Package Jitter

jit.gl.asyncread

Read back from an OpenGL framebuffer

Description

Uses Pixel Buffer Objects (PBOs) to perform asynchronous reads of the OpenGL context at high framerates. The performance gain comes from using two pixel buffer objects in tandem to amortize the cost of the read operation over time without blocking other rendering commands from executing as is typically the case when naive methods are used.

Discussion

This object requires one argument: the name of a drawing context. A named drawing context is a named instance of a jit.window, jit.pwindow, or jit.matrix object that has an instance of the jit.gl.render object associated with it. Additionally it can reference the name of a jit.gl.node sub-context. This value may also be set via the OB3D drawto attribute. If no argument is present, the object is implicitly added to the first valid drawing context or sub-context found in the current patch or by searching up the patcher hierarchy.

Arguments

None.

Attributes

matrixoutput[int]

Output a copy of the frame buffer (OpenGL render context). The output matrix dimensions adapt to the size of the window.

mode[symbol]

Sets the reading mode (default = interleaved). Possible values:

'interleaved' ( Reads an entire frame into each internal buffer, switching buffers every other frame. In interleaved mode, the readback is delayed for one frame. )
'split' ( Reads a single frame in two passes and the output is concurrent. )

out_name[symbol]
read-only

Returns the name of the internal frame buffer (OpenGL render context).

texture[symbol]

Sets the name of the texture to readback. If not set, the readback is performed on the the drawto context.

OB3D Attributes

automatic[int]

Automatic rendering flag (default = 1) When the flag is set, rendering occurs when the associated jit.gl.render object receives a bang message

drawto[symbol]

The named drawing context in which to draw (default = none) A named drawing context is a named instance of a jit.window, jit.pwindow, or jit.matrix object that has an instance of the jit.gl.render object associated with it.

enable[int]

Enable flag (default = 1) When the flag is set, drawing is enabled.

layer[int]

Object layer number (default = 0) When in automatic mode, the layer number determines the rendering order (low to high). Objects in the same layer have no guarantee which will be rendered first.

name[symbol]

The instance name (default = UID)

shader[symbol]

The name of the shader to be applied (default = none)

Common Box Attributes

Below is a list of attributes shared by all objects. If you want to change one of these attributes for an object based on the object box, you need to place the word sendbox in front of the attribute name, or use the object's Inspector.

annotation[symbol]

Sets the text that will be displayed in the Clue window when the user moves the mouse over the object.

background[int]: 0

Adds or removes the object from the patcher's background layer. background 1 adds the object to the background layer, background 0 removes it. Objects in the background layer are shown behind all objects in the default foreground layer.

color[4 floats]

Sets the color for the object box outline.

fontface[int]

Sets the type style used by the object. The options are:

plain
bold
italic
bold italic Possible values:

0 = 'regular'
1 = 'bold'
2 = 'italic'
3 = 'bold italic'

fontname[symbol]

Sets the object's font.

fontsize[float]

Sets the object's font size (in points). Possible values:

'8'
'9'
'10'
'11'
'12'
'13'
'14'
'16'
'18'
'20'
'24'
'30'
'36'
'48'
'64'
'72'

hidden[int]: 0

Toggles whether an object is hidden when the patcher is locked.

hint[symbol]

Sets the text that will be displayed in as a pop-up hint when the user moves the mouse over the object in a locked patcher.

ignoreclick[int]: 0

Toggles whether an object ignores mouse clicks in a locked patcher.

jspainterfile[symbol]

JS Painter File

patching_rect[4 floats]: 0. 0. 100. 0.

Sets the position and size of the object in the patcher window.

position[2 floats]
write-only

Sets the object's x and y position in both patching and presentation modes (if the object belongs to its patcher's presentation), leaving its size unchanged.

presentation[int]: 0

Sets whether an object belongs to the patcher's presentation.

presentation_rect[4 floats]: 0. 0. 0. 0.

Sets the x and y position and width and height of the object in the patcher's presentation, leaving its patching position unchanged.

rect[4 floats]
write-only

Sets the x and y position and width and height of the object in both patching and presentation modes (if the object belongs to its patcher's presentation).

size[2 floats]
write-only

Sets the object's width and height in both patching and presentation modes (if the object belongs to its patcher's presentation), leaving its position unchanged.

textcolor[4 floats]

Sets the color for the object's text in RGBA format.

textjustification[int]

Sets the justification for the object's text. Possible values:

0 = 'left'
1 = 'center'
2 = 'right'

varname[symbol]

Sets the patcher's scripting name, which can be used to address the object by name in pattr, scripting messages to thispatcher, and the js object.

Messages

OB3D Messages

bang

Equivalent to the draw message.

draw

Draws the object in the named drawing destination. If the matrixoutput attribute is supported and set to 1, the geometry matrices are sent out the object's left outlet.

drawraw

Equivalent to draw with the inherit_all attribute set to 1.

drawimmediate

Equivalent to draw but ignoring any potential renderer setup

jit_gl_texture

Binds the texture specified by texture-name to this object. Equivalent to setting the texture attribute to texture-name .

Arguments:
  • texture-name [symbol]

get_shader

Open an editor window containing the object's current JXS shader.

See Also

Name Description
jit.gl.node Create hierarchical rendering groups
jit.gl.pix Generates pixel processing shaders from a gen patcher
jit.gl.slab Process texture data
jit.gl.videoplane Display video in OpenGL
jit.world The Jitter world context