Commit d5d47a3c authored by Florian Hölzl's avatar Florian Hölzl
Browse files

help for advanced operator panels

refs 907
parent 0a377a2f
......@@ -91,6 +91,74 @@ In the <B>number of vertical grids</B> field you specify how many grid fields sh
<h4><font color="#336699">3D Object Viewer</font></h4>
The 3D Object Viewer output item allows to render simple 3D scenes with imported meshes and translations, rotations, and scalings computed from input port values.<BR>
The 3D Viewer comes with its own editor, which you can access by double-clicking the item in the operator panel editor or the model navigator.<BR>
The following picture is showing the example scene during the simulation:
<img src ="./pictures/opa-scene-viewer-sim.png">
The scene shows the following objects from the <I>Camera1</I> perspective:
<LI>a yellow sphere in the the center</LI>
<LI>a blue sphere, which circles the yellow one in the X-Y-plane</LI>
<LI>four white cubes, which are added as references for the X-Y-plane</LI>
<LI>another white cube, which shows the location of the light source</LI>
<LI>a hint to hit the <I>TAB</I> key to cycle through the cameras</LI>
The scene contains two cameras: the static <I>Camera1</I> (looking at the origin from a small distance along the positive Y axis) and the moving <I>Camera2</I> (looking a the origin from a small distance along the X axis and pitching from -20 to 20 degree below and above the X-Y-plane).<BR>
The whole animation is driven by a counter component, which counts from zero to 360 and back to zero.<BR>
From this input value all object positions are derived using rotation object nodes (see below).
The following picture shows the scene editor of the example.
<img src ="./pictures/opa-scene-viewer-editor.png">
You can drag objects and display nodes from the library view to scene editor tree.<BR>
<img src ="./pictures/opa-scene-viewer-lib.png">
Note that you have to drop <I>Cubes</I> and <I>Spheres</I> onto the <I>3D Viewer</I> tree entry, not the loaded objects entry.<BR>
You can replace the cube or sphere objects with arbitrary meshes from 3D modeling tools (like Blender) as described below.<BR>
<h5><font color="#336699">World Coordinates</font></h5>
The whole scene uses a world coordinate system with the positive Z axis being the upward direction of cameras.<BR>
In other words the X-Y-plane is the surface of the scene world.<BR>
Camera perspective is fixed to a 45 degree field of view with the near distance set to 0.5 and the far distance set to 400.0.<BR>
<h5><font color="#336699">Cameras and Lights</font></h5>
Each scene needs a least one camera, which means that the scene graph must contain at least one <I>Camera Node</I>.<BR>
Cameras are defined by specifying an eye position and a look target location, which may not be the same (i.e. they define a vector).<BR>
If you want the camera to be translated and/or rotated, you should set either the eye or the target location to the origin and the other one unit away in either X or Y direction.<BR>
See <I>Camera0</I> in the example for moving camera with fixed target location.
<img src ="./pictures/opa-scene-viewer-camera-prop.png">
The scene viewer can be used with or without using the OpenGL light engine.<BR>
You can switch the use of light using the property section of the <I>3D Viewer</I> tree item.<BR>
There you can also set the ambient light intensity when the light is turned on.<BR>
If the light is turned off, the ambient component of the material of loaded objects will be used as color (see next section).<BR>
A light source can be specified by adding a <I>Light Node</I> to the scene graph. There is a maximum of <B>8 lights</B> currently supported.<BR>
With the property section you can specify the properties of the light source, in particular, its ambient, diffuse, and specular intensities/colors as well as the attenuation coefficients.<BR>
<img src ="./pictures/opa-scene-viewer-light-prop.png">
Note that lights can also be positioned in the scene by using transformations (see below).<BR>
<h5><font color="#336699">Objects and Materials</font></h5>
<h5><font color="#336699">Transformations: Translation, Rotation, and Scaling</font></h5>
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