Artisan Data Types

Below are the data types most commonly used in the Artisan API.


Data Types Used In The Artisan API

Type Describes
AEGP_RenderLayerContextH State information at the time of a render request, sent to an Artisan by After Effects.
PR_RenderContextH A collection of settings defining what is to be rendered, and how.
AEGP_SoundDataH The audio settings used for a given layer.
AEGP_RenderReceiptH AEGP_FrameReceiptH Used by Artisans when rendering.
AEGP_WorldH A frame of pixels.
AEGP_RenderOptionsH The settings associated with a render queue item.

Horz? Vert?

After Effects’ matrix is row based; OpenGL’s is column based. This means more work for you. Yay, billable hours!


Implementation And Design

An Artisan is nearly an application unto itself. Because we realized early in the After Effects 5.0 that there are many ways to approach the problems inherent in 3D rendering; intersections and shading, for example.

We provided an API with which we and third parties (yes, we really do use our own APIs) could implement any 3D rendering scheme desired.


3D Compositing, Not Modeling

After Effects is not a 3D modeling application. Users work in a responsive mode, switching to higher quality only at for proofing or final output. Consider providing at least two quality modes, one for layout and another for final output. Be conscious of render time in low quality mode.


Registering An Artisan

An Artisan is an AEGP, and has a single entry point. Artisans must also register their own function entry points and have a special callback for this purpose. See AEGP_RegisterArtisan() from AEGP_RegisterSuites5.

This tables shows the functions that Artisans can support as defined by PR_ArtisanEntryPoints: only render_func is required.

Artisan Entry Points

PR_ArtisanEntryPoints  
global_setup_func0

Called only once, right after GP_Main. The global data is common across all instances of the plug-in. If you allocate memory during Global Setup, you must free it during your global_setdown_func.

PR_GlobalSetupFunc(
  const PR_InData    *in_dataP,
  PR_GlobalContextH  global_contextH,
  PR_GlobalDataH     *global_dataPH);
global_setdown_func0

Dispose of any global data you allocated.

PR_GlobalSetdownFunc(
  const PR_InData    *in_dataP,
  PR_GlobalContextH  global_contextH,
  PR_GlobalDataH     global_dataH);
global_do_about_func0

Tell the world about yourself! Use in_dataP>msg_func to display your dialog.

PR_GlobalDoAboutFunc(
  const PR_InData    *in_dataP,
  PR_GlobalContextH  global_contextH,
  PR_GlobalDataH     global_dataH);
setup_instance_func0

Allocate and instantiate any data specific to this instance of your Artisan.

PR_InstanceSetupFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceFlags     flags,
  PR_FlatHandle        flat_dataH0,
  PR_InstanceDataH     *instance_dataPH);
setdown_instance_func0

Deallocate and free any data specific to this instance of your Artisan.

PR_InstanceSetdownFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH);
flatten_instance_func0

Flatten your data in preparation to being written to disk. (making sure it’s OS independent, if your Artisan is).

PR_FlattenInstanceFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH,
  PR_FlatHandle        *flatH);
do_instance_dialog_func0

If your Artisan has a additional parameters (accessed through its Options dialog), this function will be called to get and set them.

PR_DoInstanceDialogFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH,
  PR_DialogResult      *resultP);

PR_DialogResultis is either PR_DialogResult_NO_CHANGE or PR_DialogResult_CHANGE_MADE.

frame_setup_func0

Perform any setup necessary to render a frame (called immediately before rendering).

PR_FrameSetupFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH
  PR_RenderContextH    render_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH,
  PR_RenderDataH       *render_dataPH);
frame_setdown_func0

Dispose of any setup data allocated during frame_setup (sent immediately after rendering).

PR_FrameSetdownFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH
  PR_RenderContextH    render_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH,
  PR_RenderDataH       render_dataH);
render_func

Render the scene.

