GraphicsEngine

from panda3d.core import GraphicsEngine

class GraphicsEngine

Bases:

Bases: ReferenceCount

This class is the main interface to controlling the render process. There is typically only one GraphicsEngine in an application, and it synchronizes rendering to all all of the active windows; although it is possible to have multiple GraphicsEngine objects if multiple synchronicity groups are required.

The GraphicsEngine is responsible for managing the various cull and draw threads. The application simply calls engine->render_frame() and considers it done.

Inheritance diagram

__init__(pipeline: Pipeline): Creates a new GraphicsEngine object. The Pipeline is normally left to default to NULL, which indicates the global render pipeline, but it may be any Pipeline you choose.

addWindow(window: GraphicsOutput, sort: int) → bool

This can be used to add a newly-created GraphicsOutput object (and its GSG) to the engine’s list of windows, and requests that it be opened. This shouldn’t be called by user code as makeOutput() normally does this under the hood; it may be useful in esoteric cases in which a custom window object is used.

This can be called during the rendering loop, unlike makeOutput(); the window will be opened before the next frame begins rendering. Because it doesn’t call openWindows(), however, it’s not guaranteed that the window will succeed opening even if it returns true.

property auto_flip → bool

Getter

Returns the current setting for the auto-flip flag. See setAutoFlip().

Setter

Set this flag true to indicate the GraphicsEngine should automatically cause windows to sync and flip as soon as they have finished drawing, rather than waiting for all of the windows to finish drawing first so they can flip together.

This only affects the timing of when the flip occurs. If this is true (the default), the flip occurs before renderFrame() returns. If this is false, the flip occurs whenever flipFrame() is called, or at the beginning of the next call to renderFrame(), if flipFrame() is never called.

property default_loader → Loader: Returns/Sets the Loader object that will be assigned to every GSG created with with /this this/ GraphicsEngine. See GraphicsStateGuardian.setLoader().

dispatchCompute(work_groups: LVecBase3i, sattr: ShaderAttrib, gsg: GraphicsStateGuardian)

Asks the indicated GraphicsStateGuardian to dispatch the compute shader in the given ShaderAttrib using the given work group counts. This can act as an interface for running a one-off compute shader, without having to store it in the scene graph using a ComputeNode.

Since this requires a round-trip to the draw thread, it may require waiting for the current thread to finish rendering if it is called in a multithreaded environment. However, you can call this several consecutive times on different textures for little additional cost.

The return value is true if the operation is successful, false otherwise.

extractTextureData(tex: Texture, gsg: GraphicsStateGuardian) → bool

Asks the indicated GraphicsStateGuardian to retrieve the texture memory image of the indicated texture and store it in the texture’s ram_image field. The image can then be written to disk via Texture.write(), or otherwise manipulated on the CPU.

This is useful for retrieving the contents of a texture that has been somehow generated on the graphics card, instead of having been loaded the normal way via Texture.read() or Texture.load(). It is particularly useful for getting the data associated with a compressed texture image.

Since this requires a round-trip to the draw thread, it may require waiting for the current thread to finish rendering if it is called in a multithreaded environment. However, you can call this several consecutive times on different textures for little additional cost.

If the texture has not yet been loaded to the GSG in question, it will be loaded immediately.

The return value is true if the operation is successful, false otherwise.

flipFrame(): Waits for all the threads that started drawing their last frame to finish drawing, and then flips all the windows. It is not usually necessary to call this explicitly, unless you need to see the previous frame right away.

getAutoFlip() → bool: Returns the current setting for the auto-flip flag. See setAutoFlip().

getDefaultLoader() → Loader: Returns the Loader object that will be assigned to every GSG created with this GraphicsEngine. See GraphicsStateGuardian.setLoader().

static getGlobalPtr() → GraphicsEngine

getNumWindows() → int: Returns the number of windows (or buffers) managed by the engine.

getPortalCull() → bool: Returns the current setting for the portal culling flag.

getRenderLock() → ReMutex: Returns a ReMutex object that is held by the GraphicsEngine during the entire call to renderFrame(). While you hold this lock you can be confident that no part of the frame will be rendered (at least by the app thread).

getThreadingModel() → GraphicsThreadingModel: Returns the threading model that will be applied to future objects. See setThreadingModel().

getWindow(n: int) → GraphicsOutput: Returns the nth window or buffers managed by the engine, in sorted order.

getWindows() → list

isEmpty() → bool: Returns true if there are no windows or buffers managed by the engine, false if there is at least one.

makeBuffer(host: GraphicsOutput, name: str, sort: int, x_size: int, y_size: int) → GraphicsOutput: Syntactic shorthand for makeOutput(). This is the preferred way to create an offscreen buffer, when you already have an onscreen window or another buffer to start with. For the first parameter, pass an existing GraphicsOutput object, e.g. the main window; this allows the buffer to adapt itself to that window’s framebuffer properties, and allows maximum sharing of resources.

makeBuffer(gsg: GraphicsStateGuardian, name: str, sort: int, x_size: int, y_size: int) → GraphicsOutput

Syntactic shorthand for makeOutput(). This flavor accepts a GSG rather than a GraphicsOutput as the first parameter, which is too limiting and disallows the possibility of creating a ParasiteBuffer if the user’s graphics hardware prefers that. It also attempts to request specific framebuffer properties and may therefore do a poorer job of sharing the GSG between the old buffer and the new.

