What is it?

RTRE is a Real Time Rendering Engine. The plug-in was developed by cubicspace. The new plug-in is version 2.1 about to be released by Turbo Squid http://www.turbosquid.com/FullPreview/index.cfm/ID/314042 and there will be a Trial available for the new version which has masses of new features around much better performance and support of almost every max material. The plug-in works with 3d Studio Max a 3-dimensional rendering and animation program. It is used to create executable files of a particular building model. The main benefit of an executable file is that it can be distributed easily and run without installing viewer software. This is highly beneficial when working with multiple parties.

Basics Walkthrough

Before you start

Be aware that there is a new version, called RTRE v2.0 available now, and that SP1 is expected in January 2009. These new versions support up to 3ds max 2009-32bit. 1.1 of rtre is only compatible with version 7 of 3d studio max. Max 9 does not seem to be capable of exporting to older file formats, so if you plan to visualize a model with rtre, be sure to not accidentally edit it with a new version of 3d studio. Version 2.0 has now been released, but even though it lacks support directly for radiosity lighting, you can render your lighting as a texture (RTT - Render-to-Texture) using Mental Ray which is built-into 3ds max and that way get stunning lighting solutions. Alternatively, if you have no lightign set-up, RTRE will provide a general lightign solution - which is like an envionment map - good enough to see how you unlit scene looks before spending the time of a proper lighting solution.

Step one: Create the model

This can be done directly in 3d studio, if you know how to use it. You can also use any 3d software with a file format that 3d studio can import, including DWG and DXF. Because 3ds max 7 is somewhat outdated, it can not read the AutoCAD 2007 DWG format. You will need to export it as a 2004 file before importing to 3d studio max. Once it is imported, go to Utilities Panel > rtre Controls, and click Add All. This will add the objects to the rtre view, which can be accessed either by clicking the View button on the same panel, or by right clicking the top left corner of a viewport and selecting Views > Extended > rtre 3D View

While you are working on your model, try to avoid having surfaces partially obscured by other objects. If an object changes from lit to unlit over a very small distance, the lighting will often show it as a partially lit transition, depending on the size of your radiosity meshing (explained in the lighting section). As an example, take two rooms separated by a wall. If a single plane is used for the ceiling, it will be dark where it is on top of the wall, and bright where light falls on it in the rooms. On the boundary between these two there will be several inches of partially lit ceiling. This can be avoided by cutting out the part of the ceiling that is on top of the wall.

If you haven't used 3d studio before, an important thing to be aware of is that surfaces are generally one sided. If you can see a face from one side, it will not be visible from the other. This makes life easier for editing models of rooms, because you can see through the walls from the outside in your perspective viewport. Your model likely has walls represented by boxes with thickness and faces on both sides, but the exterior layer of outside walls is no longer necessary. To delete them, select an object, and go to the Modify Panel. Select Editable Mesh, and click the red square in the Selection rollout. This will let you select individual faces of an object. Drag select or hold control and click each face to select them, then press delete to remove the faces. This is not a necessary face, but it makes the perspective viewport much easier to work with.


Step two: Add materials

Materials in 3d studio are found in the Materials Library, under the Rendering menu. This can also be accessed by pressing the M key.

Rtre supports only four types of materials: Blend, Lightscape, Multi/Sub Object, and Standard. The settings that rtre uses can be found under the Shader Basic Parameters, Blinn Basic Parameters, and Maps rollouts.


Blinn Basic Parameters
Use the diffuse color to control the color of the material. If it has a texture (diffuse map) rtre will tint the image with this color. If you want the material to be textured with the exact color of the image, set diffuse to gray with a value of 150.
Rtre also supports self illumination and opacity. Specular highlights are not used, but can be recreated using environment reflection maps.

Maps Rollout
Rtre can use maps for Diffuse Color, Reflection, and Opacity (alpha channel only). If a bitmap is used in the Opacity component, the same map must be used for Diffuse Color. Note rtre is not capable of bump mapping. Also, rtre ignores the map checkboxes, so you will need to remove a map from the slot to disable it.
For best performance, maps should have dimensions that are powers of two (i.e. 2, 4, 8, 16...)

Step three: Apply Lighting

The best method for applying lighting is to use radiosity, through 3d studio's advanced lighting system. Please see the new documentation and help file for lighting information, andnote you shoudl read up on Render-to-Texture approaches.