PR_FrameRenderFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH
  PR_RenderContextH    render_contextH,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH,
  PR_RenderDataH       render_dataH);
query_func0

Artisans can draw their own projection axes, should the need arise. After Effects will call this function to obtain the transform between the composition world and those axes, as well as for a number of other functions related to on- and off-screen preview drawing (the former is relevant only to interactive artisans).

PR_QueryFunc(
  const PR_InData      *in_dataP,
  PR_GlobalContextH    global_contextH,
  PR_InstanceContextH  instance_contextH
  PR_QueryContextH     query_contextH,
  PR_QueryType         query_type,
  PR_GlobalDataH       global_dataH,
  PR_InstanceDataH     instance_dataH);

PR_QueryType can be one of the following:

  • PR_QueryType_NONE = 0,
  • PR_QueryType_TRANSFORM,
  • PR_QueryType_INTERACTIVE_WINDOW_DISPOSE,
  • PR_QueryType_INTERACTIVE_WINDOW_CLEAR,
  • PR_QueryType_INTERACTIVE_WINDOW_FROZEN_PROXY,
  • PR_QueryType_INTERACTIVE_SWAP_BUFFER,
  • PR_QueryType_INTERACTIVE_DRAW_PROCS,
  • PR_QueryType_PREPARE_FOR_LINE_DRAWING,
  • PR_QueryType_UNPREPARE_FOR_LINE_DRAWING,
  • PR_QueryType_GET_CURRENT_CONTEXT_SAFE_FOR_LINE_DRAWING,
  • PR_QueryType_GET_ARTISAN_QUALITY

New in CS6.


The World Is Your Canvas

AEGP_RenderTexture() supplies the raw pixels of a layer, untransformed, into an arbitrarily-sized buffer.

AEGP_RenderLayer() invokes the entire After Effects render pipeline, including transforms, masking, et cetera, providing the layer as it appears in its composition, in a composition-sized buffer.

If the layer being rendered is 3D, the default (Standard 3D) Artisan is invoked to perform any 3D geometrics.

Your Artisan can use this to render track matte layers, and apply them only in a strictly 2D sense, to the transformed 3D layer.

Before rendering, the Artisans that ship with After Effects apply an inverse transform to get square pixels, then re-apply the transform before display.

For example, if the pixel aspect ratio is 10/11 (DV NTSC), we multiply by 11/10 to get square pixels. We process and composite 3D layers, then re-divide to get back to the original pixel aspect ratio.

The following suite supplies the layers, compositions, texture and destination buffers. This is a vital suite for all artisans.

AEGP_CanvasSuite8

Note

Functions below are for interactive artisans only.

Function Purpose
AEGP_GetPlatformWindowRef

Retrieves the platform-specific window context into which to draw the given PR_RenderContextH.

AEGP_GetPlatformWindowRef(
  const PR_RenderContextH  contextH,
  AEGP_PlatformWindowRef   *window_refP);
AEGP_GetViewportScale

Retrieves the source-to-frame downsample factor for the given PR_RenderContextH.

AEGP_GetViewportScale(
  const PR_RenderContextH  contextH,
  A_FpLong                 *scale_xPF,
  A_FpLong                 *scale_yPF);
AEGP_GetViewportOrigin

Retrieves to origin of the source, within the frame (necessary to translate between the two), for the given PR_RenderContextH.

AEGP_GetViewportOrigin(
  const PR_RenderContextH  contextH,
  A_long                   *origin_xPL,
  A_long                   *origin_yPL);
AEGP_GetViewportRect

Retrieves the bounding rectangle for the area to be drawn, for the given PR_RenderContextH.

AEGP_GetViewportRect(
  const PR_RenderContextH  contextH,
  A_LegacyRect             *v_rectPR);
AEGP_GetFallowColor

Retrieves the color used for the fallow regions in the given PR_RenderContextH.

AEGP_GetFallowColor(
  const PR_RenderContextH  contextH,
  PF_Pixel8                *fallow_colorP);
AEGP_GetInteractiveCheckerboard

Retrieves whether or not the checkerboard is currently active for the given PR_RenderContextH.

