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PF_PreRenderExtra

PF_PreRenderInput

描述 After Effects 需要渲染的内容(在 PF_RenderRequest 中)，以及请求的位深(在恰当命名的位深成员中)。

typedef struct {
  PF_LRect        rect;
  PF_Field        field;
  PF_ChannelMask  channel_mask;
  PF_Boolean      preserve_rgb_of_zero_alpha;
  char            unused[3];
  long            reserved[4];
} PF_RenderRequest;

rect 是在层坐标系。field 也相对于层原点;激活 field 是落在输出缓冲器的偶数扫描线还是奇数扫描线上，这取决于输出缓冲器的原点。

channel_mask 指定该效果应该为哪些通道提供输出。

写入其他通道的数据将被无视。

它将是下列的一种或多种，或组合在一起:

• PF_ChannelMask_ALPHA
• PF_ChannelMask_RED
• PF_ChannelMask_GREEN
• PF_ChannelMask_BLUE
• PF_ChannelMask_ARGB

如果 preserve_rgb_of_zero_alpha 像素为 TRUE，则该效果必须将透明像素的颜色内容传送到输出中。

这与 PF_OutFlag2_REVEALS_ZERO_ALPHA 相关，但不同于 PF_OutFlag2_REVEALS_ZERO_ALPHA ，它告诉 After Effects，该效果可以将这样的像素的 alpha 设置为非零值，恢复它们的可见性。

PF_PreRenderInput

Describes what After Effects needs rendered (in the PF_RenderRequest), and the bit depth requested (in the aptly-named bitdepth member).

typedef struct {
  PF_LRect        rect;
  PF_Field        field;
  PF_ChannelMask  channel_mask;
  PF_Boolean      preserve_rgb_of_zero_alpha;
  char            unused[3];
  long            reserved[4];
} PF_RenderRequest;

rect is in layer coordinates. field is also relative to the layer origin; whether the active field falls on even or odd scanlines of the output buffer depends on the origin of the output buffer.

channel_mask specifies for which channels the effect should provide output.

Data written to other channels will not be honored.

It will be one or more of the following, or’d together:

• PF_ChannelMask_ALPHA
• PF_ChannelMask_RED
• PF_ChannelMask_GREEN
• PF_ChannelMask_BLUE
• PF_ChannelMask_ARGB

If preserve_rgb_of_zero_alpha pixels is TRUE, the effect must propagate the color content of transparent pixels through to the output.

This is related to, but distinct from, PF_OutFlag2_REVEALS_ZERO_ALPHA, which tells After Effects that the effect may set alpha to non-zero values for such pixels, restoring them to visibility.

PF_PreRenderOutput

由 effect 填充，以告诉 After Effects 它计划根据输入生成什么输出。

typedef struct {
  PF_LRect                    result_rect;
  PF_LRect                    max_result_rect;
  PF_Boolean                  solid;
  PF_Boolean                  reserved;
  PF_RenderOutputFlags        flags;
  void*                       pre_render_data;
  PF_DeletePreRenderDataFunc  func;
} PF_PreRenderOutput;

pre_render_data 将在 PF_Cmd_SMART_RENDER 期间传递回效果。

目前，只有 PF_RenderOutputFlags 是 PF_RenderOutputFlag_RETURNS_EXTRA_PIXELS 。

PF_PreRenderOutput

Filled in by the effect to tell After Effects what output it plans to generate, based on the input.

typedef struct {
  PF_LRect                    result_rect;
  PF_LRect                    max_result_rect;
  PF_Boolean                  solid;
  PF_Boolean                  reserved;
  PF_RenderOutputFlags        flags;
  void*                       pre_render_data;
  PF_DeletePreRenderDataFunc  func;
} PF_PreRenderOutput;

pre_render_data will be passed back to the effect during PF_Cmd_SMART_RENDER.

Currently, the only PF_RenderOutputFlags is PF_RenderOutputFlag_RETURNS_EXTRA_PIXELS.