FA-10576 / Raster compositing / Open access
Plus blend clamps channel · case 01
Additive blend writes values above the normalized render-target maximum.
ROOT CAUSE
Additive blend writes values above the normalized render-target maximum.
VERIFIED REPAIR
Use the stage contract: Return saturated additive blending for normalized nonnegative channel inputs.
Unsuccessful approach: Maximum blending drops additive energy below saturation.
Case contract
Return saturated additive blending for normalized nonnegative channel inputs.
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(source, destination):
return source+destination
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(0.75, 0.5)), 1)
check('fixture 2', solve(*(0.25, 0.5)), 0.75)
check('fixture 3', solve(*(0, 0)), 0)
check('fixture 4', solve(*(1, 0)), 1)
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 | 1.25 | 1 | Failed |
| fixture 2 | 0.75 | 0.75 | Passed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 1 | 1 | Passed |
SHA-256 / 2b7a5fc723b65141598ae306dfcf43b3bdfe5308946f4e924899fccd18ddcc43
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(source, destination):
return max(source,destination)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(0.75, 0.5)), 1)
check('fixture 2', solve(*(0.25, 0.5)), 0.75)
check('fixture 3', solve(*(0, 0)), 0)
check('fixture 4', solve(*(1, 0)), 1)
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 | 0.75 | 1 | Failed |
| fixture 2 | 0.5 | 0.75 | Failed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 1 | 1 | Passed |
SHA-256 / 5d9447a4eea7a90b8181a42d7bb5656f26a94c00aab8b3635d9b8671dd4d4ec0
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(source, destination):
return min(1,source+destination)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(0.75, 0.5)), 1)
check('fixture 2', solve(*(0.25, 0.5)), 0.75)
check('fixture 3', solve(*(0, 0)), 0)
check('fixture 4', solve(*(1, 0)), 1)
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 | 1 | 1 | Passed |
| fixture 2 | 0.75 | 0.75 | Passed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 1 | 1 | Passed |
SHA-256 / ab7e84b1ceb69338d0ad475d2482f980b6fffda205e949346a97ecc91f515a81
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 2026-09-29T14:38:40.302886+00:00.
Case digest / 32cddb357aad79e799e61ca2b942a2cf2e277e2ad3fc6207c4381b8570f3a1ec