AEGP_GetInteractiveCheckerboard(
  const PR_RenderContextH  contextH,
  A_Boolean                *cboard_onPB);
AEGP_GetInteractiveCheckerboardColors

Retrieves the colors used in the checkerboard.

AEGP_GetInteractiveCheckerboardColors(
  const PR_RenderContextH  contextH,
  PF_Pixel                 *color1P,
  PF_Pixel                 *color2P);
AEGP_GetInteractiveCheckerboardSize

Retrieves the width and height of one checkerboard square.

AEGP_GetInteractiveCheckerboardSize(
  const PR_RenderContextH  contextH,
  A_u_long                 *cbd_widthPLu,
  A_u_long                 *cbd_heightPLu);
AEGP_GetInteractiveCachedBuffer

Retrieves the cached AEGP_WorldH last used for the PR_RenderContextH.

AEGP_GetInteractiveCachedBuffer(
  const PR_RenderContextH  contextH,
  AEGP_WorldH              *buffer);
AEGP_ArtisanMustRenderAsLayer

Determines whether or not the artisan must render the current AEGP_RenderLayerContextH as a layer.

AEGP_ArtisanMustRenderAsLayer(
  const PR_RenderContextH   contextH,
  AEGP_RenderLayerContextH  layer_contextH,
  A_Boolean                 *use_txturePB);
AEGP_GetInteractiveDisplayChannel

Returns which channels should be displayed by the interactive artisan.

AEGP_GetInteractiveDisplayChannel(
  const PR_RenderContextH  contextH,
  AEGP_DisplayChannelType  *channelP);

AEGP_DisplayChannelType will be one of the following:

  • AEGP_DisplayChannel_NONE
  • AEGP_DisplayChannel_RED
  • AEGP_DisplayChannel_GREEN
  • AEGP_DisplayChannel_BLUE
  • AEGP_DisplayChannel_ALPHA
  • AEGP_DisplayChannel_RED_ALT
  • AEGP_DisplayChannel_GREEN_ALT
  • AEGP_DisplayChannel_BLUE_ALT
  • AEGP_DisplayChannel_ALPHA_ALT
AEGP_GetInteractiveExposure

Returns the exposure for the given PR_RenderContextH, expressed as a floating point number.

AEGP_GetInteractiveExposure(
  const PR_RenderContextH  rcH,
  A_FpLong                 *exposurePF);
AEGP_GetColorTransform

Returns the color transform for the given PR_RenderContextH.

AEGP_GetColorTransform)(
  const PR_RenderContextH  render_contextH,
  A_Boolean                *cms_onB,
  A_u_long                 *xform_keyLu,
  void                      *xformP);
AEGP_GetCompShutterTime

Returns the shutter angle for the given PR_RenderContextH.

AEGP_GetCompShutterTime)(
  PR_RenderContextH  render_contextH,
  A_Time             *shutter_time,
  A_Time             *shutter_dur);
AEGP_MapCompToLayerTime

New in CC. Unlike AEGP_ConvertCompToLayerTime, this handles time remapping with collapsed or nested comps.

AEGP_MapCompToLayerTime(
  PR_RenderContextH         render_contextH,
  AEGP_RenderLayerContextH  layer_contextH,
  const A_Time              *comp_timePT,
  A_Time                    *layer_timePT);

Convert Between Different Contexts

Convert between render and instance contexts, and manage global data specific to the artisan.

AEGP_ArtisanUtilSuite1

Function Purpose
AEGP_GetGlobalContextFromInstanceContext

Given an instance context, returns a handle to the global context.

AEGP_GetGlobalContextFromInstanceContext(
  const PR_InstanceContextH  instance_contextH,
  PR_GlobalContextH          *global_contextPH);
AEGP_GetInstanceContextFromRenderContext

Given the render context, returns a handle to the instance context.

