Maxwell Fire provides interactive rendering within the SketchUp user-interface. Its functionality is contained in the Maxwell Fire window:

This window may be opened or closed using the Maxwell Fire menu item or toolbar button:

The implementation of Maxwell Fire in the plugin serves two main purposes, depending on the plugin version in question:

In the Standalone plugin (SA)

Maxwell Fire is both used for scene setup, and for rendering of final images. When the Standalone plugin is licensed, you can choose whether Maxwell Fire uses its Draft or Production render engine. Actual output resolution and the render engine used are set in the Maxwell Fire Settings window. Finished images are saved using the Save Image button in the Maxwell Fire window toolbar.

In the Render Suite plugin (RS)

While Maxwell Fire can be used to render final images, its primary purpose is to provide real-time feedback during scene setup. It is assumed that an MXS file will subsequently be written, and rendered in Maxwell Render.

Overview

The operation of Maxwell Fire in the plugin has been kept as simple as possible. To use Maxwell Fire, simply use the toolbar or menu to open the Maxwell Fire window:

By default, the scene will immediately be transferred to Maxwell Fire and its rendering begun, so the links shown above may only be visible for a short time. To access them at any time, use the small “left arrow” button near the top right of the window. This automatic starting of Maxwell Fire may be disabled using the Start Maxwell Fire option. The panel at the top of the window contains several different buttons, some appearing only in specific plugin builds. When Maxwell Fire is active and rendering, it appears like this:

In the main group, at center, there are five buttons:

Button	Function
Stop & Go	When Maxwell Fire is disabled, this button is yellow, and reads Fire. Clicking it in this state will perform an export if necessary, and begin rendering the scene in Maxwell Fire. If, on the other hand, Maxwell Fire is currently rendering, this button is red, and reads Stop. Clicking it in this state will disable Maxwell Fire. To completely unload Maxwell Fire and its data from memory, close the Maxwell Fire window.
Lock	Usually, it is desirable to have Maxwell Fire updated whenever something changes in the scene. However, when a final image is being rendered, it is desirable that inadvertent actions, for example, scrolling in the SketchUp viewport, be ignored, so that the rendering is not interrupted. This may be done by enabling the Lock button; when the rendering is locked, you can even proceed with working on the model, though it is important to understand that when rendering is subsequently unlocked, all changes made in the interim will be pushed into the scene, and rendering will be begun again.
Re-export Scene	This button is only shown after the scene has initially been exported. Clicking it will cause the data currently in memory to be released, and a new export will be performed. It is necessary to do this when objects have been moved, material assignments changed, or UV coordinates modified.
Save Image	This button is used to save the current image to disk. It is only shown when an image exists. Maxwell Fire supports saving images in 8-bit RGB formats only. The format written is determined by the file extension specified, which can be any one of the following: .bmp .tga\|.targa .jpg\|.jpeg .png .tif\|.tiff .jp2 .ppm .pbm .pgm If no extension is specified, the image will be saved as .png.
Engine Settings	Shows the Engine Settings window, which is used to control various Maxwell Fire settings.

Additionally, another group of smaller buttons appears near the top right of the window. Their functions are as follows:

Button	Function
Actual Size/Fit to Window	This button toggles the Maxwell Fire image display between showing the rendered image at its actual size, and fitting it to the current size of the display area of the window.
Maxwell Links	This shows and hides the Maxwell Links panel, which contains useful shortcuts to information on using the plugin (i.e. help, tutorials, etc).
HUD	This button toggles the visibility of the Maxwell Fire window’s upper and lower heads up display panels.

As mentioned above, toggling the Fire button at top-left causes the model to be exported from SketchUp into the Maxwell format. Once this process is complete, rendering will begin. Rendering progress and status messages are shown in the progress bar at the bottom of the window; if errors are encountered, a button will be shown to the right of the progress bar:

In this case, the error was caused deliberately by changing the Environment type to None, when there were no emitters in the scene. Clicking the error report button, we see what the render engine is reporting:

The engine will resume rendering once the error is corrected, though in some cases, it may be necessary to re-export the data. To do this, click the Re-export Scene button.

Maxwell Fire Settings

Clicking the Settings (gear) button pops up the Settings window:

These settings roughly correspond to the similar settings found in Maxwell Render:

Parameter	Unlicensed	Licensed	Function
SL			Sets the sampling level at which rendering will be stopped.
Threads			Sets the number of threads which will be used by the render engine, where zero means auto-detect.
Max. Res.	800x800	1920x1080	Sets the actual size of the largest dimension of the rendered image. The aspect ratio of the output is determined by the aspect ratio of the Output Resolution of the currently-rendering camera.
Extensions			Globally enables & disables render-time effects such as Maxwell Grass, Sea, and Volumetric.
Engine			Allows you to specify whether rendering be done using Maxwell Render's Draft or Production render engine. While both engines are entirely unbiased, and will eventually converge to produce the same image, they use very different calculation strategies, which are suited to very different purposes.

Render Engines

The Engine setting is only available in licensed installations; unlicensed installations are restricted to using the Draft engine.

Engine	Description
Draft	This is the default engine used by Maxwell Fire. It gives a basic idea of the final image as soon as possible, and also updates very frequently, in order to provide responsive real-time feedback.
Production	While the Draft engine is very good for real-time work, it will not, in fact, render a finished image faster than the Production engine, in many cases. This is especially true in situations which involve more complex light interactions: caustics and indirect lighting, heavy depth-of-field, etc.

Interactivity

Not all types of changes can be handled in real time; currently, there are two different classes of scene alteration:

Class	Description
Physical	This class includes changes to geometry (topology or location), assignment of materials, alteration of UV coordinates, etc.
Conceptual	This class includes changes to materials, cameras, environment, output settings, and so on.

Conceptual changes are accomplished in real time, and therefore, do not require the model to be re-transferred. Physical changes do. So, for example, changing the color of a material, the position or exposure of a camera, or the time of day are all things which will be reflected in real time in Maxwell Fire. Painting a face with a new material, or moving/deleting a component, on the other hand, are not handled in real time, and require that the scene be re-exported.

MXS Files & Memory (RS)

Whenever the Maxwell Fire window is opened, and the model has been exported, the MXS-writing functions of the plugin will behave slightly differently than normal; rather than performing a full model export, they will use the data currently held in the Maxwell Fire scene. This data will also remain in memory for as long as the Maxwell Fire window is opened, or until a different model is opened in SketchUp.

This is done both in the interest of saving time (it takes much less time to write an MXS file from existing data than it does to transfer the entire SketchUp model), and to ensure that what you see in the Maxwell Fire window is what you will see in your MXS file. If you wish to perform a full export, or to free the memory currently being used by Maxwell Fire, simply close the Maxwell Fire window.

The determination of whether to use cached data, or to perform a full export, is made using the MXS Cache Policy option.

Note that extensions such as Maxwell Grass, Sea, and Volumetric can consume a great deal of memory, depending on how they are set up.

General Notes

Following are some things to keep in mind when using Maxwell Fire.

2-Point Perspective

SketchUp's 2-Point Perspective camera mode is not supported in Maxwell Fire, due to SketchUp API limitations. However, this is not likely much of an issue, since Maxwell Fire allows you to pre-visualize the effects of Maxwell's own Shift Lens feature.

Using Threads

It is worth noting that there are actually two instances of Maxwell Fire used in the plugin: one for rendering models, and one for rendering material previews. Since they can both be active at the same time, it will be necessary to set the Threads parameters for each (Maxwell Fire, material preview) in order to achieve your desired performance. If you are on a single- or dual-core machine, it may be desirable to disable automatic preview refresh.

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