OffscreenRenderer

MLModule

genre	Visualization
status	stable
author	Felix Ritter
package	MeVisLab/Standard
dll	MLOffscreenRender
definition	MLOffscreenRenderer.def
see also	SoFramebufferRenderer, SoFramebufferTexture
keywords	Inventor, offscreen, rendering, fast, image

Purpose

The module OffscreenRenderer renders an Open Inventor scene to an ML image.

In contrast to the Viewer modules (e.g. SoExaminerViewer), the render area is not visible and may be much larger than the physical screen space (e.g. 3000x3000 pixel depending on the graphics card capabilities).

Usage

Just like any other OpenGL renderer the OffscreenRender module requires a virtual camera and at least one light source in the scene.

Have a look at the example network.

Details

Internally, the OffscreenRender uses OpenGL p-buffers to render the scene.

It is therefore quite fast, but the transfer of the frame buffer's content to the ML image highly depends on the OpenGL implementation, which may be quite slow for large images.

Windows

Default Panel

Input Fields

sceneGraph

name: sceneGraph, type: SoNode

Output Fields

output0

name: output0, type: Image

Parameter Fields

Field Index

Background Color: Color

Buffer Type: Enum

Size: Vector2

Supported: Bool

Transparency: Enum

Type: Enum

Update: Trigger

Use stencil: Bool

Visible Fields

Transparency

name: transparencyType, type: Enum, default: BLEND

Defines the transparency to be used during rendering the scene graph.

Values:

Title	Name
Screen Door	SCREEN_DOOR
Add	ADD
Delayed Add	DELAYED_ADD
Sorted Object Add	SORTED_OBJECT_ADD
Blend	BLEND
Delayed Blend	DELAYED_BLEND
Sorted Object Blend	SORTED_OBJECT_BLEND

Type

name: imageType, type: Enum, default: RGB

Defines the type of ML output image (the C-dimension).

A change to this parameter will result in a new OpenGL p-buffer.

Values:

Title	Name
Rgb	RGB
Rgba	RGBA
Rgba Float	RGBA_FLOAT

Buffer Type

name: bufferType, type: Enum, default: AUTO

Defines the used buffer type.

Values:

Title	Name
Auto	AUTO
Pixel Buffer	PIXEL_BUFFER

Supported

name: supported, type: Bool, default: TRUE

Shows whether the hardware supports p-buffers.

Use stencil

name: stencilBuffer, type: Bool, default: FALSE

If checked, the offscreen renderer uses a p-buffer with a stencil buffer.

This is needed for e.g. SoSilhouette.

Size

name: size, type: Vector2, default: 64 64

Sets the size of the offscreen render area.

Background Color

name: bgColor, type: Color, default: 0 0 0

Sets the background color that is used to clear the frame buffer before rendering.

Update

name: update, type: Trigger

If pressed, the connected OpenInventor scene is rendered anew into the p-buffer and its content is written to the ML output image.