AEGP_GetInstanceContextFromRenderContext(
  const PR_RenderContextH  render_contextH,
  PR_InstanceContextH      *instnc_ctextPH);
AEGP_GetInstanceContextFromQueryContext

Given a query context, returns a handle to the instance context.

AEGP_GetInstanceContextFromQueryContext(
  const PR_QueryContextH  query_contextH,
  PR_InstanceContextH     *instnce_contextPH);
AEGP_GetGlobalData

Given the global context, returns a handle to global data.

AEGP_GetGlobalData(
  const PR_GlobalContextH  global_contextH,
  PR_GlobalDataH           *global_dataPH);
AEGP_GetInstanceData

Given an instance context, return the associated instance data.

AEGP_GetInstanceData(
  const PR_InstanceContextH  instance_contextH,
  PR_InstanceDataH           *instance_dataPH);
AEGP_GetRenderData

Given a render context, returns the associated render data.

AEGP_GetRenderData(
  const PR_RenderContextH  render_contextH,
  PR_RenderDataH           *render_dataPH);

Smile! Cameras

Obtains the camera geometry, including camera properties (type, lens, depth of field, focal distance, aperture, et cetera).

AEGP_CameraSuite2

Function Purpose
AEGP_GetCamera

Given a layer handle and time, returns the current camera layer handle.

AEGP_GetCamera(
  PR_RenderContextH  render_contextH,
  const A_Time       *comp_timeP,
  AEGP_LayerH        *camera_layerPH);
AEGP_GetCameraType

Given a layer, returns the camera type of the layer.

AEGP_GetCameraType(
  AEGP_LayerH      aegp_layerH,
  AEGP_CameraType  *camera_typeP;

The camera type can be the following:

  • AEGP_CameraType_NONE = -1
  • AEGP_CameraType_PERSPECTIVE
  • AEGP_CameraType_ORTHOGRAPHIC
AEGP_GetDefaultCameraDistanceToImagePlane

Given a composition handle, returns the camera distance to the image plane.

AEGP_GetDefaultCamera DistanceToImagePlane(
  AEGP_CompH  compH,
  A_FpLong    *dist_to_planePF)
AEGP_GetCameraFilmSize

Retrieves the size (and units used to measure that size) of the film used by the designated camera.

AEGP_GetCameraFilmSize(
  AEGP_LayerH         camera_layerH,
  AEGP_FilmSizeUnits  *film_size_unitsP,
  A_FpLong            *film_sizePF0);
AEGP_SetCameraFilmSize

Sets the size (and unites used to measure that size) of the film used by the designated camera.

AEGP_SetCameraFilmSize)(
  AEGP_LayerH         camera_layerH,
  AEGP_FilmSizeUnits  film_size_units,
  A_FpLong            *film_sizePF0);

Notes Regarding Camera Behavior

Camera orientation is in composition coordinates, and the rotations are in layer (the camera’s layer) coordinates.

If the camera layer has a parent, the position is in a coordinate space relative to the parent.


Orthographic Camera Matrix

Internally, we use composition width and height to set the matrix described by the OpenGL specification as

glOrtho(-width/2, width/2, -height/2, height/2, -1, 100);

The orthographic matrix describes the projection. The position of the camera is described by another, scaled matrix. The inverse of the camera position matrix provides the “eye” coordinates.


Focus On Focal

Remember, focal length affects field of view; focal distance only affects depth of field.


Film Size

In the real world, film size is measured in millimeters. In After Effects, it’s measured in pixels. Multiply by 72 and divide by 25.4 to move from millimeters to pixels.

Field of view is more complex;

ϴ = 1/2 field of view

tan(ϴ) = 1/2 composition height / focal length

focal length = 2 tan(ϴ) / composition height


Hit The Lights!

Get and set the type of lights in a composition.

AEGP_LightSuite2

Function Purpose
AEGP_GetLightType

Retrieves the AEGP_LightType of the specified camera layer.