To create lights, select the create panel on the right side of the screen and click the picture of a spotlight. You can use either standard or photometric lights. If you are using light distribution webs, they can be attached under Modify Panel > Intensity/Color/Distribution rollout. Set distribution to Web, and pick a web file in the Modify Panel > Web Parameters rollout. If the rollout is not visible, right click and select it from the menu to enable it.

Now you need to subdivide your objects. This divides the surfaces into smaller facets and allows rtre to display much higher quality radiosity. Generally you would do this using the radiosity meshing parameters in advanced lighting settings, but rtre does not appear to respect this setting, so it's necessary to use the subdivide modifier instead. Select all of the objects in your model to be subdivided (Leave out the lights and other non-physical objects. Press H for the Select Objects window if you're having trouble getting the selection correct in the viewport.) Then go to the Modify Panel and pick Subdivide from the dropdown menu. Setting a small size will look more accurate, but will have slower performance, so larger subdivisions may be required for complicated models. Try starting with something between 3 and 6 inches.


Once this is done, it's time to set up radiosity. Radiosity controls are found under Rendering menu > Advanced Lighting > Radiosity. 80% is a good setting for initial quality, but for a final lighting solution, something closer to 95% is a better choice. Higher accuracy will take exponentially longer. If your radiosity comes out splotchy, try again with an increased filtering value.

[new wording in RTREv2.1 docs]

Step four: Finishing touches

Now that the model is in rtre, there are a few more small things to add to the quality of the final product. One of these is collision helpers, which are used to prevent walking though objects. Putting them on walls, floors, and ceilings makes the model feel much more real. They can also be used on less important objects like furniture, but be careful not to have objects with collisions everywhere, or the model may become difficult to navigate.

The procedure for adding collision helpers is fairly simple. First click on the Helpers button on the Create Panel, and select Cubicspace rtre from the dropdown menu. Click on Collision, then click and drag anywhere in the scene to create the helper. It doesn't matter where you put it, but placing collisions near the objects they're attached to makes them easier to keep track of. Select your new helper, and go to the Modify Panel. You should see the parameters rollout with a single button. Click the button, then select the object you're applying the collision to. Repeat this with all of your collision helpers.


Another important helper is the StartPoint. These are person sized objects used to define a point of view, and can be used either as the initial camera view when opening an rtre scene, or as other views accessed by buttons on a custom interface. They can be placed from the same panel as the Collision helper. The setting for what StartPoint rtre begins a scene at is under rtre Controls > Display rollout.

Step 5: Publishing

One of rtre's greatest strengths is the ability to publish a scene into an executable file that can be distributed and viewed without requiring the installation of a viewer program. This is done through the rtre Publisher rollout, in the Utilities Panel.

Scenes can be published with custom skins, or graphical interfaces overlaid on them. The appearance of a skin is defined by four images: Up, down, over, and gray. The up skin shows all buttons with their default appearance. Down shows them as they appear while being clicked. The hover image defines how the look when the cursor is over them. Gray is the appearance of buttons that are disabled.

The location of each button is defined by a "hit map," which is a mostly black image with the area of the button shown in white. When the mouse is over the white area, rtre will replace that portion of the up image with the same part of the over image. When it is clicked, the region is replaced with part of the down image.

All images used in a skin must have the same resolution. rtre supports the following file formats for skin imatges:
  • DDS
  • BMP
  • PNG
  • JPG
  • TGA

Buttons can be attached to many actions, but the most notable are Jump To, Info Screen, and Full Screen. Jump To moves the view to a StartPoint helper or 3d studio camera. Info Screen displays a picture over the rtre scene, and is useful for including instructions for rtre's unusual movement controls.

If you decide not to use any of these actions, there is no need for the down, hover, or gray skin images. An up image may still be desired to add a title, name, or copyright notice.

Movement Controls

The up and down arrow keys move the camera forward and backward. The left and right keys turn the camera to the left and right, but take some practice because the camera slows down gradually instead of stopping when you release the key. Delete and end are used to sidestep. Page up and page down move the camera vertically.

Holding down the right mouse button and dragging also turns the camera, and is easier to control than the arrow keys. Holding shift increases movement speed, and control decreases it. The three speeds are set in the rtre publisher settings, and may vary between scenes.

New navigation includes Fly and Orbit, accessible from the right-click menu.