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Projections with Projection Plugin
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Projection allows you to create multi-projector setups. Edge blending, non-linear image mapping, and color correction for each projection are supported. Therefore, Projection can project images onto large curved screen displays covering 360 degrees, if necessary. Moreover, each projection can be fully customized to use a required view frustum.
To launch the application and render projections:
Specify an engine plugin library (lib/Projection_*) together with the rest of required start-up arguments (such as rendering API, window size, etc.). For example:
main_x64.exe -extern_plugin Projection
You can use the 64-bit debug or release version of the library. (The engine automatically loads the appropriate version of the library depending on the specified main application.)
To change the number of displays in a row, specify -width CLI option. For example:
main_x64.exe -extern_plugin Projection -width 2
By default, up to 8 projections are supported to be output from one rendering node.
Setting Up Projections#
To set up projections, open the system menu by pressing Esc, go to the Plugins tab and click the Projection button.
The Projection Configurator window will open. This window makes it possible to:
- Rotate and flip projections.
- Control warping for each projection.
- Set up edge blending and masks for each projection.
- Correct color intensity for each projection.
You should first choose a Projection to be adjusted at the top-right corner.
The Warp tab allows you to set up geometry correction for your projections. Areas where geometry correction is required include:
- Advanced off-axis correction where projector placement is awkward and needs an advanced mapping over the keystone function in a projector
- Non-planar screens such a curved screens and hemispherical domes
- Projecting one image from one projector onto more than one surface
- Unusual projection applications onto custom designed screens
Warping is performed by modifying the displayed grid. The following options are available:
|Projection||Select a projection in the drop-down list to set up its parameters. You can also use Page Up and Page Down buttons to switch between projections.|
|Multiplier||The displacement step in pixels to be used when moving points with arrow keys. Use + to increase the value, or - to decrease it.|
The number of control points along the grid horizontal and vertical axes. A 2 x 2 grid is used by default.
The maximum grid size is 32 x 32.
Visual editor enables you to set up warping for the selected projection using control points and yellow handles. These handles are displayed for each selected control point depending on its type.
You can select control points by clicking the mouse, and also switch between them using arrow keys.
Multi-selection using the mouse is performed as a common selection of multiple objects; to add or remove points from the selected group, click on them holding the Ctrl key. Multi-selection using the keyboard is possible in a chain-like way using arrow keys with the Shift key pressed.
The Ctrl + Z / Ctrl + Y combinations are used for the Undo / Redo actions. Shift + Ctrl + Z cancels all transformations.
Points are always moved in the screen-space coordinates regardless of image orientation (whether it is flipped or not), this means if you press left arrow, the point always goes left.
The grid itself can also be moved inside the view space:
Configure the canvas for the selected projection: set rotation angle and enable vertical and horizontal flipping.
Color and Brightness Correction#
The Color tab allows you to correct color intensity, as well as to adjust color balance for the selected projection.
The Blend tab allows you to configure blending in the selected area and along the edges.
Manages blending in the selected area. The screen-space blend area is not affected by warping.
To select the area, click Add to start creating the blending area, and in the grid, click to define one side of the area, then click to define the other side — the green line will appear. The third click shows the blending direction.
The area of the screen-space blend area is divided into two parts: the part between the blue and green lines is a solid-black area, and the part between the green and red lines is a gradient area.
By default, each of these lines has two points marking the line limits. Using Resolution, you can increase the number of points along each line to adjust it as required by moving the points. Multi-selection of points is available.
Every blend area is adjusted using the following settings:
The Mask tab allows using masks to cut out certain areas of the selected projection.
To create a mask, click Add and ensure that the Creation Mode button is enabled. Then create at least three points on the grid by clicking in the required place. The corresponding area of the projection will be cut out. The list of masks for the current projection is displayed under the grid. You can add new masks and remove existing ones using the corresponding buttons.
To add new points to the mask selected in the list, ensure that the Creation Mode button is enabled. Then you can add new points by clicking within the grid area. To insert a new point into an existing mask, select the point next to which a new point is to be added, and click to insert a new one. You can drag an existing point to move it. To remove a point, right-click it.
You can also adjust your masks precisely by specifying the coordinates of each point. Select a point on the grid (its color will turn to green) and enter the coordinates in the Position fields below.
You can change the type of a selected control point using the following icons:
- — automatic linear interpolation (no control handles available)
- — symmetric control handles for smooth curves
- — asymmetric control handles (you can control each handle independently)
- — automatic smooth curve (no control handles available)
As you select a mask in the list, its parameters are displayed on the panel next to it:
The Render block of settings is located at the bottom of the Projection Configurator window. These settings are designed to facilitate fine-tuning of the projection by displaying the auxiliary elements on the actual projection.
- The Debug Color option allows you to temporarily set individual colors for different projections. This helps to visualize overlapping regions.