AEGP_GetLightType(
  AEGP_LayerH     light_layerH,
  AEGP_LightType  *light_typeP);

AEGP_LightType will be one of the following:

  • AEGP_LightType_PARALLEL
  • AEGP_LightType_SPOT
  • AEGP_LightType_POINT
  • AEGP_LightType_AMBIENT
AEGP_SetLightType

Sets the AEGP_LightType for the specified camera layer.

AEGP_SetLightType(
  AEGP_LayerH     light_layerH,
  AEGP_LightType  light_type);

Notes On Light Behavior

The formula for parallel lights is found in Foley and Van Dam’s “Introduction to Computer Graphics” (ISBN 0-201-60921-5) as is the formula for point lights.

We use the half angle variant proposed by Jim Blinn instead.

Suppose we have a point on a layer and want to shade it with the light.

Let V be the unit vector from the layer point to the eye point. Let L be the unit vector to the light (in the parallel light case this is constant). Let H be (V+L)/2 (normalized). Let N be the unit normal vector to the layer.

The amount of specular reflected light is S * power(H Dot N, shine), where S is the specular coefficient.


How Should I Draw That?

After Effects relies upon Artisans to draw 3D layer handles. If your Artisan chooses not to respond to this call, the default Artisan will draw 3D layer handles for you. Querying transforms is important for optimization of After Effects’ caching.

The coordinate system is positive x to right, positive y down, positive z into the screen. The origin is the upper left corner. Rotations are x then y then z. For matrices the translate is the bottom row, orientations are quaternions (which are applied first), then any x-y-z rotation after that. As a general rule, use orientation or rotation but not both. Also use rotations if you need control over angular velocity.


Query Transform Functions

These functions give artisans information about the transforms they’ll need in order to correctly place layers within a composition and respond appropriately to the various queries After Effects will send to their PR_QueryFunc entry point function.

As that entry point is optional, so is your artisan’s response to the queries; however, if you don’t, your users may be disappointed that (while doing interactive preview drawing) all the camera and light indicators vanish, until they stop moving! Artisans are complex beasts; contact us if you have any questions.

AEGP_QueryXFormSuite2

Function Purpose
AEGP_QueryXformGetSrcType

Given a query context, returns trasnsform source currently being modified.

AEGP_QueryXformGetSrcType(
  PR_QueryContextH     query_contextH,
  AEGP_QueryXformType  *src_type);

The query context will be one of the following:

  • AEGP_Query_Xform_LAYER,
  • AEGP_Query_Xform_WORLD,
  • AEGP_Query_Xform_VIEW,
  • AEGP_Query_Xform_SCREEN
AEGP_QueryXformGetDstType

Given a query context, returns the currently requested transform destination.

AEGP_QueryXformGetDstType(
  PR_QueryContextH     query_contextH,
  AEGP_QueryXformType  *dst_type);
AEGP_QueryXformGetLayer

Used if the source or destination type is a layer. Given a query context, returns the layer handle.

AEGP_QueryXformGetLayer(
  PR_QueryContextH  query_contextH,
  AEGP_LayerH       *layerPH);
AEGP_QueryXformGetComp

Given a query context, returns the current composition handle.

AEGP_QueryXformGetComp(
  PR_QueryContextH  query_contextH,
  AEGP_CompH        *compPH);
AEGP_QueryXformGetTransformTime

Given a query context, returns the time of the transformation.

AEGP_QueryXformGetTransformTime(
  PR_QueryContextH  query_contextH,
  A_Time            *time);
AEGP_QueryXformGetViewTime

Given a query context, returns the time of the associated view.

AEGP_QueryXformGetViewTime(
  PR_QueryContextH  query_contextH,
  A_Time            *time);
AEGP_QueryXformGetCamera

Given a query context, returns the current camera layer handle.