For these reasons, this variant is a poor choice unless you are creating an offscreen buffer for the first time, without an onscreen window already in existence. If you already have an onscreen window, you should use the other flavor of makeBuffer() instead, which accepts a GraphicsOutput as the first parameter.

makeOutput(pipe: GraphicsPipe, name: str, sort: int, fb_prop: FrameBufferProperties, win_prop: WindowProperties, flags: int, gsg: GraphicsStateGuardian, host: GraphicsOutput) → GraphicsOutput

makeParasite(host: GraphicsOutput, name: str, sort: int, x_size: int, y_size: int) → GraphicsOutput: Syntactic shorthand for makeBuffer().

openWindows(): Fully opens (or closes) any windows that have recently been requested open or closed, without rendering any frames. It is not necessary to call this explicitly, since windows will be automatically opened or closed when the next frame is rendered, but you may call this if you want your windows now without seeing a frame go by.

property portal_cull → bool

Getter: Returns the current setting for the portal culling flag.
Setter: Set this flag true to indicate the GraphicsEngine should start portal culling

readyFlip(): Waits for all the threads that started drawing their last frame to finish drawing. Returns when all threads have actually finished drawing, as opposed to ‘sync_frame’ we seems to return once all draw calls have been submitted. Calling ‘flip_frame’ after this function should immediately cause a buffer flip. This function will only work in opengl right now, for all other graphics pipelines it will simply return immediately. In opengl it’s a bit of a hack: it will attempt to read a single pixel from the frame buffer to force the graphics card to finish drawing before it returns

removeAllWindows(): Removes and closes all windows from the engine. This also cleans up and terminates any threads that have been started to service those windows.

removeWindow(window: GraphicsOutput) → bool

Removes the indicated window or offscreen buffer from the set of windows that will be processed when renderFrame() is called. This also closes the window if it is open, and removes the window from its GraphicsPipe, allowing the window to be destructed if there are no other references to it. (However, the window may not be actually closed until next frame, if it is controlled by a sub-thread.)

The return value is true if the window was removed, false if it was not found.

Unlike removeAllWindows(), this function does not terminate any of the threads that may have been started to service this window; they are left running (since you might open a new window later on these threads). If your intention is to clean up before shutting down, it is better to call removeAllWindows() then to call removeWindow() one at a time.

renderFrame(): Renders the next frame in all the registered windows, and flips all of the frame buffers.

property render_lock → ReMutex: Returns a ReMutex object that is held by the GraphicsEngine during the entire call to renderFrame(). While you hold this lock you can be confident that no part of the frame will be rendered (at least by the app thread).

resetAllWindows(swapchain: bool): Resets the framebuffer of the current window. This is currently used by DirectX 8 only. It calls a reset_window function on each active window to release/create old/new framebuffer

setAutoFlip(auto_flip: bool)

Set this flag true to indicate the GraphicsEngine should automatically cause windows to sync and flip as soon as they have finished drawing, rather than waiting for all of the windows to finish drawing first so they can flip together.

This only affects the timing of when the flip occurs. If this is true (the default), the flip occurs before renderFrame() returns. If this is false, the flip occurs whenever flipFrame() is called, or at the beginning of the next call to renderFrame(), if flipFrame() is never called.

setDefaultLoader(loader: Loader): Sets the Loader object that will be assigned to every GSG created with this GraphicsEngine. See GraphicsStateGuardian.setLoader().

setPortalCull(value: bool): Set this flag true to indicate the GraphicsEngine should start portal culling

setThreadingModel(threading_model: GraphicsThreadingModel): Specifies how future objects created via make_gsg(), makeBuffer(), and makeOutput() will be threaded. This does not affect any already-created objects.

syncFrame(): Waits for all the threads that started drawing their last frame to finish drawing. The windows are not yet flipped when this returns; see also flipFrame(). It is not usually necessary to call this explicitly, unless you need to see the previous frame right away.

property threading_model → GraphicsThreadingModel

Getter: Returns the threading model that will be applied to future objects. See setThreadingModel().
Setter: Specifies how future objects created via make_gsg(), makeBuffer(), and makeOutput() will be threaded. This does not affect any already-created objects.

property windows → Sequence[GraphicsOutput]: Returns the nth window or buffers managed by the engine, in sorted order.