- Show Grid — display the grid on the projection.
- Warp Points — display points and auxiliary red lines going from a selected point or points to the center of each side.
- Blend Lines — display screen-space blend lines and auxiliary purple lines going from a selected point or points to the center of each side.
Multiple Projections' Viewing Settings#
If more than two projections are created with Projection, the following viewing settings can be tweaked in the System menu -> Plugins.
The field of view for all projections (in this case, the Camera's Field of View option is not applicable).
FOV = 60
FOV = 80
Allows adjusting the viewing angle between projections: when projection surfaces are turned at some angle to each other, this angle can be entered as the Angle value and the projection is automatically recalculated to show the right image.
For example, if two surfaces are turned to each other at 40 degrees:
Angle = 40 degrees
|Bezel X||Compensates for the horizontal bezel of monitors. Positive values decrease the viewport space; negative ones increase it (for overlapping).|
|Bezel Y||Compensates for the vertical bezel of monitors. Positive values decrease the viewport space; negative ones increase it (for overlapping).|
Saving and Loading Presets#
After the projection configuration is set up, it can be saved to a preset file (*.proj) to be loaded at any time (e.g. to set up another projection):
- Save button to save a preset file
- Load button to load a preset file
- A *.proj file that you save contains settings only for the currently selected projection.
- Settings loaded from a *.proj file are applied to the currently selected projection.
Projection can be customized to support custom viewing frustums (symmetric or asymmetric ones) for each projection.
Projection has one primary viewport, while all other viewports are rendered as auxiliary ones. By default, the primary display is the UNIGINE engine viewport used for one-monitor configuration. It uses matrices of the Player used by the engine to view the scene. Other displays are arbitrary cameras with any perspective and facing whatever direction needed. Each display has its own model-view and projection matrices. Both the primary projection and auxiliary ones can be enabled or disabled, if necessary.
- The primary viewport can be set to any projection (for supported configurations it is already set).
- Each viewport has its own model-view and projection matrices.
- By default, only a primary one has a graphical user interface (render system GUI, editor widgets, wireframe, or the profiler). However, separate GUIs can be drawn on all projections.
- All viewports have their own Viewport and Reflection mask to selectively render nodes and reflections from them.
For default configurations, the primary viewport is set to the following projection:
- For 2 projections, the 1st viewport.
- For 3 projections, the 2nd viewport.
- For 4 projections, the 2nd viewport.
- For 5 projections, the 3rd viewport.
How to Customize Projections#
Rendering of Projection viewports is controlled by the wall.h script (found in the <UnigineSDK>/data/core/scripts/system/ folder). There are two possible setups depending on how the primary projection is rendered. It can be drawn by:
- The default engine renderer (the same as when a usual one-monitor application is rendered)
- The Projection renderer itself (which is safer if you are going to use asymmetric frustum for the center projection and modify its model-view matrix)
The following example demonstrates how to tweak cameras configuration and choose the renderer for the main projection.
1. Using default engine renderer#
The first variant is to render the main (primary) projection by the default engine renderer.
In case the created configuration is not already supported, set the primary projection via Unigine::Plugins::Projection::setPrimary():
// Set the first projection as a primary one Unigine::Plugins::Projection::get()->setPrimary(1);
Enable all non-primary projections via Unigine::Plugins::Projection::SetEnabled(). The main one should be left disabled, as it is drawn by the default engine renderer.
// Enable the 2nd projection in a row // The second argument of the function sets 'enabled' flag Unigine::Plugins::Projection::get()->setEnabled(1, 1);
// Settings for the 2nd projection CameraPtr camera1 = Projection::get()->getCamera(1, 0); camera1->setProjection(projection_1); camera1->setModelview(modelview_1);
2. Using Projection renderer#
Another variant is to render the main projection by the Projection renderer. This variant can be used, for example, if you want to set up symmetric frustums for all projections.
Set the projection to be used as a primary one and enable its rendering by Projection.
// Set the first projection as a primary one Unigine::Plugins::Projection::get()->setPrimary(1);
Disable rendering into the default UNIGINE viewport via Unigine::Render::setEnabled():
Enable all Projection projections including the primary one. As a result, all viewports will be rendered by Projection renderer itself:
// Enable all projections Unigine::Plugins::Projection::get()->setEnabled(0, 1); Unigine::Plugins::Projection::get()->setEnabled(1, 1);
Set model-view and projection matrices for all projections.
// Settings for the 1st projection CameraPtr camera0 = Projection::get()->getCamera(0, 0); camera0->setProjection(projection_0); camera0->setModelview(modelview_0); // Settings for the 2nd projection CameraPtr camera1 = Projection::get()->getCamera(1, 0); camera1->setProjection(projection_1); camera1->setModelview(modelview_1);