AEGP_QueryXformGetCamera(
  PR_QueryContextH  query_contextH,
  AEGP_LayerH       *camera_layerPH);
AEGP_QueryXformGetXform

Given a query context, returns the current matrix transform.

AEGP_QueryXformGetXform(
  PR_QueryContextH  query_contextH,
  A_Matrix4         *xform);
AEGP_QueryXformSetXform

Given a query context, return the matrix transform you compute in xform.

AEGP_QueryXformSetXform(
  PR_QueryContextH  query_contextH,
  A_Matrix4         *xform);
AEGP_QueryWindowRef

Sets the window reference to be used (by After Effects) for the given PR_QueryContextH.

AEGP_QueryWindowRef(
  PR_QueryContextH        q_contextH,
  AEGP_PlatformWindowRef  *window_refP);
AEGP_QueryWindowClear

Returns which AEGP_PlatformWindowRef (and A_Rect) to clear, for the given PR_QueryContextH.

AEGP_QueryWindowClear(
  PR_QueryContextH        q_contextH,
  AEGP_PlatformWindowRef  *window_refP,
  A_LegacyRect            *boundsPR);
AEGP_QueryFrozenProxy

Returns whether or not the textures used in the given PR_QueryContextH should be frozen.

AEGP_QueryFrozenProxy(
  PR_QueryContextH  q_contextH,
  A_Boolean         *onPB);
AEGP_QuerySwapBuffer

Sent after rendering and camera/light handle drawing is complete; After Effects returns the buffer into which the artisan should draw its output.

AEGP_QuerySwapBuffer(
  PR_QueryContextH        q_contextH,
  AEGP_PlatformWindowRef  *window_refP,
  AEGP_WorldH             *dest_bufferp);
AEGP_QueryDrawProcs

Sets the interactive drawing functions After Effects will call while drawing camera and lighting handles into the artisan’s provided context.

AEGP_QueryDrawProcs(
  PR_QueryContextH         query_contextH,
  PR_InteractiveDrawProcs  *window_refP);
AEGP_QueryPrepareForLineDrawing

Informs After Effects about the context into which it will be drawing.

AEGP_QueryPrepareForLineDrawing(
  PR_QueryContextH        query_contextH,
  AEGP_PlatformWindowRef  *window_refP,
  A_LegacyRect            *viewportP,
  A_LPoint                *originP,
  A_FloatPoint            *scaleP);
AEGP_QueryUnprepareForLineDrawing

As far as After Effects is concerned, the artisan is done drawing lines.

AEGP_QueryUnprepareForLineDrawing(
  PR_QueryContextH        query_contextH,
  AEGP_PlatformWindowRef  *window_refP);

Interactive Drawing Functions

We’ve added the ability for artisans to provide functions After Effects can use to do basic drawing functions for updating the comp window display during preview, including camera, light, and wireframe preview modeling.

PR_InteractiveDrawProcs

Function Purpose
PR_Draw_MoveToFunc
PR_Draw_MoveToFunc(
  short  x,
  short  y);
PR_Draw_LineToFunc
PR_Draw_LineToFunc(
  short  x,
  short  y);
PR_Draw_ForeColorFunc
PR_Draw_ForeColorFunc(
  const A_Color  *fore_colo
PR_Draw_FrameRectFunc
PR_Draw_FrameRectFunc(
  const A_Rect  *rectPR );
PR_Draw_PaintRectFunc
PR_Draw_PaintRectFunc(
  const A_Rect  *rectPR );

Notes On Query Time Functions

AEGP_QueryXformGetTransformTime() and AEGP_QueryXformGetViewTime() are both necessary for an artisan to build a representation of the scene to render.

AEGP_QueryXformGetTransformTime() gets the time of the transform, which is then passed to AEGP_GetCompShutterFrameRange() from AEGP_CompSuite11.

AEGP_QueryXformGetViewTime() gets the time of the view, which is used in calling AEGP_GetLayerToWorldXformFromView() from AEGP_LayerSuite8.