, 4]`	`[1, 1, 2, 2]`	Failed

SHA-256 / 7d768e8029a2fba29be902996ee4192ba8268b783b17feaa3dcfe97fff513a8c

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(a, b):
    return [max(a[0],b[0]),max(a[1],b[1]),min(a[2],b[2]),min(a[3],b[3])]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([0, 0, 4, 4], [2, 1, 6, 3])), [2, 1, 4, 3])
check('fixture 2', solve(*([0, 0, 1, 1], [3, 3, 4, 4])), [3, 3, 3, 3])
check('fixture 3', solve(*([0, 0, 2, 2], [2, 0, 3, 2])), [2, 0, 2, 2])
check('fixture 4', solve(*([0, 0, 4, 4], [1, 1, 2, 2])), [1, 1, 2, 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	`[2, 1, 4, 3]`	`[2, 1, 4, 3]`	Passed
fixture 2	`[3, 3, 1, 1]`	`[3, 3, 3, 3]`	Failed
fixture 3	`[2, 0, 2, 2]`	`[2, 0, 2, 2]`	Passed
fixture 4	`[1, 1, 2, 2]`	`[1, 1, 2, 2]`	Passed

SHA-256 / b2cf299ea26f733f55900cb06f866af8abc0f04d1dde65c726407fcba11fec5f

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(a, b):
    return [max(a[0],b[0]),max(a[1],b[1]),max(max(a[0],b[0]),min(a[2],b[2])),max(max(a[1],b[1]),min(a[3],b[3]))]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([0, 0, 4, 4], [2, 1, 6, 3])), [2, 1, 4, 3])
check('fixture 2', solve(*([0, 0, 1, 1], [3, 3, 4, 4])), [3, 3, 3, 3])
check('fixture 3', solve(*([0, 0, 2, 2], [2, 0, 3, 2])), [2, 0, 2, 2])
check('fixture 4', solve(*([0, 0, 4, 4], [1, 1, 2, 2])), [1, 1, 2, 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	`[2, 1, 4, 3]`	`[2, 1, 4, 3]`	Passed
fixture 2	`[3, 3, 3, 3]`	`[3, 3, 3, 3]`	Passed
fixture 3	`[2, 0, 2, 2]`	`[2, 0, 2, 2]`	Passed
fixture 4	`[1, 1, 2, 2]`	`[1, 1, 2, 2]`	Passed

SHA-256 / c2c11907d5819d00538283ba80b330d3f5cf5775698c2273c0cf70ef83629eb8

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 2026-09-29T14:38:41.008914+00:00.

Case digest / 12f028614a84350ba80f3fba46b68c42fb6e400e4b4c84496d5a6184811ff888